Marine natural products

Contents

• 1 Introduction

• 2 Marine microorganisms and phytoplankton

• 3 Green algae

• 4 Brown algae

• 5 Red algae

• 6 Sponges

• 7 Coelenterates

• 8 Bryozoans

• 9 Molluscs

• 10 Tunicates (ascidians)

• 11 Echinoderms

• 12 Miscellaneous

• References

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Abstract

This review covers the marine natural products literature for the year 2000 and is organized phylogenetically, with sections on marine microorganisms and phytoplankton, green algae, brown algae, red algae, sponges, coelenterates, bryozoans, molluscs, tunicates, echinoderms and miscellaneous marine organisms. There is an emphasis on new structures, stressing their biological activities, source organisms and countries of origin, and also syntheses that confirm the structures of known compounds. The review contains 869 structures and 592 references, of which 434 appeared between January and December 2000.

Covering: 2000. Previous review: 2001, 18, 1.

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1 Introduction

This report is a review of the marine natural products literature for 2000. Earlier reports published in this journal cover the period from 1977 to December 1999. After many years of steady expansion in marine natural products chemistry, the number of papers published in 2000 has declined slightly when compared with 1999.¹ Sponges were again the most studied of the marine organisms, closely followed by tunicates and coelenterates. The most significant increase is in the number of papers reporting studies of marine microorganisms. It is hard to say whether this is driven by advances in marine biotechnology or by the increasing difficulty of obtaining permits to collect marine invertebrates. There is currently a great interest, aided by advances in molecular genetics, in the possible production of bioactive compounds from marine invertebrates by associated microorganisms.² Studies of the biosynthesis of marine natural products, which also bear the mark of the latest genetic techniques, are reviewed elsewhere in this journal.³ Marine natural products continue to be prime targets for synthesis although papers reporting partial and formal syntheses, which are not included in this review, outnumber the papers that record total syntheses and synthetic studies that redefine the structures of marine natural products. This report continues to emphasize the bioactivity of new marine natural products while specifically excluding biochemical and pharmacological studies of known marine natural products. The patent literature is not covered in this report. The format for this review is identical to its predecessor.

A number of reviews of specific topics appeared during 2000. The major work entitled Comprehensive Natural Products Chemistry contained an extensive review of “Marine natural products and marine chemical ecology”.⁴ A book entitled Drugs from the Sea consisted of a number of timely reviews running the whole gamut of marine drug discovery: “Marine microorganisms and drug discovery: current status and future potential”,⁵ “Microalgae as a drug source”,⁶ “Search for biologically active substances from marine sponges”,⁷ “Cytotoxic substances from opisthobranch mollusks”,⁸ “ω-Conotoxin MVIIA: from marine snail venom to analgesic drug”,⁹ “KRN7000 as a new type of antitumor and immunostimulatory drug”,¹⁰ “Zoanthamines, antiosteoporotic alkaloids”,¹¹ “Symbiotic bacteria in sponges: sources of bioactive substances”,¹² “Aquacultural production of bryostatin 1 and ecteinascidin 743”,¹³ and “The halichondrins: chemistry, biology, supply and delivery”.¹⁴ Marine natural products are featured extensively in a review of “Naturally occurring isocyano/isothiocyanato and related compounds”.¹⁵ There have been several reviews of individual marine natural products especially those that are either in or approaching clinical trials: these include didemnin B, aplidine and ecteinascidin 743, which are reviewed in “Antitumor compounds from tunicates”,¹⁶ “The chemistry and biology of discodermolide”,¹⁷ “Chemistry and clinical biology of the bryostatins”,¹⁸ “The guanidine metabolites of Ptilocaulis spiculifer and related compounds; isolation and synthesis”,¹⁹ “Chemical constituents and their biological activities of the sponge family Aplysinellidae: A review”,²⁰ “Marine polyether triterpenes”,²¹ and “The structure elucidation and biological activity of high molecular weight algal toxins: maitotoxin, prymnesins and zooxanthellatoxins”.²² In addition to the reviews listed above, an alarming number of possibly relevant reviews have been published in books and journals that were not readily available to this author: these references may be found by searching databases such as CAS Online or MarinLit.

2 Marine microorganisms and phytoplankton

As part of an overall increase in interest in cultured marine organisms, the upswing in studies of marine fungi was particularly noticeable. Interest in marine bacteria was maintained at a significant but relatively constant level. A seawater culture of a new Microbacterium sp. isolated from the Adriatic sponge Halichondria panicea contained four cell-associated glycoglycerolipids 1–4 and a diphosphatidylglycerol 5.²³ A complex mixture of gentiobosyl diglycerides was isolated from Bacillus pumilis that was associated with the ascidian Halocynthia aurantium.²⁴ The structures of flavochristamides A 6 and B 7, which are sulfonolipids from a marine Flavobacterium sp.,²⁵ were confirmed by total synthesis.²⁶ The 4-amino-3-hydroxybenzoic acid derivatives, B-5354a 8, b 9 and c 10 are inhibitors of sphingosine kinase that were isolated from a Ruegeria sp. (SANK 71896) that was isolated from seawater.²⁷ Lornemides A 11 and B 12 are mildly antimicrobial aromatic amides from a marine actinomycete isolated from beach sand in Southern Australia.²⁸ Four new butenolides consisting of 4,10-dihydroxy-10-methyldodec-2-en-1,4-olide 13, two diastereoisomeric 4,11-dihydroxy-10-methyldodec-2-en-1,4-olides 14 and 15, and 4-hydroxy-10-methyl-11-oxododec-2-en-1,4-olide 16 were isolated from marine Streptomyces strains B 5632 and B 3497, both of which were isolated from marine sediments.²⁹ The antibacterial activity of a Bacillus sp. (Sc026) from a marine sediment was shown to be due to the known compound macrolactin F and the new compounds 7-O-succinylmacrolactin F 17 and 7-O-succinylmacrolactin A 18.³⁰ IB-96212 19, the stereochemistry of which remains undetermined, is a cytotoxic macrolide from a marine species of Micromonospora.³¹ An unidentified marine actinomycete (strain # CNH-099) from a sediment obtained near San Diego contained the cytotoxins neomarinone 20, isomarinone 21, hydroxydebromomarinone 22 and methoxydebromomarinone 23.³²N-Acetyl-γ-hydroxyvaline lactone 24, obtained from a streptomycete isolated from a marine sediment from Brazil, belongs to a class of compounds implicated in quorum sensing.³³ The absolute and relative stereochemistry of korormicin 25, which is a metabolite of Pseudoalteromonas sp. F-420,³⁴ has been deduced by the synthesis of four possible diastereoisomers.³⁵

A Pseudomonas or Alteromonas sp. (DF-1), isolated from a Black Sea specimen of the sponge Dysidea fragilis, produced the tripeptide 26.³⁶ A culture of Pseudoalteromonas luteoviolacea isolated from the surface of the Hawaiian alga Padina australis produced the diketopiperazine cyclo(L-phenylalanyl-4R-hydroxy-L-proline) 27, which stimulated antibiotic production in this strain, and 2,4-dibromo-6-chlorophenol 28, which showed activity against methicillin-resistant Staphylococcus aureus and Burkholderia cepacia.³⁷ The stereochemistry of thiocoraline 29, which is a potent antitumor antibiotic from Micromonospora sp. L-13-ACM2–092,³⁸ has been determined by total synthesis.³⁹ Two new cytotoxic staurosporine derivatives, 4′-N-methyl-5′-hydroxystaurosporine 30 and 5′-hydroxystaurosporine 31, were obtained from a marine Micromonospora sp. (strain # L-31-CLCO-02) isolated from a homogenate of the sponge Clathrina coriacea from the Canary Islands.⁴⁰

Marine derived fungi have become a dominant source of new marine metabolites. Coruscol A 32 is a relatively simple 1,3-dioxane from a Penicillium sp. cultured from the bivalve mollusc Mytilus coruscus from Okinawa.⁴¹ An unidentified fungal strain (I96S215), which was obtained from a tissue sample of an unidentified marine sponge collected in Indonesia, produced iso-cladospolide B 33 and seco-patulolide 34, together with the macrolides pandangolides 1 35 and 2 36.⁴² Spiciferol A 37 and butoxyl-spiciferin 38 were obtained from an isolate of Drechslera hawaiiensis obtained from an Indonesian sponge, Callyspongia aerizusa.⁴³ (+)-Macrosphelide E 39, which is a metabolite of Periconia byssoides isolated from the gastrointestinal tract of the sea hare Aplysia kurodai,⁴⁴ has been synthesized in high yield by using a chemoenzymatic reaction as a key step in the synthesis.⁴⁵ A salt-water culture of Aspergillus niger (culture # 94–1212) obtained from the sponge Hyrtios proteus from the Dry Tortugas National Park, Florida, contained asperic acid 40 and several known metabolites.⁴⁶ Tanzawaic acids E 41 and F 42 are additional members of that series that were isolated, together with 3,7-dimethyl-1,8-dihydroxy-6-methoxyisochroman 43, from a culture of Penicillium steckii obtained from an unidentified tunicate.⁴⁷ An undescribed Microsphaeropsis sp. from the Mediterranean sponge Aplysina aerophoba contained the tyrosine kinase inhibitors 10-hydroxy-18-methoxybetaenone 44, 10-hydroxy-18-[N-(2-naphthyl)-N-phenylamino]betaenone 45, and three 1,3,6,8-tetrahydroxyanthraquinones 46–48.⁴⁸ Paecilospirone 49, which is an inhibitor of microtubule assembly, was among the metabolites isolated from a Paecilomyces sp. obtained from a coral reef at Yap, Micronesia.^49,50 Phomopsidin 50 was obtained from a Phomopsis sp. cultured from a fallen mangrove branch from Pohnpei, Micronesia.⁵⁰ A Penicillium sp. from the Okinawan bivalve Mytilus coruscus contained sculezonones A 51 and B 52.⁵¹ A new trichothecene, verrol 4-acetate 53 was obtained from the deuteromycete Acremonium neocaledoniae, which was isolated from driftwood in New Caledonia.⁵² Synthetic studies of trichodenones A–C, which are cytotoxic metabolites of a strain of Trichoderma harzianum OUPS-N115 isolated from the sponge Halichondria okadai,⁵³ revealed that trichodenone A 54 was a scalemic mixture in which the (R)-enantiomer predominated and established the absolute configurations of trichodenones B 55 and C 56.⁵⁴ The absolute stereochemistry of harzialactone A 57, which was also isolated from the same strain of T. harzianum,⁵³ was determined by total synthesis from D-glucose.⁵⁵ The absolute stereostructure of gymnastatin A 58, which is a cytotoxic metabolite of Gymnasella dankialiensis,^56,57 has been confirmed by total synthesis.⁵⁸

A specimen of Aspergillus niger that was cultured from a tissue homogenate of an orange Aplidium sp. tunicate produced the meroterpenoids yanuthones A–E 59–63, 1-hydroxyyanuthone A 64, 1-hydroxyyanuthone C 65 and 22-deacetylyanuthone A 66.⁵⁹ Two diterpene glycosides, virescenosides M 67 and N 68, were isolated from a strain of Acremonium striatisporum associated with the holothurian Eupentacta fraudatrix.⁶⁰ Mangicols A–G 69–75 are sesterterpene polyols from a Fusarium sp. (strain # CNC-477), tentatively identified as F. heterosporum, that was isolated from driftwood collected in the Bahamas.⁶¹ A Fusarium sp. (strain # CNL-619), which was isolated from the green alga Avrainvillea sp. from the US Virgin Islands, produced N-methylsansalvamide 76.⁶² The structure of sansalvamide A 77, which was isolated from a related Fusarium sp. (strain # CNL-292),⁶³ was confirmed by a rapid, high-yield solid-phase synthesis.⁶⁴ A Hyphomycetes sp. cultured from a Zooanthus sp. produced the azetinone kasarin 78, which showed weak antibacterial and cytotoxic activities.⁶⁵ The antimicrobial alkaloids ascosalipyrrolidinones A 79 and B 80 and ascosalipyrone 81 were isolated from an obligate marine fungus Ascochyta salicorniae, which was cultured from Ulva sp., a green alga collected from the German coast of the North Sea.⁶⁶ An Acremonium sp. isolated from the surface of the tunicate Ecteinascidia turbinata from the Bahamas contained oxepinamides A–C 82–84 and fumiquinazolines H 85 and I 86, of which oxepinamide A 82 showed good anti-inflammatory activity.⁶⁷ The structures of fumiquinazolines A 87, B 88, F 89 and G 90, which were isolated from a strain of Aspergillus fumigatus from the gastrointestinal tract of the fish Pseudolabrus japonicus,⁶⁸ have been confirmed by total synthesis.^69,70 Penacillazine 91 is a quinoline derivative produced by a Penicillium sp. (strain # 386) from the South China Sea.⁷¹

It often appears that Lyngbya majuscula is the only marine cyanobacterium being investigated, which on the basis of its chemical diversity, is not entirely unexpected. Kalkitoxin 92 is an unusual thiazoline derivative from Caribbean specimens of L. majuscula that is ichthyotoxic, cytotoxic, neurotoxic and inhibits IL-1β-induced sPLA₂ secretion from HepG2 cells.⁷² The structure of kalkitoxin 92 was confirmed by total synthesis.⁷² The structure and absolute stereochemistry of (+)-tanikolide 93, which was isolated from a specimen of L. majuscula from Madagascar,⁷³ have been confirmed by total synthesis.⁷⁴ The absolute stereochemistry of pitiamide A 94, which was isolated from a mixed assemblage of L. majuscula and Microcoleus sp.,⁷⁵ was determined by optical rotation studies and confirmed by total synthesis.⁷⁶ The absolute stereochemistry of antillatoxin, which is a metabolite of L. majuscula from Curaçao,⁷⁷ was revised from 95 to 96 as the result of synthetic studies.⁷⁸ A specimen of L. majuscula from Papua New Guinea contained hermitamides A 97 and 98, which are toxic to brine shrimp and mildly toxic to goldfish.⁷⁹ Malyngamides Q 99 and R 100 are additional members of the series that were isolated from L. majuscula from Madagascar.⁸⁰ A Hawaiian specimen of L. majuscula contained isomalyngamides A 101 and B 102, which are geometrical isomers of malyngamides A and B about the chloromethylene moiety.⁸¹ Malyngamides O and P were isolated from a sea hare. A simple indanone 103 from a specimen of L. majuscula collected in Guam inhibited hypoxia-induced activation of the VEGF gene promotor in Hep3B human liver tumour cells in vitro.⁸² The structure of dechlorobarbamide 104, from a Curaçao collection of L. majuscula, was elucidated as part of a paper that described the biosynthetic pathway and origin of the chlorinated methyl group in barbamide.⁸³ Two collections of L. majuscula from Apra Harbor, Guam contained a series of linear lipopeptides, apramides A–G 105–111.⁸⁴ A mixed assemblage of L. majuscula and Schizothrix sp. from Fiji contained the cyclic depsipeptides yanucamides A 112 and B 113, which contain a 2,2-dimethyl-3-hydroxyoct-7-ynoic acid moiety found previously in metabolites of the mollusc Philinopsis speciosa.⁸⁵ Lyngbyabellins A 114 and B 115 are cytotoxic and antifungal cyclic depsipeptides from specimens of L. majuscula from Guam and the Dry Tortugas National Park, Florida, that contain a 7,7-dichloro-2,2-dimethyl-3-hydroxyoctanoic acid moiety.^86–88 The Guam specimen of L. majuscula also contained lyngbyapeptin A 116, previously reported from a Papua New Guinea specimen of L. bouillonii,⁸⁹ for which the absolute configuration was also determined.⁸⁷ A Palauan collection of L. majuscula contained dolastatin 3 117, previously obtained as a very minor cytotoxic metabolite from the sea hare Dolabella auricularia,^90,91 homodolastatin 3 118 and kororamide 119: dolastatin 3 117 was found to be an inhibitor of HIV-1 integrase.⁹² Three depsipeptides, malevamides A–C 120–122, were isolated from a specimen of Symploca laeteviridis from Oahu.⁹³

The dinoflagellate Amphidinium sp. (strain # Y-56), which is a symbiont of the flatworm Amphiscolops sp., contained the 19-membered macrolide amphidinolide T 123,⁹⁴ while Amphidinium sp. (strain # Y-5) produced a 14-membered macrolide, amphidinolide V 124.⁹⁵ The absolute stereochemistries of amphidinolides G 125 and H 126, which are potent cytotoxic 27- and 26-membered macrolides from Amphidinium sp. (strain # Y-72),⁹⁶ were determined by X-ray diffraction analysis and interconversion.⁹⁷ The structure and absolute stereochemistry of (−)-amphidinolide P 127, which is a 15-membered lactone from Amphidinium sp.,^98,99 have been confirmed by a convergent total synthesis.¹⁰⁰ The structures elucidated for colopsinols D 128 and E 129, which are additional polyhydroxylated metabolites from an Amphidinium sp. (strain # Y-5), lack key stereochemical data.¹⁰¹ Cultures of the dinoflagellate Gymnodinium selliforme, implicated in occurrences of neurotoxic shellfish poisoning in New Zealand, contained gymnodimine B 130.¹⁰² A number of ciguatoxin congeners have been proposed on the basis of FAB tandem mass spectrometry.¹⁰³ The absolute configurations of gambieric acids A–D 131–134, which are potent antifungal polyethers from Gambierdiscus toxicus,¹⁰⁴ have been determined by using the modified Mosher method, NMR analysis and chiral HPLC.¹⁰⁵

Two important sedimentary sesterterpenoids, the geometrical isomers 135 and 136 have been isolated from the marine diatom Pleurosigma intermedium.¹⁰⁶ Bacillariolides I–III 137–139, which are oxylipins from the diatom Pseudonitzschia multiseries,¹⁰⁷ have been synthesized from (R)-malic acid.¹⁰⁸ The marine chromophyte Aureoumbra lagunensis, known as ‘Texas brown tide’, contains 24-propylcholesterol 140, the structure of which was confirmed by synthesis.¹⁰⁹

3 Green algae

The metabolite of Bryopsis sp. from Oahu that caused ecdysis in the dinoflagellate Gambierdiscus toxicus was identified as 1-O-palmitoyl-3-O-(6′-sulfo-α-D-quinovopyranosyl)-sn-glycerol 141.¹¹⁰ A specimen of Udotea petiolata from the Greek coast contained udoteal B 142, together with several known compounds.¹¹¹ Four closely-related monocyclic diterpenes 143–146 were isolated from Caulerpa trifaria from Tasmania.¹¹² The antiinflammatory agent produced by Ulva lactuca was identified as 3-O-β-D-glucopyranosylstigmasta-5,25-diene 147.¹¹³ An additional depsipeptide, kahalalide O 148, was found in both the green alga Bryopsis sp. from Oahu and the sacoglossan mollusc Elysia ornata that feeds upon it.¹¹⁴

4 Brown algae

The majority of papers reviewed below concern the synthesis of brown algal metabolites rather than the discovery of new examples. The total synthesis of all four stereoisomers of lamiroxene, which is a spermatozoid-releasing and -attracting pheromone of Laminaria spp.,¹¹⁵ showed that (1′S,2R,3S)-lamiroxene 149 was the most active isomer.¹¹⁶ A total synthesis of (3R,4S)-dictyopterene A 150, which is a sex pheromone of a Hawaiian Dictyopteris sp.,¹¹⁷ used an optically active tributylstannylcyclopropane as a key intermediate.¹¹⁸ (2S,3S,5R)-5-[(1R)-1-Hydroxydec-9-enyl]-2-pentyltetrahydrofuran-3-ol 151 and (2S,3S,5S)-5-[(1S)-1-hydroxydec-9-enyl]-2-pentyltetrahydrofuran-3-ol 152, both of which were isolated from Notheia anomala,¹¹⁹ have been synthesized in an enantiocontrolled manner.¹²⁰

The brown alga Stypopodium schimperi from the Aegean Sea contained the new meroterpenoid schimperiol 153.¹²¹ The sesquiterpene hydroquinones zonarol 154 and isozonarol 155 and the corresponding quinones zonarone and isozonarone, which are metabolites of Dictyopteris zonaroides,¹²² have been synthesized by a common route from β-ionone.¹²³ The structure of sporochnol A 156, which is a fish feeding inhibitor from the Caribbean alga Sporochnus bolleanus,¹²⁴ has been confirmed by total synthesis of the racemate.¹²⁵ Two diastereoisomers 157 and 158 of an arsenomethionine-based structure were isolated from Sargassum lacerifolium.¹²⁶

5 Red algae

Four oxylipins (5R,6S,7E,9E,11Z,14Z)-5,6-dihydroxyicosa-7,9,11,14-tetraenoic acid 159, (5R*,6S*,7E,9E,11Z,14Z,17Z)-5,6-dihydroxyicosa-7,9,11,14,17-pentaenoic acid 160, (6E,8Z,11Z,14Z)-5-hydroxyicosa-6,8,11,14-tetraenoic acid 161, and (6E,8Z,11Z,14Z,17Z)-5-hydroxyicosa-6,8,11,14,17-pentaenoic acid 162 were isolated from Rhodymenia pertusa.¹²⁷ The structures of constanolactones A 163 and B 164, which are eicosanoids from Constantinea simplex,¹²⁸ have been confirmed by total synthesis.¹²⁹ An unusual fatty ester, pentyl hentriacontanoate, was obtained from an Indian specimen of Chondria armata.¹³⁰ Several brominated anisoles and cresols were detected by GC-MS from an extract of Polysiphonia sphaerocarpa obtained by a rather harsh steam distillation–solvent extraction technique.¹³¹Symphyocladia latiuscula from Korea contained (2R)-2-(2,3,6-tribromo-4,5-dihydroxybenzyl)cyclohexanone 165, which was shown to be a radical scavenger.¹³² Obtusallenes V 166, VI 167, VII 168, VIII 169 and IX 170, some of which show conformational mobility, were obtained from a Turkish Mediterranean Sea specimen of Laurencia obtusa.¹³³ A highly convergent synthesis of trans-(+)-laurediol 171, which was obtained from Laurencia nipponica,¹³⁴ was described.¹³⁵ The syntheses of (+)-prelaureatin 172 and (+)-laurallene 173, both of which are metabolites of L. nipponica,^136,137 employed a ring-closing metathesis reaction.¹³⁸ An Indonesian specimen of the red alga Ceratodictyon spongiosum and its symbiotic sponge Sigmadocia symbiotica contained the antiinflammatory cyclic heptapeptides cis,cis-ceratospongamide 174 and trans,trans-ceratospongamide 175.¹³⁹ (−)-Polycavernosamide A 176, which is a toxic constituent of Polycavernosa tsudai,¹⁴⁰ has been synthesized in a stereocontrolled manner.¹⁴¹

Two additional polyhalogenated monoterpenes 177 and 178 were isolated from an Eastern Tasmanian sample of Plocamium cartilagineum.¹⁴² The antitumor agent halomon 179 from Portieria hornemannii¹⁴³ has been synthesized in its racemic form by an efficient 3 step synthesis.¹⁴⁴ A palladium-catalyzed cycloreduction of a 1,6-enyne was employed in the synthesis of (±)-laurene 180,¹⁴⁵ which is a metabolite of L. glandulifera.¹⁴⁶Laurencia microcladia from Il Rogiolo, Tuscany, contained the diterpenes neorogioldiol 181, rogioldiol D 182 and O¹¹,15-cyclo-14-bromo-14,15-dihydrorogiol-3,11-diol 183, together with their putative biosynthetic precursor (−)-geranyllinalool 184.¹⁴⁷ The structure and absolute configuration of 3-bromobarekoxide 185, which is an unusual diterpene from a Japanese specimen of L. luzonensis, were determined by X-ray crystallography.¹⁴⁸Jania rubens from Tunisia contained a cytotoxic steroid, 16β-hydroxy-5α-cholestane-3,6-dione 186.¹⁴⁹ Six cycloartenol sulfates 187–192, two 29-nor-cycloartenol sulfates 193 and 194 and two 29-nor-lanosterol sulfates 195 and 196 were obtained from Tricleocarpa fragilis from Hawaii.¹⁵⁰ The protein phosphatase 2A inhibitor, thyrsiferyl 23-acetate 197, which was isolated from Laurencia obtusa,¹⁵¹ has been synthesized by using a convergent strategy.¹⁵²

6 Sponges

Once again sponges have provided more marine natural products than any other phylum, due in part to their propensity to produce bioactive metabolites. The dimethylated fatty acid 9,13-dimethyltetradecanoic acid 198 was isolated from the Caribbean sponge Calyx podatypa and its structure was confirmed by total synthesis.¹⁵³ The calcareous sponge Leucetta microraphis contained (2E,6Z,9Z)-2-methylicosa-2,6,9-trienal 199, which exhibited moderate cytotoxicity.¹⁵⁴ Halicholactone 200, which is a lipoxygenase inhibitor from Halichondria okadai,¹⁵⁵ was synthesized by using the chirality of (diene)Fe(CO)₃ complexes to induce asymmetry.¹⁵⁶ A South China Sea specimen of Pachychalina sp. contained 3-heptacosoxypropane-1,2-diol 201.¹⁵⁷ Two additional prenylated glycosphingolipids, plakosides C 202 and D 203, were isolated from Ectyoplasia ferox from the Bahamas.¹⁵⁸ The structures of plakosides A 204 and B 205, which were reported as immunosuppressive agents from Plakortis simplex,¹⁵⁹ have been confirmed by total synthesis but the synthetic materials were less active than previously reported.¹⁶⁰ The absolute configurations of (−)-rhizochalin 206, which is a metabolite of the calcareous sponge Rhizochalina incrustata from Madagascar,¹⁶¹ and oceanapiside 207, which is an antifungal agent from Oceanapia phillipensis,¹⁶² were determined by using circular dichroism.^163,164Haliclona vansoesti from Curaçao contained large quantities (5% dry wt.) of (2R,3R,7Z)-2-aminotetradec-7-ene-1,3-diol 208.¹⁶⁵ Three additional N-acyl-2-methylene-β-alanine methyl esters, hurghamides E–G 209–211, were isolated from a Red Sea species of Hippospongia.¹⁶⁶

The antimicrobial constituent of a Japanese Oceanapia sp. was identified as the bis-acetylene 212.¹⁶⁷ Strongylodiols A 213, B 214 and C 215, which occur as enantiomeric mixtures of different ratios (A: 91% R, B: 97% R, C: 84% R), are cytotoxic acetylenic alcohols from a Strongylophora sp. from Okinawa.¹⁶⁸ A Taiwanese specimen of S. durissima contained two additional acetylenes, durissimols A 216 and B 217, as well as a new meroditerpenoid.¹⁶⁹ Six polyacetylenes, aikupikanynes A–F 218–223 were obtained from a Callyspongia sp. from the Red Sea.¹⁷⁰ An Indonesian Haliclona sp. contained lembehyne A 224, which induced neuritogenesis in pheochromocytoma PC12 and neuroblastoma Neuro 2A cells.¹⁷¹ An additional polyacetylene, pellynol I 225 was isolated from a Pellina sp. from Tonga.¹⁷² The polyacetylene carboxylic acid haliclonyne 226 was obtained from a Haliclona sp. from the Red Sea.¹⁷³

A Bahamian specimen of Plakortis simplex contained two additional cytotoxic cyclic peroxides, plakortides I 227 and J 228, together with seco-plakortides H 229 and I 230.¹⁷⁴Melophlus sarassinorum from Indonesia contained melophlins A 231 and B 232, which reverse the phenotype of ras-transformed cells.¹⁷⁵ Mycalamides C 233 and D 234 are additional cytotoxins from a newly described Australian Stylinos sp. from Heron Island.¹⁷⁶ Mycalamide D 234 was also isolated from a Mycale sp. from New Zealand.¹⁷⁷ Mycalamides A 235 and B 236, which were obtained from a New Zealand Mycale sp.,¹⁷⁸ and theopederin D 237 from a Theonella sp.,¹⁷⁹ have been synthesized.^180,181 A New Zealand Mycale sp. also contained peloruside A 238, which is a potent cytotoxic macrolide.¹⁸² The macrolide lactams, chondropsins A 239 and B 240, are tumor cell growth inhibitors from a Chondropsis sp. from Wollongong, Australia.¹⁸³ A specimen of Penares sp. from Japan contained penarolide sulfates A₁241 and A₂242, which were shown to be α-glucosidase inhibitors.¹⁸⁴

The total synthesis of sponge metabolites, particularly macrolides, appears to be a very popular research area. In addition to a detailed description of the evolution of a gram-scale synthesis of discodermolide 243,¹⁸⁵ which is an anti-cancer agent from Discodermia dissoluta,¹⁸⁶ a total synthesis featuring boron-mediated aldol reactions has been reported.^187,188 Manzamenones A 244, C 245 and F 246 and the proposed biosynthetic precursor untenone A 247, all of which are metabolites of a Plakortis sp.,^189,190 have been synthesized as the corresponding racemates from 2-furanacetonitrile.¹⁹¹ The structure of another metabolite of a Plakortis sp.,¹⁹² (2S,3S,4R)-plakoridine A 248, has been confirmed by total synthesis.¹⁹³ The absolute configuration of salicylihalamide A 249, which is a cytotoxin from a Haliclona sp.,¹⁹⁴ was revised as a result of an asymmetric total synthesis.^195,196 The first total synthesis of (−)-mycothiazole 250,¹⁹⁷ which was isolated from Spongia mycofijiensis, employed a convergent strategy: the optical rotation of the synthetic product was significantly larger, albeit of the same sign, than that of the natural material.¹⁹⁸ An additional synthesis of (−)-hennoxazole A 251, which is an antiviral agent from a Polyfibrospongia sp.,¹⁹⁹ has been accomplished by using a convergent approach.²⁰⁰ The structure and absolute configuration of leucascandrolide A 252, which is an antifungal and cytotoxic metabolite of Leucascandra caveolata,²⁰¹ has been confirmed by total synthesis.²⁰² A total synthesis of (−)-pateamine 253, which is an immunosuppressive agent from Mycale sp.,²⁰³ employed a concise and convergent route.²⁰⁴ (−)-Laulimalide 254 from a Hyattella sp.,²⁰⁵ also known as fijianolide B from Spongia mycofijiensis,²⁰⁶ has been synthesized in a stereocontrolled manner.²⁰⁷ The total synthesis of phorboxazole B 255, which is an antifungal and cytotoxic macrolide from Phorbas sp.,²⁰⁸ has been accomplished in a stereoselective manner.^209,210 The structure and stereochemistry of (−)-mycalolide A 256, which is an antifungal and cytotoxic trisoxazole from Mycale sp.,²¹¹ have been confirmed by total synthesis.^212,213

Herbacic acid 257, which is the simplest to date of the 5,5,5-trichlorinated leucine derivatives, was isolated from a Great Barrier Reef specimen of Dysidea herbacea.²¹⁴ A specimen of D. herbacea from the Great Barrier Reef contained (−)-neodysidenin 258, the absolute configuration of which was determined by capillary electrophoresis of Marfey's derivatives.²¹⁵ The structure and stereochemistry of (−)-dysiherbaine 259, which is a neurotoxic amino acid from D. herbacea,²¹⁶ have been confirmed by three independent total syntheses.^217–219 Miraziridine A 260, which was isolated from a Japanese lithistid sponge Theonella aff. mirabilis, is a most unusual linear pentapeptide that inhibited the protease cathepsin B.²²⁰ A specimen of Haliclona nigra from Papua New Guinea contained two cyclic hexapeptides, haligramides A 261 and B 262, that showed an unusual pattern of selectivity in the National Cancer Institute's 60 cell-line panel.²²¹ Microsclerodermins F–I 263–266 are additional cytotoxic and antifungal cyclic peptides that were isolated from a deep-water Microscleroderma sp. from Palau.²²²Theonella cupola from Okinawa contained dehydromicroscerodermins C 267 and D 268, the stereochemistries of which are not defined.²²³ The cyclic peptides barangamides B–D 269–271 and the cyclic depsipeptide theonellapeptolide IIe 272 are additional metabolites of a specimen of T. swinhoei from Indonesia.²²⁴ An additional synthesis of arenostatin A 273, which is a cytotoxin from Dysidea arenaris,²²⁵ provides a route that is amenable to structural modifications in the side chain.²²⁶ Both solution-phase and solid-phase syntheses of phakellistatin 5 274, which was reported to be a cytotoxic constituent of Phakellia costada,²²⁷ have been accomplished but the products, while chemically identical, were not biologically identical.²²⁸ (±)-Anchinopeptolide D 275, which is a metabolite of Anchinoe tenacior,²²⁹ has been synthesized in seven steps in 10% yield.²³⁰

Two unusual acetylenic alkaloids, clathculins A 276 and B 277, were isolated as an inseparable mixture from a South African specimen of Clathrina aff. reticulum.²³¹Mycale tenuispiculata from the Thiruvananthapuram coast of India contained three additional 5-alkylpyrrole-2-carbaldehyde derivatives, (6′Z)-5-(23′-cyanotricos-6′-enyl)pyrrole-2-carbaldehyde 278, mycaleoxime 279 and (6′E)-5-(pentadec-6′-enyl)pyrrole-2-carbaldehyde 280.²³² The calcareous sponge Leucetta cf. chagosensis from the Egyptian Red Sea contained an additional imidazole alkaloid, naamine D 281, that was both antifungal and inhibited nitric oxide synthase.²³³ The structures of naamine A 282 and naamidine A 283, which are metabolites of L. chagosensis,²³⁴ have been confirmed by total synthesis.²³⁵ The structure of clathridine A 284, which was obtained from Clathrina clathrus,²³⁶ has been confirmed by total synthesis.²³⁷ Erebusinone 285, a simple pigment from the Antarctic sponge Isodictya erinacea, caused a significant reduction of molting and increased mortality when fed to sympatric predatory amphipods.²³⁸ Mimosamysin 286, which was identified as a constituent of Reniera,²³⁹Petrosia²⁴⁰ and Xestospongia spp.,²⁴¹ has been synthesized in eight steps with a 13% overall yield.²⁴² Isoaaptamine 287, which is a protein kinase C inhibitor from Aaptos aaptos,^243,244 has been synthesized together with several analogues.²⁴⁵ The structure of purpurone 288, which is an alkaloid from an Iotrochota sp.,²⁴⁶ has been confirmed by total synthesis.²⁴⁷

Cribochalines A 289, a moderately active antifungal agent, and B 290 are 3-alkylpyridine alkaloids from a specimen of Cribochalina sp. from Pohnpei that also contained ikimine A 291²⁴⁸ as a 2.8 ∶ 1 mixture of the (S)- and (R)-enantiomers.²⁴⁹ The moderately cytotoxic 3-alkylpyridine alkaloids hachijodines A 292, B 293, C 289 and D 294 were isolated from a Japanese Xestospongia sp. while hachijodines E–G 295–297 were isolated from an Amphimedon sp. from Japan.²⁵⁰ The structures of cribochaline A 289 and hachijodine C are identical but the reported spectral data, albeit in different solvents, are strikingly different. Pyrinodemins B–D 298–300 are additional potent cytotoxic bis-pyridine alkaloids that were isolated from an Okinawan Amphimedon sp. together with the antimicrobial 3-alkylpyridine alkaloids 301–304.²⁵¹ A specimen of Xestospongia exigua from Papua New Guinea contained xestosin A 305, the structure of which was determined by X-ray crystallography.²⁵² An Indonesian Echinochalina sp. contained a very unusual macrocyclic alkaloid, 'upenamide 306, the complete stereochemistry of which, although drawn, remains to be determined.²⁵³N-Methyl-epi-manzamine D 307, the structure of which was determined by X-ray analysis, and epi-manzamine D 308 were isolated as cytotoxic agents from an unidentified Palauan sponge.²⁵⁴ A synthesis of manzamine C 309, which is an alkaloid from a Haliclona sp.,²⁵⁵ involved the use of the Ramburg–Bäcklund rearrangement for the formation of the aza-macrocycle.²⁵⁶ The endemic Brazilian sponge Arenosclera brasiliensis contained arenosclerins A–C 310–312 and haliclonacyclamine E 313.²⁵⁷ Motuporamine C 314, which is a metabolite of Xestospongia exigua from Papua New Guinea,²⁵⁸ has been synthesized by using a ring-closing metathesis reaction.²⁵⁹

Two additional members of the oroidin family of alkaloids, cyclooroidin 315 and the antihistaminic agent taurodispacamide A 316, were isolated from Agelas oroides from the Bay of Naples.²⁶⁰Agelas ceylonica from the Mandapam coast of India yielded (S)-(+)-hanashin methyl ester 317a,²⁶¹ rather than the racemate reported previously from a Homaxinella sp. from Japan.²⁶² A late-arriving paper reported the isolation of 3-debromohanishin methyl ester 317b from an Indian specimen of Axinella tenuidigitata.⁵⁹² Both oroidin 318, which is a metabolite of Agelas oroides,²⁶³ and the corresponding (Z)-isomer have been synthesized.²⁶⁴ The absolute configurations of manzacidins A 319 and C 320, which were isolated from an Okinawan Hymeniacidon sp.,²⁶⁵ have been determined by total synthesis.²⁶⁶ (Z)-Debromohymenialdisine 321, which was first isolated from Phakellia flabellata,²⁶⁷ has been synthesized in four steps and 34% overall yield: (Z)-3-bromohymenialdisine 322, which was isolated from Stylissa carteri,²⁶⁸ was an intermediate in the synthesis.²⁶⁹ The total syntheses of slagenins A 323, B 324 and C 325, recently isolated from Agelas nakamurai,²⁷⁰ have also been reported.²⁷¹ Matemone 326 is a mildly cytotoxic and antimicrobial bromo-indole derivative from Iotrochota purpurea from Matebo Island in the western Indian Ocean.²⁷² A specimen of Ircinia spinulosa from Turkey contained the plant auxin tryptophol 327.²⁷³ A Coscinoderma sp. from Papua New Guinea contained three bis-indole alkaloids, coscinamides A–C 328–330.²⁷⁴Rhaphisia lacazei from the Mediterranean contained seven additional bis-indole alkaloids 331–337 of the dihydrohamacanthin family.²⁷⁵ Dragmacidin F 338 is an antiviral bromoindole alkaloid from a Halicortex sp. from the Italian coast.²⁷⁶ Topsentin A 339, which was first obtained from Topsentia genitrix,²⁷⁷ and nortopsentins B 340 and D, 341, which are metabolites of Spongosorites ruetzleri²⁷⁸ and Dragmacidon sp.,²⁷⁹ respectively, have been synthesized in a concise manner.²⁸⁰ Both dragmacidins A 342 and B 343, which were isolated from a Hexadella sp.,²⁸¹ have been synthesized in good yields.^282,283 Two Antarctic sponges of the family Latrunculidae, Latrunculia sp. and Negombata sp., contained the antibacterial agent discorhabdin R 344.²⁸⁴ A Cribrochalina sp. from the Maldives contained three isoquinoline alkaloids, cribrostatins 3–5 345–347, as minor antimicrobial agents.²⁸⁵ The polycyclic guanidine alkaloid dehydrobatzelladine C 348 was isolated from Monanchora arbuscula from Belize while crambescidins 359 349 and 431 350 were obtained from M. unguiculata from the Seychelles.²⁸⁶ The syntheses of ptilomycalin A 351, which was isolated from a Red Sea Hemimycale sp.²⁸⁷ and a Caribbean Batzella sp.,²⁸⁸ originally identified as Ptilocaulis aff. spiculifera,²⁸⁷ crambescidins 800 352 and 657 353 from the related Mediterranean sponge Crambe crambe,²⁸⁹ and neofolitispate 2 354 from an Indian Neofolitispa dianchora,²⁹⁰ confirmed the earlier stereochemical assignments and established the (S)-absolute stereochemistry of the hydroxyspermidine residue in crambiscidin 800 352.²⁹¹ A similar synthetic strategy was used for the total syntheses of 13,14,15-isocrambescidins 657 355 and 800 356, which are metabolites of Crambe crambe,^289,292 again confirming the relative and absolute stereochemistries.²⁹³ A Spongosorites sp. from Southern Australia contained the base 1,9-dimethylhypoxanthine 357.²⁹⁴

Only one additional minor bromotyrosine derivative 358 was isolated from Verongula gigantea from the Bahamas.²⁹⁵ An undescribed Verongid sponge from Molokai contained N-methylceratinamine 359 and wai'anaeamines A 360 and B 361.²⁹⁶ The mololipids 362–364, which inhibit HIV-1, were also isolated from a Hawaiian Verongid sponge as an inseparable mixture of compounds, the structures of which were elucidated by hydrolysis and GC-MS analysis of the lipid components.²⁹⁷ A Suberea sp. from Okinawa contained the cytotoxic pyrazin-2(1H)-ones, ma'edamines A 365 and B 366.²⁹⁸ Ianthesines A–D 367–370, which showed potent Na,K-ATPase activity, are additional dibromotyrosine derivatives from an Australian Ianthella sp.²⁹⁹ A specimen of Aplysina gerardogreeni from the Sea of Cortez contained the interesting bis-epoxide calafianin 371.³⁰⁰ Four additional cytotoxic bromotyrosine metabolites that also inhibit farnesyl protein transferase and leucine aminopeptidase, psammaplins A₁372 and A₂373, and aplysinellins A 374 and B 375, were isolated from specimens of Aplysinella rhax collected at both Pohnpei and Palau.³⁰¹ Another specimen of A. rhax from the Great Barrier Reef contained psammaplin A 11′-sulfate 376 and bisaprasin 11′-sulfate 377, both of which inhibited [³H]-1,3-dipropyl-8-cyclopentylxanthine binding to rat-brain adenosine A₁ receptors.³⁰² An additional polybrominated diphenyl ether 378, the structure of which was determined by X-ray analysis, was isolated from Dysidea herbacea from the Great Barrier Reef.³⁰³ A Dysidea sp. from Lizard Island contained 2-(2′,4′-dibromophenoxy)-4,6-dibromoanisole 379, together with two sesquiterpenes (see below).³⁰⁴

A Hyrtios sp. from the Seychelles contained the merosesquiterpenoids hyrtiophenol 380, 5-epi-hyrtiophenol 381, 18-hydroxy-5-epi-hyrtiophenol 382 and 18-hydroxyhyrtiophenol 383, while H. tubulatus from Curaçao contained 21-hydroxy-19-methoxyarenarone 384 together with known metabolites.³⁰⁵ Pelorol 385 was reported from a Great Barrier Reef specimen of Dactylospongia elegans and, accompanied by 5-epi-smenospongine 386, from Petrosiaspongia metachromia from Yap, Micronesia.^306,307 A Dysidea sp. from Vanuatu contained the oxidized and rearranged merosesquiterpene dysidotronic acid 387, which selectively inhibited phospholipase A₂.³⁰⁸ The structure of frondosin B 388, which was isolated from Dysidea frondosa,³⁰⁹ was confirmed by total synthesis.³¹⁰ Fulvanin 2 389, which is a merosesquiterpenoid from Reniera fulva,³¹¹ has been synthesized from (−)-sclareol.³¹² Strongylophorines 9 390 and 11 391 are additional meroditerpenoids from Strongylophora durissima from Taiwan.^313,169 The meroditerpenoids cacospongins B–D 392–394 were obtained, together with the diterpene furan cacospongin A 395, from a Cacospongia sp. from the Philippines.³¹⁴ The structure of cacospongin A was recently revised from 395 to 396.³¹⁵ Adociasulfate 10 397, which inhibits the kinesin family of motor proteins, is an additional merohexaprenoid sulfate from Haliclona (aka Adocia) sp. from Palau.³¹⁶ A Haliclona sp. from Indonesia contained two new merotriterpenes, haliclotriols A 398 and B 399.³¹⁷ A Clathria sp. from southern Australia contained clathrins A–C 400–402, which might be examples of meroterpenoids or rearranged terpenoids.³¹⁸

The structure of tsitsikammafuran 403, which was isolated from a Dysidea sp. from South Africa, was confirmed by total synthesis from thymol.³¹⁹ A specimen of D. fragilis from southern India contained (+)-furodysinin lactone 404, (+)-O-methylfurodysinin lactone 405 and spirofragilide 406.³²⁰ A specimen of D. herbacea from the Great Barrier Reef yielded 6-hydroxyfurodysinin-O-methyl lactone 407 and dehydroherbadysidolide 408, in addition to the polybrominated diphenyl ether 379 (see above).³⁰⁴ Great Barrier Reef specimens of Acanthella cavernosa contained 10-isothiocyanatocadin-4-ene 409, 8-hydroxyisokalihinol 410 and two isocyanobifloradiene epoxides 411 and 412.³²¹ Both enantiomers of 2-thiocyanatoneopupukeanane 413, which was isolated from both Phycopsis terpnis and Axinyssa aplysinoides,^322,323 have been synthesized from (R)-carvone.³²⁴ The absolute configuration of the sesquiterpene alkaloid stellettamide A 414, which is a metabolite of a Stelletta sp.,³²⁵ was confirmed by total synthesis of its enantiomer.³²⁶

Phorbasin A 415 is an unstable diterpene polyene from a southern Australian Phorbas sp.³²⁷ A specimen of Coscinoderma mathewsi from Pohnpei contained the aldehyde 416 and the γ-hydroxybutenolide 417, which appears to be identical to spongiabutenolide A.^328,329 The relative configuration at C-13 in nakamurol A 418, which is a metabolite of Agelas nakamurai from Okinawa,³³⁰ has been tentatively assigned as the result of total synthesis of the racemate.³³¹ A reinvestigation of the constituents of Hamigera tarangaensis has resulted in the reassignment of the structure of 419³³² to hamigeran E 420 and the isolation of hamigerans A–D 421–424, debromohamigerans A 425 and E 426 and 4-bromohamigeran B 427, among which hamigeran B 422 showed in vitro antiviral activity and others were moderately cytotoxic.³³³ Asmarines A–F 428–433 are cytotoxic diterpene alkaloids that contain an adenine residue from a Raspailia sp. from Eritrea.³³⁴ A Hippospongia sp. from Goa, India contained ent-untenospongin A 434.³³⁵ The structure of luffarin W 435, which was obtained from Luffariella geometrica,³³⁶ was confirmed by a total synthesis that involved the thermal rearrangement of an ozonide.³³⁷

Two additional sesterterpenes 436 and 437 were isolated from Hyrtios cf. erecta from Fiji but the major bioactive compounds of this sponge were known.³³⁸ The absolute stereochemistries of the known antiinflammatory agents manoalide 438 and cacospongionolide B 439 were determined by comparison of their CD spectra with those of synthetic model compounds.³³⁹ The absolute configuration of (−)-hyrtiosal 440, which is a cytotoxic sesterterpene from H. erectus (= erecta ?),³⁴⁰ was determined by synthesis from sclareol.³⁴¹ Three additional scalaranes, hyrtiolide 441, 16-hydroxyscalariolide 442 and 12-deacetyl-Δ¹⁷-hyrtial 443 were obtained from an Okinawan specimen of H. erectus.³⁴²

Four sesterterpene pyridinium alkaloids, spongidines A–D 444–447, together with 21-hydroxypetrosiaspongiolides K 448 and P 449, were isolated as antiinflammatory agents from a Spongia sp. from Vanuatu.³⁴³Strepsichordaia aliena from Indonesia contained a total of eighteen new bishomoscalaranes, honulactones A–L 450–461, honu'enone 462, phyllofolactones H–K 463–466 and phyllofenone 467: honulactones A–D 450–453, of which the structures of 451 and 453 were determined by X-ray analysis, were shown to be cytotoxic.^344,345 Four additional syntheses of the cytotoxic agent dysidiolide 468, which was isolated from Dysidea etheria,³⁴⁶ have been reported.^347–350

A specimen of Theonella swinhoei from the Philippines contained 7α-hydroxytheonellasterol 469 as a mildly cytotoxic constituent of the sterol fraction.³⁵¹Polymastia sobustia from the South China Sea contained 3β-hydroxystigmast-5-en-7-one 470.³⁵² Two 26,27-cyclosterols 471 and 472 were isolated from a Japanese specimen of Strongylophora corticata.³⁵³ A mixture of 5α,8α-epidioxy sterols 473–482 was identified as a cytotoxic component of Luffariella cf. variabilis.³⁵⁴ A Dysidea sp. from Northern Australia contained three polyoxygenated sterols 483–485 that inhibit the binding of IL-8 to the human recombinant IL-8 receptor type A.³⁵⁵ The ecdysteroid 2β,3β,14α,20β-tetrahydroxy-22α-(2-hydroxyacetyloxy)-5β-cholest-7-en-6-one 486 was obtained from Iotrochota birotulata from the Bahamas.³⁵⁶ Polysterol A 487 and polysterol B sulfate 488 were obtained from a Japanese Epipolasis sp.³⁵⁷ Specimens of Erylus formosus from the Bahamas contained eryloside F 489, a potent thrombin receptor antagonist that inhibits human platelet aggregation in vitro.³⁵⁸ (23R)-23H-Isocalysterol 490, a metabolite of Calyx niceansis,³⁵⁹ and (23S)-23H-isocalysterol 491, which was obtained from C. podotypa,³⁶⁰ have both been synthesized.³⁶¹ (6E,24R)-24-Ethyl-6-hydroxyiminocholest-4-en-3-one 492, which was isolated from Cinachyrella spp. sponges,³⁶² was synthesized from β-sitosterol in 30% overall yield.³⁶³

Six additional cytotoxic isomalabaricane derivatives, globstellatic acid E methyl ester 493, 3-O-acetyljaspiferal methyl esters B 494, D 495 and G 496 and the dimethyl esters of jaspiferoic acids A 497 and B 498, were obtained from a new species of Jaspis from Vanuatu, after methylation with diazomethane to obtain the corresponding methyl esters.³⁶⁴ Three additional isomalabaricanes, 29-hydroxystelliferin D 499, 3-epi-29-hydroxystelliferin E 500 and 3-epi-29-hydroxystelliferin A 501, that induce morphological changes in rat fibroblasts, were obtained from a Japanese specimen of Stelletta globostellata.³⁶⁵ Aurorals 1–4 502–505 are truncated isomalabaricanes from Rhabdastrella globostellata from New Caledonia.³⁶⁶Melophlus isis from Guam contained four additional triterpenoid saponins 506–509.³⁶⁷ A Petrosia sp. from Eritrea contained bacteriohopanehexol 510, which is proposed to be a metabolite of an associated bacterium.³⁶⁸ 12-Methylbacteriohopanetetraol 511 is the first such 12-methylhopanoid from Plakortis simplex from the Bahamas.³⁶⁹ The same specimen of P. simplex contained the unusual heptaprenylglycoside, plakopolyprenoside 512.³⁷⁰ The proposed structure of naurol A 513, which was isolated from an unidentified Pacific sponge,³⁷¹ has been disproved by total synthesis.³⁷²

7 Coelenterates

The chemistry of coelenterates (gorgonians, soft corals, hydroids, etc.) was again dominated by reports of diterpenes, sesquiterpenes and polyhydroxylated sterols. Among the few lipids reported was 2-hydroxy-3-(octadecyloxy)propyl-α-D-fucopyranoside 514, which was isolated from both a Sinularia sp. and S. gravis from India.³⁷³ Humesamide 515 is a ceramide from the soft coral Cladiella humesi from Hainan, China.³⁷⁴ An unusual 15-ketoprostaglandin 516 was isolated from Sarcophyton crassocaule from the Indian Ocean.³⁷⁵ Three additional prostaglandins, (5Z,15S)-15-acetylprostaglandin B₂ methyl ester 517, (5E,15S)-15-acetylprostaglandin B₂ methyl ester 518 and (5Z,13Z)-9-oxoprosta-5,10,13-trienoic acid methyl ester 519, were obtained as minor metabolites of Plexaura nina from the Bahamas.³⁷⁶ The scleractinian coral Montipora sp. from Korean waters contained six acetylenic compounds, montiporynes A–F 520–525.³⁷⁷ The hydroid Corydendrium parasiticum contained two isomeric piperidinol alkaloids, corydendramines A 526 and B 527, which were isolated as potent fish feeding inhibitors.³⁷⁸

Five suberosane sesquiterpenes, suberosenol A 528, suberosenol B 529, suberosanone 530, suberosenol A acetate 531 and suberosenol B acetate 532, were isolated as cytotoxic components of the gorgonian Isis hippuris.³⁷⁹ Studies of the volatile oils of the soft corals Clavularia viridis and Sarcophyton acutangulum from Japan resulted in the isolation of cyclosinularane 533 and (+)-alloaromadendrene 534, the enantiomer of the known terrestrial plant metabolite, respectively.³⁸⁰ Alcyopterosins A–O 535–549 are sesquiterpenes of the illudin class that were isolated from Alcyonium paessleri from South Georgia Island: the nitrate esters 536, 537, 539–542, 544 and 547 are the first to have been encountered as natural products.³⁸¹ 6-Hydroxy-α-muurolene 550 was isolated as an antifungal constituent of a Heteroxenia sp. from the Philippines.³⁸² An additional seco-africanane, 4-acetoxy-3,15-dinor-2,3-seco-african-2-one 551, was isolated from an Indian specimen of Sinularia dissecta.³⁸³ The Indian soft coral Nephthea chabrollii contained four additional sesquiterpenes, 10α-methoxy-4β-hydroxyguai-6-ene 552, 6β,7β-epoxy-4α-hydroxyguai-10-ene 553, 4,15-dihydroguaia-6,10-diene 554 and guaia-4,6-dien-10α-ol 555.³⁸⁴ An Indian Nephthea sp. contained (1S,3R,4S,5S,7S)-3,4-epoxyguaia-10(12)-ene 556, together with a new diterpene 557 and known compounds.³⁸⁵Sarcophyton buitendijki from the Andoman and Nicobar Islands contained 10α-hydroxy-4α-methoxyguai-6-ene 558 and 4α-ethoxy-10α-hydroxyguai-6-ene 559, together with known compounds.³⁸⁶ The Caribbean gorgonian Pseudopterogorgia rigida contained mochiquinone 560 along with known aromatic sesquiterpenes.³⁸⁷ (+)-Curcuphenol 561, (−)-curcuquinone 562 and (+)-curcuhydroquinone 563, which are antimicrobial metabolites of Pseudopterogorgia rigida,³⁸⁸ have been synthesised by using Brewer's yeast to accomplish the resolution step.³⁸⁹ Suberosenone 564, which is a metabolite of Subergorgia suberosa,³⁹⁰ has been synthesized as the corresponding racemate.³⁹¹

The soft coral Cladiella kashmani from Mozambique contained flaccidoxide 13-acetate 565 together with the known compound flaccidoxide 566,³⁹² the absolute stereochemistry of which was determined for the first time.³⁹³ A specimen of Nephthea brassica from Taiwan yielded an unusual cembranoid 567 that incorporated a methylenecyclopropene moiety.³⁹⁴ Lobocrassolide 568 is a cytotoxic cembranoid from a Taiwanese specimen of Lobophytum crassum.³⁹⁵ A Lobophytum sp. from the Philippines contained the cembranoid 569, formally derived by addition of dimethylamine to lobohedleolide, as an HIV-inhibitory agent.³⁹⁶ Three cytotoxic cembranoids, sarcocrassolide 570, crassolide 571 and 13-acetoxysarcocrassolide 572, were isolated from Sarcophyton crassocaule from Taiwan.³⁹⁷ Seven cembranoids 573–579, one of which 573 exhibited significant cytotoxicity, were obtained from Clavularia koellikeri from Okinawa.³⁹⁸ Capillolide 580 was isolated together with known cembranoids from Sinularia capillosa from Hainan Island in the South China Sea.^399,400 As part of a paper describing the synthesis of analogues of uprolides D–G, which are cembranoids from Eunicea mammosa,^401,402 the structures of uprolide F diacetate and uprolide G acetate were revised from 581 and 582 to 583 and 584, respectively.⁴⁰³Pachyclavularia violacea from Papua New Guinea contained two cembranoids, pachyclavulariolides E 585 and F 586, and four simple briaranes, pachyclavulariolides A–D 587–590.⁴⁰⁴ The structure of pachyclavulariolide B 588 was confirmed by X-ray crystallography and pachyclavulariolide F 586 was cytotoxic.⁴⁰⁴ A Sarcophyton sp. from Kalipur Island, India, contained two additional tricyclic diterpenes, sarcophytin B 591, the structure of which was determined by X-ray crystallography and sarcophytin C 592.⁴⁰⁵Sinularia inelegans from Taiwan contained the cytotoxic lobane hydrocarbon 593.⁴⁰⁶

A number of cembranoids from soft corals have been synthesized. The absolute stereochemistry of (+)-11,12-epoxysarcophytol A 594, which was isolated from an Australian Lobophyton sp.,⁴⁰⁷ has been determined by total synthesis.⁴⁰⁸ (+)-11,12-Epoxy-11,12-dihydrocembrene C [(+)-11,12-epoxycembrene C] 595 from Sinularia grayi,⁴⁰⁹ and (−)-7,8-epoxy-7,8-dihydrocembrene C 596 from Sarcophyton crassocaule,⁴¹⁰ have been synthesized by using enantioselective routes.^411,412

There have been a relatively large number of studies of the Caribbean gorgonian Pseudopterogorgia elisabethae, resulting in the discovery of some very interesting diterpenes. A specimen of P. elisabethae from Columbia contained columbiasin A 597, which possessed the new colombiane carbon skeleton.⁴¹³ Cumbiasins A–C 598–600 from the same specimen of P. elisabethae incorporate two more new carbon skeletons called cumbiane and seco-cumbiane, respectively.⁴¹⁴ The same specimen later yielded elisabethin D 601, elisabethin D acetate 602, 3-epi-elisabanolide 603, elisapterosins A 604, B 605, which displayed strong in vitro anti-tuberculosis activity, and elisapterosins C 606, elisabatin C 607, elisabetholide 608, the benzoquinone 609, amphilectolide 610, 4-acetylamphilectolide 611 and amphiphenalone 612.^415–417 The structures of elisabethin D 601, 3-epi-elisabanolide 603 and elisapterosin B 605 were determined by using X-ray crystallography.⁴¹⁵ Elisabethamine 613 is a diterpene alkaloid from P. elisabethae from the Florida Keys.⁴¹⁸ Elisabethatriene 614 was identified as a key intermediate in the biosynthesis of the pseudopterosins in P. elisabethae.⁴¹⁹ The structures of the aglycone of pseudopterosins G–J from P. elisabethae⁴²⁰ and helioporin E from Heliopora coerulea⁴²¹ were revised from 615 and 616 to 617 and 618 respectively as the result of a total synthesis.⁴²² 12-Acetoxypseudopterolide 619 from P. elisabethae from the Florida Keys showed modest anti-cancer activity.⁴²³ A specimen of P. bipinnata from Columbia contained the dimeric pseudopterane, biskallolide A 620, which appears to be a solvolysis product of kallolide.⁴²⁴ The same specimen of P. bipinnata also contained seco-bipinnatin J 621, bipinnatolide K 622 and verrillin 623.^425,426 Among the fish feeding inhibitors isolated from the Brazilian gorgonian Lophogorgia violacea were two additional lophotoxin derivatives, 7-acetoxy-8-hydroxylophotoxin 624 and 3-methoxy-8-hydroxylophotoxin 625.⁴²⁷

As part of a paper that reported the absolute configurations of xeniolide-A 626 and xenialactol 627, a new xenicane-type diterpene, xeniaoxolane 628, was identified in a Xenia sp. from Okinawa.⁴²⁸ Six additional xenicanes, 11-O-methylflorlide A 629, 2β-epoxyfloridicin 630, xeniafaraunol B 631 and florlides F–H 632–634, were obtained from a Japanese specimen of X. florida.⁴²⁹Acalycigorgia inermis from Korea contained four additional xenicanes, acalycixeniolides D–G 635–638: the structure assigned as acalycixeniolide C in this paper has been reassigned as acalycixeniolide G.⁴³⁰ The structure of coraxeniolide-A 639, which is a metabolite of the pink coral Corallium sp.,⁴³¹ has been confirmed by total synthesis.⁴³²

The gorgonian Muricella sp. from Korea contained muricellin 640, which is a diterpenoid of the cladiellin class that is mildly cytotoxic and inhibits phospholipase A₂.⁴³³ The structures of sclerophytins A and B, which were originally isolated from Sclerophytum capitalis from Eniwetak,⁴³⁴ have been revised from 641 and 642 to 643 and 644, respectively.⁴³⁵ Two total syntheses of the proposed structure 641 of (−)-sclerophytin A clearly disproved the proposed structure.^436,437Eunicella cavolinii from Marseille contained eight additional cladiellins 645–652, while E. singularis from the same location contained three related metabolites 653–655.⁴³⁸ Anthoptilides A–E 656–660 are relatively simple members of the briarane class from the Australian sea pen Anthoptilum cf. kukenthali: anthoptilides B 657 and C 658 inhibited the binding of [³H]-1,3-dipropyl-8-cyclopentylxanthine on adenosine A₁ receptors.⁴³⁹ Umbraculolides B–D 661–663 are additional briaranes from the Indian gorgonian Gorgonella umbraculum.⁴⁴⁰ A Japanese Briareum sp. has yielded three additional briaranes, violides N–P 664–666, of which violide N 664 exhibited moderate cytotoxicity.⁴⁴¹ Junceellolides E–G 667–669 are additional briaranes from the gorgonian Junceella fragilis from Taiwan.⁴⁴² The gorgonian Erythropodium caribaeorum from several sites in the Southern Caribbean contained the known microtubule stabilizing compound eleutherobin 670, which had previously been isolated from a rare Eleutherobia sp. from Western Australia,⁴⁴³ together with desmethyleleutherobin 671, desacetyleleutherobin 672, isoeleutherobin 673, Z-eleutherobin 674, caribaeoside 675 and caribaeolin 676.⁴⁴⁴

Two 17β,20β-epoxysterols 677 and 678 and a dihydroxygorgost-5-ene 679 were obtained from the Indian Ocean soft coral Sarcophyton crassocaule.⁴⁴⁵ The gorgonian Acalycigorgia inermis from Korea contained three cytotoxic sterols 680–682.⁴⁴⁶ Melithasterol A 683, which is a metabolite of the gorgonian Melithaea ocracea,⁴⁴⁷ has been synthesized from the corresponding sterol peroxide by microwave irradiation.⁴⁴⁸ The soft coral Sinularia inexplicata from the South China Sea yielded 24-methylenecholesta-3β,6β,9α,19-tetraol 684.³⁵² Three cytotoxic steroids, (20S)-20-hydroxycholestane-3,16-dione 685, (16S,20S)-16,20-dihydroxycholestan-3-one 686 and (20S)-20-hydroxycholest-1-ene-3,16-dione 687, were obtained from the Spanish gorgonian Leptogorgia sarmentosa.⁴⁴⁹ The soft coral Sarcophyton trocheliophorum from Singapore contained a cytotoxic steroid 688, the side-chain stereochemistry of which remains to be determined.⁴⁵⁰ Sarcoaldosterol A 689 is an antifungal agent from a Heteroxenia sp. from the Philippines.³⁸² The structure of hippuristerone A 690, which was obtained from the Taiwanese gorgonian Isis hippuris, was determined by X-ray crystallography.⁴⁵¹ The polyhydroxylated sterol 691 from an Indian Ocean specimen of Gorgonella umbraculum contained an unusual side-chain ketal functionality.⁴⁵² Six 1-ketosterols, yonasterols A–F 692–697 were isolated from an Okinawan specimen of Clavularia viridis.⁴⁵³ The Japanese octacoral Dendronephthea gigantea is the source of dendronesterols A 698 and B 699, the latter of which was mildly cytotoxic.⁴⁵⁴ The Caribbean gorgonian Eunicella laciniata contained a new gorgosterol derivative, gorgostane-3β,5α,6β,9α,11α-pentaol 700, as well as gorgost-5-ene-3β,9α,11α-triol 701, the stereochemistry of which was determined for the first time.⁴⁵⁵ The cytotoxic sterol peroxide, (22R,23R,24R)-5α,8α-epidioxy-22,23-methylene-24-methylcholest-6-en-3β-ol 702, was isolated from a Sinularia sp. from Taiwan.⁴⁵⁶ The Caribbean gorgonian Pseudopterogorgia americana contained two cytotoxic secosterols, 1β,3β-dihydroxy-5α,6α-epoxy-9-oxo-9,11-secogorgostan-11-ol 703 and 3β-hydroxy-5α,6α-epoxy-9-oxo-9,11-secogorgostan-11-ol 704.⁴⁵⁷ Riiseins A 705 and B 706 are cytotoxic sterol glycosides from the Brazilian octocoral Carijoa (Telesto) riisei.⁴⁵⁸

8 Bryozoans

There have been no new compounds formally identified from bryozoans although three syntheses of bryozoan metabolites were reported. The structure of an orange anthrathiophene pigment 707 from a Japanese bryozoan⁴⁵⁹ was confirmed by total synthesis.⁴⁶⁰ Convalutamines A 708, C 709 and F 710, together with the yet to be reported lutamides A 711 and C 712, which are metabolites of Amathia convoluta from Florida,^461,462 have all been synthesized in a straightforward manner.⁴⁶³ Bryostatin 3 713, which is a cytotoxic metabolite of Bugula neritina,⁴⁶⁴ has been synthesized in an enantioselective manner.⁴⁶⁵

9 Molluscs

The benefits of examining different collections of shell-less marine molluscs is illustrated by the finding that a recollection of the sea hare Stylocheilus longicauda from Black Point, Oahu, contained a different suite of metabolites than had previously been obtained from specimens from Kaheohe Bay, Oahu. The new collection contained makalika ester 714, makalikone ester 715, which is mildly cytotoxic, lyngbyatoxin A acetate 716, which occurs as a 5 ∶ 1 mixture of conformers, and malyngamides O 717 and P 718, all of which are thought to be metabolites of the cyanobacterium Lyngbya majuscula.^466,467 A specimen of Aplysia sp. from Madagascar contained a non-halogenated sesquiterpene 719 that is probably the rearrangement product of a known chamigrane.⁴⁶⁸ Three collections of A. dactylomela from Tenerife contained three new sesquiterpenes, puertitol B acetate 720, caespitenone 721 and 8-acetylcaespitol 722, and two new diterpenes, dactylopyranoid 723 and isopinnatol B 724, as well as a number of known metabolites of red algae of the genera Laurencia and Plocamium, the bioactivity profiles of which are reported.⁴⁶⁹

The sacoglossan Elysia ornata contained kahalalide O 148, a metabolite of the green alga Bryopsis sp. on which it feeds.¹¹⁴ The structure of kahalalide B 725, which was isolated from both E. rufescens and Bryopsis sp.,⁴⁷⁰ has been confirmed by total synthesis.⁴⁷¹ The sacoglossan Ascobulla ulla from the Mexican Caribbean coast contained the sesquiterpenes ascobullins A 726 and B 727, which resemble metabolites of green algae: the stereochemistry about the 3,4-double bond in ascobullin B 727 was not determined.⁴⁷² (1S,6R)-Volvatellin 728, which is a metabolite of the herbivorous mollusc Volvatella sp.,⁴⁷³ has been synthesized from oxytoxin-1, a metabolite of the green alga Caulerpa taxifolia,⁴⁷⁴ in a highly diastereoselective manner.⁴⁷⁵

A collection of the sacoglossan Placobranchus ocellatus from the Philippines contained six additional polypropionate pyrones, tridachiapyrones G–J 729–732 and tridachiahydropyrones B 733 and C 734.⁴⁷⁶ In a paper describing the isolation of the rearranged polypropionate siserrone A 735 from Siphonaria serrata from South Africa, the natural product status of rearranged polypropionates, particularly the baconipyrones from S. baconi,⁴⁷⁷ was questioned.⁴⁷⁸ The absolute stereochemistry of (−)-baconipyrone C 736 was determined by an asymmetric total synthesis.⁴⁷⁹ Prostaglandin E₂-1,15-lactone 737, which was isolated from the nudibranch Tethys fimbria,⁴⁸⁰ has been synthesized in a stereoselective manner by using a ring-closing alkyne metathesis reaction.⁴⁸¹ The dorid nudibranch Jorunna funebris from the Mandapam coast of India, found on a sponge of the genus Oceanapia, contained the cytotoxic isoquinoline alkaloid jorumycin 738.⁴⁸² The stereochemistry of janolusimide 739, which is a tripeptide neurotoxin from the nudibranch Janolus cristatus,⁴⁸³ has been determined by total synthesis.⁴⁸⁴ A total synthesis of the proposed structure, which was based on molecular modelling of a “dummy” metal chelate, of ulapualide A 740, which was isolated from the egg-masses of Hexabranchus sanguineus,⁴⁸⁵ suggested that the proposed relative stereochemistry differed from that of the natural product at one of the stereogenic centers in the side chain.⁴⁸⁶ Five alkyl phenols 741–745, which are proposed to be alarm pheromones of the cephalaspidean mollusc Haminoea callidegenita,⁴⁸⁷ have been synthesized by using a convergent strategy based on a Stille coupling reaction.⁴⁸⁸ Costa Rican specimens of Glossodoris sedna contained two new sesterterpenes 746, an inhibitor of phospholipase A₂, and 747, while specimens of G. dalli from the same location contained different but known sesterterpenes.⁴⁸⁹ Two groups have synthesized (+)-albicanol 748 and (+)-albicanyl acetate 749, which are metabolites of the nudibranch Cadlina luteomarginata,⁴⁹⁰ by resolving key intermediates using lipase-catalyzed acetylations.^491,492 A full paper on the synthesis of (±)-2-isocyanoallopupukeanane 750, which is a metabolite of Phyllidia pustulosa,⁴⁹³ has been published.⁴⁹⁴ A general method for the synthesis of chiral glycerides of diterpenes such as 751 and 752 from Archidoris montereyensis,⁴⁹⁵ has been reported.⁴⁹⁶

Pinnamine 753 is an alkaloidal toxin from the viscera of the bivalve Pinna muricata from Okinawa.⁴⁹⁷ Experimental details of the isolation of turbotoxins A 754 and B 755 from the gastropod Turbo marmorata have been presented.⁴⁹⁸ A new analogue of yessotoxin, carboxyyessotoxin 756, has been isolated from DSP (diarrhetic shellfish poisoning)-infested mussels Mytilus galloprovincialis from the Italian coast of the Adriatic Sea.⁴⁹⁹ The absolute configuration at C-45 in 45-hydroxyyessotoxin 757, which was isolated from shellfish, has been determined by using the modified Mosher's method.⁵⁰⁰ The bivalve Callista chione from the Aegean Sea contained 1,1′-dimethyl-[2,2′]-bipyridyldiium salt 758, which had previously been synthesized⁵⁰¹ but had not been reported as a natural product.⁵⁰²

10 Tunicates (ascidians)

A collection of Cystodytes cf. dellechiajei from Tunisia contained a medley of sphingosines 759, of which only one sphingosine 760 was characterized, that inhibited phospholipase A₂ and the corresponding ceramides 761.⁵⁰³ A major cyclic peroxide, stolonoxide A 762, and the minor peroxides, stolonoxides B 763, C 764 and D 765, were isolated as both the free acids and the corresponding sodium salts from the Mediterranean tunicate Stolonica socialis.^504,505 Stolonic acids A 766 and B 767 were isolated as the cytotoxic metabolites of a Stolonica sp. from the Indian Ocean.⁵⁰⁶ The Mediterranean ascidian Halocynthia papillosa contained two additional cytotoxic sulfates, 6-methylheptyl sulfate 768 and (E)-oct-5-enyl sulfate 769.⁵⁰⁷ The stereochemistry of cyclodidemniserinol trisulfate 770, which was isolated from a Palauan specimen of Didemnum guttatum as an inhibitor of HIV-1 integrase, was only partially determined.⁵⁰⁸ An unidentified tunicate of the family Polyclinidae from Ukeshima Island, Japan, contained the cytotoxic amino alcohols, amainols A 771 and B 772.⁵⁰⁹ Pseudodistomin F 773, which is a metabolite of Pseudodistoma kanoko,^510,511 has been synthesized by using a general method to construct 2,4,5-trisubstituted piperidines from enantiopure β-amino esters.⁵¹² (−)-Lepadin B 774, which was isolated from Clavelina lepadiformis and the flatworm Prostheceraeus villatus,⁵¹³ has been synthesized in an enantioselective manner.⁵¹⁴ Two groups^515,516 have synthesized piclavines A1 775 and A2 776, which are metabolites of Clavelina picta,⁵¹⁷ and one of these groups has also prepared piclavines A3 777 and A4 778.⁵¹⁶ The structure of fascicularin 779, which was isolated from Nephteis fascicularis,⁵¹⁸ has been confirmed and the structure of lepadoformine, a metabolite of C. lepadiformis,⁵¹⁹ has been revised from 780 to 781 as a result of the total synthesis of their racemates by using a stereocontrolled intramolecular Diels–Alder reaction.^520,521 Dytesinins A 782 and B 783 are cyclopropane-containing diterpenes from an Okinawan species of Cystodytes.⁵²²

Six additional brominated aromatic pigments, rubrolides I–N 784–789, some of which showed significant cytotoxicity, were isolated as minor constituents of Synoicum blochmanni from Spain.⁵²³ The related metabolites prepolycitrin A 790 and polycitone B 791 were isolated as minor metabolites of Polycitor africanus from Madagascar.⁵²⁴ The structure of polycitrin B 792, which is an alkaloid isolated from Polycitor sp.,⁵²⁵ has been confirmed by total synthesis.⁵²⁶ Ningalin C 793, which was isolated from an unidentified Didemnum sp.,⁵²⁷ has been synthesized in five steps with an overall yield of 19%.²⁴⁷ The related metabolite, ningalin B 794, was synthesized and shown to be a multi-drug resistant reversal agent.⁵²⁸ Lamellarin L 795, which is a metabolite of a Didemnum sp.,⁵²⁹ has been synthesized by using a biomimetic strategy.⁵³⁰ Meridianins C–E 796–798, which are metabolites of Aplidium meridianum,⁵³¹ have been synthesized in good yields from appropriately substituted N-protected 3-acylindoles.⁵³² Meridianin D 797 was synthesized by using a palladium catalyzed cross-coupling reaction as the key step.⁵³³ An improved synthesis of isogranulatimide 799, which is a G2 checkpoint inhibitor from Didemnum granulatum,⁵³⁴ has been reported together with the syntheses of a variety of derivatives.⁵³⁵ The structure of rhopaladin D 800, which is an antibacterial agent from an Okinawan Rhopalaea sp.,⁵³⁶ has been confirmed by total synthesis.⁵³⁷ The human C-glycoconjugate C²-α-D-mannosylpyranosyl-L-tryptophan 801 was isolated from Leptoclinides dubius and Pharyngodictyon cauliflos and its N^α-methyl derivative 802 was obtained from Ritterella rete.⁵³⁸ The structure of cystodamine, which is a pentacyclic aromatic alkaloid from the Mediterranean ascidian Cystodytes delle chiajei,⁵³⁹ has been revised from 803 to 804 as a result of synthetic studies.⁵⁴⁰ Cycloshermilamine D 805, which was isolated in minute amounts from Cystodytes violatinctus from the Comoros Islands, is an additional alkaloid of the pyridoacridine group that possesses a new heterocyclic ring system.⁵⁴¹ The structures of arnoamines A 806 and B 807, which are pyridoacridine alkaloids from a Cystodytes sp. from Arno Atoll,⁵⁴² have been confirmed by total synthesis.⁵⁴³ The syntheses of ascididemin 808 and 11-hydroxyascididemin 804, which are metabolites of Didemnum and Leptoclinides species, respectively,^544,545 employ similar methodologies.^546,547 As part of a structure–activity study, ascididemin 808 and a number of analogs were synthesized and evaluated in a wide range of assays.⁵⁴⁸ The N-methylpyridinium alkaloid sulcatin 809 from a Mediterranean specimen of Microcosmus vulgaris showed interesting in vitro antiproliferative activity.⁵⁴⁹

As part of a paper that described the use of NOE-restrained molecular dynamics to confirm the absolute stereochemistry of lissoclinamides from an Indonesian specimen of Lissoclinum patella, two additional cyclic peptides, lissoclinamides 9 810 and 10 811, were described.⁵⁵⁰ Prepatellamide A 812 was isolated as a minor metabolite of an Indonesian specimen of L. patella.⁵⁵¹ The configuration of cyclodidemnamide, which was isolated from Didemnum molle,⁵⁵² has been reassigned from 813 to 814 as a result of its total synthesis.⁵⁵³ A similar synthetic strategy allowed the configurations of lissoclinamides 4 and 5, which are metabolites of L. patella,⁵⁵⁴ to be revised from 815 and 816 to 817 and 818, respectively.⁵⁵⁵ The structure of trunkamide A, which is a metabolite of an Australian Lissoclinum sp.,⁵⁵⁶ has been revised from 819 to 820 as the result of a total synthesis.⁵⁵⁷ The cytotoxic cyclic depsipeptides tamandarins A 821 and B 822, which are related to the didemnins, were isolated from an unidentified didemnid ascidian from Brazil.⁵⁵⁸ The structure of tamandarin B 822 has been confirmed by total synthesis⁵⁵⁹ by the same group that reported the synthesis of tamandarin A 821 last year.⁵⁶⁰ Plicatamide 823 is a modified octapeptide from the blood of a San Diego Bay specimen of Styela plicata.⁵⁶¹ The structure of 2,5-bis(6′-bromo-3′-indolyl)piperazine 824, which is a metabolite of Didemnum candidum,⁵⁶² has been confirmed by employing a 4 step synthesis.²⁸³ An efficient synthesis of ecteninascidin 743 825, which is a cytotoxic agent from Ecteinascidia turbinata,^563,564 from the fermentation product cyanosafracin B 826 can provide a sufficient quantity for clinical trials.⁵⁶⁵ (−)-Eudistomins C 827, E 828, F 829, K 830 and L 831, which are metabolites of Eudistoma olivaceum,⁵⁶⁶ have been synthesized from the corresponding N-hydroxytryptamines and D-cysteinal.⁵⁶⁷ 1,3,7-Trimethylisoguanine 832 is a new purine derivative from a New Zealand collection of Pseudodistoma cereum.⁵⁶⁸

11 Echinoderms

The number of papers reporting the chemistry of echinoderms is steadily declining. Two additional gangliosides, acanthagangliosides I 833 and J 834 were obtained from an Okinawan specimen of the sea star Acanthaster planci.⁵⁶⁹Linckia laevigata from Vietnam contained a ganglioside 835 with an 8-O-methyl-N-glycylneurmic acid residue.⁵⁷⁰ The same residue was found in less well defined gangliosides from the sea star Evasterias ecinosoma.⁵⁷¹ The Japanese sea cucumber Holothuria pervicax contained the trisialo-ganglioside HPG-7 836, which showed neuritogenic activity toward the PC-12 rat pheochromocytoma cell line.⁵⁷² Pucherrimine 837 is a bitter-tasting amino acid from the ovaries of the Japanese sea urchin Hemicentrotus pulcherrimus.⁵⁷³

The metabolite of the seastar Plazaster borealis that induced an avoidance reaction in the sea urchin Strongylocentrotus nudus was identified as (3β,5α,6α,23S)-cholest-9(11)-ene-3,6,23-triol 3,6-disulfate disodium salt 838.⁵⁷⁴ A reinvestigation of the polar constituents of the seastar Aphelasterias japonica from the Russian shore of the Sea of Japan resulted in the isolation of aphelasteroside C 839 and aphelaketotriol 840 together with known saponins.⁵⁷⁵ An additional steroidal glycoside, asterosaponin P₂841, has been isolated from Patiria (Asterina) pectinifera collected at the Sea of Japan.⁵⁷⁶ The Antarctic seastar Labidiaster annulatus contained labidiasteroside A 842 and (25S)-5α-cholestane-3β,6β,15α,16β,26-pentaol 843.⁵⁷⁷ The seastar Goniopecten demonstrans contained the saponins goniopectenosides A–C 844–846 that significantly inhibited settlement of the biofouling alga Hincksia irregulatus.⁵⁷⁸ Ruberosides A–D 847–850, the structures of which were elucidated by using LC-NMR-MS, are steroidal saponins from the Baltic seastar Asterias rubens.⁵⁷⁹ Studies of the sea cucumber Pentamera calcigera from the Gulf of Peter the Great have resulted in the identification of calcigerosides B 851, C₁852, C₂853, D₁854, D₂855 and E 856.^580,581

12 Miscellaneous

The crustacean Ligia exotica from Korea contained 3′-O-(α-D-glucosyl)inosine 857, the structure of which was confirmed by total synthesis.⁵⁸² One of the sexual pheromones of the hair crab Erimacrus isenbeckii was identified as ceramide 858, which is only one of a group of homologous ceramides.⁵⁸³ Cypridina luciferin 859, which is involved in the bioluminescence of the crustacean Cypridina hilgendorfi,⁵⁸⁴ has been synthesized as the racemate by using Pd-mediated cross-coupling reactions.⁵⁸⁵ (+)-Bromoxone 860, which is a metabolite of the acorn worm Ptychodera sp.,⁵⁸⁶ has been prepared in an enantiopure form by using an enzymatic resolution.⁵⁸⁷ The total synthesis of lipogrammistin-A 861, which was isolated from the skin mucus of the soapfish Diploprion bifasciatum and Aulacocephalus temmincki,⁵⁸⁸ employs an efficient macrolactonization step.⁵⁸⁹ Seven additional aminosterols 862–868 have been obtained as antimicrobial agents from the liver of the dogfish shark Squalus acanthias.⁵⁹⁰ Muscle tissue of the reef fish Abudefduf vaigiensis contained significant amounts of trimethy(2-carboxyethyl)arsonium inner salt 869.⁵⁹¹

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