Cytotoxic polyphenols from the marine-derived fungus Penicillium expansum

Isolation and structure determination of a new bisabolane-type sesquiterpenoid with cytotoxicity from Penicillium oxalicum MZY-202312-521

Endophytic fungi can produce attractive secondary metabolites with various biological activities that have contributed significantly to pharmacotherapy. In this study, three bisabolane-type sesquiterpenoids, including a new one, namely, inonotic acid C (1), together with previously reported compounds (S)-(+)-11-dehydrosydonic acid (2) and sydonic acid (3), were isolated from a marine algal-derived endophytic fungus Penicillium oxalicum MZY-202312-521. Their structures were determined by means of extensive spectroscopic analyses. The absolute configurations of inonotic acid C (1) were established by single-crystal X-ray diffraction method. In vitro cytotoxic experiments on human A549, MCF-7, HeLa, and HepG2 carcinoma cell lines were carried out. The new compound inonotic acid C (1) was found to possess strong inhibitory activity against the MCF-7 cell line, with an IC50 value of 7.7 μM.

MPoMA protects against lung epithelial cell injury via p65 degradation

Numerous cases of lung injury caused by viral infection were reported during the coronavirus disease-19 pandemic. While there have been significant efforts to develop drugs that block viral infection and spread, the development of drugs to reduce or reverse lung injury has been a lower priority. This study aimed to identify compounds from a library of compounds that prevent viral infection that could reduce and prevent lung epithelial cell damage. We investigated the cytotoxicity of the compounds, their activity in inhibiting viral spike protein binding to cells, and their activity in reducing IL-8 production in lung epithelial cells damaged by amodiaquine (AQ). We identified N-(4-(4-methoxyphenoxy)-3-methylphenyl)-N-methylacetamide (MPoMA) as a non-cytotoxic inhibitor against viral infection and AQ-induced cell damage. MPoMA inhibited the expression of IL-8, IL-6, IL-1β, and fibronectin induced by AQ and protected against AQ-induced morphological changes. However, MPoMA did not affect basal IL-8 expression in lung epithelial cells in the absence of AQ. Further mechanistic analysis confirmed that MPoMA selectively promoted the proteasomal degradation of inflammatory mediator p65, thereby reducing intracellular p65 expression and p65-mediated inflammatory responses. MPoMA exerted potent anti-inflammatory and protective functions in epithelial cells against LPS-induced acute lung injury in vivo. These findings suggest that MPoMA may have beneficial effects in suppressing viral infection and preventing lung epithelial cell damage through the degradation of p65 and inhibition of the production of inflammatory cytokines.

Cytotoxic Compounds from Marine Fungi: Sources, Structures, and Bioactivity

Marine fungi, such as species from the Penicillium and Aspergillus genera, are prolific producers of a diversity of natural products with cytotoxic properties. These fungi have been successfully isolated and identified from various marine sources, including sponges, coral, algae, mangroves, sediment, and seawater. The cytotoxic compounds derived from marine fungi can be categorized into five distinct classes: polyketides, peptides, terpenoids and sterols, hybrids, and other miscellaneous compounds. Notably, the pre-eminent group among these compounds comprises polyketides, accounting for 307 out of 642 identified compounds. Particularly, within this collection, 23 out of the 642 compounds exhibit remarkable cytotoxic potency, with IC50 values measured at the nanomolar (nM) or nanogram per milliliter (ng/mL) levels. This review elucidates the originating fungal strains, the sources of isolation, chemical structures, and the noteworthy antitumor activity of the 642 novel natural products isolated from marine fungi. The scope of this review encompasses the period from 1991 to 2023.

Mangrove-associated endomycota: diversity and functional significance as a source of novel drug leads

Endophytic fungi are known for their unprecedented ability to produce novel lead compounds of clinical and pharmaceutical importance. This review focuses on the unexplored fungal diversity associated with mangroves, emphasizing their biodiversity, distribution, and methodological approaches targeting isolation, and identification. Also highlights the bioactive compounds reported from the mangrove fungal endophytes. The compounds are categorized according to their reported biological activities including antimicrobial, antioxidant and cytotoxic property. In addition, protein kinase, α-glucosidase, acetylcholinesterase, tyrosinase inhibition, antiangiogenic, DNA-binding affinity, and calcium/potassium channel blocking activity are also reported. Exploration of these endophytes as a source of pharmacologically important compounds will be highly promising in the wake of emerging antibiotic resistance among pathogens. Thus, the aim of this review is to present a detailed report of mangrove derived endophytic fungi and to open an avenue for researchers to discover the possibilities of exploring these hidden mycota in developing novel drug leads.

Diketopiperazine Alkaloids and Bisabolene Sesquiterpenoids from Aspergillus versicolor AS-212, an Endozoic Fungus Associated with Deep-Sea Coral of Magellan Seamounts

Two new quinazolinone diketopiperazine alkaloids, including versicomide E (2) and cottoquinazoline H (4), together with ten known compounds (1, 3, and 5-12) were isolated and identified from Aspergillus versicolor AS-212, an endozoic fungus associated with the deep-sea coral Hemicorallium cf. imperiale, which was collected from the Magellan Seamounts. Their chemical structures were determined by an extensive interpretation of the spectroscopic and X-ray crystallographic data as well as specific rotation calculation, ECD calculation, and comparison of their ECD spectra. The absolute configurations of (-)-isoversicomide A (1) and cottoquinazoline A (3) were not assigned in the literature reports and were solved in the present work by single-crystal X-ray diffraction analysis. In the antibacterial assays, compound 3 exhibited antibacterial activity against aquatic pathogenic bacteria Aeromonas hydrophilia with an MIC value of 18.6 μM, while compounds 4 and 8 exhibited inhibitory effects against Vibrio harveyi and V. parahaemolyticus with MIC values ranging from 9.0 to 18.1 μM.

Structure Revisions of Phenolic Bisabolane Sesquiterpenes and a Ferroptosis Inhibitor from the Marine-Derived Fungus Aspergillus versicolor YPH93

Seven new phenolic bisabolane sesquiterpenoids (1-7), along with 10 biogenetically related analogues (8-17), were obtained from the deep-sea-derived fungus Aspergillus versicolor YPH93. The structures were elucidated based on extensive analyses of the spectroscopic data. Compounds 1-3 are the first examples of phenolic bisabolanes that contain two hydroxy groups attached to the pyran ring. The structures of sydowic acid derivatives (1-6 and 8-10) were carefully studied, leading to the structure revisions of six known analogues, including a revision of the absolute configuration for sydowic acid (10). All metabolites were evaluated for their effects on ferroptosis. Compound 7 exerted inhibition on erastin/RSL3-induced ferroptosis with EC50 values ranging from 2 to 4 μM, while it exhibited no effects on TNFα-induced necroptosis or H2O2-induced cell necrosis.

Ferroptosis Inhibitory Compounds from the Deep-Sea-Derived Fungus Penicillium sp. MCCC 3A00126

Two new xanthones (1 and 2) were isolated from the deep-sea-derived fungus Penicillium sp. MCCC 3A00126 along with 34 known compounds (3-36). The structures of the new compounds were established by spectroscopic data. The absolute configuration of 1 was validated by comparison of experimental and calculated ECD spectra. All isolated compounds were evaluated for cytotoxicity and ferroptosis inhibitory activities. Compounds 14 and 15 exerted potent cytotoxicity against CCRF-CEM cells, with IC₅₀ values of 5.5 and 3.5 μM, respectively, whereas 26, 28, 33, and 34 significantly inhibited RSL3-induced ferroptosis, with EC₅₀ values of 11.6, 7.2, 11.8, and 2.2 μM, respectively.

Undescribed diphenyl ethers betaethrins A-I from a desert plant endophytic strain of the fungus Phoma betae A.B. Frank (Didymellaceae)

Ten diphenyl ethers (DPEs), including nine undescribed analogs named betaethrins A-I, were isolated from the desert plant endophytic fungus Phoma betae A.B. Frank (Didymellaceae). Their structures were determined mainly by NMR, HR-ESI-MS spectral and X-ray diffraction experiments. Betaethrins D-I possessed different fatty acid chains connected with the B-ring, which was the first report in all DPEs. The shielding effect of the B-ring on H-6 (A-ring) in methyl barceloneate, betaethrin A and betaethrins D-F (asterric acid analogs) was first observed and analyzed, which could differentiate the ¹H-NMR chemical shift values of H-4/H-6 without the assistance of 3-OH. An empirical rule was then suggested: the steric hindrance between the A- and B-rings in asterric acid analogs might prevent these two aromatic rings from rotating freely, which led to the ¹H-NMR chemical shift value of H-6 being in the high field zone due to the shielding effect of the B-ring on H-6. Based on the empirical rule, the chemical shift values of the A-ring in methyl barceloneate were revised. The possible biosynthesis of these isolates was postulated. Betaethrin H showed moderate cytotoxicity against MCF-7 and HepG2 cancer cell lines. Betaethrins A-F, H and I displayed strong antioxidant activities. These results further implied that endophytic fungi from unique environments, such as desert plants, with few chemical studies are an important resource of undescribed and bioactive metabolites.

Bioactive Microbial Metabolites in Cancer Therapeutics: Mining, Repurposing, and Their Molecular Targets

The persistence and resurgence of cancer, characterized by abnormal cell growth and differentiation, continues to be a serious public health concern critically affecting public health, social life, and the global economy. Hundreds of putative drug molecules of synthetic and natural origin were approved for anticancer therapy in the last few decades. Although conventional anticancer treatment strategies have promising aspects, several factors such as their limitations, drug resistance, and side effects associated with them demand more effort in repositioning or developing novel therapeutic regimens. The rich heritage of microbial bioactive components remains instrumental in providing novel avenues for cancer therapeutics. Actinobacteria, Firmicutes, and fungi have a plethora of bioactive compounds, which received attention for their efficacy in cancer treatment targeting different pathways responsible for abnormal cell growth and differentiation. Yet the full potential remains underexplored to date, and novel compounds from such microbes are reported regularly. In addition, the advent of computational tools has further augmented the mining of microbial secondary metabolites and identifying their molecular targets in cancer cells. Furthermore, the drug-repurposing strategy has facilitated the use of approved drugs of microbial origin in regulating cancer cell growth and progression. The wide diversity of microbial compounds, different mining approaches, and multiple modes of action warrant further investigations on the current status of microbial metabolites in cancer therapeutics. Hence, in this review, we have critically discussed the untapped potential of microbial products in mitigating cancer progression. The review also summarizes the impact of drug repurposing in cancer therapy and discusses the novel avenues for future therapeutic drug development against cancer.

Bisabolane Sesquiterpenes with Anti-Inflammatory Activities from the Endophytic Fungus Penicillium citrinum DF47

Seven new bisabolane-type sesquiterpenes (1-7), namely penicibisabolanes A-G, together with eight known analogs (8-15) were obtained from the AcOEt extract of the millet fermentation broth of the endophytic fungus Penicillium citrinum DF47, which was isolated from the fresh root of Codonopsis pilosula (Franch.) Nannf. The gross structures of new metabolites were determined on the basis of the spectroscopic data (HR-ESI-MS, 1D and 2D NMR spectra), while their absolute configurations were resolved by comparison of the experimental and calculated ECD spectra, in association with specific rotation data. Compound 1 is a rare seco-trinor-bisabolane sesquiterpene found in nature, while 3 is the first example of phenolic bisabolanes bearing a methoxy group at C-1. All the isolates were evaluated their inhibitory effects against NO production in lipopolysaccharides (LPS) stimulated RAW264.7 cells. Among them, compounds 7 and 13 showed moderately anti-inflammatory effects with the inhibitory rate more than 50 % at the concentration of 20 μM.

Homo/Hetero-Dimers of Aromatic Bisabolane Sesquiterpenoids with Neuroprotective Activity from the Fungus Aspergillus versicolor A18 from South China Sea

Chromatographic fractionation of the EtOH extracts of the marine-derived fungus Aspergillus versicolor A18 has led to the isolation of 11 homo/hetero-dimers of aromatic bisabolane sesquiterpenoids including eight diphenyl ether-coupled aromatic bisabolanes (1a/1b and 5−10) and three homodimers (2−4), together with their monomers including three aromatic bisabolanes (11−13) and two diphenyl ethers (14 and 15). Their structures and absolute configurations were elucidated by extensive spectroscopic analysis including HRESIMS, 1D/2D NMR, calculated ECD, and the optical rotatory data. Among the four new compounds, (+/−)-asperbisabol A (1a/1b), asperbisabol B (2), and asperbisabol C (3), the enantiomers 1a and 1b represent an unprecedented skeleton of diphenyl ether-coupled aromatic bisabolane sesquiterpenoids with a spiroketal core moiety. The neuroprotective effects of selected compounds against sodium nitroprusside (SNP)-induced injury were evaluated in PC12 cells by the MTT assay. Five compounds (1a, 6, and 8−10) showed remarkable neuroprotective activities at 10 μM, being more active than the positive control edaravone.

Insights into the Chemical Diversity of Selected Fungi from the Tza Itzá Cenote of the Yucatan Peninsula

Cenotes are habitats with unique physical, chemical, and biological features. Unexplored microorganisms from these sinkholes represent a potential source of bioactive molecules. Thus, a series of cultivable fungi (Aspergillus spp. NCA257, NCA264, and NCA276, Stachybotrys sp. NCA252, and Cladosporium sp. NCA273) isolated from the cenote Tza Itzá were subjected to chemical, coculture, and metabolomic analyses. Nineteen compounds were obtained and tested for their antimicrobial potential against ESKAPE pathogens, Mycobacterium tuberculosis, and nontuberculous mycobacteria. In particular, phenylspirodrimanes from Stachybotrys sp. NCA252 showed significant activity against MRSA, MSSA, and mycobacterial strains. On the other hand, the absolute configuration of the new compound 17-deoxy-aspergillin PZ (1) isolated from Aspergillus sp. NCA276 was established via single-crystal X-ray crystallography. Also, the chemical analysis of the cocultures between Aspergillus and Cladosporium strains revealed the production of metabolites that were not present or were barely detected in the monocultures. Finally, molecular networking analysis of the LC-MS-MS/MS data for each fungus was used as a tool for the annotation of additional compounds, increasing the chemical knowledge on the corresponding fungal strains. Overall, this is the first systematic chemical study on fungi isolated from a sinkhole in Mexico.

Chemistry and Bioactivity of Marine-Derived Bisabolane Sesquiterpenoids: A Review

Natural products, characterized by intriguing scaffold diversity and structural complexity, as well as significant agricultural and medicinal activities, have been a valuable source of agrochemicals/drugs development and have historically made a huge contribution to pharmacotherapy. Structurally, bisabolanes are a family of naturally occurring sesquiterpenoids that featured a hexatomic ring core incorporating with eight continuous carbons, which cause high structural variability along the alkyl side chain to form abundant functionalities. Moreover, apart from their interesting structures, bisabolanes have shown multitudinous bioactivities. Bisabolanes are distributed in a variety of marine invertebrates, terrestrial plant, and microbial sources. Interestingly, bisabolanes characterized from marine environment possess unique characteristics both structurally and biologically. A total of 296 newly-discovered bisabolanes were searched. Among them, 94 members were isolated from marine organisms. This review particularly focuses on the new bisabolanes characterized from marine organisms (covering from 2000 to 2021), including marine-derived fungi, algae, soft corals, and sponges, with emphasis on the diversity of their chemical structures as well as the novelty and differences between terrestrial and marine sources. Moreover, a wide range of bioactivities of marine-derived bisabolanes, including antimicrobial, anti-inflammatory, enzyme inhibitory, and cytotoxic properties, are presented herein, which is considered to be a promising resource for the discovery of new drug leads and agrochemicals.

Bioremediation of heavy metals from industrial effluents by endophytes and their metabolic activity: Recent advances

Worldwide, heavy metals pollution is mostly caused by rapid population growth and industrial development which is accumulated in food webs causing a serious public health risk. Endophytic microorganisms have a variety of mechanisms for metal sequestration having metal biosorption capacities.Endophytic organisms like bacteria and fungi provide beneficial qualities that help plants to improve their health, reduce stress, and detoxify metals. Endophytes have a higher proclivity for improving metal and mineral solubility by cells that secrete low-molecular-weight organic acids and metal-specific ligands like siderophores, which change the pH of the soil and improve binding activity. Protein-related approaches like chromatin immunoprecipitation sequencing (ChIP-Seq) and modified enzyme-linked immunosorbent assay (ELISA test) can represent endophytic bacterial community and DNA-protein interactions during metal reduction. This review explored the role of endophytes in bioremediation approaches that can help in analyzing the potential and prospects in response to industrial effluents' detoxification.

Secondary metabolites from mangrove-associated fungi: source, chemistry and bioactivities

Covering 1989 to 2020The mangrove forests are a complex ecosystem occurring at tropical and subtropical intertidal estuarine zones and nourish a diverse group of microorganisms including fungi, actinomycetes, bacteria, cyanobacteria, algae, and protozoa. Among the mangrove microbial community, mangrove associated fungi, as the second-largest ecological group of the marine fungi, not only play an essential role in creating and maintaining this biosphere but also represent a rich source of structurally unique and diverse bioactive secondary metabolites, attracting significant attention of organic chemists and pharmacologists. This review summarizes the discovery relating to the source and characteristics of metabolic products isolated from mangrove-associated fungi over the past thirty years (1989-2020). Its emphasis included 1387 new metabolites from 451 papers, focusing on bioactivity and the unique chemical diversity of these natural products.

Antimicrobial and cytotoxic phenolic bisabolane sesquiterpenoids from the fungus Aspergillus flavipes 297

Phenolic bisabolane-type sesquiterpenoids (PBS) represent a rare class of natural products with diverse biological activities. In this study, chemical investigations of the fungus Aspergillus flavipes 297 resulted in the isolation and identification of seven PBS, including a pair of new enantiomers (+)-1a and (-)-1b, a new derivative 2, and five previously reported ones 3-7. The chemical structures of the isolated PBS were determined by extensive NMR and HRESIMS spectroscopic analysis. The absolute configurations of the separated enantiomers (+)-1a and (-)-1b were solved by comparison of the experimental ECD spectra with those of the TDDFT-ECD calculated spectra. The new compounds 1 and 2 represent rare cases of PBS bearing a methylsulfinyl group, which was distinct from the commonly-observed PBS structurally. All the isolated compounds 1-7 were evaluated their antimicrobial and cytotoxic activities. As a result, the tested compounds showed selective antimicrobial activity against several pathogenic bacteria and fungi with the MIC (minimum inhibiting concentrations) values ranging from 2 to 64 μg/mL. Moreover, enantiomers (+)-1a and (-)-1b, together with compound 2, exhibited promising cytotoxicity against MKN-45 and HepG2 cell lines, respectively, indicating that the methylsulfinyl substituent enhanced cytotoxicity to a certain degree.

New bisabolane-type phenolic sesquiterpenoids from the marine sponge Plakortis simplex

Six new bisabolane-type phenolic sesquiterpenoids, including plakordiols A-D (1-4), (7R, 10R)-hydroxycurcudiol (5) and (7R, 10S)-hydroxycurcudiol (6) were isolated from the marine sponge Plakortis simplex collected from the South China Sea. Their structures were determined based on extensive analysis of spectroscopic data. Their configurations were assigned by coupling constant analysis, NOESY correlations, and the modified Mosher's method. Furthermore, their cytotoxic and antibacterial activities were evaluated.

An Updated Review of Secondary Metabolites from Marine Fungi

Marine fungi are valuable and richest sources of novel natural products for medicinal and pharmaceutical industries. Nutrient depletion, competition or any other type of metabolic stress which limits marine fungal growth promotes the formation and secretion of secondary metabolites. Generally secondary metabolites can be produced by many different metabolic pathways and include antibiotics, cytotoxic and cyto-stimulatory compounds. Marine fungi produce many different types of secondary metabolites that are of commercial importance. This review paper deals with around 187 novel compounds and 212 other known compounds with anticancer and antibacterial activities with a special focus on the period from 2011-2019. Furthermore, this review highlights the sources of organisms, chemical classes and biological activities (anticancer and antibacterial) of metabolites, that were isolated and structurally elucidated from marine fungi to throw a helping hand for novel drug development.

Bioactive Properties of Marine Phenolics

Phenolic compounds from marine organisms are far less studied than those from terrestrial sources since their structural diversity and variability require powerful analytical tools. However, both their biological relevance and potential properties make them an attractive group deserving increasing scientific interest. The use of efficient extraction and, in some cases, purification techniques can provide novel bioactives useful for food, nutraceutical, cosmeceutical and pharmaceutical applications. The bioactivity of marine phenolics is the consequence of their enzyme inhibitory effect and antimicrobial, antiviral, anticancer, antidiabetic, antioxidant, or anti-inflammatory activities. This review presents a survey of the major types of phenolic compounds found in marine sources, as well as their reputed effect in relation to the occurrence of dietary and lifestyle-related diseases, notably type 2 diabetes mellitus, obesity, metabolic syndrome, cancer and Alzheimer's disease. In addition, the influence of marine phenolics on gut microbiota and other pathologies is also addressed.

Chemical Constituents from Endophytic Fungus Annulohypoxylon cf. stygium in Leaves of Anoectochilus roxburghii

The chemical investigation on endophytic fungus Annulohypoxylon cf. stygium in leaves of Anoectochilus roxburghii (Wall.) Lindl. has been performed. Sixteen compounds were isolated and their structures were identified as (-)-notoamide A, (-)-notoamide B, (+)-versicolamide B, notoamide C, notoamide D, stephacidin A, sterigmatocystin, dihydrosterigmatocystin, secosterigmatocystin, versiconol, averufanin, kipukasin D, kipukasin E, diorcinal, palmarumycin CP2 and (-)-(3R)-mellein methyl ether, respectively, by spectroscopic analysis and comparison with literature data. All the compounds were isolated from Annulohypoxylon genus for the first time. Sterigmatocystin and palmarumycin CP2 showed selective cytotoxic activities against HepG2, HeLa, MCF-7 and HT-29.

Cytotoxic Secondary Metabolites Isolated from the Marine Alga-Associated Fungus Penicillium chrysogenum LD-201810

A new pentaketide derivative, penilactonol A (1), and two new hydroxyphenylacetic acid derivatives, (2'R)-stachyline B (2) and (2'R)-westerdijkin A (3), together with five known metabolites, bisabolane-type sesquiterpenoids 4-6 and meroterpenoids 7 and 8, were isolated from the solid culture of a marine alga-associated fungus Penicillium chrysogenum LD-201810. Their structures were elucidated based on extensive spectroscopic analyses, including 1D/2D NMR and high resolution electrospray ionization mass spectra (HRESIMS). The absolute configurations of the stereogenic carbons in 1 were determined by the (Mo₂(OAc)₄)-induced circular dichroism (CD) and comparison of the calculated and experimental electronic circular dichroism (ECD) spectra, while the absolute configuration of the stereogenic carbon in 2 was established using single-crystal X-ray diffraction analysis. Compounds 2 and 3 adapt the 2'R-configuration as compared to known hydroxyphenylacetic acid-derived and O-prenylated natural products. The cytotoxicity of 1-8 against human carcinoma cell lines (A549, BT-549, HeLa, HepG2, MCF-7, and THP-1) was evaluated. Compound 3 exhibited cytotoxicity to the HepG2 cell line with an IC₅₀ value of 22.0 μM. Furthermore, 5 showed considerable activities against A549 and THP-1 cell lines with IC₅₀ values of 21.2 and 18.2 μM, respectively.

Antimicrobial bisabolane-type sesquiterpenoids from the deep-sea sediment-derived fungus Aspergillus versicolor SD-330

One new aromatic bisabolene-type sesquiterpenoid (1), along with four known analogues (2-5) were isolated and identified from the deep-sea sediment-derived fungus Aspergillus versicolor SD-330. Their structures were elucidated by NMR, HRESIMS, X-ray crystallographic analysis, and quantum chemical ECD calculations as well as comparison of those data with literature data. Compounds 1-5 were evaluated for antimicrobial activities against human and aquatic pathogenic bacteria. Compounds 1, 2 and 5 exhibited selective inhibitory activities against zoonotic pathogenic bacteria such as Aeromonas hydrophilia, Escherichia coli, Edwardsiella tarda and Vibrio harveyi, with the MIC values ranging from 1.0 to 8.0 μg/mL.

Studies on the antifungal and serotonin receptor agonist activities of the secondary metabolites from piezotolerant deep-sea fungus Ascotricha sp

The potent antifungal agent sesquiterpenes and serotonin 5-HT_2C agonist ascotricin were produced by a newly isolated deep-sea fungus Ascotricha sp. This fungus was isolated from deep-sea sediment collected at a depth of 1235 m and characterized. Piezotolerance was successfully tested under high pressure-low temperature (100 bar pressure and 20ºC) microbial cultivation system. Production of secondary metabolites was enhanced at optimized culture conditions. The in-vivo antifungal activity of sesquiterpenes was studied using the Caenorhabditis elegans – Candida albicans model system. The sesquiterpenes affected the virulence of C. albicans and prolonged the life of the host C. elegans. These findings suggest that sesquiterpenes are attractive antifungal drug candidates. The 5-HT_2C receptor agonist is a potential target for the development of drugs for a range of central nervous system disorders. The interaction of 5-HT_2C agonist ascotricin with the receptor was studied through bioinformatic analysis. The in silico molecular docking and molecular dynamic simulation studies demonstrated that they fit into the serotonin 5-HT_2C active site and the crucial amino acid residues involved in the interactions were identified. To our knowledge, this is first report of in vivo antifungal analysis of sesquiterpenes and in silico studies of serotonin 5-HT_2C receptor-ascotricin complex.

Seven chromanoid norbisabolane derivatives from the marine-alga-endophytic fungus Trichoderma asperellum A-YMD-9-2

An examination of the endophytic fungus Trichoderma asperellum A-YMD-9-2 obtained from the marine red alga Gracilaria verrucosa led to the isolation of seven new chromanoid norbisabolane derivatives, trichobisabolins I-L (1-4) and trichaspsides C-E (5-7). Their structures and relative configurations were established on the basis of spectroscopic techniques, mainly including 1D/2D NMR and MS, and the absolute configuration of 1 was assigned by X-ray crystallographic analysis using Cu Kα radiation. All of these isolates feature a 1,9-epoxy ring system, and 5-7 represent the second occurrence of norbisabolane aminoglycosides. Compounds 1-7 exhibited potent inhibition of several marine phytoplankton species.

Diphenyl Ethers from a Marine-Derived Aspergillus sydowii

Six new diphenyl ethers (1⁻6) along with eleven known analogs were isolated from the ethyl acetate extract of a marine-derived Aspergillus sydowii guided by LC-UV-MS. Their structures were unambiguously characterized by HRESIMS, NMR, as well as chemical derivatization. Compounds 1 and 2 are rare diphenyl ether glycosides containing d-ribose. The absolute configuration of the sugar moieties in compounds 1⁻3 was determined by a LC-MS method. All the compounds were evaluated for their cytotoxicities against eight cancer cell lines, including 4T1, U937, PC3, HL-60, HT-29, A549, NCI-H460, and K562, and compounds 1, 5, 6, and 8⁻11 were found to exhibit selective cytotoxicity against different cancer cell lines.

Meroterpenoids and Isocoumarinoids from a Myrothecium Fungus Associated with Apocynum Venetum

Four new meroterpenoids 1⁻4 and four new isocoumarinoids 5⁻8, along with five known isocoumarinoids (9⁻13), were isolated from the fungus Myrothecium sp. OUCMDZ-2784 associated with the salt-resistant medicinal plant, Apocynum venetum (Apocynaceae). Their structures were elucidated by means of spectroscopic analysis, X-ray crystallography, ECD spectra and quantum chemical calculations. Compounds 1⁻5, 7, 9 and 10 showed weak α-glucosidase inhibition with the IC₅₀ values of 0.50, 0.66, 0.058, 0.20, 0.32, 0.036, 0.026 and 0.37 mM, respectively.

α-Glucosidase Inhibitors: Diphenyl Ethers and Phenolic Bisabolane Sesquiterpenoids from the Mangrove Endophytic Fungus Aspergillus flavus QQSG-3

Two new diphenyl ethers (1 and 2) and four new phenolic bisabolane sesquiterpenoids (3–6), together with five known related derivatives, were isolated from the culture of the endophytic fungus Aspergillus flavus QQSG-3 obtained from a fresh branch of Kandelia obobata, which was collected from Huizhou city in the province of Guangdong, China. The structures of compounds 1–6 were determined by analyzing NMR and HRESIMS data. The absolute configurations of 5 and 6 were assigned by comparing their experimental ECD spectra with those reported for similar compounds in the literature. All isolates were evaluated for their α-glucosidase inhibitory activity, of which compounds 3, 5, 10, and 11 showed strong inhibitory effects with IC₅₀ values in the range of 1.5–4.5 μM.

Polyketides From the Endophytic Fungus Cladosporium sp. Isolated From the Mangrove Plant Excoecaria agallocha

Five new polyketides (2–6) and ten known compounds (1 and 7–15) were obtained from the fermentation products of the endophytic fungus Cladosporium sp. OUCMDZ-302 with the mangrove plant, Excoecaria agallocha (Euphorbiaceae). The new structures of 2–6 were established on the basis of ECD, specific rotation and spectroscopic data as well as the chemical calculation. Compound 7 showed cytotoxicity against H1975 cell line with an IC₅₀ value of 10.0 μM. Compounds 4 and 8–10 showed radical scavenging activity against DPPH with the IC₅₀ values of 2.65, 0.24, 5.66, and 6.67 μM, respectively. In addition, the absolute configuration of compound 1 was solidly determined by X-ray and sugar analysis of the acidic hydrolysates for the first time as well as those of compounds 8–10 in this paper.

Aspergoterpenins A⁻D: Four New Antimicrobial Bisabolane Sesquiterpenoid Derivatives from an Endophytic Fungus Aspergillus versicolor

Aspergoterpenins A⁻D (1⁻4), four new bisabolane sesquiterpenoid derivatives, were obtained from the endophytic fungus, Aspergillus versicolor, together with eight known compounds (5⁻12), and their structures were elucidated by a comprehensive analysis of their NMR (Nuclear Magnetic Resonance), MS (Mass Spectrum) and CD (Circular Dichroism) spectra. Aspergoterpenin A (1) was the first example with a characteristic ketal bridged-ring part in the degraded natural bisabolane-type sesquiterpene structures. The compounds 1⁻12 displayed no significant activities against four cancer cell lines (A549, Caski, HepG2 and MCF-7). Further, the antimicrobial activities to Erwinia carotovora sub sp. Carotovora were evaluated, and the results showed that compounds 1⁻12 displayed antimicrobial activities with MIC values ranging from 15.2 to 85.2 μg/mL.

Endophytic Fungi-Alternative Sources of Cytotoxic Compounds: A Review

Cancer is a major cause of death worldwide, with an increasing number of cases being reported annually. The elevated rate of mortality necessitates a global challenge to explore newer sources of anticancer drugs. Recent advancements in cancer treatment involve the discovery and development of new and improved chemotherapeutics derived from natural or synthetic sources. Natural sources offer the potential of finding new structural classes with unique bioactivities for cancer therapy. Endophytic fungi represent a rich source of bioactive metabolites that can be manipulated to produce desirable novel analogs for chemotherapy. This review offers a current and integrative account of clinically used anticancer drugs such as taxol, podophyllotoxin, camptothecin, and vinca alkaloids in terms of their mechanism of action, isolation from endophytic fungi and their characterization, yield obtained, and fungal strain improvement strategies. It also covers recent literature on endophytic fungal metabolites from terrestrial, mangrove, and marine sources as potential anticancer agents and emphasizes the findings for cytotoxic bioactive compounds tested against specific cancer cell lines.

Fatty acid derivatives from the halotolerant fungus Cladosporium cladosporioides

Halotolerant fungus Cladosporium cladosporioides OUCMDZ-187 was isolated from the mangrove plant Rhizophora stylosa collected in Shankou, Guangxi Province of China. Three new fatty acid esters cladosporesters A-C (1-3) and 5 new fatty acids cladosporacids A-E (4-8) were isolated from the ethyl acetate extract of the fermentation broth of OUCMDZ-187 in a hypersaline (10% salt) medium. Their structures were elucidated by UV, IR, MS, specific rotation, and 1D and 2D NMR data.

Marine-Derived Penicillium Species as Producers of Cytotoxic Metabolites

Since the discovery of penicillin, Penicillium has become one of the most attractive fungal genera for the production of bioactive molecules. Marine-derived Penicillium has provided numerous excellent pharmaceutical leads over the past decades. In this review, we focused on the cytotoxic metabolites * (* Cytotoxic potency was referred to five different levels in this review, extraordinary (IC₅₀/LD₅₀: <1 μM or 0.5 μg/mL); significant (IC₅₀/LD₅₀: 1~10 μM or 0.5~5 μg/mL); moderate (IC₅₀/LD₅₀: 10~30 μM or 5~15 μg/mL); mild (IC₅₀/LD₅₀: 30~50 μM or 15~25 μg/mL); weak (IC₅₀/LD₅₀: 50~100 μM or 25~50 μg/mL). The comparative potencies of positive controls were referred when they were available). produced by marine-derived Penicillium species, and on their cytotoxicity mechanisms, biosyntheses, and chemical syntheses.

Marine natural products

Covering: 2015. Previous review: Nat. Prod. Rep., 2016, 33, 382-431This review covers the literature published in 2015 for marine natural products (MNPs), with 1220 citations (792 for the period January to December 2015) referring to compounds isolated from marine microorganisms and phytoplankton, green, brown and red algae, sponges, cnidarians, bryozoans, molluscs, tunicates, echinoderms, mangroves and other intertidal plants and microorganisms. The emphasis is on new compounds (1340 in 429 papers for 2015), together with the relevant biological activities, source organisms and country of origin. Reviews, biosynthetic studies, first syntheses, and syntheses that lead to the revision of structures or stereochemistries, have been included.

New metabolites from the sponge-derived fungus Aspergillus sydowii J05B-7F-4

Two new metabolites, diorcinolic acid (1) and β-d-glucopyranosyl aspergillusene A (8), together with six diphenylethers (2-7), a diketopiperazine (9), a chromone (10) and a xanthone (11) were isolated from the fungus Aspergillus sydowii derived from the marine sponge Stelletta sp. The planar structures and their relative configurations were elucidated by analysing 1D, 2D NMR and HRESIMS data. Compound 8 is the first glycoside of phenolic bisabolane sesquiterpenes. Compounds 1 and 8 exhibited mild cytotoxicity against KB (human nasopharyngeal carcinoma cells), HepG2 (human liver cancer cells) and HCT 116 (human colon cancer cells). All compounds were evaluated for antibacterial activity and their abilities to suppress LPS-induced nitric oxide (NO) production. Compounds 2 and 4-7 showed mild antibacterial activity against human pathogen Staphylococcus aureus and fish pathogens Streptococcus iniae and Vibrio ichthyoenteri, and compounds 4 and 7 weakly suppressed NO production.

Identification and biological evaluation of secondary metabolites from the endolichenic fungus Aspergillus versicolor

A chemical investigation of the endolichenic fungus Aspergillus versicolor (125a), which was found in the lichen Lobaria quercizans, resulted in the isolation of four novel diphenyl ethers, named diorcinols F-H (1-3, resp.) and 3-methoxyviolaceol-II (4), eight new bisabolane sesquiterpenoids, named (-)-(R)-cyclo-hydroxysydonic acid (5), (-)-(7S,8R)-8-hydroxysydowic acid (6), (-)-(7R,10S)-10-hydroxysydowic acid (7), (-)-(7R,10R)-iso-10-hydroxysydowic acid (8), (-)-12-acetoxy-1-deoxysydonic acid (9), (-)-12-acetoxysydonic acid (10), (-)-12-hydroxysydonic acid (11), and (-)-(R)-11-dehydrosydonic acid (12), two new tris(pyrogallol ethers), named sydowiols D (13) and E (14), and fifteen known compounds, 15-29. All of the structures were determined by spectroscopic analyses, and a number of them were further identified through chemical transformations and electronic circular dichroism (ECD) calculations. Preliminary bioassays of these isolates for the determination of their inhibitory activities against the fungus Candida albicans, and their cytotoxicities against the human cancer cell lines PC3, A549, A2780, MDA-MB-231, and HEPG2 were also evaluated.