Rana Hussein Nasera,
Zahraa Falah Azeezb,
Zinab Alatawic,
Amani Albalawid,
Taghreed Shamranief,
Aisha M. A. Shahlol
g,
Mohammad EL-Nablawayhi,
Hanadi A. Alahmadij,
Ghfren S. Alorainik,
Nagwa A. Tharwatl,
Amr Foudam and
Ahmed Ghareeb
*n
aDepartment of Science, College of Basic Education, University of Diyala, 32001 Baqubah, Iraq. E-mail: ranaalqaysi@uodiyala.edu.iq
bCollege of Biotechnology, University of Al-Qadisiyah, Iraq. E-mail: zahraa.azeez@qu.edu.iq
cDepartment of Family and Community Medicine, Faculty of Medicine, University of Tabuk, Tabuk 47512, Saudi Arabia. E-mail: zalatawi@ut.edu.sa
dFamily Medicine Department, King Salman Armed Forces Hospital, Tabuk, Saudi Arabia. E-mail: aalbalawi10@nwafh.med.sa
eDepartment of Clinical Biochemistry, Faculty of Medicine, King Abdulaziz University, Jeddah, Saudi Arabia. E-mail: tshumrani@kau.edu.sa
fFood, Nutrition and Lifestyle Unit, King Fahd Medical Research Centre, King Abdulaziz University, Jeddah, Saudi Arabia
gMedical Lab Technology Department, Faculty of Medical Technology, Wadi-Al-Shatii University, Brack, Libya. E-mail: as.shahlol@wau.edu.ly
hDepartment of Basic Medical Sciences, College of Medicine, AlMaarefa University, P. O. Box 71666, Riyadh, 11597, Saudi Arabia. E-mail: mnablawi@um.edu.sa
iDepartment of Medical Biochemistry, Faculty of Medicine, Mansoura University, Mansoura, 35516, Egypt. E-mail: medo_bio@mans.edu.eg
jCollege of Health Science and Nursing, Al-Rayan National Colleges, Madinah, 42541, Saudi Arabia. E-mail: ha.alahmadi@amc.edu.sa
kDepartment of Medical Laboratory, College of Applied Medical Sciences, Prince Sattam Bin Abdulaziz University, Al-Kharj 11942, Saudi Arabia. E-mail: g.aloraini@psau.edu.sa
lDepartment of Botany and Microbiology, Faculty of Science, Cairo University, Giza 12613, Egypt. E-mail: nagwa@sci.cu.edu.eg
mBotany and Microbiology Department, Faculty of Science, Al-Azhar University, Nasr City, Cairo 11884, Egypt. E-mail: amr_fh83@azhar.edu.eg
nBotany and Microbiology Department, Faculty of Science, Suez Canal University, Ismailia 41522, Egypt. E-mail: aghareeb@science.suez.edu.eg
First published on 22nd May 2025
This study explored the metabolites and bioactive potential of the ethyl acetate extract from a marine-derived fungal strain, Aspergillus oryzae NGM91, isolated from Red Sea sediments. Chemical profiling through FT-IR, GC-MS, and HPLC analysis revealed a complex composition dominated by benzyl benzoate (79.99%) and rosmarinic acid (162.15 μg ml−1) as major constituents. The fungal extract exhibited potent free radical scavenging activity (DPPH IC50 = 17.26; ABTS IC50 = 27.91 μg ml−1), with high total antioxidant capacity (476.57 μg per mg AAE) and ferric reducing power (302.62 μg per mg AAE). It demonstrated selective COX inhibition (COX-1 IC50: 20.66 μg ml−1; COX-2 IC50: 36.32 μg ml−1). Cytotoxic screening showed significant activity against PC3 cells (IC50: 70.47 μg ml−1), PANC-1 (IC50: 90.42 μg ml−1), HepG2 (IC50: 100.36 μg ml−1), and Caco-2 cells (IC50: 104.69 μg ml−1), while exhibiting lower cytotoxicity towards normal Wi-38 fibroblasts (IC50: 230.31 μg ml−1). In PC3 cells, the extract induced oxidative stress markers (MDA: 13.63 μmol mg−1; NO: 66.13 μmole per mg), modulated antioxidant enzyme activities, upregulated antioxidant genes (CAT: 1195%, SOD: 788%, GPx: 473%, GST: 251%), increased DNA damage (205.1%), activated apoptotic pathways via BCL-2 downregulation and BAX/P53/Caspase-3 upregulation, and induced G1 phase arrest (72.97%). These findings demonstrate A. oryzae NGM91's therapeutic potential through oxidative stress-mediated DNA damage and apoptotic cell death induction in PC3 cancerous cells.
Oncologists commonly use surgery, radiation, and chemotherapy as their primary approaches in cancer treatment, and chemotherapy is the most common alongside surgery.3 Nevertheless, the constant administration of drug-based cancer treatment can impair the patient's immune system.4 Furthermore, the increasing ability of cancer cells to become resistant to currently available anti-cancer drugs poses a serious concern.5 As a result, natural products have become recognized as a potential alternative source in the search for new, potent, and pharmaceutically active anti-cancer agents.6 Most of the anti-cancer drugs available commercially today originate from natural compounds or synthetic versions.7 Some well-known anti-cancer medications like camptothecin, podophyllotoxin, vinblastine, vincristine, and Taxol are derived from natural products and continue to be isolated from their plant sources.8 However, the cultivation, procurement, and authentication of plant materials for natural product drug discovery involve intensive labor inputs, considerable time investments, and substantial ecological and financial costs.7
Prostate cancer prevalence has grown markedly worldwide, with age-standardized incidence rates climbing 13.16% between 1990–2019. The Eastern Mediterranean saw the steepest increase at 72.43%, while North Africa and the Middle East regions experienced 77% higher incidence and 144% greater prevalence during this period, despite unchanged mortality rates.9,10 This expanding health challenge is further complicated by tumors frequently developing resistance to both androgen-deprivation therapy (ADH) and chemotherapy treatments.11 Fungal metabolites show significant promise against prostate cancer, particularly the treatment of castration-resistant prostate cancer (CRPC).12 Recent research has identified several metabolites with potent anticancer properties, for example, acetyl aszonalenin, derived from Aspergillus neoniveus, effectively blocks proliferation and migration across numerous prostate cancer cells, notably in CRPC variants. This compound works through cannabinoid receptor engagement, revealing a distinctive therapeutic pathway.13 Penicillium dimorphosporum produces deoxy-14,15-dehydroisoaustamide, which tackles drug resistance by demolishing specific androgen receptor variants, renewing prostate cancer susceptibility to enzalutamide treatments. Deoxy-14,15-dehydroisoaustamide from fungus Penicillium dimorphosporum breaks down resistance-linked androgen receptor variants, reactivating enzalutamide's effectiveness (androgen receptor blockers) against resistant prostate tumors.14
Fungi are eukaryotic microorganisms and macroorganisms that belong to the Kingdom Mycota. They have been a part of human existence for millennia. Ancient civilizations utilized fungi for a variety of functions including as a food source, to produce alcoholic drinks, for medicinal purposes, and for cultural practices.15 The fungal kingdom is estimated to have between 2.2 to 3.8 million diverse species. Of these, about 120000 species have been scientifically accepted and classified. Furthermore, new fungal species are continually being uncovered in various environments like aquatic habitats, tropical forest flora, and soil ecosystems associated with insects.16 Fungi collected from various habitats have been thoroughly studied for their elaborate secondary metabolites. These metabolites exhibit great structural variety and unique chemical and biological activities.17
The fungal genera Aspergillus and Penicillium account for around one-third of all fungal metabolites discovered. Aspergillus is a ubiquitous, fast-growing fungus with approximately 378 known species, 180 of which are of pharmaceutical and commercial value according to the World Data Centre for Microorganisms (WDCM).18,19 Compared to other fungal genera, the secondary metabolites extracted from Aspergillus display particularly diverse and fascinating biological activities like antimicrobial, antioxidant, cytotoxic, and antiviral effects.20,21 Given its immense diversity, Aspergillus remains one of the most prolific and important sources of novel secondary metabolites exhibiting anti-inflammatory, anticancer, antioxidant and antibacterial properties. Its abundance and metabolic variety cement Aspergillus as a prime target for investigations aimed at discovering new bioactive compounds.22,23 For example, investigations into the fungus Aspergillus oryzae revealed its ability to generate L-glutaminase, an amidohydrolase enzyme that breaks down L-glutamine into L-glutamic acid and ammonia, recognized for its role in lymphoblastic leukemia. The isolated strain demonstrated notable enzymatic productivity, reaching peak activity measurements of 217.65 IU, and exhibited anti-cancer properties against MCF-7 breast cancer cells, with a reported IC50 of 283.288 μg ml−1.24 Additionally, two fungal isolates – Neosartorya hiratsukae and Neosartorya pseudofischeri were obtained from soil samples and screened for activity against HepG2, MCF-7, L929, HeLa, HT-29, KB, Vero and P388 cancer cell lines, IC50s values ranged from 144.31 to 267.73 μg ml−1.25 Another study on the fungus Chaetomium globosum led to the isolation of the compound methoxy-2,2-dimethyl-4-octa-4,6-dienyl-2H-naphthalene-1-one, which displayed potent anti-cancer effects against the A549, MCF-7, PC-3, and THP-1 cancer cell lines when tested in a dose-dependent manner with IC50 concentrations of 9.89–54 μg ml−1.26
Marine organisms inhabiting the Red Sea shores represent an untapped frontier for discovering novel bioactive compounds, with fungi particularly standing out as an understudied group. Our research focused on fungi collected from Red Sea coastal sediments, investigating their potential as sources of therapeutic agents. After isolating various fungal strains from these marine sediments, we conducted comprehensive screening that led to the identification of Aspergillus oryzae NGM91 as the most promising isolate. Extensive chemical profiling of the fungal extract was carried out using FT-IR, HPLC, and GC-MS. The research examined the extract's ability to neutralize free radicals and modulate inflammatory responses. Furthermore, we evaluated its selective cytotoxicity against multiple cancer cell lines while sparing normal cells. The study also elucidated the underlying cellular stress responses, particularly focusing on oxidative stress-induced DNA damage and apoptotic cell death in PC3 cancerous cells.
The fungal isolates were then grown in yeast extract broth by inoculating the broth and incubating for 14 days at 25 °C. After incubation, the fungal mycelium was separated from the surrounding supernatant by filtration using Whatman filter paper no. 1. The recovered supernatant underwent three sequential liquid–liquid extractions with ethyl acetate (1:
1 v/v, 250 ml each), with 15 minutes of vigorous shaking per extraction cycle. This process efficiently transferred the bioactive compounds from the aqueous phase to the organic phase. Using liquid–liquid extraction to transfer compounds into the organic phase.28 The ethyl acetate fraction was pooled and concentrated by rotary evaporation to obtain the concentrated extract containing secreted fungal metabolites.
Fungal genomic DNA was extracted using DNeasy plant kit (Qiagen, CA, USA). PCR amplification was performed in a 50 μl reaction containing 25 μl Master Mix, 3 μl each of ITS-1 and ITS-4 primers (10 pmol μl−1), 3 μl template DNA (10 ng μl−1), and 16 μl dH2O. Amplicons were purified and sequenced via Sanger Sequencing on a 3500 Series Genetic Analyzer (Applied Biosystems, USA). 18S rRNA gene sequences were analyzed using BLAST, deposited in GenBank, and a neighbor-joining phylogenetic tree was constructed using MEGA7 software.29
DPPH scavenging% = (A0 − A1)/A0 × 100 |
ABTS˙+ inhibition% = (Ac − As)/Ac × 100 |
Cox-inhibition% = (1 − As/Ac) × 100 |
A 96-well tissue culture plate was seeded with 100 μl per well containing 1 × 105 cells per ml of WI38 normal human lung fibroblasts and incubated at 37 °C for 24 hours to allow formation of a complete cell monolayer sheet. The cytotoxicity of fungal extract was first tested against the WI38 cells to determine its toxicity. The fungal extract was then tested as an anti-cancer agent against four cancerous cell lines: Caco-2 colon cancer cells, PC-3 prostate cancer cells, PANC-1 pancreatic cancer cells, and HepG2 hepatocellular carcinoma cells. The cancer cell lines were acquired from VACSERA (Holding Company for Biological Products and Vaccines) located in Cairo, Egypt. Serial two-fold dilutions of fungal extract were added to wells containing confluent cell monolayers that had been washed twice after growth medium removal. The preparation used RPMI medium containing 2% serum (maintenance medium), with three wells reserved as controls containing only maintenance medium. Plates underwent incubation at 37 °C while being monitored for cytotoxicity signs. An MTT solution at 5 mg ml−1 in PBS was added to each well, shaken at 150 rpm for 5 minutes, and incubated at 37 °C and 5% CO2 for 4 hours to allow MTT metabolism. The media was discarded, the plate dried, and the formazan resuspended in DMSO by shaking at 150 rpm for 5 minutes and the optical density was measured at 560 nm.40
The nitrite concentration in μmole L−1 was calculated as: (absorbance of fungal extract/absorbance standard) × 50.
qRT-PCR was performed using StepOne™ System (Applied Biosystems, USA). Each 25 μl reaction contained 12.5 μl SYBR Premix Ex Taq (TaKaRa), 0.5 μl each of sense and antisense primers (0.2 mM), 5 μl cDNA template, and 6.5 μl distilled water. Primers for antioxidant genes (CAT, SOD, GPx, GST) and apoptotic genes (Bcl-2, BAX, P53, Caspase-3)48,49 were designed as listed in Table S1.† Melting curve analysis at 95 °C verified primer quality. Gene expression was calculated using 2−ΔΔCT method.50
DNA fragmentation was calculated using 600 nm absorbance readings.
% fragmented DNA = [OD(S)/(OD(S) + OD(P))] × 100 |
![]() | ||
Fig. 1 (A) Microscopic examination of Aspergillus oryzae NGM91 (B) phylogenetic association of isolate NGM91 with closely related Aspergillus species. |
Molecular identification through sequence analysis (accession number PP493927) confirmed the morphological findings, placing the isolate NGM91 within a well-supported A. oryzae clade in the phylogenetic tree. The phylogenetic analysis demonstrates particularly close evolutionary relationships with A. oryzae isolate Gharib 10 (PP373780) and isolate SML5 (MW762713), as evidenced by their high bootstrap value of 98–99%, suggesting very recent common ancestry (Fig. 1b).
Observed peak wavelength (cm−1) | Functional group | Bond type | Characteristic absorption range (cm−1) | Relative intensity |
---|---|---|---|---|
3423 | O–H stretch | Hydrogen bond | 3200–3600 | Strong, broad |
2927 | C–H stretch | Alkane | 2850–3000 | Strong |
1647 | C![]() |
Carbonyl | 1690–1760 | Medium |
1541 | N–H bend | Amine | 1500–1600 | Medium |
1242 | C–N stretch | Amine | 1210–1360 | Strong |
1078 | C–O stretch | Alcohol | 1000–1300 | Strong |
The tallest peak at 41.09 minutes corresponded to phenylmethyl benzoate (benzyl benzoate), which dominated the sample with an overwhelming 79.99% area percentage. Other significant components included 3-ethoxy-4-hydroxybenzaldehyde(ethyl vanillin) (29.11 minutes, 4.38% area), (2E)-3,7,11,15-tetramethylhexadec-2-en-1-yl(9Z,12Z)-octadeca-9,12-dienoate (phytyl linoleate) (85.14 minutes, 3.61% area), and 5-amino-2-(4-methoxyphenyl)-2-methyl-2H-[1,2,4]triazolo[1,5-a][1,3,5]triazine(44.41 minutes, 2.90% area). Interestingly, the analysis identified several minor constituents with area percentages below 1%, such as 2-ethoxyphenol (16.73 minutes, 0.11%), 2-tert-butyl-4-methoxyphenol (32.71 minutes, 0.05%), and (3β,5Z)-3,17-dihydroxypregn-5-en-20-one (52.96 minutes, 0.15%) (Fig. 3) (Table 2).
![]() | ||
Fig. 3 GC-MS chromatogram of crude extract from Aspergillus oryzae NGM91 revealing the presence of numerous compounds including benzyl benzoate as the major constituent. |
RT | Compound name | Chemical formula | MW | Area% |
---|---|---|---|---|
5.18 | N-Ethylhydroxylamine | C2H7NO | 61 | 0.15 |
5.27 | 2-(Methylamino)-2-methylpropanoic acid | C5H11NO2 | 117 | 0.03 |
5.39 | 1-Ethoxy-1,3,3-trimethoxypropane | C8H18O4 | 150 | 0.03 |
5.69 | 1-Acetyloxypropan-2-one | C5H8O3 | 146 | 0.07 |
5.76 | 2-(1-Methylpropyl)-2-methylpropane-1,3-diyl dicarbamate | C10H20N2O4 | 232 | 0.03 |
5.98 | Cyclopent-4-ene-1,3-dione | C5H4O2 | 96 | 0.16 |
6.44 | Trans-cyclopentane-1,2-diol | C5H10O2 | 102 | 0.09 |
7.08 | 5-O-Methyl-N,N-dimethyl-D-gluconamide | C9H19NO6 | 237 | 0.08 |
7.42 | Ethyl (1,2,4-triazol-1-ylmethyl) carbonate | C6H9N3O3 | 171 | 0.05 |
8.64 | 4-Methyl-6-phenyl-1,3-oxazinane-2-thione | C11H13NOS | 207 | 0.03 |
9.02 | Prop-2-en-1-ol | C3H6O | 58 | 0.16 |
11.13 | 2-[(7-Chloro-4-quinolyl)amino]benzoic acid 2-(dimethylamino)ethyl ester | C19H17CIN2O4 | 372 | 0.07 |
16.73 | 2-Ethoxyphenol | C8H10O2 | 138 | 0.11 |
26.3 | 2-(N,N,N-Trimethylhydrazino)-1,3-benzothiazole | C10H13N3S | 207 | 0.12 |
29.11 | 3-Ethoxy-4-hydroxybenzaldehyde | C9H10O3 | 166 | 4.38 |
32.59 | 3,5-Di-tert-butylphenol | C14H22O | 206 | 0.08 |
32.71 | 2-Tert-butyl-4-methoxyphenol | C11H16O2 | 180 | 0.05 |
32.85 | 3-[N,N-Dimethyl-N-(dodecyl)ammonio]propane-1-sulfonate | C17H37NO3S | 335 | 0.33 |
37.38 | 2-(3-Acetyloxy-4,4,14-trimethylandrost-8-en-17 yl)propanoic acid | C27H42O4 | 430 | 0.20 |
37.88 | (5α)-17-(2-Hydroxyethylidene)-17-ethylenedioxy-5α-cholestane | C29H50O2 | 430 | 0.06 |
39.52 | (Z)-1-Chlorooctadec-9-ene | C18H35Cl | 286 | 0.12 |
41.09 | Phenylmethyl benzoate | C14H12O2 | 212 | 79.99 |
44.41 | 5-Amino-2-(4-methoxyphenyl)-2-methyl-2H-[1,2,4]triazolo[1,5-a][1,3,5]triazine | C12H14N6O | 258 | 2.90 |
45.68 | 6-(4-Methylcyclohex-3-en-1-yl)hexan-2-one | C18H26O | 258 | 0.22 |
47.5 | Methyl hexadecanoate | C17H34O2 | 270 | 1.00 |
49.14 | (3-Bromo-2,6,6-trimethylcyclohex-1-en-1-yl)(phenyl)methanone | C16H19BrO | 306 | 0.38 |
49.7 | Ethyl hexadecanoate | C18H36O2 | 284 | 0.42 |
51.03 | [(2-Fluorophenyl)methyl]-9H-purin-6-amine | C12H10FN5 | 243 | 0.26 |
52.46 | Methyl 4,6-O-benzylidene-α-D-hexopyranoside | C14H18O6 | 282 | 0.19 |
52.76 | Methyl (Z)-octadec-9-enoate | C19H36O2 | 296 | 1.05 |
52.96 | (3β,5Z)-3,17-Dihydroxypregn-5-en-20-one | C21H32O3 | 332 | 0.15 |
53.1 | Methyl octadeca-10,13-diynoate | C19H30O2 | 290 | 0.11 |
53.75 | Methyl octadecanoate | C19H38O2 | 298 | 0.81 |
54.98 | Ethyl (Z)-octadec-9-enoate | C20H38O2 | 310 | 0.41 |
56.64 | 3′,4′,7-Trimethoxy-5-hydroxy-2-phenyl-4H-chromen-4-one | C18H16O7 | 344 | 0.14 |
60.88 | 6-Methoxy-2-phenyl-hexahydro-pyrano[3,2-d][1,3]dioxine-7,8-diol | C14H18O6 | 282 | 0.03 |
61.43 | [(2-Fluorophenyl)methyl]-9H-purin-6-amine | C12H10FN5 | 243 | 0.36 |
62.61 | (2R)-2-Phenyl-1,3-dioxolan-4-ylmethyl hexadecanoate | C26H42O4 | 418 | 0.18 |
63.33 | 6,8-Di-C-β-D-glucopyranosyl-5,7,3′,4′-tetrahydroxyflavone | C27H30O16 | 610 | 0.14 |
67.44 | (3α,5α)-3,14-Dihydroxybufa-20,22-dienolide | C24H34O4 | 386 | 0.05 |
68.99 | (3α,5α,14α,20α,22α,25R)-3-Hydroxy-11-oxospirost-8-en-11-one | C27H40O4 | 428 | 0.11 |
72.38 | (Z)-Docos-13-enamide | C22H43NO | 337 | 0.51 |
74.32 | 12-Hydroxy-2,2,8,8-tetramethyl-13-(3-methylbutanoyl)-1,7-dioxadispiro[4.0.5.3]tetradec-12-ene-11,14-dione | C21H30O6 | 378 | 0.22 |
76.29 | 1,2,7,8-Tetrahydro-ψ,ψ-carotene-1-ol | C40H58O | 554 | 0.18 |
78.8 | 5,7-Dihydroxy-4′-hydroxy-flavone 5,7-di-O-β-D-glucopyranoside | C27H30O15 | 594 | 0.05 |
79 | 1,1′-Dimethoxy-1,1′,2,2′-tetrahydro-ψ,ψ-carotene | C42H64O2 | 600 | 0.11 |
81.75 | 3,3′-Dihydroxy-β,β-carotene-4,4′-dione | C40H52O4 | 596 | 0.03 |
85.14 | (2E)-3,7,11,15-Tetramethylhexadec-2-en-1-yl (9Z,12Z)-octadeca-9,12-dienoate | C38H70O2 | 558 | 3.61 |
A. oryzae NGM91 crude extract | |||
---|---|---|---|
Area | Conc. (μg ml−1) | Conc. (μg g−1) | |
Gallic acid | 401.78 | 35.54 | 1776.92 |
Chlorogenic acid | 72.23 | 9.37 | 468.61 |
Methyl gallate | 6.89 | 0.35 | 17.35 |
Caffeic acid | 270.44 | 20.93 | 1046.41 |
Syringic acid | 91.52 | 6.69 | 334.65 |
Rutin | 57.64 | 8.50 | 425.12 |
Ellagic acid | 16.92 | 1.69 | 84.49 |
Coumaric acid | 74.81 | 2.66 | 133.11 |
Vanillin | 203.98 | 7.58 | 379.02 |
Ferulic acid | 61.33 | 3.56 | 178.14 |
Naringenin | 572.32 | 52.31 | 2615.60 |
Rosmarinic acid | 1512.36 | 162.15 | 8107.61 |
Daidzein | 41.30 | 2.32 | 115.82 |
Quercetin | 42.23 | 5.70 | 285.00 |
Cinnamic acid | 105.01 | 1.88 | 94.02 |
Kaempferol | 201.39 | 12.70 | 635.18 |
Hesperetin | 17.84 | 0.88 | 43.86 |
In ABTS˙+ testing, the lowest concentration tested of 1.95 μg ml−1 exhibited only minimal ABTS˙+ scavenging ability at 13.8%. The 500 μg per ml concentration yielded a considerable 85.7% ABTS˙+ radical scavenging. While the highest concentration of 1000 μg ml−1 displayed the maximum scavenging potential, nearing 90% at 89.6% (Fig. 6). Its IC50 value was calculated to be 27.91 μg ml−1 compared to 2.54 of gallic acid. Several moderate scavenging effects were observed with mid-range concentrations. For instance, 15.62 μg ml−1 resulted in 42.7% scavenging, while a higher 125 μg ml−1 concentration showed improved 71% activity.
The data presented in Table 4 demonstrates that the crude fungal extract possesses antioxidant capacity as measured by both (TAC) and (FRAP) assays. TAC evaluates the overall antioxidant power, while FRAP determines explicitly the ability to reduce ferric iron. The fungal extract exhibited considerable antioxidant activity in the TAC assay, with a mean value of 476.57 ± 0.68 μg per mg ascorbic acid equivalents (AAE). This high TAC activity reflects the sample's significant capacity to act as an antioxidant. Additionally, the extract showed antioxidant effects in the FRAP assay at a mean value of 302.62 ± 3.59 μg per mg AAE.
A. oryzae crude extract (AAE) μg mg−1 | TAC (AAE) μg mg−1 | FRAP (AAE) μg mg−1 |
476.57 ± 0.68 | 302.62 ± 3.59 |
Based on the comprehensive chemical profiling and antioxidant analyses, the metabolites from Aspergillus oryzae NGM91 demonstrate substantial antioxidant capacity through multiple mechanisms. The FT-IR spectroscopy revealed the presence of phenolic compounds, evidenced by the broad O–H stretch at 3423 cm−1 (Table 1), constituting a primary structural feature responsible for free radical scavenging. The HPLC analysis particularly illuminated the abundance of potent antioxidant compounds, with rosmarinic acid emerging as the predominant constituent (162.15 μg ml−1), followed by significant concentrations of gallic acid (35.54 μg ml−1) and naringenin (52.31 μg ml−1) (Table 3). These phenolic acids and flavonoids possess multiple hydroxyl groups, facilitating electron donation to neutralize free radicals. The GC-MS profile further substantiated the presence of antioxidant-active compounds, notably ethyl vanillin (4.38%) and various phenolic derivatives (Table 2).
The considerable total antioxidant capacity (476.57 ± 0.68 μg per mg AAE) and ferric reducing power (302.62 ± 3.59 μg per mg AAE) (Table 4) correlate directly with the identified phenolic and flavonoid compounds. This synergistic interaction between rosmarinic acid, gallic acid, naringenin, and other identified phenolic compounds establishes the mechanistic basis for the extract's potent antioxidant properties through electron donation and radical neutralization pathways.56,57
Similarly, the COX-2 inhibition assay displayed a concentration-dependent response, with inhibition percentages increasing from 5.98% at 0.5 μg ml−1 to 91.47% at 1000 μg ml−1 of the crude extract. The IC50 was calculated as 36.32 ± 1.24 μg ml−1 compared to 3.73 ± 0.29 μg ml−1 of celecoxib. At lower concentrations between 0.5 and 15.6 μg ml−1, the fungal extract showed minimal COX-2 inhibition ranging from 5.98% to 38.29%. At higher concentrations starting from 31.25 μg ml−1, there was a steep increase in COX-2 inhibition, approaching maximum 91.47% inhibition at 1000 μg ml−1 (Fig. 7).
![]() | ||
Fig. 9 IC50 concentrations of A. oryzae NGM91 extract inhibiting 50% viability of each cell line. Data are presented as mean ± SD. |
Concerning the colon cancer (Caco-2) cell line, untreated Caco-2 colon cancer cells displayed typical epithelial morphology, with a polygonal shape and clear, defined cell edges. After treatment with varying extract concentrations, concentration-dependent morphological changes were observed. Cells were severely damaged at higher concentrations with complete loss of normal morphology. Nearly all cells appeared rounded and shrunken, with blurred, indistinct edges. Cellular debris was visible, indicating cell disintegration (Fig. S2†). As the concentration decreased, cell morphology improved, with some polygonal-shaped cells visible alongside rounded cells and debris. At the lowest tested concentrations, cell morphology approached that of untreated cells, though some residual indicators of toxicity remained. The quantitative assessment revealed severe cytotoxicity at higher concentrations, with 3.5% and 5.6% viability at 1000 and 500 μg ml−1, respectively (Fig. 8). Viability rose in a concentration-dependent manner to 10.3% at 250 μg ml−1, 36.5% at 125 μg ml−1, 78.2% at 62.5 μg ml−1, and 98.3% at 31.25 μg ml−1 and the IC50 was 104.69 ± 1.67 μg ml−1 (Fig. 9).
Next, the cytotoxicity of A. oryzae extract was then tested against hepatocellular carcinoma cells (HepG2) at concentrations ranging from 1000 μg ml−1 to 31.25 μg ml−1. Untreated HepG2 cells appear healthy and normal in morphology. They are adhered to the plate surface and have a polygonal shape with defined cell borders. While treatment of HepG2 cells with the extract results in both concentration-dependent morphological changes, including cell shrinkage and rounding, as well as decreases in cell viability (Fig. S3†). The fungal crude extract was highly cytotoxic at the highest concentrations of 1000 μg ml−1 and 500 μg ml−1, reducing cell viability to only 4.7% and 7.5%, respectively (Fig. 8). Toxicity decreased at 250 μg ml−1 (viability 10.3%) and further dropped at 125 μg ml−1 (viability 31.9%). Much lower toxicity was observed at 62.5 μg ml−1 (viability 78.8%) and 31.25 μg ml−1 (viability 97.8%), its IC50 value was calculated to be 100.36 ± 1.76 μg ml−1 (Fig. 9).
Treatment of prostate cancer (PC3) cells with the fungal extract induced both concentration-dependent cytotoxicity, with an IC50 of 70.47 ± 0.26 μg ml−1 (Fig. 9), as well as morphological alterations ranging from cell shrinkage and rounding at low concentrations to near-complete cell death and detachment at the highest concentrations. The untreated PC3 cells appear healthy and normal, adhered to the plate surface with defined cell borders. After treatment with crude extract, a concentration-dependent cytotoxic effect was observed. At 1000 μg ml−1 of the extract, only 2.9% of PC3 cells remain viable. Viability increases slightly to 4.6% and 6.3% at 500 and 250 μg ml−1 of the fungal extract, respectively. At the lower concentrations of 125, 62.5, and 31.25 μg ml−1, viability continues to improve, ranging from 9.5% to 91.6% (Fig. 8). Morphologically, at the highest extract concentrations of 1000 and 500 μg ml−1, nearly all PC3 cells have died and detached from the plate. At 250 μg ml−1, there is also significant cell death and loss of adherence. As the concentration decreases, more cells remain attached, but they appear less confluent and smaller compared to untreated cells (Fig. S4†). At the lowest concentrations of 62.5 and 31.25 μg ml−1, morphological changes are more subtle, with some rounding up, but most cells remain attached and viable.
Finally, for the pancreatic cancer (PANC-1) cell line, microscope images reveal noticeable morphological differences between control, untreated, and treated PANC-1 cells. The untreated PANC-1 cells appear healthy with normal morphology, cells are well spread with defined edges and retain their epithelial shape. In contrast, the crude extract treated PANC-1 cells exhibit progressive morphological anomalies and deterioration correlated with increasing extract concentration. At lower concentrations, like 31.25 μg ml−1, cells start rounding up and shrinking, with some floating dead cells visible. Higher concentrations of 250 and 500 μg ml−1 induce more extensive cytotoxic effects, with most cells severely shrunken and detached, indicating widespread cell death. Ultimately, at the highest tested concentration of 1000 μg ml−1, the fungal extract results in complete death of PANC-1 cell morphology with predominantly cell debris present (Fig. S5†).
Quantitative cytotoxicity assays demonstrate the promising in vitro anticancer effects of the fungal extract against PANC-1 cells across a wide dosage range from 31.25 to 1000 μg ml−1. At its highest tested concentration of 1000 μg ml−1, the crude extract exhibited potent toxicity with only 4.7% cell viability and 95.3% inhibition (Fig. 8). Appreciable toxicity of 93.4% was retained even at a lower 500 μg per ml concentration. Notably, even at the lowest tested dose of 31.25 μg ml−1, the extract maintained considerable cytotoxicity of 9.1% against PANC-1 cells, and its IC50 value quantitatively was calculated as 90.42 ± 0.87 μg ml−1 (Fig. 9).
The selective cytotoxicity profile of the explored fungal metabolite emerges from the synergistic actions of multiple compounds rather than the effect of a single constituent. The FT-IR spectroscopic profile, particularly the strong O–H stretch at 3423 cm−1 and carbonyl stretch at 1647 cm−1, indicates a rich presence of phenolic and carbonyl-containing compounds. These functional groups, coupled with the amine signatures (N–H bend at 1541 cm−1) (Table 1), suggest structures capable of hydrogen bonding and electron donation – properties crucial for interaction with cellular targets. The high concentration of rosmarinic acid (8107.61 μg g−1) is particularly significant given its documented abilities in reactive oxygen species modulation and inflammatory pathway regulation.58 The substantial presence of naringenin (2615.60 μg g−1) and gallic acid (1776.92 μg g−1) (Fig. 4) suggests multiple mechanisms of action, including potential epigenetic modulation and cell cycle regulation.59,60
The presence of multiple phenolic compounds (chlorogenic acid: 468.61 μg g−1, caffeic acid: 1046.41 μg g−1) alongside flavonoids (kaempferol: 635.18 μg g−1, quercetin: 285 μg g−1) indicates potential synergistic interactions. This phytochemical profile directly correlates with the extract's high antioxidant capacity (TAC: 476.57 ± 0.68 μg per mg AAE; FRAP: 302.62 ± 3.59 μg per mg AAE) and impressive IC50 values in DPPH (17.26 μg ml−1) and ABTS (27.91 μg ml−1) assays. These compounds traditionally act through distinct but complementary pathways, from direct antioxidant activities to modulation of cell signalling cascades and apoptotic pathways.61–63 The hydroxyl groups in these polyphenols facilitate electron donation for radical neutralization, explaining both their antioxidant properties and paradoxical pro-oxidant effects in cancer cells (evidenced by increased MDA and NO in treated PC3 cells). Such structure–activity relationship becomes apparent when examining the FT-IR data (O–H stretch at 3423 cm−1), confirming phenolic structures capable of redox modulation.
The GC-MS analysis revealed benzyl benzoate as the dominant compound (79.99%), which merits attention given its potential role in membrane permeability modulation.64 Also, ethyl vanillin (4.38%) and phytyl linoleate (3.61%) hint synergistic effects. Minor constituents like 3,17-dihydroxypregn-5-en-20-one (0.15%) (Table 2) and flavonoid derivatives may also contribute to the anticancer activity despite their lower concentrations (Ullah et al., 2020; Zhang et al., 2019). The concentration-dependent morphological changes observed in cancer cells (Fig. S1–S5†), particularly the progression from cell shrinkage to complete membrane disruption, suggest a multi-targeted approach rather than a single mechanism.65,66
For PC3 cells, the extract triggered more pronounced oxidative stress responses. MDA levels increased from 5.20 ± 0.26 to 13.63 ± 0.40 μmol per mg protein, while NO levels surged from 21.43 ± 1.22 to 66.13 ± 5.87 μmole per mg protein. The antioxidant defense markers showed substantial alterations, with catalase decreasing from 64.07 ± 1.11 to 21.17 ± 1.35 U per mg protein, glutathione peroxidase increasing from 10.18 ± 0.23 to 14.47 ± 0.71 U per mg protein, reduced glutathione dropping from 13.45 ± 1.10 to 4.23 ± 0.26 U per mg protein, and SOD levels elevating from 18.10 ± 0.36 to 34.47 ± 0.80 U per mg protein (Fig. 10).
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Fig. 11 The alterations of CAT, SOD, GPx and GST expression in untreated and treated PC3 cells with the fungal extract. Mean ± SD represents all data values. ***p ≤ 0.001, ****p ≤ 0.0001. |
The oxidative stress markers, as shown in Fig. 10, support this interpretation, with MDA levels increasing by 162% (from 5.20 to 13.63 μmol per mg protein) and NO levels surging by 208% (from 21.43 to 66.13 μmole per mg protein). This substantial increase in oxidative stress markers, despite elevated antioxidant gene expression, indicates that the cells' defensive responses were overwhelmed. This oxidative burden is reflected in the significant reduction of reduced glutathione (68.5% decrease), a critical cellular antioxidant defensive reservoir.
The downstream effects of this oxidative assault are evident in the DNA damage analysis. The comet assay revealed that the untreated PC3 cancer cell line showed a significant decrease in DNA damage values (11.2 ± 0.85) in comparison with the treated PC3 (P < 0.05). In contrast, the DNA damage values were raised significantly in the treated PC3 cancer cell line sample (19.8 ± 2.50) compared with the negative control (11.2 ± 1.71) (P < 0.01) (Tables 5 and 6). In addition, the DNA damage in PC3 cancer cell lines showed a higher percentage of class 3 displaying high tail length migration than those in negative PC3 cell lines (Fig. 12).
Treatment | No. of samples | No. of cells | Classb | DNA damaged cells% (mean ± SD) | ||||
---|---|---|---|---|---|---|---|---|
Analyzeda | Comets | 0 | 1 | 2 | 3 | |||
a Number of cells examined per group.b Class 0 = no tail; 1 = tail length < diameter of nucleus; 2 = tail length between 1× and 2× the diameter of nucleus; and 3 = tail length > 2× the diameter of nucleus. Means with different superscripts (a, b) between groups in the same treatment are significantly different at P < 0.05. Data are presented as mean ± SD. | ||||||||
Untreated PC3 cells | 4 | 600 | 67 | 533 | 29 | 23 | 15 | 11.2 ± 1.71b |
Treated PC3 cells | 4 | 600 | 119 | 481 | 43 | 37 | 39 | 19.8 ± 2.50a |
Treatment | DNA fragmentation% (mean ± SD) | % of control |
---|---|---|
a Means bearing distinct superscripts (a, b) between groups within identical columns indicate significant differences at P < 0.05. | ||
PC3 cell line (−ve) | 13.6 ± 1.66b | 100.0 |
Treated PC3 cell line | 27.9 ± 1.96a | 205.1 |
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Fig. 12 Visual scoring of DNA damage using comet assay in PC3 cells. (A) Image showing normal DNA (class 0) and damaged DNA (class 1). (B) Image showing higher levels of DNA damage (classes 2 and 3) in PC3 cells treated with the fungal extract. DNA fragmentation analysis further confirmed this early DNA damage. The results proved that negative control PC3 cell lines revealed a significant decrease (P < 0.01) in DNA fragmentation rates (13.6 ± 1.66) compared with those in treated samples. Nevertheless, the DNA fragmentation values were increased significantly (P < 0.01) in treated PC3 cell lines (27.9 ± 1.96) compared with negative control cancer cell lines (13.6 ± 1.66) (Table 6) (Fig. S6†). |
The cellular response to this damage is reflected in the expression patterns of apoptotic regulators. The anti-apoptotic BCL-2 showed a 61% decrease, while pro-apoptotic genes demonstrated substantial upregulation: BAX (343%), p53 (525%), and most notably, Caspase-3 (806%). These changes in expression ratios, particularly the BAX/BCL-2 ratio shift, strongly indicate the activation of apoptotic pathways (Fig. 13).
Looking at the cell cycle analysis of untreated PC3 cells, the data revealed distinctive distribution patterns across different phases. Most cells (58.62%) were found in the G1 phase, representing the initial growth period. Following this, 23.70% of the cells were observed in the S phase, where DNA replication occurs. A smaller fraction of cells (11.11%) resided in the G0 phase, indicating a quiescent state. The G2-M phase, marking the preparation for and execution of cell division, contained the smallest population at 6.52% (Fig. 14). This distribution suggests that most PC3 cells in the untreated condition maintain normal proliferation patterns, predominantly occupying the G1 phase while actively progressing through the cell cycle stages.
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Fig. 14 Cell cycle phase distribution of control PC3 cells demonstrating normal proliferation patterns. |
On the other hand, the cell cycle analysis of PC3 cells treated with the fungal extract displayed a significant shift in phase distribution. The G1 phase shows a marked increase to 72.97% of the cell population, indicating substantial G1 arrest. Notably, the S phase fraction dropped dramatically to 4.39%, reflecting a strong reduction in DNA synthesis activity. The G2–M population decreased sharply to just 0.43%, demonstrating minimal cell division activity. Meanwhile, the G0 phase showed an elevation to 21.78%, suggesting that more cells entered a quiescent state (Fig. 15). These alterations in cell cycle distribution, particularly the pronounced G1 accumulation and diminished S phase population, strongly point to the fungal extract's antiproliferative effect on PC3 cells through G1 phase arrest mechanisms.
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Fig. 15 Quantitative analysis of cell cycle arrest in PC3 cells treated with A. oryzae's extract, revealing G1 phase accumulation and diminished G2/M population. |
Integrating these findings reveals a clear mechanistic pathway. The initial molecular changes, evidenced by the dramatic upregulation of antioxidant genes, appear to be a cellular response to oxidative stress, as validated by the increased MDA and NO levels (Fig. 10). This oxidative stress environment, despite the compensatory increase in antioxidant gene expression, led to significant DNA damage, as demonstrated by both comet assay and DNA fragmentation analyses (Fig. S6†). The concurrent activation of the p53-dependent apoptotic pathway, shown by the substantial increases in P53, BAX, and Caspase-3 expression, along with the decrease in BCL-2, suggests that the extract triggers cell death through oxidative stress-mediated DNA damage (Fig. 13). This comprehensive data set demonstrated that A. oryzae NGM91 extract induces PC3 cancer cell death through a well-coordinated sequence of molecular and cellular events, making it a promising candidate for further anti-cancer research.
Future work should include in vivo studies to validate the anticancer effects, examine potential toxicity in animal models, and evaluate pharmacokinetic properties. Additional research could explore synergistic effects with existing cancer treatments, develop targeted delivery systems for the active compounds, and investigate the extract's potential against metastatic and drug-resistant cancers. Furthermore, isolating and characterizing individual bioactive compounds could lead to more potent and selective anticancer agents. Engineering studies for optimized production and standardization of the extract would be valuable for potential therapeutic development.
Footnote |
† Electronic supplementary information (ESI) available. See DOI: https://doi.org/10.1039/d5ra02028j |
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