Abstract:

This study aims to investigate the secondary metabolites produced by Nigrospora sp., an endophytic fungus derived from Psidium cattleianum Afzel. ex Sabine. All metabolites were separated from the methanolic extract of the solid-state fermentation culture of this fungus using positive-phase silica gel column, Sephadex LH-20 column, and medium pressure liquid chromatographies. Spectroscopic methods and quantum chemical calculations of NMR and ECD data were employed for structure determination. CCK-8 assay and two-fold dilution method were adopted to test the antitumor and antimicrobial properties, respectively. Eleven compounds were isolated and identified as nigrolactam A (1), ergosta-4,6,8(14),22-tetraen-3-one (2), ganodermaside B (3), 9α,11α-dihydroxyergosta-4,6,8(14),22-tetraen-3-one (4), (22E,24R)-24-methyl-5α-cholesta-7,22-dien-3β,5,6β-triol (5), 3β,5α,9α-trihydroxy-(22E,24R)-ergosta-7,22-dien-6-one (6), indole-3-carboxylic acid (7), (1H-indol-3-yl) oxoacetamide (8), 3-indolecarbaldehyde (9), pestalotiopyrone A (10), nigrosporapyrone D (11). Among them, none of the compounds exhibited antimicrobial activity, and compound 1 was a new steroidal alkaloid and exhibited cytotoxic activity against triple-negative breast cancer MDA-MB-231 cells, with an IC50 value of 20.46 μmol/L.

Key words:

Psidium cattleianum, Nigrospora sp., secondary metabolite, nigrolactam A, anti-triple negative breast cancer activity