Phytotoxic and Antimicrobial Terrein Derivatives and Butenolides Isolated from the Endophytic Fungus Aspergillus terreus HT5

Two new terrein derivatives, aspergilethers A and B (1 and 2), two known analogues (3 and 4), and three known butenolides (5-7) were isolated from the endophyte Aspergillus terreus HT5. Their structures were determined by spectroscopic analysis and ECD and NMR calculations. Interestingly, 1 and 2 had unpresented medium aliphatic side chains in terrein derivatives, with different absolute configurations at C-7, which was very scarce. (+)-Terrein (3) exhibited potent postemergence phytotoxicity toward Amaranthaceae, Portulacaceae, and Fabaceae, with MIC values of 250-1000 μg/mL. Transcriptome analysis and qRT-PCR suggested that (+)-terrein induced the transcriptional expression of aging-related genes to accelerate organ senescence and stimulated plant detoxification response. The conjugated system between keto carbonyl and double bonds in the cyclopentenone ring and side chain, and the configurations of C-2 and C-3, played critical roles in the phytotoxicity of terrein derivatives. Meanwhile, 3 was first reported to display moderate antioomycetes activity toward Phytophthora nicotiana.

Bioactive Aspergteroids G-J from Soft-Coral-Associated Symbiotic and Epiphytic Fungus Aspergillus terreus EGF7-0-1

Two new disubstituted maleimides, aspergteroids G-H (1-2), and two trisubstituted butenolides aspergteroids I-J (3-4), along with four known analogs, were isolated and structurally identified from the fermentation extract of soft-coral-associated symbiotic and epiphytic fungus Aspergillus terreus EGF7-0-1. The structures of the new compounds were established mainly via spectroscopic data analyses, and their absolute configurations were determined via X-ray diffraction analysis and comparison of the calculated and experimental electronic circular dichroism. Myocardial protection assays showed that compounds 1, 2, 5, and 6 possess protective effects against tert-butyl hydroperoxide (TBHP)-induced H9c2 (rat myocardial cells) apoptosis at low concentrations. Based on the analyses of the protein-protein interaction (PPI) network and Western blotting, compound 1 may inhibit the apoptosis and inflammatory response of cardiomyocytes after TBHP induction and improve the antioxidant capacity of cardiomyocytes. We speculate that the anti-inflammatory response of compound 1 is suppressed by the glycogen synthase kinase-3 beta (GSK-3β), downregulated by the NOD-like receptor thermal protein domain associated protein 3 (NLRP3) inflammasome activation, and suppressed by the expression of cysteinyl aspartate specific proteinase-3 (caspase-3) and B-cell lymphoma-2 associated X protein (Bax).

C-4-Modified Isotetrones Prevent Biofilm Growth and Persister Cell Resuscitation in Mycobacterium smegmatis

Hyperphosphorylated nucleotide (p)ppGpp, synthesized by Rel protein, regulates the stringent response pathway responsible for biofilm and persister cell growth in mycobacteria. The discovery of vitamin C as an inhibitor of Rel protein activities raises the prospect of tetrone lactones to prevent such pathways. The closely related isotetrone lactone derivatives are identified herein as inhibitors of the above processes in a mycobacterium. Synthesis and biochemical evaluations show that an isotetrone possessing phenyl substituent at C-4 inhibit the biofilm formation at 400 μg mL^-1, 84 h post-exposure, followed by moderate inhibition by the isotetrone possessing the p-hydroxyphenyl substituent. The latter isotetrone inhibits the growth of persister cells at 400 μg mL^-1 f.c. when monitored for 2 weeks, under PBS starvation. Isotetrones also potentiate the inhibition of antibiotic-tolerant regrowth of cells by ciprofloxacin (0.75 μg mL^-1) and thus act as bioenhancers. Molecular dynamics studies show that isotetrone derivatives bind to the Rel_Msm protein more efficiently than vitamin C at a binding site possessing serine, threonine, lysine, and arginine.

Natural epidithiodiketopiperazine alkaloids as potential anticancer agents: Recent mechanisms of action, structural modification, and synthetic strategies

Cancer has become a grave health crisis that threatens the lives of millions of people worldwide. Because of the drawbacks of the available anticancer drugs, the development of novel and efficient anticancer agents should be encouraged. Epidithiodiketopiperazine (ETP) alkaloids with a 2,5-diketopiperazine (DKP) ring equipped with transannular disulfide or polysulfide bridges or S-methyl moieties constitute a special subclass of fungal natural products. Owing to their privileged sulfur units and intriguing architectural structures, ETP alkaloids exhibit excellent anticancer activities by regulating multiple cancer proteins/signaling pathways, including HIF-1, NF-κB, NOTCH, Wnt, and PI3K/AKT/mTOR, or by inducing cell-cycle arrest, apoptosis, and autophagy. Furthermore, a series of ETP alkaloid derivatives obtained via structural modification showed more potent anticancer activity than natural ETP alkaloids. To solve supply difficulties from natural resources, the total synthetic routes for several ETP alkaloids have been designed. In this review, we summarized several ETP alkaloids with anticancer properties with particular emphasis on their underlying mechanisms of action, structural modifications, and synthetic strategies, which will offer guidance to design and innovate potential anticancer drugs.

Facile access to chiral γ-butyrolactones via rhodium-catalysed asymmetric hydrogenation of γ-butenolides and γ-hydroxybutenolides

The highly efficient Rh/ZhaoPhos-catalysed asymmetric hydrogenation of γ-butenolides and γ-hydroxybutenolides was successfully developed. This protocol provides an efficient and practical approach to the synthesis of various chiral γ-butyrolactones, which are synthetically valuable building blocks of diverse natural products and therapeutic substances, with excellent results (up to >99% conversion and 99% ee). Further follow-up transformations have been revealed to accomplish creative and efficient synthetic routes for several enantiomerically enriched drugs via this catalytic methodology.

Unearthing the fungal endophyte Aspergillus terreus for chemodiversity and medicinal prospects: a comprehensive review

Aspergillus terreus microorganism represents a promising prospective source for drug discovery since it is rich in diverse kinds of bioactive secondary metabolites. It contributed to many biotechnological applications and its metabolites are used in the synthesis of certain pharmaceuticals and food products, in addition to its useful uses in fermentation processes. There are about 346 compounds identified from marine and terrestrial-derived A. terreus from 1987 until 2022, 172 compounds of them proved a vast array of bioactivity. This review aimed to create an up-to-date comprehensive literature data of A. terreus's secondary metabolites classes supported by its different bioactivity data to be a scientific record for the next work in drug discovery.

Polyketides as Secondary Metabolites from the Genus Aspergillus

Polyketides are an important class of structurally diverse natural products derived from a precursor molecule consisting of a chain of alternating ketone and methylene groups. These compounds have attracted the worldwide attention of pharmaceutical researchers since they are endowed with a wide array of biological properties. As one of the most common filamentous fungi in nature, Aspergillus spp. is well known as an excellent producer of polyketide compounds with therapeutic potential. By extensive literature search and data analysis, this review comprehensively summarizes Aspergillus-derived polyketides for the first time, regarding their occurrences, chemical structures and bioactivities as well as biosynthetic logics.

In silico prediction of natural compounds as potential multi-target inhibitors of structural proteins of SARS-CoV-2

The severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) has caused a colossal loss to human health and lives and has deeply impacted socio-economic growth. Remarkable efforts have been made by the scientific community in containing the virus by successful development of vaccines and diagnostic kits. Initiatives towards drug repurposing and discovery have also been undertaken. In this study, we compiled the known natural anti-viral compounds using text mining of the literature and examined them against four major structural proteins of SARS-CoV-2, namely, spike (S) protein, nucleocapsid (N) protein, membrane (M) protein and envelope (E) protein. Following computational approaches, we identified fangchinoline and versicolactone C as the compounds to exhibit strong binding to the target proteins and causing structural deformation of three structural proteins (N, S and M). We recommend the inhibitory effects of these compounds from our study should be experimentally validated against SARS-CoV-2.Communicated by Ramaswamy H. Sarma.

Butenolide derivatives from Aspergillus terreus selectively inhibit butyrylcholinesterase

Two undescribed butenolide derivatives, asperteretal J (1) and K (2), together with 13 known ones (3-15) were isolated from an endophytic fungus Aspergillus terreus SGP-1, the fermentation product of which exhibited selective inhibitory activity toward butyrylcholinesterase. The structures of the new compounds were elucidated based on HRMS and NMR data, and the absolute configurations were determined by specific optical rotation comparison. All compounds were evaluated for cholinesterase inhibitory effects with galantamine as a positive control. Compounds 4-8 selectively inhibited butyrylcholinesterase with IC₅₀ values of 18.4-45.8 µM in a competitive manner, with Ki values of 12.3-38.2 µM. The structure-activity relationship was discussed. Molecular docking and dynamic simulation of the inhibitor-enzyme complex were performed to better understand the interactions.

Terrien, a metabolite made by Aspergillus terreus, has activity against Cryptococcus neoformans

Antimicrobial compounds, including antibiotics, have been a cornerstone of modern medicine being able to both treat infections and prevent infections in at-risk people, including those who are immune-compromised and those undergoing routine surgical procedures. Their intense use, including in people, animals, and plants, has led to an increase in the incidence of resistant bacteria and fungi, resulting in a desperate need for novel antimicrobial compounds with new mechanisms of action. Many antimicrobial compounds in current use originate from microbial sources, such as penicillin from the fungus Penicillium chrysogenum (renamed by some as P. rubens). Through a collaboration with Aotearoa New Zealand Crown Research Institute Manaaki Whenua-Landcare Research we have access to a collection of thousands of fungal cultures known as the International Collection of Microorganisms from Plants (ICMP). The ICMP contains both known and novel species which have not been extensively tested for their antimicrobial activity. Initial screening of ICMP isolates for activity against Escherichia coli and Staphylococcus aureus directed our interest towards ICMP 477, an isolate of the soil-inhabiting fungus, Aspergillus terreus. In our investigation of the secondary metabolites of A. terreus, through extraction, fractionation, and purification, we isolated nine known natural products. We evaluated the biological activity of selected compounds against various bacteria and fungi and discovered that terrein (1) has potent activity against the important human pathogen Cryptococcus neoformans.

Antimicrobial secondary metabolites from an endophytic fungus Aspergillus polyporicola

Two new nucleoside derivatives, kipukasins O (1) and P (2), one new cyclohexenone derivative, arthropsadiol D (5), and one new natural product, (+)-2,5-dimethyl-3(2H)-benzofuranone (6), together with eleven known compounds (3, 4, 7-15), were obtained from the culture broth of the endophytic fungus Aspergillus polyporicola R2 isolated from the roots of Synsepalum dulcificum. Among them, the absolute configuration of compound 5 was determined by quantum chemical calculations of NMR chemical shifts and ECD spectrum. The antimicrobial activities of these compounds were evaluated. Compound 11 exhibited obvious inhibitory activity against MRSA, Staphylococcus aureus, Salmonella typhimurium, Botrytis cinerea, and Fusarium graminearum with MIC values of 4, 4, 4, 32, and 16 μg/mL, respectively. Compound 12 exhibited antibacterial activity against S. typhimurium and MRSA with MIC values of 4 and 16 μg/mL. Compound 6 exhibited antifungal activity against F. graminearum with MIC value of 32 μg/mL.

Bioactive pulvinones from a marine algicolous fungus Aspergillus terreus NTU243

Marine fungi are regarded as an under-explored source of structurally interesting and bioactive natural products with the potential to provide attractive lead compounds for drug discovery. In this study, several fungal strains were isolated from marine algae collected from the northeastern coast of Taiwan. In the preliminary antimicrobial screening against bacteria and fungi, the ethyl acetate extract of the fermented products of Aspergillus terreus NTU243 derived from a green alga Ulva lactuca was found to exhibit significant antimicrobial activities. Therefore, bioassay-guided separations of the active principle from liquid and solid fermented products of A. terreus NTU243 were undertaken, which resulted in the isolation and purification of 16 compounds. Their structures were elucidated by spectroscopic analysis to be four previously undescribed aspulvinones S-V as well as twelve known compounds. All the isolates were assessed for anti-inflammatory activity by measuring the amount of nitric oxide (NO) production in lipopolysaccharide (LPS)-induced BV-2 cells, and aspulvinone V, butyrolactone I, and (+)-terrein inhibited 45.0%, 34.5%, and 49.2% of NO production, respectively, at 10 μM concentration. Additionally, zymography showed that the conditioned medium of THP-1 cells post-LPS challenged significantly enhanced matrix metalloproteinase (MMP)-9-mediated gelatinolysis, and pretreatment with aspulvinones U and V significantly attenuated MMP-9-mediated gelatinolysis by 56.0% and 67.8%, separately.

Trityl Cation-Catalyzed Hosomi-Sakurai Reaction of Allylsilane with β,γ-Unsaturated α-Ketoester to Form γ,γ-Disubstituted α-Ketoesters

(Ph3C)[BPh(F)4]-catalyzed Hosomi-Sakurai allylation of allylsilanes with β,γ-unsaturated α-ketoesters has been developed to give γ,γ-disubstituted α-ketoesters in high yields with excellent chemoselectivity. Preliminary mechanistic studies suggest that trityl cation dominates the catalysis, while the silyl cation plays a minor role.

γ-Aromatic Butenolides of Microbial Source - A Review of Their Structures, Biological Activities and Biosynthesis

γ-Aromatic butenolides (γ-AB) are an important type of structures found in many bioactive microbial secondary metabolites (SMs). γ-AB refer to a group of natural products (NPs) containing five-membered (unsaturated) lactones with 3-phenyl and 4-benzyl substituents. Their wide-range biological activities have inspired pharmaceutical chemists to explore its biosynthesis mechanisms and design strategies to construct the γ-AB skeleton. Recently, there are a great deal of interesting research progress on the structures, biological activities and biosynthesis of γ-AB. This review will focus on these aspects and summarize the important achievements of γ-AB from 1975 to 2021.

Anti‐Inflammatory, Antiallergic and COVID‐19 Main Protease (M pro ) Inhibitory Activities of Butenolides from a Marine‐Derived Fungus Aspergillus costaricaensis

Amid the current COVID‐19 pandemic, the emergence of several variants in a relatively high mutation rate (twice per month) strengthened the importance of finding out a chemical entity that can be potential for developing an effective medicine. In this study, we explored ethyl acetate (EtOAc) extract of a marine‐derived fungus Aspergillus cosatricaensis afforded three butenolide derivatives, butyrolactones I, VI and V (1–3), two naphtho‐γ‐pyrones, TMC‐256 A1 (4) and rubrofusarin B (5) and methyl p‐hydroxyphenyl acetate (6). Structure identification was unambiguously determined based on exhaustive spectral analyses including 1D/2D NMR and mass spectrometry. The isolated compounds (1–6) were assessed for their in vitro anti‐inflammatory, antiallergic, elastase inhibitory activities and in silico SARS‐CoV‐2 main protease (M^pro). Results exhibited that only butenolides (1 and 2) revealed potent activities similar to or more than reference drugs unlike butyrolactone V (3) suggesting them as plausible chemical entities for developing lead molecules.

Butenolides from the Coral-Derived Fungus Aspergillius terreus SCSIO41404

Five undescribed butenolides including two pairs of enantiomers, (+)-asperteretal G (1a), (−)-asperteretal G (1b), (+)-asperteretal H (2a), (−)-asperteretal H (2b), asperteretal I (3), and para-hydroxybenzaldehyde derivative, (S)-3-(2,3-dihydroxy-3-methylbutyl)-4-hydroxybenzaldehyde (14), were isolated together with ten previously reported butenolides 4–13, from the coral-derived fungus Aspergillus terreus SCSIO41404. Enantiomers 1a/1b and 2a/2b were successfully purified by high performance liquid chromatography (HPLC) using a chiral column, and the enantiomers 1a and 1b were new natural products. Structures of the unreported compounds, including the absolute configurations, were elucidated by NMR and MS data, optical rotation, experimental and calculated electronic circular dichroism, induced circular dichroism, and X-ray crystal data. The isolated butenolides were evaluated for antibacterial, cytotoxic, and enzyme inhibitory activities. Compounds 7 and 12 displayed weak antibacterial activity, against Enterococcus faecalis (IC₅₀ = 25 μg/mL) and Klebsiella pneumoniae (IC₅₀ = 50 μg/mL), respectively, whereas 6 showed weak inhibitory effect on acetylcholinesterase. Nevertheless, most of the butenolides showed inhibition against pancreatic lipase (PL) with an inhibition rate of 21.2–73.0% at a concentration of 50 μg/mL.

Diverse Secondary Metabolites from the Coral-Derived Fungus Aspergillus hiratsukae SCSIO 5Bn1003

Three new metabolites, including a cyclic tetrapeptide asperhiratide (1), an ecdysteroid derivative asperhiratine (2), and a sesquiterpene lactone asperhiratone (3), were isolated and identified from the soft coral-derived fungus Aspergillus hiratsukae SCSIO 5Bn₁003, together with 10 known compounds. Their structures were elucidated via spectroscopic analysis, X-ray diffraction analysis, and electronic circular dichroism calculations. In addition, the absolute configuration of 1 was determined by Marfey’s technique and an analysis of the acid hydrolysates using a chiral phase HPLC column. Among all the compounds, 6 and 8 showed medium cytotoxic activities against four tumor cell lines (SF-268, HepG-2, MCF-7, and A549), with IC₅₀ values ranging from 31.03 ± 3.04 to 50.25 ± 0.54 µM. Meanwhile, they strongly inhibited α-glucosidase activities, with IC₅₀ values of 35.73 ± 3.94 and 22.00 ± 2.45 µM, which were close to and even stronger than the positive control acarbose (IC₅₀ = 32.92 ± 1.03 µM). Compounds 6–8 showed significant antibacterial activities against Bacillus subtilis, with MIC values of 10.26 ± 0.76 µM, 17.00 ± 1.25 µM, and 5.30 ± 0.29 µM, respectively. Compounds 9 and 12 exhibited potent radical scavenging activities against DPPH, with IC₅₀ values of 12.23 ± 0.78 µM and 7.38 ± 1.16 µM. In addition, asperhiratide (1) was evaluated for anti-angiogenic activities in the in vivo zebrafish model, which showed a weak inhibitory effect on intersegmental vessel (ISV) formation.

Synthesis of novel phytol-derived γ-butyrolactones and evaluation of their biological activity

The synthesis of phytol-derived γ-butyrolactones as well as their evaluation for deterrent activity towards peach-potato aphid Myzus persicae and antiproliferative activity against four selected cancer cell lines are reported. Products were obtained in good yields (19-96%) and their structures were fully characterized by spectroscopic data (NMR, HRMS). Four synthesized δ-halo-γ-lactones (4-7) are new and have not been previously described in the literature. In the choice test phytol (1) appeared deterrent to M. persicae, whereas modifications of its structure did not cause the avoidance of the treated leaves by the aphids. In contrast, aphids were attracted to the leaves treated with the new trans-δ-chloro-γ-lactone (6). Electrical Penetration Graph (EPG) technique applied to explore the aphid probing and feeding activity revealed that neither phytol nor lactone 6 affected aphid probing and the consumption of phloem sap, which means that both phytol and the lactone 6 might have acted as postingestive modifiers of aphid behavior. The results of in vitro antitumor assays showed that obtained phytol derivatives exhibit cytotoxic activity against studied cancer cell lines (leukemia, lung and colon carcinoma and its doxorubicin resistant subline). Halolactones 4-6 were identified as the compounds, which arrest cell cycle of leukemia cells mainly in G2/M and S phases.

Bioactive secondary metabolites from the deep-sea derived fungus Aspergillus sp. SCSIO 41029

Two new compounds classified as one new lumazine peptide, penilumamide K (1) and one new sesquiterpene (2), were obtained from the deep-sea derived fungus Aspergillus sp. SCSIO 41029, together with eleven known compounds (3-13). The structures of 1-13 including absolute configurations were determined by detailed NMR spectroscopy, HR-ESI-MS, chemical derivatization, and optical rotation data. Among them, compound 1 represents the first lumazine peptide reported from deep-sea derived fungus. The bioactive assay exhibited that compounds 1, 3, 4, 5, 7 and 10 had significant potency against α-glucosidase with IC₅₀ values ranging from 18.61 to 109.06 μΜ. In addition, compounds 4 and 9 showed strong antibacterial activity against Staphylococcus aureus with MIC values of 0.78 and 6.25 μg ml^-1, respectively.

A new diphenolic metabolite isolated from the marine-derived fungus Aspergillus niger 102

A new diphenolic derivative asperdiphenol A (1), along with nine known compounds (2-10), was isolated from the marine-derived fungus Aspergillus niger 102. Their structures were elucidated on the basis of spectroscopic analysis including NMR and MS spectrometry. Compound 1 was suggested to be a chiral mixture by the specific rotation and chiral HPLC. Compound 1 was evaluated for its anti-inflammatory, antibacterial, and cytotoxic activity.

Butenolide Derivatives with α-Glucosidase Inhibitions from the Deep-Sea-Derived Fungus Aspergillus terreus YPGA10

Three new butenolide derivatives, namely aspernolides N–P (1–3), together with six known analogues (4–9), were isolated from the ethyl acetate (EtOAc) extract of the deep sea-derived fungus Aspergillus terreus YPGA10. The structures of compounds 1–3 were determined on the basis of comprehensive analyses of the nuclear magnetic resonance (NMR) and mass spectroscopy (MS) data, and the absolute configurations of 1 and 2 were determined by comparisons of experimental electronic circular dichroism (ECD) with calculated ECD spectra. Compound 1 represents the rare example of Aspergillus-derived butenolide derivatives featured by a monosubstituted benzene ring. Compounds 6–9 exhibited remarkable inhibitory effects against α-glucosidase with IC₅₀ values of 3.87, 1.37, 6.98, and 8.06 μM, respectively, being much more active than the positive control acarbose (190.2 μM).

Water enables an asymmetric cross reaction of α-keto acids with α-keto esters for the synthesis of quaternary isotetronic acids

A water promoted asymmetric aldol/lactonization/enolization cascade reaction of α-keto acids and α-keto esters affords chiral quaternary isotetronic acids with excellent enantioselectivity.

Open-Ring Butenolides from a Marine-Derived Anti-Neuroinflammatory Fungus Aspergillus terreus Y10

To investigate structurally novel and anti-neuroinflammatory natural compounds from marine-derived microorganisms, the secondary metabolites of Aspergillus terreus Y10, a fungus separated from the sediment of the coast in the South China Sea, were studied. Three new compounds (2⁻4), with novel open-ring butenolide skeletons, were isolated from the ethyl acetate extract of the culture medium. In addition, a typical new butenolide, asperteretal F (1), was found to dose-dependently inhibit tumor necrosis factor (TNF-α) generation with an IC50 of 7.6 μg/mL. The present study shows the existence of open-ring butenolides, and suggests that butenolides such as asperteretal F (1) are a promising new anti-neuroinflammatroy candidate for neurodegenerative diseases.

Deep-Sea-Derived Butyrolactone I Suppresses Ovalbumin-Induced Anaphylaxis by Regulating Mast Cell Function in a Murine Model

Deep-sea-derived butyrolactone I (BTL-I), which was identified as a type of butanolide, was isolated from Aspergillus sp. Ovalbumin (OVA)-induced BALB/c anaphylaxis was established to explore the antifood allergic activity of BTL-I. As a result, BTL-I was able to alleviate OVA-induced allergy symptoms, reduce the levels of histamine and mouse mast cell proteinases, inhibit OVA-specific IgE, and decrease the population of mast cells in the spleen and mesenteric lymph nodes. BTL-I also significantly suppressed mast-dependent passive cutaneous anaphylaxis. Additionally, the maturation of bone marrow-derived mast cells (BMMCs) declined as BTL-I caused down-regulation of c-KIT receptors. Furthermore, molecular docking analyses revealed that BTL-I interacted with the inhibitory receptor, FcγRIIB. In conclusion, the reduction of mast cell function by deep-sea-derived BTL-I as well as its interactions with the inhibitory receptor, FcγRIIB, may contribute to BTL-I-related protection against food anaphylaxis.

New butenolide derivatives from the marine sponge-derived fungus Aspergillus terreus

Two new butenolide derivatives (±)-asperteretal D ((±)-1) and asperteretal E (2) containing rare 2-benzyl-3-phenyl substituted lactone core, together with nine known analogues (3-11) were obtained from a fungus Aspergillus terreus derived from the marine sponge Phakellia fusca. All the structures were elucidated on the basis of extensive NMR spectroscopic data. The chiral chromatography analyses allowed the separation of the (±)-asperteretal D, of which the absolute configurations were determined by comparing the experimental to calculated electronic circular dichroic (ECD) spectra. Compounds (±)-1, 2-5, and 7 exhibited potent inhibitory activities against α-glucosidase with IC₅₀ values ranging from 8.65 to 20.3 µM (positive control acarbose with an IC₅₀ value of 320 µM). In addition, derivatives 5-8 also showed moderate antioxidant activities.

Aspernolides L and M, new butyrolactones from the endophytic fungus Aspergillus versicolor

During the systematic search of active compounds from endophytic fungi, two new butyrolactones, namely aspernolides L (2) and M (4), together with four known compounds: 1-O-acetylglycerol (1), butyrolactone I (3), butyrolactone VI (5), and (+) alantrypinone (6) were characterized from the EtOAc extract of the endophytic fungus Aspergillus versicolor isolated from the roots of Pulicaria crispa (Asteraceae). Extensive spectroscopic analysis, including 1D, 2D NMR, and HRESIMS, was used to elucidate their structures. Compounds 1, 5, and 6 are reported for the first time from this fungus.

Phenylisotertronic acids from the TCM endophytic fungus Phyllosticta sp

Four new phenylisotertronic acids (1a/1b, 2a, and 3a) were isolated from a TCM endophytic fungal strain Phyllosticta sp. J13-2-12Y obtained from the leaves of Acorus tatarinowii, along with two known ones (2b and 3b). Compounds 1-3 all existed as mixtures of enantiomers, and their corresponding optically pure enantiomers were successfully isolated by chiral HPLC. The structures of isolated compounds were determined by comprehensive spectroscopic analyses and X-ray diffraction. Their absolute configurations were determined by ECD experiments and quantum chemical calculations. In addition, the antimicrobial activities and the cytotoxicities of these three pairs of optically pure enantiomers (1a/1b, 2a/2b, and 3a/3b) had been evaluated.

γ-Butyrolactones from Aspergillus Species: Structures, Biosynthesis, and Biological Activities

Recently, numerous metabolites possessing uncommon structures and potent bioactivity have been isolated from strains of fungi collected from diverse environments. The genus Aspergillus is known as a rich source of γ-butyrolactones. These are a group of fungal secondary metabolites, consisting of a five-membered lactone bearing two aromatic rings, which shows a great variety of biological activities. This review summarizes the research on the biosynthesis, source, and biological activities of the naturally occurring γ-butyrolactones that have been isolated from Aspergillus species published over the last decades. More than 75 compounds are described and 65 references are cited.

Bioactive compounds of Aspergillus terreus-F7, an endophytic fungus from Hyptis suaveolens (L.) Poit

The compounds terrein (1), butyrolactone I (2), and butyrolactone V (3) were isolated from the ethyl acetate extract (EtOAc) of the endophytic fungus Aspergillus terreus-F7 obtained from Hyptis suaveolens (L.) Poit. The extract and the compounds presented schistosomicidal activity against Schistosoma mansoni; at 100 µg/mL for EtOAc extract, 1297.3 µM for compound 1, 235.6 µM for compound 2, and 454.1 µM for compound 3, they killed 100% of the parasites after 72 h of treatment. Compounds 1, 2, and 3 exerted moderate leishmanicidal activity against Leishmania amazonensis (IC₅₀ ranged from 23.7 to 78.6 µM). At 235.6 and 227.0 µM, compounds 2 and 3, respectively, scavenged 95.92 and 95.12% of the DPPH radical (2,2-diphenyl-1-picryl-hydrazyl), respectively. Regarding the cytotoxicity against the breast tumor cell lines MDA-MB-231 and MCF-7, compound 2 gave IC₅₀ of 34.4 and 17.4 µM, respectively, while compound 3 afforded IC₅₀ of 22.2 and 31.9 µM, respectively. At 117.6 µM, compound 2 inhibited the growth of and killed the pathogen Escherichia coli (ATCC 25922). Compounds 1, 2, and 3 displayed low toxicity against the normal line of human lung fibroblasts (GM07492A cells), with IC₅₀ of 15.3 × 10³, 3.4 × 10³, and 5.8 × 10³ µM, respectively. This is the first report on (i) the in vitro schistosomicidal and leishmanicidal activities of the EtOAc extract of A. terreus-F7 and compounds 1, 2, and 3; and (ii) the antitumor activity of compounds 2 and 3 against MDA-MB-231 and MCF-7 cells.

α-Glucosidase Inhibitors from the Marine-Derived Fungus Aspergillus flavipes HN4-13

Three new butenolide derivatives, flavipesolides A-C (1-3), along with 13 known compounds (4-13, aspulvinone Q, monochlorosulochrin, and dihydrogeodin), were isolated from the marine-derived Aspergillus flavipes HN4-13 from a Lianyungang coastal sediment sample. The structures were elucidated by spectroscopic evidence. Compounds 4-6 and 9 were noncompetitive α-glucosidase inhibitors with K_i/IC₅₀ values of 0.43/34, 2.1/37, 0.79/19, and 2.8/90 μM, respectively. Compounds 1-3, 8, 10, and 13 are mixed α-glucosidase inhibitors with K_i/IC₅₀ values of (2.5, 19)/44, (3.4, 14)/57, (9.2, 4.7)/95, (6.3, 5.5)/55, (1.4, 0.60)/9.9, and (2.5, 7.2)/33 μM, respectively (IC₅₀ 101 μM for acarbose and 79 μM for 1-deoxynojirimycin).

Three New Butenolides from the Fungus Aspergillus sp. CBS-P-2

Three new butenolides aspernolides H–J (1–3) together with seven known ones (4–10) were isolated from the fungus Aspergillus sp. CBS-P-2. Their chemical structures were established on the basis of 1D- and 2D-NMR spectroscopic data, HR-ESI-MS analysis, and their absolute configuration were determined by circular dichroism (CD) analysis. All the compounds were evaluated for the antioxidant effects by DPPH and ABTS methods, the antitumor activities against four human tumor cell lines (HL-60, ASPC1, HCT-116 and PC-3) and antimicrobial activities. Compounds 4–10 showed significant activity against DPPH (IC₅₀ = 15.9–34.3 μM) and compounds 1–10 exhibited significant ABTS free radical scavenging activity (IC₅₀ = 2.8–33.1 μM). Compounds 2, 5 and 11 showed potent cytotoxic activities against HL-60 cell lines with IC₅₀ values of 39.4, 13.2 and 16.3 μM, respectively. Compound 10 showed good antimicrobial activity against Staphylococcus aureus with minimum inhibitory concentration (MIC) of 21.3 μM.

Two new asterriquinols from Aspergillus sp. CBS-P-2 with anti-inflammatory activity

Two new bisindolylbenzenoid alkaloids asterriquinol E (1) and asterriquinol F (2), together with four known compounds (3-6) were isolated from the fermentation products of the fungus Aspergillus sp. CBS-P-2. Their structures were established on the basis of extensive spectroscopic analysis, including HR-ESI-MS, UV, IR, 1D, and 2D NMR (HSQC, HMBC, and NOESY) methods. The stereochemical structure of 2 was confirmed via the CD data of the in situ formed [Rh2(OCOCF3)4] complex method. All of the isolated compounds were tested for inhibitory activity against LPS (lipopolysaccharide)-induced nitric oxide production in microglia.

Butenolide derivatives from the plant endophytic fungus Aspergillus terreus

Three new butenolides containing 5-hydroxyfuran-2(5H)-one core, asperteretal A (1), asperteretal B (2), and asperteretal C (3), together with seven known butenolides (4-10), were obtained from an endophytic fungus Aspergillus terreus PR-P-2 isolated from the plant Camellia sinensis var. assamica. The structures of compounds 1-3 were elucidated on the basis of detailed spectroscopic analysis including UV, IR, HRESIMS, 1D and 2D NMR, and ECD spectra. Compounds 1, 3, 5 and 6-8 showed potent inhibitory effects on NO production in RAW 264.7 lipopolysaccharide-induced macrophages, and compounds 5 and 8 also exhibited moderate cytotoxicity against HL-60 cell line.

Bioactive natural products derived from mangrove-associated microbes

This review summarizes new findings concerning the sources and characteristics of various natural products that can be extracted from mangrove-associated microbes over the past three years (January 2011–December 2013).

Territrem and butyrolactone derivatives from a marine-derived fungus Aspergillus terreus

Seventeen lactones including eight territrem derivatives (1–8) and nine butyrolactone derivatives (9–17) were isolated from a marine-derived fungus Aspergillusterreus SCSGAF0162 under solid-state fermentation of rice. Compounds 1–3 and 9–10 were new, and their structures were elucidated by spectroscopic analysis. The acetylcholinesterase inhibitory activity and antiviral activity of compounds 1–17 were evaluated. Among them, compounds 1 and 2 showed strong inhibitory activity against acetylcholinesterase with IC₅₀ values of 4.2 ± 0.6, 4.5 ± 0.6 nM, respectively. This is the first time it has been reported that 3, 6, 10, 12 had evident antiviral activity towards HSV-1 with IC₅₀ values of 16.4 ± 0.6, 6.34 ± 0.4, 21.8 ± 0.8 and 28.9 ± 0.8 μg·mL⁻¹, respectively. Antifouling bioassay tests showed that compounds 1, 11, 12, 15 had potent antifouling activity with EC₅₀ values of 12.9 ± 0.5, 22.1 ± 0.8, 7.4 ± 0.6, 16.1 ± 0.6 μg·mL⁻¹ toward barnacle Balanus amphitrite larvae, respectively.