Bingda Sun

Diketopiperazines from the Cordyceps-Colonizing Fungus Epicoccum nigrum

New diketopiperazines, epicoccins E-H (1-4) and diphenylalazines A (5) and B (6), have been isolated from the solid-substrate fermentation culture of the Cordyceps-colonizing fungus Epicoccum nigrum. The structures of 1-6 were determined primarily by NMR experiments, and the structure of 1 was confirmed by X-ray crystallography. The absolute configurations of 3 and 5 were assigned using the modified Mosher (3) and Marfeys (5) methods, respectively. Compounds 3-5 showed inhibitory effects on HIV-1 replication in C8166 cells.

Polyketides from the Ascomycete Fungus Leptosphaeria sp.

The new polyketides leptosphaerins A-G (1-7) and the known compounds monodictysin B (8), 2-(2,6-dihydroxybenzoyl)-3-hydroxy-5-methylbenzoic acid (9), and 2-(2,6-dihydroxy-4-methylbenzoyl)-6-hydroxybenzoic acid (10) have been isolated from solid cultures of the ascomycete fungus Leptosphaeria sp. The absolute configurations of compounds 1, 2, and 6 were assigned using the modified Mosher method, whereas that of C-2 in 3 was determined via the circular dichroism data of the [Rh(2)(OCOCF(3))(4)] complex. Compound 7 showed antifungal activity against Aspergillus flavus.

Cytosporolides A−C, Antimicrobial Meroterpenoids with a Unique Peroxylactone Skeleton from Cytospora sp.

Cytosporolides A-C (1-3), three caryophyllene-derived meroterpenoids with a unique peroxylactone skeleton, were isolated from cultures of the fungus Cytospora sp. Their structures were elucidated by NMR spectroscopy, and the absolute configuration of the 5,6-diol moiety in 1 was assigned using Snatzkes method. Compounds 1-3 showed significant antimicrobial activity against the Gram-positive bacteria Staphylococcus aureus and Streptococcus pneumoniae.

Bioactive Asterric Acid Derivatives from the Antarctic Ascomycete Fungus Geomyces sp

Five new asterric acid derivatives, ethyl asterrate (3), n-butyl asterrate (4), and geomycins A-C (6-8), have been isolated from cultures of an isolate of the Antarctic ascomycete fungus Geomyces sp. The structures of these metabolites were elucidated by NMR spectroscopy. The absolute configuration of 8 was determined by application of the CD excitation chirality method. Compound 7 displayed antifungal activity against Aspergillus fumigatus, whereas 8 showed antimicrobial activities against gram-positive and gram-negative bacteria.