Diterpenoids of terrestrial origin

Contents

• 1 Introduction

• 2 Acyclic and related diterpenoids

• 3 Bicyclic diterpenoids
  • 3.1 Labdanes
  • 3.2 Halimanes and clerodanes

• 4 Tricyclic diterpenoids
  • 4.1 Pimaranes
  • 4.2 Abietanes
  • 4.3 Cassanes

• 5 Tetracyclic diterpenoids

• 6 Macrocyclic diterpenoids and their cyclization products

• 7 Miscellaneous diterpenoids

• References

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Abstract

Covering January to December 2015. Previous review; Nat. Prod. Rep., 2015, 32, 1654–1663.

This review covers the isolation and chemistry of diterpenoids from terrestrial as opposed to marine sources and includes labdanes, clerodanes, abietanes, pimaranes, kauranes, cembranes and their cyclization products. There are 214 references.

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1 Introduction

This report covering the period January to December, 2015, follows the pattern of its predecessors^1,2 and includes the identification and chemistry of diterpenoids of terrestrial as opposed to marine origin. The latter are covered in the articles on marine natural products.³ Traditional Chinese medicines have continued to be a treasure trove of novel diterpenoids. Many of these warrant a further examination of their structure–biological activity relationships in order to identify the pharmacophores. There are a number of diterpenoids that are sufficiently abundant to provide suitable starting materials for partial synthesis. Several studies in this context have been reported during the year including work on the abietane diterpenoids. This has been reviewed.^4,5

Advances in the synthesis of multi-functionalized decalins,⁶ the bicyclo[3,2,l]-octane system of the ent-kauranoids,^7,8 the atisane diterpenoids,⁹ the neodolastanes,¹⁰ the pseudopterosin aglycones,¹¹ and vinigrol,¹² together with the use of dehydrogenation to access diterpenoid degradation products that are found in the environment,¹³ have all been reviewed. Other articles on the diterpenoid composition of Pinus sibirica¹⁴ and various aspects of the diterpene biosynthetic synthases including their genetics, have appeared.^15,16 Genetic studies have led to the identification of diterpene gene clusters¹⁷ and of silent pathways that can be activated to produce diterpenoids.¹⁸

2 Acyclic and related diterpenoids

The syntheses of C-8, C-9 and C-10 deuteriated geranylgeraniols have been reported.¹⁹

3 Bicyclic diterpenoids

3.1 Labdanes

Labdanolic acids have been identified as biomarkers for the botanical origin of French ambers²⁰ whilst copalic acid and its relatives have been associated²¹ with the biological activity of the resins from Copaifera species. The lanceolatanols, including some rare hydroperoxides such as the 12-hydroperoxide 1, have been isolated²² from the Chinese fir, Cunninghamia lanceolata (Cupressaceae) which is grown in plantations for timber production. The lanceolatins A–G (e.g. A, 2) are a group of labdanes and abietanes which were obtained²³ from Cephalotaxus lanceolata (Cephalotaxaceae). Some of the abietanes described in this paper were formulated without comment, as a dienone tautomer of a phenol.

A number of the labdanes which have been found in members of the Zingiberaceae, e.g. Alpinia japonica,²⁴Curcuma longa²⁵ and Hedychium longipetalum²⁶ such as the hedylongnoids A–C (e.g. A, 3), inhibit the production of nitric oxide. The paraguhenryisins A–D (e.g. C, 4) which were isolated²⁷ from the capitate glandula trichomes of Paragutzlaffi henryi (Acanthaceae), have phytotoxic properties and may provide a defensive measure against other invasive plants. The absolute configuration at C-14 of the labdanes from Physalis nicandroides (Solanaceae) has been established.²⁸

Labdane glycosides have been reported²⁹ as constituents of Diplopterygium rufopilosum (Gleicheniaceae) whilst examination of the seeds and leaves of Colophospermum mopane [Fabaceae (Leguminosae)]³⁰ and Leonotis leonurus (Lamiaceae)³¹ has yielded some further labdanes and clerodanes. Continued examination of Leonurus japonicus gave leojaponin D³² whilst the macranthins (e.g. A, 5) were anti-inflammatory labdanes which were obtained³³ from L. macranthus. Further studies on white horehound (Marrubium vulgare, Lamiaceae) afforded³⁴ 12(S)-hydroxymarrubiin. The structure 6 has been assigned³⁵ to cinereanoid A which was isolated from Roylea cinerea (Lamiaceae) whilst the vitexolides A–E were similar anti-bacterial γ-hydroxy-αβ-unsaturated 15→16-lactones which were obtained³⁶ from Vitex vestita (Lamiaceae).

Isodon species (Lamiaceae) are renowned for the tetracyclic diterpenoid constituents of their leaves. However examination of the roots of I. adenantha afforded³⁷ the labdanes, adenanthic acids A and B (e.g. A, 7) and the adenanthosides A–C whilst two other labdanes were obtained³⁸ from I. yuennanensis.

A large number of labdanes have been detected in Chinese liverworts including the haplomintrins (e.g. A, 8) from Haplomitrium minioides³⁹ in which a cyclobutane ring has been formed by the possible photochemical addition of a side-chain furan across the double bond of a 7,8-en-6-one. Other examples of labdanes which have been isolated include the ptychantins P and R from Ptychanthus striatus⁴⁰ and the scapairrins A–Q from Scapania irrigua.⁴¹

Various methods for the recovery of useful compounds from Stevia rebaudiana (Asteraceae) have been reviewed.⁴² The fermentation of S. rebaudiana with the yeast Saccharomyces cerevisiae has led⁴³ to the formation of some modified sterebins arising from the selective epoxidation and hydration of the 14,15-double bond. Examination of the Taiwanese shrub, Callicarpa randaiensis (Verbenaceae) in the search for anti-inflammatory agents afforded⁴⁴ the randainins A–D. As an alternative to the biosynthesis suggested in the original paper, their structures (e.g. A, 9) may arise by the oxidative cleavage of a 5,10-double bond of a halimane followed by aldol condensations of the 5,10-diketone to form the trans 7/5 and 5/7 ring systems of these diterpenoids.

The cleavage of ring A has been encountered in a number of diterpenoids including labdanes. A 3-nor-2,3-secolabdane structure 10 has been assigned⁴⁵ to penioxalicin which was obtained from the fungus, Penicillium oxalicum and to paecilomycine A from an insect pathogenic fungus, Paecilomyces sp.⁴⁶ Further examination⁴⁷ of the stems of the highly poisonous mangrove plant, Excoecaria agallocha (Euphorbiaceae) gave excolide 11 in a study which also led to a revision of the structure of rhizophorin A. The structure of the spiro-ketal, leonuketal 12 obtained⁴⁸ from Leonurus japonicus, may be derived by a retro-Prins cleavage of the 8 : 9-bond in a 7,9-dihydroxylabdane followed by a cyclization involving the 3-hydroxyl group, the 9-ketone and C-15.

Derivatives of the readily available labdanes such as polyalthic acid⁴⁹ and copalic acid⁵⁰ have been evaluated for the treatment of various diseases. The merosesquiterpenes, neopterosiquinones A and B have been synthesized⁵¹ from trans-communic acid. The anti-fungal activity of sclareol⁵² and some derivatives⁵³ has been examined. Sclareol has been used⁵⁴ as the starting material for the synthesis of the sesterterpenes, luffarin L and 16-epiluffarin and for a biomimetic synthesis of two salmahyrtisanes.⁵⁵ Work has continued^56–58 to prepare derivatives of andrographolide in order to study structure–biological activity relationships. The enzyme systems responsible for the biosynthesis of 13(R)-manoyl oxide have been transferred⁵⁹ from Sitka spruce to a cyanobacterium, Synechocystis sp.

3.2 Halimanes and clerodanes

18-Hydroxy-ent-halima-1(10),13(E)-dien-15-oic acid has been isolated⁶⁰ from Hymenaea stigonocarpa (Fabaceae) whilst investigations of the anti-microbial activity of Vellozia kolbekii (Velloziaceae) afforded⁶¹ 15,16-dihydroxy-ent-halima-1(10)-ene. The halimane structure 13 has been assigned⁶² to isoleojaponin from Leonurus japonicus.

The clerodane pyrrole 14 was amongst⁶³ the anti-plasmodial constituents of Polyalthia longifolia varⁿ.pendula (Annonaceae), the bark of which is used in West African folk medicine for the treatment of malaria. 2β-Acetoxyhardwickiic acid and a number of other clerodanes were anti-bacterial constituents of Salvia adenophora (Lamiaceae)⁶⁴ and S. buchananii.⁶⁵ Further structural modifications of salvinorin have been made⁶⁶ including some 2-alkyl-2-methoxymethyl ethers in order to examine its structure–activity relationships as a selective κ-opioid receptor agonist. ent-2β,18,19-Trihydroxycleroda-3,13-dien-15,16-olide has been obtained⁶⁷ from Crassocephalum bauchiense (Asteraceae) which is a herb that is used in Cameroon folk medicine. The dichrocephnoids A–E (e.g. A, 15) which possess anti-HIV integrase activity, were isolated⁶⁸ from Dichrocephala benthamii (Asteraceae). Further examination of the Chinese medicinal herb, Scutellaria barbata (Lamiaceae) has led to the isolation of the anti-viral scutolides A–L (e.g. A, 16)⁶⁹ and the scutebatins A–C⁷⁰ which inhibit NO production. The scutefolides (e.g. A, 17) were obtained⁷¹ from S. coleifolia whilst the teufruintins A–G (e.g. A, 18) were obtained⁷² from the aerial parts of the herb, Teucrium fruticans (Lamiaceae) which had been cultivated in China. Examination of Isodon scoparius (Lamiaceae) afforded⁷³ the scopariusicides A 19 and B which were unusual cyclobutane derivatives which were formed by the cycloaddition of an ester of 4-hydroxycinnamic acid to the clerodane side chain. The unusual spirocyclic ring system 20 which may be derived from a clerodane, has been assigned⁷⁴ to teotihuacanin, which was obtained from the Mexican plant, Salvia amarissima. It has shown activity against multi-drug resistance in cancer cells.

A number of new cis-clerodanes have been isolated including linarenone A from Linaria japonica (Plantaginaceae),⁷⁵ the crotocurins A–C from Croton europhyllus (Euphorbiaceae)⁷⁶ and the graveopenes A–J (e.g. A, 21) from Casearia graveolens (Flacourtiaceae).⁷⁷ The latter were shown to stimulate NGF-mediated neurite out-growth which is of interest in the context of neuron degeneration in Alzheimer's disease. The related caseagrewifolins were obtained⁷⁸ from C. grewifolia. Further examination of Tinospora sagittata (Menispermaceae) gave⁷⁹ tinosporin A and B.

4 Tricyclic diterpenoids

4.1 Pimaranes

The arabinofuranoside of isopimara-7,15-dien-19-ol has been identified⁸⁰ amongst the anti-fungal constituents of Sagittaria latifolia (Alismataceae). A series of isopimaranes known as the kaempulchraols A–I have been obtained^81–83 from the rhizomes of Kaempferia pulchra (Zingiberaceae). Some constituents of the roots of Oryza sativa (rice) including momilactone D 22 have been shown⁸⁴ to inhibit the production of NO. Further studies^85–87 on the tubers of the Nigerian herbal medicine Icacina trichantha (Icacinaceae) have revealed the presence of more 9β-H-pimaranes and some aromatic 17-norpimaranes, the icacinlactones A–H (e.g. A, 23). The xylabisboeins A and B were anti-bacterial pimarane 14,16-ethers which were isolated⁸⁸ from an endophytic Xylaria sp. obtained from the leaves of Bisboeckiera microcephala. Isopimaranes (e.g.24) were amongst⁸⁹ the anti-inflammatory constituents of Dysoxylum gotadhora. A group of 16-norditerpenoids have been obtained⁹⁰ from the aerial parts of Flickingeria fimbriata (Orchidaceae) whilst some pentahydroxypimaranes were isolated⁹¹ from Aerva lanata (Amaranthaceae), a plant which is used in Ayurvedic medicine. The dienone 25 and the corresponding 11,14-α- and β-epidioxides and diols were isolated⁹² from the stems of Croton insularis which was found in the Australian rain forest. A group of rosanes, e.g. stachyrosane I 26 have been reported^93–95 as constituents of Stachys parviflora (Lamiaceae).

4.2 Abietanes

The intervention of quinone methides in the anti-oxidant activity of the phenolic diterpenoids ferruginol⁹⁶ and carnosic acid⁹⁷ has been described. The anti-fungal activity of some abietic acid esters in the context of their use as wood preservatives⁹⁸ and the anti-viral activity of podocarpic acid derivatives⁹⁹ have been examined. The action of a visible light LED on the N-chlorosulfonamide of dehydroabietylamine afforded¹⁰⁰ a 6α-chloro compound. Dehydroabietic acid has been shown¹⁰¹ to regulate liver glucose levels which may be linked to the use of Abies balsamea in a folk medicine treatment for type 2 diabetes. The brevistylumsides A and B, obtained from Illicium brevistylus have been identified¹⁰² as glycosides of dehydroabietic acid. The structure 27 has been assigned¹⁰³ to the o-quinone teuvisone which was obtained from Teucrium viscidum. The dimeric biteuvisones A and B arose by addition of the corresponding o-catechol across the 8,9-bond.

Further examples of diterpenoids in which ring A has been cleaved have been isolated from Salvia species. Thus salviaprione 29 was isolated¹⁰⁴ as a racemate from S. prionitis. It may be formed by the cyclization of salvisyrianone 28. 1-Ketoethiopinone 30 was obtained¹⁰⁵ from the roots of S. sahendica. The diacetate of dihydroethiopinone inhibits the growth of breast cancer cells. The roots of S. grandifolia yielded¹⁰⁶ the grandifolias A–F (e.g. A, 31). These include some modified abietanes arising from the cleavage of ring C. The quinone, caryopterone A possesses a methylcyclopropane ring in place of the isopropyl group of the abietanes. It was isolated¹⁰⁷ from the roots of Caryopteris mongolica (Lamiaceae). Some of the abietanes from this plant showed¹⁰⁸ cholinesterase inhibitory activity. The macrophypenes A–E, obtained¹⁰⁹ from Callicarpa macrophylla (Verbenaceae) included some rearranged abietanes (e.g. A, 32).

The constituents of the genus Chloranthus have been reviewed.¹¹⁰ent-Abietanes have been obtained¹¹¹ from C. henryi whilst the chlorabietols A–C isolated¹¹² from C. oldhamii included an unusual phloroglucinol-abietane adduct (A, 33). Rings B and C have been cleaved in the formation of various sessilifols A–N (e.g. C, 34) obtained¹¹³ from C. sessilifolius.

Further studies on the traditional Chinese medicine Tripterygium wilfordii (Celastraceae) have afforded more highly oxidized 18(4→3)-abeo-abietanoid derivatives including the triptergulides A and B (e.g. B, 35),¹¹⁴ the wilfordosides A and B,¹¹⁵ and the tripterlides A–F (e.g. A, 36)¹¹⁶ in which ring C has also undergone rearrangement. A range of abietanes, pimaranes and kauranes have been isolated¹¹⁷ from T. hypoglaucom.

Examination of the anti-proliferative constituents of Ethiopean Podocarpus falcatus led¹¹⁸ to the isolation of 16-hydroxynagilactone F and a revision of the stereochemistry of 2α-hydroxynagilactone F to the 2β-epimer. The botryosphaerins G and H (e.g. G, 37) which were obtained¹¹⁹ from a Botryospbaeria endophyte of Huperzia serrata, have a seco ring C structure or they may be tetranorlabdanes.

Some further icetexanes have been isolated¹²⁰ from Perovskia atriplicifoiia (Lamiaceae). The hispidanols A and B (e.g. B, 38) were sempervirane relatives which were obtained¹²¹ from the rhizomes of Isodon hispida. The roots of Pygmacopremna herbacea (Verbenaceae), which have been used in Ayurvedic medicine as an anti-inflammatory agent, yielded a quinone which was assigned¹²² the somewhat unusual structure 39 in which ring B has been expanded but the C-20 methyl group has been retained. Another unusual structure 40 involving a curious biosynthesis, has been assigned¹²³ to plebeianiol A which was obtained from Salvia plebeia. Neoboutomannin A 41 isolated¹²⁴ from the West African Neoboutonia macrocalyx (Euphorbiaceae) may be a degraded abietane.

4.3 Cassanes

Cassane diterpenoids are characteristic constituents of the Caesalpiniaceae. Further examination of Caesalpinia bonducella has yielded¹²⁵ the bonducellpins H–P whilst C. crista afforded¹²⁶ the phangininoxys D and E. The echinalides H–U were obtained¹²⁷ from C. echinata. Many of these compounds have been shown to possess anti-inflammatory and anti-oxidative properties. The cassanes from several studies^128–130 of C. minax have been examined in this context. These included the caesalmins I–M¹²⁸ and a seco ring A compound neocaesalminin A 42.¹³⁰ The caesalsappanins A–L (e.g. A, 43) which were isolated¹³¹ from C. sappan, have been studied for their anti-malarial and anti-proliferative activity. Other cassanes have been isolated from Erythrophleum suaveolens¹³² and Swartzia simplex.¹³³ The activation by epigenetic mining of a silent biosynthetic pathway in the fungus Calcarisporium arbuscula led to the isolation¹⁸ of arbusculic acid A 44. A new phytoalexin phytocassane F 45 has been identified¹³⁴ in rice leaves that had been subjected to UV radiation.

The cleistanthanes phyllanembloids A–F (e.g. A, 46) have been obtained¹³⁵ from the roots of Phyllanthus emblica which are used in Chinese traditional medicine.

5 Tetracyclic diterpenoids

The ent-kauranes which have been obtained¹³⁶ from the fruits of Annona glabra (Annonaceae) as part of a study of their anti-inflammatory activity, include 7β,16α,17-trihydroxy-ent-kauran-19-oic acid. 4β,16α,17,19-Tetrahydroxy-18-nor-ent-kaurane has been isolated¹³⁷ from Wedelia trilobata (Asteraceae) whilst some ent-kaurenoic acid glycosides have been found¹³⁸ in Ageratina cylindrica (Asteraceae). It has been estimated that over a thousand diterpenoids, many of which possess interesting biological activity, have been detected in Isodon (Lamiaceae) species. Further examples include the neolaxiflorins I–Y¹³⁹ and the unusual laxiflorol A 47¹⁴⁰ from I. eriocalyx varⁿ.laxiflora. Extraction of I. excisoides,¹⁴¹I. parvifolius¹⁴² and I. scoparius¹⁴³ provided other examples. The 7,20-azakaurenes, kaurines A and B (e.g. A, 48) were isolated¹⁴⁴ from I. rubescens together with a compound containing an unusual 17-succinimide moiety. Xerophilusin B has been shown¹⁴⁵ to induce cell cycle arrest and apoptosis in esophageal squamosus cell carcinoma. The total synthesis of maoecrystal V has been described.¹⁴⁶

The helikaurolides A–D which were obtained from Helianthus annuus varⁿ.arianna, have been assigned¹⁴⁷ structures based on a combination of a sesquiterpene lactone (helivypolide L) and an ent-kauranoic acid.

The steviol glycosides from Stevisa rebaudiana have continued to attract attention particularly in the food industry. The relationship between the conformation of rebaudioside A in solution and its sweetness¹⁴⁸ and molecular modeling studies of the docking of rebaudioside A with the human sweet taste receptor¹⁴⁹ have been reported. Dereplication of the NMR profiles of mixed steviol glycosides¹⁵⁰ and the application of new separation techniques¹⁵¹ have been described. 15α-Hydroxyrebaudioside M has been isolated¹⁵² from S. rebaudiana. The ready availability of isosteviol from the acid-hydrolysis of the mixed glycosides from S. rebaudiana has led to its use as the starting material for a number of studies.^153–156 The X-ray crystal structure of a dimeric isosteviol sulfite has been described.¹⁵⁷

The prinsosides A–C which were isolated¹⁵⁸ from Prinsepia utilis (Rosaceae) included the seco-ring B ent-kaurane (C, 49). Two glycosides, ranunculosides A and B that were isolated¹⁵⁹ from Ranunculus muricatus (Ranunculaceae), were described as ent-kaurane glycosides but were drawn with an ent-phyllocladene structure 50.

Cafestol has been shown¹⁶⁰ to stimulate insulin production and it has been suggested that cafestol may contribute to the effect of coffee on reducing type 2 diabetes. The known furanokaurane, mozambioside 51 has been identified¹⁶¹ as a bitter tasting glycoside that is specific to Coffea arabica as opposed to C. robusta. The tricalysins A–H that were found¹⁶² in Tricalysia fruticosa (Rubiaceae), have been shown to be cafestol relatives and to have anti-inflammatory properties. The frutilactones A and B (e.g. A, 52) were 2,3-seco-cafestol relatives that were isolated¹⁶³ from the same plant.

The gastroprotective activity of some derivatives of 18-hydroxybeyerenes has been described.¹⁶⁴ 2β,12β-Dihydroxygibberellin A₁₂ has been isolated¹⁶⁵ from the leaves of Scheffiera sessiliflora (Araliaceae) in a surprisingly high amount for a gibberellin. The synthesis of pharbinilic acid 53 starting from gibberellic acid has been described.¹⁶⁶ This is an allogibberic acid relative which had been obtained from Morning Glory (Pharbitis nil).

Further grayane diterpenoids have been obtained from the leaves of Rhododendron micranthum (Ericaceae)¹⁶⁷ and R. molle¹⁶⁸ both of which are used in Chinese traditional medicine. The total synthesis of atisane diterpenoids has been reported.¹⁶⁹ The biological activity of scopadulciol has been examined.¹⁷⁰

6 Macrocyclic diterpenoids and their cyclization products

Diterpenoids with the cembrane skeleton have been found in various resins. Thus the resin of the North American Bursera microphylla (Burseraceae) afforded¹⁷¹ microphyllanin 54 whilst the frankincense from Boswellia carterii (Burseraceae) yielded¹⁷² a further group of cembranoids including the boscartins. The regioselective oxidation of the tobacco component, β-cembranediol at C-9 and C-10 using cytochrome P₄₅₀ variants has been studied.¹⁷³ Some casbanes, e.g. pekinenin G 55 have been isolated¹⁷⁴ from Euphorbia pekinensis. A relative, sapidisin A was obtained¹⁷⁵ from Sapium discolor (Euphorbiaceae).

Preparative methods have been described¹⁷⁶ for the isolation of paclitaxel (taxol®) and of further taxanes from Taxus chinensis (T. wallichiana varⁿ.mairei).¹⁷⁷ The modification of the structure of ring D-seco-taxanes in the context of microtubule interactions has been examined.¹⁷⁸ Further synthetic studies directed at paclitaxel continue to be reported.¹⁷⁹

A large number of esters of jatrophanes, lathyranes, myrsinanes, daphnanes, tiglianes and ingenanes have been isolated, particularly from members of the Euphorbiaceae and Thymelaeaceae. Care must be taken in the separation of these compounds to avoid conditions that may lead to acyl migration and transesterification. The juxtaposition and consequent interactions between functional groups provide ample opportunities for these reactions in this closely related series of compounds and indeed may contribute to their biological activity. Molecular modeling and advanced NMR methods have been used in locating esters in the jatrophanes of Euphorbia amydaloides.¹⁸⁰ Some cytotoxic lathyranes including lathyranlactone and jatrocurcusenone A have been isolated¹⁸¹ from Jatropha curcas cv. nigroviens rugosus whilst further jatrophane and myrsinane esters have been obtained from E. connata,¹⁸²E. dracunculoides,^183–185E. exigua.¹⁸⁶E. osyridea,¹⁸⁷E. prolifera,¹⁸⁸ and E. wallichii.¹⁸⁹ A 12,17-cyclojatrophane, euphowelwitschine A 56 was isolated¹⁹⁰ from E. weiwitschii. Venenatin 57 which had been obtained from Excoecaria venenta (Euphorbiaceae), showed¹⁹¹ inhibitory effects on human leukaemia cells. Further daphnane esters have been isolated from Trigonostemon xyphophylloides (Euphorbiaceae),¹⁹²Daphne genkwa (Thymelaeaceae),¹⁹³Gnidia polycephela (Thymelaeaceae),¹⁹⁴ and Stellera chamaejasme (Thymelaeaceae)¹⁹⁵ whilst some more tigliane (phorbol) esters with cytotoxic and anti-viral activity were obtained from Croton tiglium (Euphorbiaceae),^196,197Daphne aurantica,¹⁹⁸ and Stillingia lineata (Euphorbiaceae).¹⁹⁹ The anti-viral activity of these compounds (e.g. 58) against the chikungunya virus was examined. The evaluation of epoxylathyrol derivatives in combating multi-drug resistance²⁰⁰ and the anti-viral activity of a number of phorbol and ingenol esters²⁰¹ has been reported. Some synthetic studies directed towards jatrophanes have been described.²⁰²

7 Miscellaneous diterpenoids

The synthesis of the 5,6,7-ring system of the mulinane diterpenoids has been achieved.²⁰³ A number of new cyathane diterpenoids have been isolated including the striatoids A–F (e.g. A, 59) from the basidiomycetes, Cyathus striatus,²⁰⁴ and from C. africanus²⁰⁵ and Hericium erinaceus.²⁰⁶ The total synthesis of the guanacastepenes N and O,²⁰⁷ dolestatrienol,²⁰⁸ and the trichoaurantiolides C and D²⁰⁹ have been reported. Further derivatives of pleuromutilin have been prepared²¹⁰ in the context of their potential anti-tubercular activity.

Dehydrovibsanin G has been isolated²¹¹ from Viburnum odoratissimum and a total synthesis of vibsanin which unambiguously defines its stereochemistry has been reported.²¹² 8-Hydroxyserrulat-14-en-19-oic acid 60 (R = CO₂H) which was isolated from the Australian medicinal plant, Eremophila neglecta (Scrophulariaceae) has been shown²¹³ to break-up and disperse bacterial biofilms with the potential for use in wound management. A number of modified serrulatanes have been synthesized²¹⁴ from leubethanol 60 (R = Me) and examined for activity against Mycobacterium tuberculosis.

8 References

1. J. R. Hanson, Nat. Prod. Rep., 2015, 32, 76–87.
2. J. R. Hanson, Nat. Prod. Rep., 2015, 32, 1654–1663.
3. J. W. Blunt, B. R. Copp, R. A. Keyzere, M. H. G. Munro and M. R. Prinsep, Nat. Prod. Rep., 2016, 33, 382–431.
4. M. A. Gonzalez, Nat. Prod. Rep., 2015, 32, 684–704.
5. M. A. Gonzalez, Tetrahedron, 2015, 71, 1883–1908.
6. S. Dhambri, S. Mohammad, O. Nguyen van Buo, G. Galvani, Y. Meyer, M.-I. Lannou, G. Sorin and J. Ardisson, Nat. Prod. Rep., 2015, 32, 841–864.
7. L. Zhu, S.-H. Huang, J. Yu and R. Hong, Tetrahedron Lett., 2015, 56, 23–31.
8. P. S. Riehl, Y. C. DePorre, A. M. Armaly, E. J. Groso and C. S. Schindler, Tetrahedron, 2015, 71, 6629–6650.
9. G. Zhu, R. Liu and B. Liu, Synthesis, 2015, 47, 2691–2708.
10. D. Markovic, M. Kolympadi, B. Deguin, F.-H. Poree and M. Turks, Nat. Prod. Rep., 2015, 32, 230–255.
11. C. G. Newton and M. S. Sherburn, Nat. Prod. Rep., 2015, 32, 865–876.
12. C. Draghici and J. T. Njardarson, Tetrahedron, 2015, 71, 3775–3793.
13. J. R. Hanson, J. Chem. Res., 2015, 39, 127–133.
14. A. D. Rogachev and N. F. Salakhutdinov, Chem. Biodiversity, 2015, 12, 1–53.
15. P. Zerbe and J. Bohlmann, Trends Biotechnol., 2015, 33, 419–428.
16. Y. J. Hong and D. J. Tantillo, Org. Biomol. Chem., 2015, 13, 10273–10278.
17. C. Nakano, M. Oshima, N. Kurashima and T. Hoshino, ChemBioChem, 2015, 16, 772–781.
18. X.-M. Mao, W. Xu, D. Li, W.-B. Yin, Y.-H. Chooi, Y. O. Li, Y. Tang and Y. Hu, Angew. Chem., Int. Ed., 2015, 54, 7591–7592.
19. Y. Totsuka, S. Ueda, T. Kuzuyama and T. Shinada, Bull. Chem. Soc. Jpn., 2015, 88, 575–577.
20. Y. A. Nohra, V. Perrichot, L. Jeanneau, L. LePolles and D. Azar, J. Nat. Prod., 2015, 78, 1284–1293.
21. F. de. S. Vargas, P. D. O. de Almeida, E. S. P. Aranha, A. P. de A. Boleti, P. Newton, M. C. de Vasconcelios, V. F. Veiga Jnr and E. S. Lima, Molecules, 2015, 20, 6194–6210.
22. S. Zhao, J. Ling, Z. Li, S. Wang, J. Hu and N. Wang, Bioorg. Med. Chem. Lett., 2015, 25, 1483–1489.
23. Y.-R. He, Y.-H. Shen, L. Shan, X. Yang, B. Wen, J. Ye, X. Yuan, H.-L. Li, X.-K. Xu and W. D. Zhang, RSC Adv., 2015, 5, 4126–4134.
24. G.-M. Li, J.-G. Luo, M.-H. Yang and L.-Y. Kong, Chem. Biodiversity, 2015, 12, 388–396.
25. J. Xu, F. Ji, J. Kang, H. Wang, S. Li, D.-Q. Jin, Q. Zhang, H. Sun and Y. Guo, J. Agric. Food Chem., 2015, 63, 5805–5812.
26. H. Zhao, G. Zeng, S. Zhao, J. Xu, L. Kong, Y. Li, N. Tan and S. Yang, Bioorg. Med. Chem. Lett., 2015, 25, 4572–4575.
27. Y. Wang, S.-H. Luo, J. Hua, Y. Liu, S.-X. Jing, X.-N. Li and S.-H. Li, J. Agric. Food Chem., 2015, 63, 10004–10012.
28. E. Maldonado, A. L. Perez-Castorena, Y. Romero and M. Martinez, J. Nat. Prod., 2015, 78, 202–207.
29. J. Hu, Y. Song, H. Li, X. Mao and X.-D. Shi, J. Asian Nat. Prod. Res., 2015, 17, 262–267.
30. K. Du, M. De Mieri, M. Neuburger, P. C. Zietsman, A. Marston, S. F. van Vuuren, D. Ferreira, M. Hamburger and J. H. van der Westhuizen, J. Nat. Prod., 2015, 78, 2494–2504.
31. Y. Narukawa, M. Komori, A. Niimura, H. Naguchi and F. Kiuchi, J. Nat. Med., 2015, 69, 130–134.
32. W.-M. Zhong, Z.-M. Cui, Z.-K. Liu, Y.-J. Dang and W.-L. Xiao, Chin. Chem. Lett., 2015, 26, 1000–1003.
33. Z. Huang, Z.-X. Zhu, Y.-T. Li, D.-R. Pang, J. Zheng, Q. Zhang, Y.-F. Zhao, D. Ferreira, J. K. Zjawlony, P.-F. Tu and J. Li, J. Nat. Prod., 2015, 78, 2276–2285.
34. M. Masoodi, Z. Ali, S. Liang, H. Yin, W. Wang and I. A. Khan, Phytochem. Lett., 2015, 13, 275–279.
35. R. Sharma, R. Chebolu and P. C. Ravikumar, Phytochem. Lett., 2015, 13, 187–193.
36. N. Corlay, M. Lesco-Bornet, E. Leborgne, F. Blanchard, X. Cachet, J. Bignon, F. Roussi, M.-J. Butel, K. Awang and M. Litauden, J. Nat. Prod., 2015, 78, 1348–1356.
37. L.-B. Wu, C.-J. Xiao, X. Jiang, L. Qiu, X. Dong and B. Jiang, Chem. Biodiversity, 2015, 12, 1229–1236.
38. Z.-Y. Huang, B. Huang, C.-J. Xiao, X. Dong and B. Jiang, Nat. Prod. Res., 2015, 29, 628–632.
39. J. Zhou, J. Zhang, A. Cheng, Y. Xiong, L. Liu and H. Lou, Org. Lett., 2015, 17, 3560–3563.
40. J.-Y. Wu, J.-Z. Zhang, Y.-Q. Kang, X. Wang, P.-H. Fan, J.-C. Zhou and H.-X. Lou, J. Asian Nat. Prod. Res., 2015, 17, 462–467.
41. J. Zhang, Y. Li, R. Zhu, Z. Zhang and H. Lou, J. Nat. Prod., 2015, 78, 2087–2094.
42. M. Koubaa, E. Roseilo-Solo, J. Sic Ziabur, A. R. Jambrak, M. Brncke, N. Grimi, N. Boussetta and F. J. Baiba, J. Agric. Food Chem., 2015, 63, 6835–6846.
43. H. Kamauchi, T. Kon, K. Kinoshita, K. Takatori, K. Takahashi and K. Koyama, Tetrahedron Lett., 2015, 56, 4377–4382.
44. H.-H. Cheng, Y.-B. Cheng, T.-L. Hwang, T.-H. Kuo, C.-H. Chen and Y.-C. Shen, J. Nat. Prod., 2015, 78, 1823–1828.
45. X. Bian, J. Bai, X. Hu, X. Wu, C. Xue, A. Han, G. Su, H. Hua and Y. Pei, Tetrahedron Lett., 2015, 56, 5013–5016.
46. K. Zhou, X.-L. Zhao, L.-P. Han, M.-M. Cao, C. Chen, B.-Z. Shi and D.-Q. Luo, Helv. Chim. Acta, 2015, 98, 642–649.
47. S. C. V. A. R. Annam, M. Ankireddy, M. B. Sura, M. G. Ponnapalli, A. V. S. Sarma and J. Basha, Org. Lett., 2015, 17, 2840–2843.
48. L. Xiong, G.-M. Zhou, Y. Zou, M.-H. Chen, L. Guo, G.-Y. Hu, Z.-H. Liu and C. Peng, Org. Lett., 2015, 17, 6238–6241.
49. C. S. Mizuno, A. B. Souza, B. L. Tekwani, S. R. Ambrosio and R. C. S. Veneziani, Bioorg. Med. Chem. Lett., 2015, 25, 5529–5531.
50. P. M. Matos, B. Mahoney, Y. Chan, D. P. Day, M. M. W. Cabral, C. H. G. Martins, R. A. Santos, J. K. Bastos, P. C. Bulman-Page and V. C. G. Heleno, Molecules, 2015, 20, 18264–18278.
51. I. Chayboun, E. Boulifa, A. I. Mansour, F. Rodriguez-Serrano, E. Carrasco, P. J. Alvarez, R. Chahboun and E. Alvarez-Manzaneda, J. Nat. Prod., 2015, 78, 1026–1036.
52. L. Mendoza, C. Sepulveda, R. Melo and M. Coloras, J. Chil. Chem. Soc., 2015, 60, 3024–3038.
53. M. Ma, J. Feng, R. Li, S.-W. Chen and H. Xu, Bioorg. Med. Chem. Lett., 2015, 25, 2773–2777.
54. A. Urosa, I. S. Marcos, D. Diez, J. M. Padron and P. Basabe, J. Org. Chem., 2015, 80, 6447–6455.
55. M. Martin, A. Urosa, I. S. Marcos, D. Diez, J. M. Padron and P. Basabe, J. Org. Chem., 2015, 80, 4566–4572.
56. Y. Luo, K. Wang, M.-H. Zhang, D.-Y. Zhang, Y.-C. Wu, X.-M. Wu and W.-Y. Hua, Bioorg. Med. Chem. Lett., 2015, 25, 2421–2424.
57. V. S. Nguyen, X. Y. Loh, H. Wijaya, J. Wang, Q. Lin, Y. Lam, W.-S. F. Wong and Y. K. Mok, J. Nat. Prod., 2015, 78, 208–217.
58. S. G. S. Kandanur, W. R. Golakoti and S. Nanduri, Bioorg. Med. Chem. Lett., 2015, 25, 5781–5786.
59. E. Englund, J. Andersen-Ranberg, R. Miao, B. Hamberger and P. Lundberg, ACS Synth. Biol., 2015, 4, 1270–1278.
60. A. F. Monteiro, J. M. Batista, M. A. Machado, R. P. Severino, E. W. Bianah, V. S. Bolzani, P. C. Vieira and V. G. P. Severino, J. Nat. Prod., 2015, 78, 1451–1455.
61. C. G. Silva, H. M. Santos Jnr, J. P. Barbosa, G. L. Costa, F. A. R. Rodrigues, D. F. Oliveira, L. V. Costa-Lotufa, R. J. Alves, E. C. A. Eleutherio and C. M. Rezende, Chem. Biodiversity, 2015, 12, 1891–1901.
62. H. Wu, S. Wang, Z. Xu, S. Sun, H. Liu, J. Wang, Y. Lv, X. Dong, G. Li, L. Zhang and Y. Shi, Molecules, 2015, 20, 839–845.
63. K. Annan, E. Ekuadzi, C. Asare, K. Sarpong, D. Pistorius, L. Oberer, B. A. Gyan and M. Ofori, Phytochem. Lett., 2015, 11, 28–31.
64. A. Bisio, A. M. Schito, S. N. Ebrahimi, M. Hamburger, G. Mele, G. Piatti, G. Romussi, F. Dai Paz and N. De Tommasi, Phytochemistry, 2015, 110, 120–132.
65. A. Bisio, A. M. Schito, A. Parricchi, G. Mele, G. Romussi, N. Malafronte, P. Oliva and N. De Tommasi, Phytochem. Lett., 2015, 14, 170–177.
66. D. Y. W. Lee, G. Deng, Z. Ma, W. Xu, L. Yang, L. Liu, R. Dai and L. Y. Liu-Chen, Bioorg. Med. Chem. Lett., 2015, 25, 4689–4692.
67. A. T. Tchinda, S. R. Mouokeu, R. A. N. Ngono, M. R. E. Ebelle, A. L. K. Mokale, D. K. Nono and M. Frederich, Nat. Prod. Res., 2015, 29, 1990–1994.
68. B. Song, G. Ding, X.-H. Tian, L. Li, C. Zhao, Q.-B. Zhang, M.-H. Wang, T. Zhang and Z.-M. Zou, Phytochem. Lett., 2015, 14, 249–253.
69. T. Wu, Q. Wang, C. Jiang, S. L. Morris-Natschke, H. Cui, Y. Wang, Y. Yan, J. Xu, K.-H. Lee and Q. Gu, J. Nat. Prod., 2015, 78, 500–509.
70. E. T. Yeon, J. W. Lee, C. Lee, Q. Jin, H. Jang, D. Lee, J. S. Ahn, J. T. Hong, Y. Kim, M. K. Lee and B. Y. Hwang, J. Nat. Prod., 2015, 78, 2292–2296.
71. S.-I. Kurimoto, J.-X. Pu, H. D. Sun, Y. Takaishi and Y. Kashiwada, Phytochemistry, 2015, 116, 298–304.
72. H.-W. Lv, J.-G. Luo, M.-D. Zhu, H.-J. Zhao and L. Y. Kong, Phytochemistry, 2015, 119, 26–31.
73. M. Zhou, X. R. Li, J.-W. Tang, Y. Liu, X.-N. Li, B. Wu, H.-B. Qin, X. Du, L.-M. Li, W.-G. Wang, J.-X. Pu and H. D. Sun, Org. Lett., 2015, 17, 6062–6065.
74. E. Bautista, M. Fragoso-Serrano, R. A. Toscano, M. R. Garcia-Peno and A. Ortega, Org. Lett., 2015, 17, 3280–3282.
75. A. Widyowati, S. Sugimoto, Y. Yamano, H. Otsuka, S. Sukardiman and K. Matsunami, Phytochem. Lett., 2015, 14, 56–62.
76. Z. Pan, D. Ning, X. Wu, S. Huang, D. Li and S. Lv, Bioorg. Med. Chem. Lett., 2015, 25, 1329–1332.
77. J. Xu, F. Ji, X. Sun, X. Cao, S. Li, Y. Ohizumi and Y. Guo, J. Nat. Prod., 2015, 78, 2648–2656.
78. H. T. T. Nguyen, N. B. Truong, H. T. M. Doan, M. Litaudon, P. Retailleau, T. T. Do, H. V. Nguyen, M. V. Chau and C. V. Pham, J. Nat. Prod., 2015, 78, 2726–2730.
79. N.-B. Qin, A.-L. Wang, D.-H. Li, K. B. Wang, B. Lin, Z.-L. Li and H.-M. Hua, Phytochem. Lett., 2015, 12, 173–176.
80. R. R. Ravu, M. Jacob, C. Jefferies, Y. Tu, S. I. Khao, A. K. Agarwal, R. K. Guy, L. A. Walker, A. M. Clark and X. C. Li, J. Nat. Prod., 2015, 78, 2255–2259.
81. N. N. Win, T. Ito, S. Armati, H. Imagawa, H. Ngwe, I. Abe and H. Morita, J. Nat. Prod., 2015, 78, 1113–1118.
82. N. N. Win, T. Ito, S. Armati, T. Kodama, H. Imagawa, H. Ngwe, Y. Asakawa, I. Abe and H. Morita, Tetrahedron, 2015, 71, 4707–4713.
83. N. N. Win, T. Ito, S. Armati, T. Kodama, T. Kodama, H. Ngwe, Y. Asakawa, I. Abe and H. Morita, J. Nat. Prod., 2015, 78, 2306–2309.
84. J.-G. Cho, B.-J. Cha, S. M. Lee, S. Shrestha, R. H. Jeong, D. S. Lee, Y.-C. Kim, D.-G. Lee, H.-C. Kang, J. Kim and N.-I. Baek, Chem. Biodiversity, 2015, 12, 1356–1364.
85. M. Zhao, M. M. Onakpa, W.-L. Chen, B. D. Santarsiero, S. M. Swanson, J. E. Burdette, I. U. Asuzu and C.-T. Che, J. Nat. Prod., 2015, 78, 789–796.
86. M. Zhao, M. M. Onakpa, W.-L. Chen, B. D. Santarsiero, X.-J. Huang, X.-Q. Zhang, J. Chen, J.-J. Cheng, R. Longnecker and C.-T. Che, Org. Lett., 2015, 17, 3834–3837.
87. M. Zhao, M. M. Onakpa, W.-L. Chen, B. D. Santarsiero, K. M. Szymulanska-Ramamurthy, S. M. Swanson, J. E. Burdette and C.-T. Che, J. Nat. Prod., 2015, 78, 2731–2737.
88. J. Sorres, C. Nirma, S. Toure, V. Eparvier and D. Stien, Tetrahedron Lett., 2015, 56, 4596–4598.
89. K. Jiang, L.-L. Chen, S.-F. Wang, Y. Wang, Y. Li and K. Gao, J. Nat. Prod., 2015, 78, 1037–1044.
90. H. Li, J.-J. Zhao, J.-L. Chen, L.-P. Zhu, D.-M. Wang, L. Jiang, D. Yang and Z.-M. Zhao, Phytochemistry, 2015, 117, 400–409.
91. Y. P. Bharitkar, A. Hazra, N. S. Apoorva Podun, A. Ash, P. R. Maulik and N. B. Mondal, Nat. Prod. Res., 2015, 29, 253–261.
92. L. A. Maslovskaya, A. I. Savchenko, V. A. Gordon, P. W. Reddell, C. J. Pierce, P. G. Parson and C. M. Williams, Aust. J. Chem., 2015, 68, 652–659.
93. U. Farooq, S. Naz, R. Sarwar, A. Khan, A. Rauf, H. Chan, M. Ahmad, A. H. Ali Shah and S. Hameed, Phytochem. Lett., 2015, 14, 198–202.
94. U. Farooq, K. Ayub, M. A. Hashmi, A. Khan and M. Ali, Rec. Nat. Prod., 2015, 9, 329–335.
95. U. Farooq, K. Ayub, M. A. Hashmi, R. Sarwar, A. Khan, M. Ali, M. Ahmmad and A. Khan, Nat. Prod. Res., 2015, 29, 813–819.
96. H. Saijo, H. Kofujita, K. Takahashi and T. Ashitani, Nat. Prod. Res., 2015, 29, 1739–1743.
97. S. Birtic, P. Dussort, F.-X. Pierre, A. C. Bily and M. Rollei, Phytochemistry, 2015, 115, 9–19.
98. H. Wang, T. T. H. Nguyen, S. Li, T. Liang, Y. Zhang and J. Li, Bioorg. Med. Chem. Lett., 2015, 25, 347–354.
99. C.-H. Chen and L. Huang, ACS Med. Chem. Lett., 2015, 6, 355–358.
100. Q. Qin and S. Yu, Org. Lett., 2015, 17, 1894–1897.
101. A. Nachar, A. Saleem, J. T. Arnason and P. S. Haddad, Phytochemistry, 2015, 117, 373–379.
102. Y. Chen, Z. Dong, D. Huang, W. Chen, F. Yao, D. Xue and L. Sun, Phytochem. Lett., 2015, 14, 27–30.
103. C. Gao, L. Han, D. Zheng, H. Jin, C. Gai, J. Wang, H. Zhang, L. Zhang and H. Fu, J. Nat. Prod., 2015, 78, 630–634.
104. Y.-J. Jiang, Y. Zhang, J. He, X.-D. Wu, L.-D. Shao, X.-N. Lim, J. Su, L.-Y. Peng, C. K. Li and Q.-S. Zhao, Tetrahedron Lett., 2015, 56, 5457–5459.
105. V. Kafil, M. Eskandani, Y. Omidi, H. Nazamiyeh and J. Barar, RSC Adv., 2015, 5, 18041–18051.
106. J. Kang, L. Li, D. Wang, H. Wang, C. Liu, B. Li, Y. Yan, L. Fang, G. Du and R. Chen, Phytochemistry, 2015, 116, 337–348.
107. E. Saruul, T. Murata, E. Selenge, K. Sasaki, F. Yoshizaki and J. Batkhuu, Bioorg. Med. Chem. Lett., 2015, 25, 2555–2558.
108. T. Murata, E. Selenge, S. Oikawa, K. Sasaki and F. Yoshizaki, J. Nat. Med., 2015, 69, 471–478.
109. J. Xu, Y. Sun, M. Wang, Q. Ren, S. Li, H. Wang, X. Sun, D.-Q. Jin, H. Sun, Y. Ohizumi and Y. Guo, J. Nat. Prod., 2015, 78, 1563–1569.
110. A.-R. Wang, H.-C. Song, H.-M. An, Q. Huang, X. Luo and J.-Y. Dong, Chem. Biodiversity, 2015, 12, 451–473.
111. C. Xie, L. Sun, K. Liao, S. Liu, M. Wang, J. Xu, M. Bartiam and Y. Guo, J. Nat. Prod., 2015, 78, 2800–2807.
112. J. Xiong, Z.-L. Hong, L.-X. Gao, J. Shen, S.-T. Liu, G.-X. Yang, J. Li, H. Zeng and J.-F. Hu, J. Org. Chem., 2015, 80, 11080–11085.
113. L.-J. Wang, J. Xiong, S.-T. Liu, L.-L. Pan, G.-X. Yang and J.-F. Hu, J. Nat. Prod., 2015, 78, 1635–1646.
114. L. Ni, J. Ma, C.-J. Li, L. Li, J.-M. Guo, S.-P. Yuan, Q. Hou, Y. Guo and D.-M. Zhang, Tetrahedron Lett., 2015, 56, 1239–1243.
115. H.-M. Li, D.-W. Wan and R.-T. Li, J. Asian Nat. Prod. Res., 2015, 17, 761–766.
116. C. Wang, C.-J. Li, J. Ma, J.-Z. Yang, X.-G. Chen, L. Li and D.-M. Zhang, RSC Adv., 2015, 5, 30046–30052.
117. X.-L. Li, L.-H. Gao, H.-M. Li, L.-T. Wang, K.-H. Lee and R.-T. Li, Phytochem. Lett., 2015, 12, 84–89.
118. E. M. Addo, H.-B. Chai, A. Hymete, M. Y. Yeshak, C. Slebodnick, D. G. I. Kingston and L. H. Rakotondraibe, J. Nat. Prod., 2015, 78, 827–835.
119. Y.-M. Chen, Y.-H. Yang, X.-N. Li, C. Zou and P.-J. Zhao, Molecules, 2015, 20, 16924–16932.
120. Z.-Y. Jiang, Y.-J. Yu, C.-G. Huang, X.-Y. Zhang and G.-P. Li, Planta Med., 2015, 81, 241–246.
121. B. Huang, Z.-Y. Huang, C.-J. Xiao, X. Dong and B. Jiang, Helv. Chim. Acta, 2015, 98, 527–533.
122. K. Satish, G. Srihari, G. Sudhakar, K. Narsimha, T. P. Rao and M. M. Murthy, Phytochem. Lett., 2015, 12, 129–132.
123. B.-B. Zhang, B.-Q. He, J.-B. Sun, B. Zeng, X.-J. Shi, Y. Zhou, Y. Niu, S.-Q. Nie, F. Feng, Y. Liang and F.-H. Wu, Molecules, 2015, 20, 14879–14888.
124. T. Maffo, P. Wafo, R. S. T. Kamdem, R. Melong, P. F. Uzor, P. Mkounga, Z. Ali and B. T. Ngadjui, Phytochem. Lett., 2015, 12, 323–331.
125. P. H. Dang, M. T. T. Nguyen, H. X. Nguyen, D. T. T. Vu, S. V. Truong and N. T. Nguyen, Phytochem. Lett., 2015, 13, 99–102.
126. Q.-B. Liu, L. Huang, L. Zhang, Q. Liu, Q.-Q. Xu, X.-J. Qin, X. Y. Fang and Y. Zeng, J. Asian Nat. Prod. Res., 2015, 17, 1073–1078.
127. T. Mitsui, R. Ishihara, K. Hayashi, N. Matsuura, H. Akashi and H. Nozaki, Phytochemistry, 2015, 116, 349–358.
128. J.-S. Zhang, Y.-Q. Guo, J.-M. Bao, M.-H. Jiang, S.-L. Lin, Z.-Y. Su, G.-H. Tang and S. Yin, Helv. Chim. Acta, 2015, 98, 1387–1394.
129. L. Lian, X.-B. Li, J.-Z. Yuan, L. Cheng, Z. Wu and H. Gao, J. Asian Nat. Prod. Res., 2015, 17, 893–899.
130. R. Dong, J. Yuan, S. Wu, J. Huang, X. Xu, Z. Wu and H. Gao, Phytochemistry, 2015, 117, 325–331.
131. G. Ma, H. Wu, D. Chen, N. Zhu, Y. Zhu, Z. Sun, P. Li, J. Yang, J. Yuan and X. Xu, J. Nat. Prod., 2015, 78, 2364–2371.
132. J. M. E. Dade, L. A. Kablan, T. Okpekon, M. Say, K. D. Yapo, G. Komlaga, J. B. Boti, A. P. Koffi, L. E. Guei, L. A. Djakoure and P. Champy, Phytochem. Lett., 2015, 12, 224–231.
133. Q. Favre-Godal, S. Dorsaz, E. F. Queiroz, L. Marcourt, S. N. Ebrahimi, P.-M. Allard, F. Voinesco, M. Hamburger, M. P. Gupta, K. Gindro, D. Sanglard and J.-L. Wolfender, J. Nat. Prod., 2015, 78, 2994–3004.
134. K. Horie, Y. Inoue, M. Sakai, Q. Yuo, Y. Tanimoto, J. Koga, H. Toshima and M. Hasegawa, J. Agric. Food Chem., 2015, 63, 4050–4059.
135. J.-J. Lv, S. Yu, Y. Xin, H.-T. Zhu, D. Wang, R.-R. Cheng, C.-R. Yang, M. Xu and Y.-J. Zhang, RSC Adv., 2015, 5, 29096–29107.
136. N. X. Nhiem, N. T. T. Hien, B. H. Tai, H. L. T. Ahn, D. T. T. Hang, T. H. Quang, P. V. Kiem, C. V. Minh, W. Ko, S. Lee, H. Oh, S. H. Kim and Y. H. Kim, Bioorg. Med. Chem. Lett., 2015, 25, 254–258.
137. H. Ren, Q. L. Xu, Y. Luo, M. Zhang, Z.-Y. Zhou, L.-M. Dong and J. W. Tan, Phytochem. Lett., 2015, 11, 260–263.
138. C. Bustos-Brito, M. Sanchez-Castellanos, B. Esquivel, J. S. Calderon, F. Calzada, L. Yepez-Mulia, P. Joseph-Nathan, G. Cuevas and L. Quijano, J. Nat. Prod., 2015, 78, 2580–2587.
139. W.-G. Wang, J. Yang, H.-Y. Wu, L.-M. Kong, J. Su, X.-N. Li, X. Du, R. Zhan, M. Zhou, Y. Li, J.-X. Pu and H. D. Sun, Tetrahedron, 2015, 71, 8161–8171.
140. W.-G. Wang, J.-W. Tang, Y.-M. Shi, X. Du, X.-N. Li, H. Y. Wu, Y. Li, H.-Y. Jiang, J.-X. Pu and H. D. Sun, RSC Adv., 2015, 5, 6132–6135.
141. L.-P. Dai, C. Li, H.-Z. Yang, Y.-Q. Lu, H.-Y. Yu, H.-M. Gao and Z.-M. Wang, Molecules, 2015, 20, 17544–17556.
142. L. Yang, S. Liu, H. Wang and Y. Suo, Rec. Nat. Prod., 2015, 9, 526–529.
143. M. Zhou, X.-R. Li, J.-W. Tang, J.-X. Pu and H. D. Sun, Org. Lett., 2015, 17, 6062–6065.
144. X. Liu, J. Yang, W.-G. Wang, Y. Li, J.-Z. Wu, J.-X. Pu and H. D. Sun, J. Nat. Prod., 2015, 78, 196–201.
145. R. Yao, Z. Chen, C. Zhou, M. Luo, X. Shi, J. Li, Y. Gao, F. Zhou, J. Pu, H. D. Sun and J. He, J. Nat. Prod., 2015, 78, 10–16.
146. W.-B. Zhang, G. Lin, W.-B. Shao, J.-X. Gong and Z. Yang, Chem.–Asian J., 2015, 10, 903–909.
147. A. Torres, J. M. G. Molinillo, R. M. Varela, L. Casas, C. Mantell, E. J. Martinez de la Ossa and F. A. Macias, Org. Lett., 2015, 17, 4730–4733.
148. P. D. Chopade, B. Sarma, E. E. Santiso, J. Simpson, J. C. Fry, N. Yurttas, K. L. Biermann, J. Chen, B. L. Trout and A. S. Myerson, J. Chem. Phys., 2015, 143, 244–301.
149. Mayank and V. Jaitak, Phytochemistry, 2015, 116, 12–20.
150. J. G. Napolitano, C. Simmler, J. B. McAlpine, D. C. Lankin, S.-N. Chen and G. F. Pauli, J. Nat. Prod., 2015, 78, 658–665.
151. J. Hubert, N. Borie, S. Chollet, J. Dayde and J. H. Renault, Planta Med., 2015, 81, 1614–1620.
152. I. Prakesh, G. Ma, C. Bunders, T. M. Snyder and C. Priedemann, Nat. Prod. Commun., 2015, 10, 1159–1161.
153. B. F. Garifullin, R. R. Sharipova, I. Yu Strobykina, M. A. Kravchenko and V. E. Kataev, Russ. J. Org. Chem., 2015, 51, 1488–1498.
154. O. V. Andreeva, R. R. Sharipova, I. Yu Strobykina, R. Musin and V. E. Kataev, Russ. J. Org. Chem., 2015, 51, 1324–1333.
155. I. Yu Strobykina, M. G. Belenkov, M. N. Semenova, V. F. Mironov and V. E. Kataev, J. Nat. Prod., 2015, 78, 1300–1318.
156. B. F. Garifullin, R. R. Sharipova, I. Yu Strobykina, O. V. Andreeva and V. E. Kataev, Chem. Nat. Compd., 2015, 51, 886–889.
157. A. G. Dobrynin, O. V. Andreeva and I. A. Litvinov, J. Struct. Chem., 2015, 56, 477.
158. Q. Zhang, H.-X. Liu, H. B. Tan and S.-X. Qiu, Tetrahedron, 2015, 71, 9415–9419.
159. B. L. Wu, H. L. Zou, F.-M. Qin, H.-Y. Li and G.-X. Zhou, Molecules, 2015, 20, 22445–22453.
160. F. B. Mellbye, P. B. Jeppesen, K. Hermansen and S. Gregersen, J. Nat. Prod., 2015, 78, 2447–2451.
161. R. Lang, S. Klade, A. Beusch, A. Dunkel and T. Hofmann, J. Agric. Food Chem., 2015, 63, 10492–10499.
162. C. P. Shen, J. G. Luo, M.-H. Yang and L.-Y. Kong, J. Nat. Prod., 2015, 78, 1322–1329.
163. C. P. Shen, J. G. Luo, M.-H. Yang and L.-Y. Kong, Tetrahedron Lett., 2015, 56, 1328–1331.
164. T. Parra, J. Benites, L. M. Ruiz, B. Sepulveda, M. Simirgiotis and C. Areche, Bioorg. Med. Chem. Lett., 2015, 25, 2813–2817.
165. T. P. Nguyen, T. T. V. Tran, D. T. Mai, N. M. Phan and T. D. Bui, Nat. Prod. Res., 2015, 29, 1432–1436.
166. J. R. Annand, P. A. Bruno, A. K. Mapp and C. S. Schindler, Chem. Commun., 2015, 51, 8990–8993.
167. M. Zhang, Y. Xie, G. Zhan, L. Lei, P. Shu, Y. Chen, Y. Xue, Z. Luo, Q. Wan, G. Yao and Y. Zhang, Phytochemistry, 2015, 117, 107–115.
168. Y. Li, Y.-B. Liu, J.-J. Zhang, Y. Liu, S.-G. Ma, J. Qu, H.-N. Lv and S. S. Yu, J. Nat. Prod., 2015, 78, 2887–2895.
169. L. Song, G. Zhu, Y. Liu, B. Liu and S. Qin, J. Am. Chem. Soc., 2015, 137, 13706–13714.
170. R. G. Puentes, K. Toume, M. A. Aral, S. K. Sadhu, F. Ahmed and M. Ishibashi, J. Nat. Prod., 2015, 78, 864–872.
171. F. Messina, M. Curini, C. D. Sano, C. Zadra, G. Gigliarelli, L. A. Rascon-Valenzuela, R. E. Robles-Zepeda and M. C. Marcotullio, J. Nat. Prod., 2015, 78, 1184–1188.
172. J. Ren, Y.-G. Wang, A.-G. Wang, L.-G. Wu, H.-J. Zhang, W.-J. Wang, Y.-L. Su and H.-L. Qin, J. Nat. Prod., 2015, 78, 2322–2331.
173. P. Le-Huu, T. Heidt, B. Claasen, S. Laschat and V. B. Urlacher, ACS Catal., 2015, 5, 1772–1780.
174. K. Wang, H. Yu, H. Wu, X. Wang, Y. Pan, Y. Chen, L. Liu, Y. Jin and C. Zhang, Nat. Prod. Res., 2015, 29, 1456–1460.
175. H.-B. Liu, H. Zhang, J.-H. Yu and J.-M. Yue, J. Asian Nat. Prod. Res., 2015, 17, 1117–1128.
176. Z.-K. Liang, R.-G. Huang, Z.-S. Kie and X.-J. Xu, Nat. Prod. Res., 2015, 29, 327–330.
177. Z.-H. Sun, Y. Chen, Y.-Q. Guo, J. Qiu, C.-G. Zhu, J. Jin, G.-H. Tang, X.-Z. Bu and S. Yin, Bioorg. Med. Chem. Lett., 2015, 25, 1240–1243.
178. S.-R. Wang, C.-G. Yang, P. A. Sanchez-Murcia, J. P. Snyder, N. Yan, G. Saez-Calve, J. F. Diaz, F. Gago and W. S. Fang, Org. Lett., 2015, 17, 6098–6101.
179. K. Fukaya, K. Kodama, Y. Tanaka, H. Yamazaki, T. Sugai, Y. Yamaguchi, H. Watanabe, T. Oishi, T. Sato and N. Chida, Org. Lett., 2015, 17, 2574–2577.
180. L.-F. Nothias-Scaglia, J.-F. Gallard, V. Dumontet, F. Roussi, J. Costa, B. I. Iorga, J. Paolini and M. Litaudon, J. Nat. Prod., 2015, 78, 2423–2431.
181. J. Q. Liu, J. F. Yang, J. J. Xia, X. Y. Li, Z. R. Li, L. Zhou and M. Qiu, Phytochemistry, 2015, 117, 462–468.
182. S. Shadi, H. Saeidi, M. Ghanadian, M. R. Rahimnejad, M. Aghaei, S. M. Ayarollahi and M. I. Choudhary, Nat. Prod. Res., 2015, 29, 607–614.
183. L. Wang, Y.-T. Ma, Q.-Y. Sun, X.-N. Li, Y. Yan, J. Yang, F.-M. Yang, F.-Y. Liu, Z. Zang, X.-H. Wu, S.-X. Huang and Y. Zhao, Tetrahedron, 2015, 71, 5485–5493.
184. L. Wong, J. Yang, Y.-Q. Chi, W.-B. Ouyang, Z. Zang, S.-X. Huang, P. Cao and Y. Zhao, Nat. Prod. Res., 2015, 29, 1406–1413.
185. L. Wang, Z. Zang, J. Zhang, P. Cao and Y. Zhao, Rec. Nat. Prod., 2015, 9, 374–378.
186. D. Redei, K. Bores, P. Forgo, J. Molnar, Z. Kele, I. Palinko, C. Pinke and J. Hohmann, Chem. Biodiversity, 2015, 12, 1214–1221.
187. M. Ghanadian, H. Saeidi, M. Aghaei, M. R. Rahiminejad, E. Ahmadi, S. M. Ayatollahi, M. I. Choudhary and B. Bahmani, Phytochem. Lett., 2015, 12, 302–307.
188. J. Xu, J. Kang, X. Cao, X. Sun, S. Yu, X. Zhang, H. Sun and Y. Guo, J. Agric. Food Chem., 2015, 63, 5902–5910.
189. D. S. Yang, W.-B. Peng, Y.-P. Yang, K.-C. Liu, X.-L. Li and W.-L. Xiao, J. Asian Nat. Prod. Res., 2015, 17, 946–951.
190. M. A. Reis, V. Andre, M. T. Duarte, H. Lage and M. J. U. Ferreira, J. Nat. Prod., 2015, 78, 2684–2690.
191. D.-S. Ning, L.-Y. Peng, S.-H. Lv, D.-P. Li and Z.-H. Pan, Nat. Prod. Res., 2015, 29, 524–528.
192. B. Yang, Z. Meng, Z. Li, L. Sun, Y. Hu, Z. Wang, G. Ding, W. Xiao and C. Han, Phytochem. Lett., 2015, 11, 270–274.
193. H.-L. Jiang, R. Wang, J.-Y. Li and Y.-P. Shi, Nat. Prod. Res., 2015, 29, 1878–1883.
194. H. De Mieri, K. Du, M. Neuburger, P. Saxena, P. Zietsman, S. Hering, J. H. van der Westhuizen and M. Hamburger, J. Nat. Prod., 2015, 78, 1697–1707.
195. M. Yan, Y. Lu, C.-H. Chen, Y. Zhao, K.-H. Lee and D.-F. Chen, J. Nat. Prod., 2015, 78, 2712–2718.
196. J.-F. Wang, S.-H. Yang, Y.-Q. Liu, D.-X. Li, W.-J. He, X.-X. Zhang, Y.-H. Liu and X.-J. Zhou, Bioorg. Med. Chem. Lett., 2015, 25, 1986–1989.
197. D.-D. Zhang, B. Zhou, J.-H. Yu, C.-H. Xu, J. Ding, H. Zhang and J.-M. Yue, Tetrahedron, 2015, 71, 9638–9644.
198. S.-Z. Huang, X. Zhang, Q.-Y. Ma, Y.-T. Zheng, H.-F. Dai, Q. Wang, J. Zhou and Y.-X. Zhao, RSC Adv., 2015, 5, 80254–80263.
199. F. Oiivon, H. Palenzuela, E. Girard-Valenciennes, J. Neyts, C. Pannecouque, F. Roussi, I. Grondin, P. Leyssen and M. Litaudon, J. Nat. Prod., 2015, 78, 1119–1128.
200. A. M. Matos, M. Reis, N. Duarte, G. Spengler, J. Molnar and M. J. U. Ferreira, J. Nat. Prod., 2015, 2215–2228.
201. L.-F. Nothias-Scaglia, C. Pannecouque, F. Renucci, L. Delang, J. Neyts, F. Roussi, J. Costa, P. Leyssen, M. Litaudon and J. Paolini, J. Nat. Prod., 2015, 78, 1277–1283.
202. P. Mohan, K. Koushik and M. J. Fuertes, Tetrahedron Lett., 2015, 56, 61–65.
203. K. P. Reber, J. Xu and C. A. Guerrero, J. Org. Chem., 2015, 80, 2397–2406.
204. R. Bai, C.-C. Zhang, X. Yin, J. Wei and J.-M. Gao, J. Nat. Prod., 2015, 78, 783–788.
205. J.-J. Han, L. Zhang, J.-K. Xu, L. Bao, F. Zhao, Y.-H. Chen, W. K. Zhang and H.-W. Liu, J. Asian Nat. Prod. Res., 2015, 17, 541–549.
206. Z. Zhang, R.-N. Liu, Q.-J. Tang, J.-S. Zhang, Y. Yang and X.-P. Shang, Phytochem. Lett., 2015, 11, 151–156.
207. S.-Z. Peng and C.-K. Sha, Org. Lett., 2015, 17, 3486–3489.
208. L. T. Leung and P. Chiu, Chem.–Asian J., 2015, 10, 1042–1049.
209. D. R. Williams, P. T. Gladen and J. R. Pinchman, J. Org. Chem., 2015, 80, 5474–5493.
210. Y.-J. Dong, Z.-H. Meng, Y.-Q. Mi, C. Zhang, Z.-H. Cui, P. Wang and Z.-B. Xu, Bioorg. Med. Chem. Lett., 2015, 25, 1799–1803.
211. F.-J. Li, J.-H. Yu, G.-C. Wang, H. Zhang and J.-M. Yue, J. Asian Nat. Prod. Res., 2015, 17, 475–481.
212. K.-I. Takao, K. Tsunoda, T. Kurisu, A. Sakama, Y. Nishimura, K. Yoshida and K.-I. Tadano, Org. Lett., 2015, 17, 756–759.
213. H. H. Mon, S. N. Christo, C. F. Ndi, H. J. Griesser and S. J. Semple, J. Nat. Prod., 2015, 78, 3031–3034.
214. R. Escarcena, J. Perez-Meseguer, E. del Olmo, B. Alanis-Garza, E. Garza-Gonzalez, R. Salazar-Aranda and N. Waksman de Torres, Molecules, 2015, 20, 7245–7262.

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