New Bioactive Polyketides from the Mangrove-Derived Fungus Penicillium sp. SCSIO 41411

Three new polyketides, including three ester derivatives (1, 3, and 5) and a new natural product, which was a benzoquinone derivative, embelin A (4), together with nine known ones (2 and 6-13), were isolated from the mangrove-derived fungus Penicillium sp. SCSIO 41411. Their structures were determined by detailed NMR and MS spectroscopic analyses. The X-ray single-crystal diffraction analysis of 4 was described for the first time. Compound 9 displayed obvious inhibition against PDE4 with an inhibitory ratio of 40.78% at 10 μM. Compound 12 showed DPPH radical scavenging activity, with an EC50 of 16.21 µg/mL, compared to the positive control (ascorbic acid, EC50, 11.22 µg/mL). Furthermore, compound 4 exhibited cytotoxicity against PC-3 and LNCaP with IC50 values of 18.69 and 31.62 µM, respectively.

Phenylhydrazone Alkaloids from the Deep-Sea Cold Seep Derived Fungus Talaromyces amestolkiae HDN21-0307

Alkaloids with a phenylhydrazone architecture are rarely found in nature. Four unusual phenylhydrazone alkaloids named talarohydrazones A-D (1-4) were isolated from the deep-sea cold seep derived fungus Talaromyces amestolkiae HDN21-0307 using the one strain-many compounds (OSMAC) approach and MS/MS-based molecular networking (MN) combined with network annotation propagation (NAP) and the unsupervised substructure annotation method MS2LDA. Their structures were elucidated by spectroscopic data analysis, single-crystal X-ray diffraction, and quantum chemical calculations. Talarohydrazone A (1) possessed an unusual skeleton combining 2,4-pyridinedione and phenylhydrazone. Talarohydrazone B (2) represents the first natural phenylhydrazone-bearing azadophilone. Bioactivity evaluation revealed that compound 1 exhibited cytotoxic activity against NCI-H446 cells with an IC50 value of 4.1 μM. In addition, compound 1 displayed weak antibacterial activity toward Staphylococcus aureus with an MIC value of 32 μg/mL.

Facile access to benzofuran derivatives through radical reactions with heteroatom-centered super-electron-donors

The development of suitable electron donors is critical to single-electron-transfer (SET) processes. The use of heteroatom-centered anions as super-electron-donors (SEDs) for direct SET reactions has rarely been studied. Here we show that heteroatom anions can be applied as SEDs to initiate radical reactions for facile synthesis of 3-substituted benzofurans. Phosphines, thiols and anilines bearing different substitution patterns work well in this inter-molecular radical coupling reaction and the 3-functionalized benzofuran products bearing heteroatomic functionalities are given in moderate to excellent yields. The reaction mechanism is elucidated via control experiments and computational methods. The afforded products show promising applications in both organic synthesis and pesticide development.

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.

A new alkaloid from Thespesia populnea endophytic fungus Penicillium sp. TM-Y1-1

A new alkaloid (3), together with three known compounds, were isolated from the Thespesia populnea endophytic fungus TM-Y1-1. Their structures were elucidated by extensive spectroscopic methods. The absolute configuration of compound 3 was determined for the first time by ECD calculation and DP4+ analysis. All compounds were evaluated for antimicrobial activity. The results showed that compounds 1 and 2 both exhibited moderate inhibitory activity against banana Colletotrichum gloeosporioides with MIC value of 31.25 μg/ml.

Hamamelis virginiana L. Leaf Extracts Inhibit the Growth of Antibiotic-Resistant Gram-Positive and Gram-Negative Bacteria

Virginian witch hazel (WH; Hamamelis virginiana L.; family: Hamamelidaceae) is a North American plant that is used traditionally to treat a variety of ailments, including bacterial infections. Solvents of varying polarity (water, methanol, ethyl acetate, hexane and chloroform) were used to prepare extracts from this plant. Resuspensions of each extract in an aqueous solution were tested for growth-inhibitory activity against a panel of bacteria (including three antibiotic-resistant strains) using agar disc diffusion and broth microdilution assays. The ethyl acetate, hexane and chloroform extracts were completely ineffective. However, the water and methanolic extracts were good inhibitors of E. coli, ESBL E. coli, S. aureus, MRSA, K. pneumoniae and ESBL K. pneumoniae growth, with the methanolic extract generally displaying substantially greater potency than the other extracts. Combining the active extracts with selected conventional antibiotics potentiated the bacterial growth inhibition of some combinations, whilst other combinations remained non-interactive. No synergistic or antagonistic interactions were observed for any WH extracts/antibiotic combinations. Gas chromatography-mass spectrometry analysis of the extracts identified three molecules of interest that may contribute to the activities observed, including phthalane and two 1,3-dioxolane compounds. Putative modes of action of the active WH extracts and these molecules of interest are discussed herein.

The Outstanding Chemodiversity of Marine-Derived Talaromyces

Fungi in the genus Talaromyces occur in every environment in both terrestrial and marine contexts, where they have been quite frequently found in association with plants and animals. The relationships of symbiotic fungi with their hosts are often mediated by bioactive secondary metabolites, and Talaromyces species represent a prolific source of these compounds. This review highlights the biosynthetic potential of marine-derived Talaromyces strains, using accounts from the literature published since 2016. Over 500 secondary metabolites were extracted from axenic cultures of these isolates and about 45% of them were identified as new products, representing a various assortment of chemical classes such as alkaloids, meroterpenoids, isocoumarins, anthraquinones, xanthones, phenalenones, benzofurans, azaphilones, and other polyketides. This impressive chemodiversity and the broad range of biological properties that have been disclosed in preliminary assays qualify these fungi as a valuable source of products to be exploited for manifold biotechnological applications.

Straightforward Synthesis of Bis[(trifluoromethyl)sulfonyl]ethylated Isocoumarins from 2-Ethynylbenzoates

Herein, we report a facile isocoumarin and isoquinolone preparation by taking advantage of an initial bis(triflyl)ethylation [triflyl = (trifluoromethyl)sulfonyl] reaction, followed by heterocyclization, which contrasts with our previous results on cyclobutene formation. The efficiency of the catalyst- and irradiation-free heterocyclization/bis(triflyl)ethylation sequence showed exquisite dependence on the electronic nature of the substituents at the 2-ethynylbenzoate(benzamide) precursors. Molecular docking of model bis(triflyl)ethylated isocoumarins on human acetylcholinesterase (hAChE) revealed promising biological activities through selective coordination on both the catalytic active site and peripheral active site.

Recent advances in the discovery, biosynthesis, and therapeutic potential of isocoumarins derived from fungi: a comprehensive update

Microorganisms still remain the main hotspots in the global drug discovery avenue. In particular, fungi are highly prolific producers of vast structurally diverse specialized secondary metabolites, which have displayed a myriad of biomedical potentials. Intriguingly, isocoumarins is one distinctive class of fungal natural products polyketides, which demonstrated numerous remarkable biological and pharmacological activities. This review article provides a comprehensive state-of-the-art over the period 2000-2022 about the discovery, isolation, classifications, and therapeutic potentials of isocoumarins exclusively reported from fungi. Indeed, a comprehensive list of 351 structurally diverse isocoumarins were documented and classified according to their fungal sources [16 order/28 family/55 genera] where they have been originally discovered along with their reported pharmacological activities wherever applicable. Also, recent insights around their proposed and experimentally proven biosynthetic pathways are also briefly discussed.

Two previously undescribed phthalides from Talaromyces amestolkiae, a symbiotic fungus of Syngnathus acus

Amestolkins A (1) and B (2), two previously undescribed phthalides sharing the same planar structure of (1, 5-dihydroxyhexyl)-7-hydroxyisobenzofuran-1(3H)-one were isolated from Talaromyces amestolkiae. Their absolute configurations were elucidated by comprehensive analyses of spectroscopic evidences in high-resolution electrospray mass spectra (HRESIMS) and nuclear magnetic resonance (NMR) combined with electronic circular dichroism (ECD) and NMR calculations. 1 and 2 showed anti-neuroinflammatory activity by inhibiting the gene expressions of proinflammatory factors including C-C motif chemokine ligand 2 (CCL-2), tumor necrosis factor-α (TNF-α) and interleukin 6 (IL-6), as well as attenuating the excretion of inducible nitric oxide synthase (iNOS) in BV-2 microglial cells at the concentration of 30 μM.

New Meroterpenoid and Isocoumarins from the Fungus Talaromyces amestolkiae MST1-15 Collected from Coal Area

Three new compounds including a meroterpenoid (1) and two isocoumarins (8 and 9), together with thirteen known compounds (2-7, 10-16) were isolated from the metabolites of Talaromyces amestolkiae MST1-15. Their structures were identified by a combination of spectroscopic analysis. The absolute configuration of compound 1 was elucidated on the basis of experimental and electronic circular dichroism calculation, and compounds 8 and 9 were determined by Mo₂(OAc)₄-induced circular dichroism experiments. Compounds 7-16 showed weak antibacterial activities against Stenotrophomonas maltophilia with MIC values ranging from 128 to 512 μg/mL (MICs of ceftriaxone sodium and levofloxacin were 128 and 0.25 μg/mL, respectively).

Combination of biochar and AMF promotes phosphorus utilization by stimulating rhizosphere microbial co-occurrence networks and lipid metabolites of Phragmites

Agricultural biochar and arbuscular mycorrhizal fungi were used to promote the growth of Phragmites in the structural damaged and nutritional imbalanced littoral zone soils. Wheat straw biochar played a significant role in improving soil porosity and supplementing available phosphorus to 79.20 ± 3.20 mg/kg, compared with CK at 17.50 ± 0.88 mg/kg. The addition of Diversispora versiformis improved the plant net photosynthetic rate reaching up to 25.66 ± 0.65 μmol·m^-2·s^-1, which was 36.60 % higher than CK. The combination of biochar and fungi contributed to the whole plant dry weight biomass of 32.30 % and 234.00 % higher than the single biochar or AMF amendment groups, respectively. Meanwhile, the analysis of microbial co-occurrence networks showed the most relevant networks node species were mainly Talaromyces, Chaetomiacea and Gemmatimonadetes etc. Root lipid metabolite of Glycerophospholines further proved that phosphorus utilization was also enhanced endogenously in the rhizosphere soil. These results indicate that the combination of biochar and arbuscular mycorrhizal fungi play synergic role in enhancing phosphorus utilization endogenously and exogenously.

Critical Assessment of In Vitro Screening of α-Glucosidase Inhibitors from Plants with Acarbose as a Reference Standard

Postprandial hyperglycemia is treated with the oral antidiabetic drug acarbose, an intestinal α-glucosidase inhibitor. Side effects of acarbose motivated a growing number of screening studies to identify novel α-glucosidase inhibitors derived from plant extracts and other natural sources. As "gold standard", acarbose is frequently included as the reference standard to assess the potency of these candidate α-glucosidase inhibitors, with many outperforming acarbose by several orders of magnitude. The results are subsequently used to identify suitable compounds/products with strong potential for in vivo efficacy. However, most α-glucosidase inhibitor screening studies use enzyme preparations obtained from nonmammalian sources (typically Saccharomyces cerevisiae), despite strong evidence that inhibition data obtained using nonmammalian α-glucosidase may hold limited value in terms of identifying α-glucosidase inhibitors with actual in vivo hypoglycemic potential. The aim was to critically discuss the screening of novel α-glucosidase inhibitors from plant sources, emphasizing inconsistencies and pitfalls, specifically where acarbose was included as the reference standard. An assessment of the available literature emphasized the cruciality of stating the biological source of α-glucosidase in such screening studies to allow for unambiguous and rational interpretation of the data. The review also highlights the lack of a universally adopted screening assay for novel α-glucosidase inhibitors and the commercial availability of a standardized preparation of mammalian α-glucosidase.

Talaromarins A-F: Six New Isocoumarins from Mangrove-Derived Fungus Talaromyces flavus TGGP35

Six new isocoumarin derivative talaromarins A-F (1-6), along with 17 known analogues (7-23), were isolated from the mangrove-derived fungus Talaromyces flavus (Eurotiales: Trichocomaceae) TGGP35. Their structures were identified by detailed IR, UV, 1D/2D NMR and HR-ESI-MS spectra. The absolute configurations of new compounds were determined by the modified Mosher's method and a comparison of their CD spectra with dihydroisocoumarins described in the literature. The antioxidant, antibacterial, anti-phytopathogenic and inhibitory activity against α-glucosidase of all the isolated compounds were tested. Compounds 6-11, 17-19 and 21-22 showed similar or better antioxidant activity than the IC50 values ranging from 0.009 to 0.27 mM, compared with the positive control trolox (IC50 = 0.29 mM). Compounds 10, 18, 21 and 23 exhibited strong inhibitory activities against α-glucosidase with IC50 values ranging from 0.10 to 0.62 mM, while the positive control acarbose had an IC50 value of 0.5 mM. All compounds showed no antibacterial or anti-phytopathogenic activity at the concentrations of 50 μg/mL and 1 mg/mL, respectively. These results indicated that isocoumarins will be useful to developing antioxidants and as diabetes control agents.

Isolation, Identification and Insecticidal Activity of the Secondary Metabolites of Talaromyces purpureogenus BS5

The fungal strain BS5 was isolated from a soil sample collected in the Tibetan Plateau, which displayed good insecticidal activity and was identified as Talaromyces purpureogenus based on morphological and molecular analysis. This study aimed to evaluate the insecticidal activity and identify the active compound of the strain BS5 against the locust Locusta migratoria manilensis. The insecticidal activity of the fermented broth of BS5 was at 100% after 7 days against locusts. We extracted the fermented broth of BS5 and then evaluated the insecticidal activity of the extracts against locusts. The ethyl acetate extract exhibited promising activity levels with an LC₅₀ value of 1077.94 μg/mL and was separated through silica gel column chromatography. The UPLC-Q-Exactive Orbitrap/MS system was employed to analyze the active fraction Fr2.2.2 (with an LC₅₀ value of 674.87 μg/mL), and two compounds were identified: phellamurin and rubratoxin B.

A Brief Talk on the Design of Biopharmaceutical Separation and Purification Technology Course

Biological separation and purification technology is the basic technology of modern biotechnology, which is widely used in the pharmaceutical industry, especially the biopharmaceutical industry. In recent years, the biopharmaceutical industry has had a lot of room for development in the development of science and technology in South Korea, and the research on biopharmaceutical equipment and pharmaceutical technology has also achieved good research results. This article proposes a brief discussion on the design of biopharmaceutical separation and purification technology courses. In this study, by analyzing the synthesis potential of the secondary metabolites of the strain, using the α-glucosidase inhibition rate as an inspection indicator, the fermentation medium of the strain was optimized, and batch fermentation was carried out, and then, the metabolites were separated and purified, and the following conclusion was obtained: the α-glucosidase inhibition rate of the crude extract of the strain in the optimized fermentation medium is 35% higher than that of the initial medium.

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.

Absolute configuration of polypropionate derivatives: Decempyrones A-J and their MptpA inhibition and anti-inflammatory activities

Under guidance of ¹H NMR, ten new polypropionate derivatives, decempyrones A-J (1-10) along with two known analogues (11 and 12), were isolated from the marine-derived fungusFusarium decemcellulare SYSU-MS6716. The planar structures were elucidated on the basis of extensive spectroscopic analyses (1D and 2D NMR, and HR-ESIMS). The absolute configuration of the chiral centers in the side chain is a major obstacle for the structure identification of natural polypropionate derivatives. Herein, the J-based configurational analysis (JBCA), chemical degradation, geminal proton rule, and the modified Mosher's method were adopted to fix their absolute configurations in the side chain. Compounds 3 and 10 exhibited potent anti-inflammatory activity by inhibiting the production of NO in RAW264.7 cells activated by lipopolysaccharide with IC₅₀values 22.4 ± 1.8 and 21.7 ± 1.1 μM. In addition, compounds 3 and 10 displayed MptpA inhibitory activity with an IC₅₀ value of 19.2 ± 0.9 and 33.1 ± 2.9 µM. Structure-activity relationships of the polypropionate derivatives were discussed.

New Diterpenoids and Isocoumarin Derivatives from the Mangrove-Derived Fungus Hypoxylon sp

Two new diterpenoids, hypoxyterpoids A (1) and B (2), and four new isocoumarin derivatives, hypoxymarins A–D (4–7), together, with seven known metabolites (3 and 8–13) were obtained from the crude extract of the mangrove-derived fungus Hypoxylon sp. The structures of the new compounds were elucidated on the basis of 1- and 2-dimensional (1D/2D) nuclear magnetic resonance (NMR) spectroscopic and mass spectrometric analysis. The absolute configurations of compounds 1, 2, 4, 5, and 7 were determined by comparison of experimental and calculated electronic circular dichroism (ECD) spectra, and the absolute configurations of C-4′ in 6 and C-9 in 7 were determined by [Rh₂(OCOCF₃)₄]-induced ECD spectra. Compound 1 showed moderate α-glucosidase inhibitory activities with IC₅₀ values of 741.5 ± 2.83 μM. Compounds 6 and 11 exhibited DPPH scavenging activities with IC₅₀ values of 15.36 ± 0.24 and 3.69 ± 0.07 μM, respectively.

Neuroprotective Activities of Constituents from Phyllosticta capitalensis, an Endophyte Fungus of Loropetalum chinense var. rubrum

One new dioxolanone derivative, guignardianone G (1) and twelve known compounds (2-13) were isolated from the 95 % ethanol extract of the plant endophytic fungus Phyllosticta capitalensis cultured in rice medium. Among these known compounds, isoaltenuene (3), brassicasterol (7), 5,6-epoxyergosterol (8), citreoanthrasteroid A (9), demethylincisterol A (10), and chaxine C (11) were reported from Phyllosticta sp. for the first time. The structure of 1 was elucidated by 1D- and 2D-NMR experiments and HR-ESI-MS data analysis, and its absolute configuration was established through the comprehensive use of the methods of modified Mosher methods, calculations of ECD spectra and optical rotation values. The neuroprotective activity of compounds (1-9, 11-13) were evaluated on PC12 cells damage induced by glutamate, and compounds 9 and 12 showed potential neuroprotective activities with half effective concentration (EC₅₀ ) of 24.2 and 33.9 μM, respectively.

Genome Mining Discovery of a C4-Alkylated Dihydroisocoumarin Pathway in Fungi

A fungal C₄-alkylated dihydroisocoumarin pathway was discovered and elucidated. This pathway includes the following (1) a nonreducing polyketide synthase and a P450 collaboratively synthesize hydroxylated C₃-methylated isocoumarin 3; (2) a methyltransferase methylates 3 to 8; and (3) importantly, an esterase specifically catalyzes a ring reconstruction process of 8 to C₄-alkylated dihydroisocoumarin 10. Our discovery fills the gap in the enzymatic transformation process of natural C₄-alkylated isocoumarin derivates.

Resorcylic Acid Lactones Produced by an Endophytic Penicillium ochrochloron Strain from Kadsura angustifolia

Four new β-resorcylic acid lactones, including penochrochlactone A (2: ), 4-O-desmethyl-aigialomycin B (4: ), and penochrochlactones C and D (5: and 6: ), two compounds isolated from a natural source for the first time, 5α, 6β-acetonide-aigialomycin B (1: ) and penochrochlactone B (3: ), together with six known compounds, aigialomycin F (7: ), aigialomycins A, B, and D (8: -10: ), zeaenol (11: ), and oxozeaenol (12: ), were isolated from a mycelial solid culture of the endophytic fungus Penicillium ochrochloron SWUKD4.1850 from the medicinal plant Kadsura angustifolia by sequential purification over silica gel, Sephadex LH-20 column chromatography, and preparative HPLC. Their structures were elucidated by extensive spectroscopic analysis and chemical conversions. In addition, all the new compounds were evaluated for their cytotoxic and antibacterial activities in vitro. Penochrochlactone C (5: ) displayed moderate cytotoxicity against the HeLa tumor cell line with an IC₅₀ value of 9.70 µM. In the antibacterial assays, compounds 4:  - 6: exhibited moderate activities against Staphylococcus aureus, Bacillus subtilis, Escherichia coli, and Pseudomonas aeruginosa with MIC values between 9.7 and 32.0 µg/mL.

Biflavanones, Chalconoids, and Flavonoid Analogues from the Stem Bark of Ochna holstii

Two new biflavanones (1 and 2), three new bichalconoids (3-5), and 11 known flavonoid analogues (6-16) were isolated from the stem bark extract (CH3OH-CH2Cl2, 7:3, v/v) of Ochna holstii. The structures of the isolated metabolites were elucidated by NMR spectroscopic and mass spectrometric analyses. The crude extract and the isolated metabolites were evaluated for antibacterial activity against Bacillus subtilis (Gram-positive) and Escherichia coli (Gram-negative) as well as for cytotoxicity against the MCF-7 human breast cancer cell line. The crude extract and holstiinone A (1) exhibited moderate antibacterial activity against B. subtilis with MIC values of 9.1 μg/mL and 14 μM, respectively. The crude extract and lophirone F (14) showed cytotoxicity against MCF-7 with EC50 values of 11 μg/mL and 24 μM, respectively. The other isolated metabolites showed no significant antibacterial activities (MIC > 250 μM) and cytotoxicities (EC50 ≥ 350 μM).

Marine Pharmacology in 2016-2017: Marine Compounds with Antibacterial, Antidiabetic, Antifungal, Anti-Inflammatory, Antiprotozoal, Antituberculosis and Antiviral Activities; Affecting the Immune and Nervous Systems, and Other Miscellaneous Mechanisms of Action

The review of the 2016-2017 marine pharmacology literature was prepared in a manner similar as the 10 prior reviews of this series. Preclinical marine pharmacology research during 2016-2017 assessed 313 marine compounds with novel pharmacology reported by a growing number of investigators from 54 countries. The peer-reviewed literature reported antibacterial, antifungal, antiprotozoal, antituberculosis, and antiviral activities for 123 marine natural products, 111 marine compounds with antidiabetic and anti-inflammatory activities as well as affecting the immune and nervous system, while in contrast 79 marine compounds displayed miscellaneous mechanisms of action which upon further investigation may contribute to several pharmacological classes. Therefore, in 2016-2017, the preclinical marine natural product pharmacology pipeline generated both novel pharmacology as well as potentially new lead compounds for the growing clinical marine pharmaceutical pipeline, and thus sustained with its contributions the global research for novel and effective therapeutic strategies for multiple disease categories.

Three new isocoumarin derivatives from the mangrove endophytic fungus Penicillium sp. YYSJ-3

Three new isocoumarin derivatives, (S)-6,8-dihydroxy-5-(methoxymethyl)-3,7-dimethylisochroman-1-one (1), (S)-6,8-dihydroxy-3,5,7-trimethyl-isochroman-1-one (2) and (R)-2-chloro-3-(8-hydroxy-6-methoxy-1-oxo-1H-isochromen-3-yl) propyl acetate (3), along with four known compounds (4-7) were isolated from a mangrove endophytic fungus Penicillium sp. YYSJ-3. Their structures were established on the basis of the extensive spectroscopic data and HR-ESI-MS analysis. The absolute configurations of 1-3 were further determined by X-ray diffraction analysis and optical rotations. Compounds 3, 6 and 7 showed promising inhibitory activity against α-glucosidase, which were stronger than that of the positive control 1-deoxynojirimycin (IC₅₀ 141.2 μmol·L^-1).

Natural isocoumarins: Structural styles and biological activities, the revelations carry on …

Isocoumarins and dihydroisocoumarins are lactonic phytochemicals plentiful in microbes and higher plants. These are an amazing small scaffolds consecrated with all types of pharmacological applications. Our previous review covered the period 2000-2016, documenting the then known natural products of this class; the current article is a critical account of discovery of known as well as undescribed structural types and pharmacological activities reported in the course of 2016-2020. The classification revealed in our previous review based on the biogenetic origin is further buttressed by discovery of new members of each class and some new structural types hitherto unknown have also been identified. Similarly, the biological activities and SAR conclusions identified were found to be valid as well, nonetheless with new accompaniments. The most recent available literature on the structural diversity and biological activity of these natural products has been included. The information documented in this article are collected from scientific journals, books, electronic search engines and scientific databases.

Antibiotics from Extremophilic Micromycetes

Extremophilic microorganisms, which are capable of functioning normally at extremely high or low temperatures, pressure, and in other environmental conditions, have been in the focus of microbiologists' attention for several decades due to the biotechnological potential of enzymes inherent in extremophiles. These enzymes (also called extremozymes) are used in the production of food and detergents and other industries. At the same time, the inhabitants of extreme econiches remained almost unexplored for a long time in terms of the chemistry of natural compounds. In recent years, the emergence of new antibiotic-resistant strains of pathogens, which affect humans and animals has become a global problem. The problem is compounded by a strong slowdown in the development of new antibiotics. In search of new active substances and scaffolds for medical chemistry, researchers turn to unexplored natural sources. In recent years, there has been a sharp increase in the number of studies on secondary metabolites produced by extremophiles. From the discovery of penicillin to the present day, micromycetes, along with actinobacteria, are one of the most productive sources of antibiotic compounds for medicine and agriculture. Many authors consider extremophilic micromycetes as a promising source of small molecules with an unusual mechanism of action or significant structural novelty. This review summarizes the latest (for 2018-2019) experimental data on antibiotic compounds, which are produced by extremophilic micromycetes with various types of adaptation. Active metabolites are classified by the type of structure and biosynthetic origin. The data on the biological activity of the isolated metabolites are summarized.

Continuous Electrochemical Synthesis of Iso-Coumarin Derivatives from o-(1-Alkynyl) Benzoates under Metal- and Oxidant-Free

A non-oxidant and metal-free strategy for synthesizing iso-coumarin by using a continuous electrochemical microreactor to initiate an oxidative cyclization reaction of o-(1-alkynyl) benzoate and radicals. This efficient and clean continuous electrosynthesis method not only avoids the complicated gas protection operation and production of by-products in the batch processes, but also help to overcome the difficulty that batch metal catalysis and electrocatalysis are difficult to scale up, and has the potential for pilot-scale experiment.

Chemistry and Bioactivities of Secondary Metabolites from the Genus Talaromyces

Fungi have especially captured the interest and fascination of natural product chemists in that they produce a dizzying array of natural organic molecules with many unique functional groups and atom arrangements. In this review, we focus on the genus Talaromyces (Trichocomaceae) which has been a hot spot of natural product studies over the last three decades. This review summarized the discovery, structures, and bioactivities of various classes of 151 compounds isolated from both terrestrial and marine derived fungal strains of the genus Talaromyces reported from 1994 to 2019.

Naphthalenones and Naphthols Isolated from the Saussurea laniceps Endophytic Fungus Didymella glomerata X223

One new naphthalenone, didymelol A, and three new naphthols, didymelol B-D, together with three known naphthalenones, (3S,4R)-3,4,6-trihydroxy-3,4-dihydronaphthalen-1(2H)-one, (4S)-4,6-dihydroxy-3,4-dihydronaphthalen-1(2H)-one, (4S)-4-hydroxy-3,4-dihydronaphthalen-1(2H)-one, were isolated from the Saussurea laniceps endophytic fungus Didymella glomerata X223. The structures of the isolates were elucidated based on extensive spectroscopic data analysis. The absolute configuration of didymelol A was established through single-crystal X-ray diffraction data and didymelols B-D were identified through comparisons of experimental and calculated ECD spectra. All compounds were evaluated for cytotoxic activity against human non-small cell lung cancer A549 cells and human breast carcinoma MDA-MB-435 cells.

Benzopyran Derivatives and an Aliphatic Compound from a Mangrove Endophytic Fungus Penicillium citrinum QJF-22

Two new benzopyran derivatives, (2R,4S)-5-methoxy-2-methyl-3,4-dihydro-2H-1-benzopyran-4-ol and (2S,4R,2'S,4'R)-4,4'-oxybis(5-methoxy-2-methyl-3,4-dihydro-2H-1-benzopyran), and a new aliphatic compound, (3E,5Z,8S,10E)-8-hydroxytrideca-3,5,10,12-tetraen-2-one, together with three known benzopyran derivatives, were obtained from a mangrove endophytic fungus Penicillium citrinum QJF-22 collected in Hainan island. Their structures were determined by analysis of spectroscopic data and the relative configuration of (2R,4S)-5-methoxy-2-methyl-3,4-dihydro-2H-1-benzopyran-4-ol was also confirmed by single-crystal X-ray diffraction. The absolute configurations of four compounds were established by comparison of ECD spectra to calculations. The configuration of (3E,5Z,8S,10E)-8-hydroxytrideca-3,5,10,12-tetraen-2-one was confirmed by comparison of optical value to the similar compound. The configurations of the compounds (2S,4S)-5-methoxy-2-methyl-3,4-dihydro-2H-1-benzopyran-4-ol and (2R,4R)-5-methoxy-2-methyl-3,4-dihydro-2H-1-benzopyran-4-ol were first determined. (3R,4S)-3,4,8-Trihydroxy-3,4-dihydronaphthalen-1(2H)-one exhibited moderate inhibitory effects on LPS-induced NO production in RAW264.7 cells with IC₅₀ of 44.7 μM, and without cytotoxicity to RAW264.7 cells within 50 μM.

Nitrogen-Containing Compounds From Mangrove-Derived Fungus Aspergillus sp. 87

Nine nitrogen-containing compounds including 1 new alkaloid, aspergilamide A (1), and 8 known alkaloids and dipeptides, pseurotin A (2), fumigaclavine C (3), isochaetominine (4), cyclo(L-Pro-L-tyr) (5), cyclo- trans-4-OH-(L)-Pro-(L)-Phe (6), brevianamide F (7), and spirotryprostatins A and B (8 and 9), were obtained from the mangrove-derived fungus Aspergillus sp. 87. Their structures were identified by extensive spectroscopic analyses. All compounds did not show significant antibacterial activities.

Naturally Occurring Isocoumarins Derivatives from Endophytic Fungi: Sources, Isolation, Structural Characterization, Biosynthesis, and Biological Activities

Recently, the metabolites separated from endophytes have attracted significant attention, as many of them have a unique structure and appealing pharmacological and biological potentials. Isocoumarins represent one of the most interesting classes of metabolites, which are coumarins isomers with a reversed lactone moiety. They are produced by plants, microbes, marine organisms, bacteria, insects, liverworts, and fungi and possessed a wide array of bioactivities. This review gives an overview of isocoumarins derivatives from endophytic fungi and their source, isolation, structural characterization, biosynthesis, and bioactivities, concentrating on the period from 2000 to 2019. Overall, 307 metabolites and more than 120 references are conferred. This is the first review on these multi-facetted metabolites from endophytic fungi.

Fused multicyclic polyketides with a two-spiro-carbon skeleton from mangrove-derived endophytic fungus Epicoccum nigrum SCNU-F0002

A pair of uncommon fused multicyclic polyketides, (±)-isoepicolactone and one new isobenzofuranone monomer, together with four other known biosynthetically related compounds were isolated from the fermentation of fungus Epicoccum nigrum SCNU-F0002.

New Dihydroisocoumarin Root Growth Inhibitors From the Sponge-Derived Fungus Aspergillus sp. NBUF87

Six new dihydroisocoumarins, aspergimarins A-F (1-6), were discovered together with five known analogs (7-11) from a monoculture of the sponge-derived fungus Aspergillus sp. NBUF87. The structures of these compounds were elucidated through comprehensive spectroscopic methods, and absolute configurations were assigned after X-ray crystallography, use of the modified Mosher's method, and comparison of electronic circular dichroism (ECD) data with literature values for previously reported analogs. Compounds 1-11 were evaluated in a variety of bioassays, and at 100 μM, both 1 and 5 showed significant inhibitory effects on the lateral root growth of Arabidopsis thaliana Columbia-0 (Col-0). Moreover, at 100 μM, 5 also possessed notable inhibition against the primary root growth of Col-0. Meanwhile, 1-11 were all found to be inactive in vitro against acetylcholinesterase (AChE) (IC50 > 100 μM), four different types of human-derived cancer cell lines (IC50 > 50 μM), as well as methicillin-resistant Staphylococcus aureus and Escherichia coli (MIC > 50 μg/mL), and Plasmodium falciparum W2 (EC50 > 100 μg/mL), in phenotypic tests.

α-Glucosidase inhibitors from a mangrove associated fungus, Zasmidium sp. strain EM5-10

BACKGROUND

Mangroves plants and their endophytes represent a natural source of novel and bioactive compounds. In our ongoing research on mangrove endophytes from the Panamanian Pacific Coast, we have identified several bioactive endophytic fungi. From these organisms, an isolate belonging to the genus Zasmidium (Mycosphaerellaceae) showed 91.3% of inhibition against α-glucosidase enzyme in vitro.

RESULTS

Zasmidium sp. strain EM5-10 was isolated from mature leaves of Laguncularia racemosa, and its crude extract showed good inhibition against α-glucosidase enzyme (91.3% of inhibition). Bioassay-guided fractionation of the crude extract led to obtaining two active fractions: L (tripalmitin) and M (Fungal Tryglicerides Mixture). Tripalmitin (3.75 µM) showed better inhibitory activity than acarbose (positive control, IC50 217.71 µM). Kinetic analysis established that tripalmitin acted as a mixed inhibitor. Molecular docking and molecular dynamics simulations predicted that tripalmitin binds at the same site as acarbose and also to an allosteric site in the human intestinal α-glucosidase (PDB: 3TOP).

CONCLUSIONS

Zasmidium sp. strain EM5-10 represents a new source of bioactive substances that could possess beneficial properties for human health.

Fungal Diversity in Intertidal Mudflats and Abandoned Solar Salterns as a Source for Biological Resources

Intertidal zones are unique environments that are known to be ecological hot spots. In this study, sediments were collected from mudflats and decommissioned salterns on three islands in the Yellow Sea of South Korea. The diversity analysis targeted both isolates and unculturable fungi via Illumina sequencing, and the natural recovery of the abandoned salterns was assessed. The phylogeny and bioactivities of the fungal isolates were investigated. The community analysis showed that the abandoned saltern in Yongyudo has not recovered to a mudflat, while the other salterns have almost recovered. The results suggested that a period of more than 35 years may be required to return abandoned salterns to mudflats via natural restoration. Gigasporales sp. and Umbelopsis sp. were selected as the indicators of mudflats. Among the 53 isolates, 18 appeared to be candidate novel species, and 28 exhibited bioactivity. Phoma sp., Cladosporium sphaerospermum, Penicillium sp. and Pseudeurotium bakeri, and Aspergillus urmiensis showed antioxidant, tyrosinase inhibition, antifungal, and quorum-sensing inhibition activities, respectively, which has not been reported previously. This study provides reliable fungal diversity information for mudflats and abandoned salterns and shows that they are highly valuable for bioprospecting not only for novel microorganisms but also for novel bioactive compounds.

An update on benzofuran inhibitors: a patent review

Introduction: Benzofuran is a fundamental unit in numerous bioactive heterocycles. They have attracted chemists and medical researchers due to their broad range of biological activity, where some of them possess unique anticancer, antitubercular, antidiabetic, anti-Alzheimer and anti-inflammatory properties. The benzofuran nucleus is present in a huge number of bioactive natural and synthetic compounds. Benzofuran derivatives have potent applications in pharmaceuticals, agriculture, and polymers. The recent developments considering the biological activities of benzofuran compounds are reported. They have a vital role as pronounced inhibitors against a number of diseases, viruses, fungus, microbes, and enzymes. Areas covered: This review covers the recent developments of biological activities of benzofurans during the period 2014-2019. The covered areas here comprised antimicrobial, anti-inflammatory, antitumor, antitubercular, antidiabetic, anti-Alzheimer, antioxidant, antiviral, vasorelaxant, anti-osteoporotic and enzyme inhibitory activities. Expert opinion: In addition to the already commercialized 34 benzofurans-based drugs in the market, this chapter outlines several potent benzofuran derivatives that may be useful as potential pro-drugs. It is also focused on providing details of SAR and the effect of certain functional groups on the activity of the benzofuran compounds. The presence of -OH, -OMe, sulfonamide, or halogen contributed greatly to increasing the therapeutic activities comparing with reference drugs.

Natural source, bioactivity and synthesis of benzofuran derivatives

Benzofuran compounds are a class of compounds that are ubiquitous in nature. Numerous studies have shown that most benzofuran compounds have strong biological activities such as anti-tumor, antibacterial, anti-oxidative, and anti-viral activities. Owing to these biological activities and potential applications in many aspects, benzofuran compounds have attracted more and more attention of chemical and pharmaceutical researchers worldwide, making these substances potential natural drug lead compounds. For example, the recently discovered novel macrocyclic benzofuran compound has anti-hepatitis C virus activity and is expected to be an effective therapeutic drug for hepatitis C disease; novel scaffold compounds of benzothiophene and benzofuran have been developed and utilized as anticancer agents. Novel methods for constructing benzofuran rings have been discovered in recent years. A complex benzofuran derivative is constructed by a unique free radical cyclization cascade, which is an excellent method for the synthesis of a series of difficult-to-prepare polycyclic benzofuran compounds. Another benzofuran ring constructed by proton quantum tunneling has not only fewer side reactions, but also high yield, which is conducive to the construction of complex benzofuran ring systems. This review summarizes the recent studies on the various aspects of benzofuran derivatives including their important natural product sources, biological activities and drug prospects, and chemical synthesis, as well as the relationship between the bioactivities and structures.

Two new dihydroisocoumarins with antimicrobial activities from the fungus Penicillium sp. XR046 collected from Xinren coal area

Two new dihydroisocoumarins (1 and 2), together with six known compounds (3-8), were isolated from the fungus Penicillium sp. XR046 collected from the Xinren coal area of Guizhou province in China. Their structures were elucidated on the basis of spectroscopic analysis. The absolute configurations of C-3 in 1 and 2 were established by comparison of their CD data with those of known compounds. Compounds 1-6 showed anti-microbial activities with MIC values in the range of 50∼100 μg/mL against Candida albicans, Staphylococcus epidermidis, Bacillus subtilis, and Escherichia coli.

Chemical Investigation Of Secondary Metabolites Produced By Mangrove Endophytic Fungus Phyllosticta Capitalensis

Chemical investigation of endophytic fungus Phyllosticta capitalensis, isolated from the hypocotyls of the Chinese mangrove Bruguiera sexangula led to the isolation of eight known secondary metabolites, including four meroterpenes guignardone A (1), 12-hydroxylated guignardone A (2), guignardone J (3), guignardone M (4), and four polyketides xenofuranone B (5), 6,8-dihydroxy-5-methoxy-3-methyl-1H-isochromen-1-one (6), regiolone (7), 3,4-dihydroxybenzoic acid (8). Their structures were elucidated unambiguously based on the comprehensive spectroscopic analysis and comparison with literature data. This is the first report of these compounds being isolated from this fungal species. All compounds isolated were subjected to antimicrobial and cytotoxic activities evaluation.

The Purification, Characterization, and Biological Activity of New Polyketides from Mangrove-Derived Endophytic Fungus Epicoccum nigrum SCNU-F0002

Six new polyketides, including one coumarin (1), two isocoumarins (2 and 3), dihydroradicinin (4), and two benzofuranone derivatives (7 and 8), together with seven known analogues (5–6 and 9–13) were isolated from the culture of the mangrove endophytic fungus Epicoccum nigrum SCNU-F0002. The structures were elucidated on the interpretation of spectroscopic data. The absolute configuration of Compounds 2 and 3 were determined by comparison of their ECD spectra with the data of their analogue dihydroisocoumarins described in the literature. The absolute configuration of 4 was determined by single-crystal X-ray diffraction. All the compounds were screened for their antioxidant, antibacterial, anti-phytopathogenic fungi and cytotoxic activities. Using a DPPH radical-scavenging assay, Compounds 10–13 showed potent antioxidant activity with IC₅₀ values of 13.6, 12.1, 18.1, and 11.7 μg/mL, respectively. In addition, Compounds 6 and 7 showed antibacterial effects against Bacillus subtilis (ATCC 6538), Escherichia coli (ATCC 8739), and Staphylococcus aureus (ATCC 6538), with MIC values in the range of 25–50 μg/mL.

Four New Isocoumarins and a New Natural Tryptamine with Antifungal Activities from a Mangrove Endophytic Fungus Botryosphaeria ramosa L29

Four new isocoumarin derivatives, botryospyrones A (1), B (2), C (3), and D (4), and a new natural tryptamine, (3aS, 8aS)-1-acetyl-1, 2, 3, 3a, 8, 8a-hexahydropyrrolo [2,3b] indol-3a-ol (5), were isolated from a marine mangrove endophytic fungus Botryosphaeria ramosa L29, obtained from the leaf of Myoporum bontioides. Their structures were elucidated using spectroscopic analysis. The absolute configurations of compounds 3, 4, and 5 were determined by comparison of their circular dichroism (CD) spectra with the calculated data. The inhibitory activities of compound 1 on Fusarium oxysporum, of compounds 2 and 3 on F. oxysporum and Fusarium graminearum, and of compound 5 on F. oxysporum, Penicillium italicum, and F. graminearum were higher than those of triadimefon, widely used as an agricultural fungicide. Compound 5 was produced after using the strategy we called "using inhibitory stress from components of the host" (UISCH), wherein (2R, 3R)-3, 5, 7-trihydroxyflavanone 3-acetate, a component of M. bontioides with weak growth inhibitory activity towards B. ramosa L29, was introduced into the culture medium.