Synthesis, structure and antimicrobial activity of novel metabolites from a marine actinomycete in Vietnam's east sea

Abstract

A naturally new ester, 2,4-dichlorophenyl 2,4-dichloro benzoate (1) and a new compound, 4,5-dihydroxy-7-methylphthalide (2), along with eight known compounds were isolated from the fermentation broth of the marine-derived actinomycete Streptomyces sp. (strain G212). The structures of these compounds were established by their spectral data analysis, including MS, and 2D-NMR. To confirm the structures of the two new compounds 1 and 2, their total syntheses were achieved. These syntheses also allow obtaining enough quantities of 1 and 2 for their biological screening. The isolated compounds and synthetic samples were evaluated for their antimicrobial activity against a panel of clinically significant microorganisms. Except for 8 and 10, the remaining compounds were active against at least one tested microbial strain with the MIC values in range of 32-256 μg/mL. Compounds 5, 6, 17 and 2a were found to have a broad-spectrum of antimicrobial activity.