Five new alkaloidal metabolites cordycepamides A-E (1-5), and one glycoside metabolite cordyglycoside A (6), together with six known compounds (7-12) were isolated from the entomopathogenic fungus Cordyceps sp. (LB1.18060004) from unidentified insect collected in Baoshan City, Yunnan Province, People's Republic of China. The structures were characterized by NMR and HRESIMS spectroscopic analyses. Cordycepamides A and B (1 and 2) were mixtures of two isomers in 5:4 ratio by integration of 1H NMR spectra. In additional, the structure of cordycepamide A (1) was further confirmed by X-ray crystallography as a pair of enantiomers. Absolute configurations of sugar moiety of cordyglycoside A (6) was confirmed by the acid hydrolysis and subsequent HPLC analysis. The isolated metabolites were evaluated for antimicrobial, cytotoxicity, and the DPPH scavenging assay, only 4 showed modest antioxidant effects in the DPPH scavenging assay (IC50 = 51.42 ± 3.08 μM).
Keywords: Alkaloidal metabolite; Cordyceps sp.; Enantiomer; Entomopathogenic fungus.
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