Chemical Constituents From the Marine Microalgae Thraustochytrium pachydermum

Objectives: Isolation, structure determination, and antimicrobial activities evaluation of compounds from the methanol extract of the marine microalga Thraustochytrium pachydermum TSL10.Methods: Using chromatographic methods to isolate compounds from the methanol extract of the T pachydermum. The chemical structures were elucidated by analyses of HR-ESI-MS and NMR spectral data. The antimicrobial activities of compounds were evaluated using the dilution turbidimetric broth method as the standard protocol published by the Clinical and Laboratory Standard Institute.Results: One new sterol, (24R)-ergosta-7,22-diene-3 beta,5 alpha,9 alpha-triol (1), and 16 known compounds, ergosta-7,22-diene-3 beta,5 alpha-diol (2), cerevisterol (3), (22E,24S)-5 alpha,6 alpha-epoxy-ergosta-8(9),22-diene-3 beta,7 alpha-diol (4), ergosterol (5), 5 alpha,8 alpha-epidioxyergosta-6,22-diene-3 beta-ol (6), linoleic acid (7), 4-((9Z,12Z)-octadeca-9,12-dienoyloxy) butanoic acid (8), 1-linoleoyl-sn-glycero-3-phosphocholine (9), cibotiglycerol (10), gingerglycolipid B (11), oleic acid (12), 4-((9Z)-octadec-9-enoyloxy)butanoic acid (13), (2S)-1-O-(9Z)-octadec-9-enoyl)-3-O-(6-sulfo-D-quinovopyranosyl)glycerol (14), 6 '-O-linoleylsucrose (15), gingerglycolipid C (16), and (S)-3-stearoyl-sn-glycerol (17) were identified from the marine microalga Thraustochytrium pachydermum TSL10. Sterols 1-6 were found to exhibit significant antimicrobial activities on Gram-(+) bacteria (Enterococcus faecalis ATCC29212, Staphylococcus aureus ATCC25923, and Bacillus cereus ATCC14579) and the yeast (Candida albicans ATCC10231) with MIC values ranging from 32 to 256 mu g/mL. Conclusions: The results suggested sterols 1-6 could be potential antimicrobial agents against Gram-(+) bacteria.