Novel 11-norbetaenone isolated from an entomopathogenic fungus Lecanicillium antillanum

Discovery of New Antifungal Polyketides Cladrioides A-N against Phytopathogenic Fungi from Cladosporium cladosporioides LD-8

During the search for natural fungicides, 14 new australifungin analogues cladrioides A-S (1-14) and two known ones (15 and 16) were obtained from Cladosporium cladosporioides LD-8. Their structures were elucidated by comprehensive analysis of NMR and HRESIMS data, as well as ECD calculations. Compounds 1 and 2 possess a novel 6/6/5-fused tricyclic scaffold. Most of the compounds exhibited remarkable antifungal activities against the tested phytopathogenic fungi. Among them, compounds 7, 10, and 16 showed excellent activities with IC50 values ranging from 1.71 to 16.63 μg/mL. Their inhibitory activities against A. brassicicola and A. alternata were higher than that of the commercial fungicide hymexazol. Compound 16 displayed potent in vivo antifungal activity against A. solani at 100 μg/mL with an inhibitory rate of 96.82%. The structure-activity relationship of antifungal australifungin analogues was analyzed for the first time. Therefore, our study provides promising candidates for the development of new fungicides for plant protection.

Bioactive polyketides from the pathogenic fungus of Epicoccum sorghinum

We discovered and identified a series of characteristic substances, including one new polyketide, epicorepoxydon B, of the important pathogenic fungus, Epicoccum sorghinum, of sorghum. The fungal extract and some isolated polyketides are sensitive to a malignant triple-negative breast cancer cell line, MDA-MB-231. Sorghum (Kaoliang) grain is an important crop with high economic value and several applications. In Taiwan, sorghum has been used in the wine industry, and "Kinmen Kaoliang Liquor" is a well-known Asian brand. Fungal contamination is one of the major threats affecting the production of sorghum grain resulting in economic losses as well as human and animal health problems. Several fungal species can infect sorghum grain and generate some toxic secondary metabolites. Epicoccum sorghinum is one of the major fungal contaminants of sorghum grains and a potent producer of mycotoxins such as tenuazonic acid (TeA). However, except for TeA, few studies focused on chemical compounds produced by this fungus. To explore the potential biological and toxic effects of E. sorghinum, a chemical investigation was carried out on the ethyl acetate extract of the fungus because it showed cytotoxic activity against a triple-negative breast cancer cell line, MDA-MB-231 (54.82% inhibition at 20 µg/mL). One new polyketide, epicorepoxydon B (1), along with six known compounds including 4,5-dihydroxy-6-(6'-methylsalicyloxy)-2-hydroxymethyl-2-cyclohexenl-one (2), epicorepoxydon A (3), 3-hydroxybenzyl alcohol (4), 6-methylsalicylic acid (5), gentisyl alcohol (6), and 6-(hydroxymethyl)benzene-1,2,4-triol (7) were obtained, and their structures were established by the interpretation of their MS and NMR spectroscopic data. The cytotoxic activity of all isolated polyketides 1-7 was evaluated, and compounds 2, 6, and 7 exhibited potent activities against A549, HepG2, and MDA-MB-231 human cancer cell lines with IC₅₀ value ranging from 1.86 to 18.31 μM. The structure-activity relationship of the isolated compounds was proposed.

Secondary metabolites from hypocrealean entomopathogenic fungi: novel bioactive compounds

Covering: 2014 up to the third quarter of 2019 Entomopathogens constitute a unique, specialized trophic subgroup of fungi, most of whose members belong to the order Hypocreales (class Sordariomycetes, phylum Ascomycota). These Hypocrealean Entomopathogenic Fungi (HEF) produce a large variety of secondary metabolites (SMs) and their genomes rank highly for the number of predicted, unique SM biosynthetic gene clusters. SMs from HEF have diverse roles in insect pathogenicity as virulence factors by modulating various interactions between the producer fungus and its insect host. In addition, these SMs also defend the carcass of the prey against opportunistic microbial invaders, mediate intra- and interspecies communication, and mitigate abiotic and biotic stresses. Thus, these SMs contribute to the role of HEF as commercial biopesticides in the context of integrated pest management systems, and provide lead compounds for the development of chemical pesticides for crop protection. These bioactive SMs also underpin the widespread use of certain HEF as nutraceuticals and traditional remedies, and allowed the modern pharmaceutical industry to repurpose some of these molecules as life-saving human medications. Herein, we survey the structures and biological activities of SMs described from HEF, and summarize new information on the roles of these metabolites in fungal virulence.

Secondary Metabolites and Bioactivities of Aspergillus ochraceopetaliformis Isolated from Anthurium brownii

Five new polyketides, asperochrapyran (1) and asperochralactones A-D (2-5), along with 12 known polyketides (6-17), were obtained from the fungal strain Aspergillus ochraceopetaliformis. Structures of all isolates were elucidated by their spectroscopic parameters. The relative configurations of the new compounds were deduced by the data of coupling constants and NOESY spectra. The absolute configurations were determined by the comparison of experimental and calculated ECD spectra. Moreover, the plausible biosynthesis pathway of major isolates was proposed as well. Anti-inflammatory activity of compounds 5 and 7-17 were evaluated with human neutrophils in response to the stimulation of formyl-methionyl-leucyl phenylalanine (fMLP). Asperlactone (9), aspyrone (13), and (-)-(3R)-mellein (14) exerted superoxide anion inhibition at 30 ± 9%, 29 ± 9%, and 26 ± 12%, respectively, at 10 μM. The capacities of asperlactone (9), aspilactonol B (10), penicillic acid (12), and (-)-(3R)-mellein (14) in elastase release inhibition were revealed as 25 ± 4%, 38 ± 8%, 25 ± 5%, and 34 ± 9%, respectively, at 10 μM.

Anti-inflammatory, Antiplatelet Aggregation, and Antiangiogenesis Polyketides from Epicoccum sorghinum: Toward an Understating of Its Biological Activities and Potential Applications

The ethyl acetate extract of an endophyte Epicoccum sorghinum exhibited anti-inflammatory activity at a concentration of <10 μg/mL. By bioassay-guided fractionation, one new compound, named epicorepoxydon A (1), and one unusual bioactive compound, 6-(hydroxymethyl)benzene-1,2,4-triol (6), together with six known compounds, were isolated from E. sorghinum. The structures of all isolates were established by spectroscopic analyses. The relative configuration of 1 was deduced by the NOESY spectrum and its absolute configuration was determined by X-ray single-crystal analysis. The biological activities of all isolates were evaluated using four types of bioassays including cytotoxicity, anti-inflammatory, antiplatelet aggregation, and antiangiogenesis activities. Compounds 4 and 6 showed potent anti-inflammatory activity, compound 2 possessed potent antiplatelet aggregation and antiangiogenesis activities, and compound 6 demonstrated antiangiogenesis activity. This fungal species can cause a human hemorrhagic disorder known as onyalai. In this study, we identified the active components with antiplatelet aggregation and antiangiogenesis activities, which may be related to the hemorrhagic disorder caused by this fungus. Moreover, we proposed a biosynthetic pathway of the isolated polyketide secondary metabolites and investigated their structure-activity relationship (SAR). Our results suggested that E. sorghinum is a potent source of biologically active compounds that can be developed as antiplatelet aggregation and anti-inflammatory agents.