Chemical Constituents From the Marine Microalgae <i>Thraustochytrium pachydermum</i>

<jats:sec><jats:title>Objectives</jats:title><jats:p> Isolation, structure determination, and antimicrobial activities evaluation of compounds from the methanol extract of the marine microalga Thraustochytrium pachydermum TSL10. </jats:p></jats:sec><jats:sec><jats:title>Methods</jats:title><jats:p> 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. </jats:p></jats:sec><jats:sec><jats:title>Results</jats:title><jats:p> One new sterol, (24 R)-ergosta-7,22-diene-3 β,5 α,9 α-triol (1), and 16 known compounds, ergosta-7,22-diene-3 β,5 α-diol (2), cerevisterol (3), (22 E,24 S)-5 α,6 α-epoxy-ergosta-8(9),22-diene-3 β,7 α-diol (4), ergosterol (5), 5 α,8 α-epidioxyergosta-6,22-diene-3 β-ol (6), linoleic acid (7), 4-((9 Z,12 Z)-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), (2 S)-1- O-(9 Z)-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 µg/mL. </jats:p></jats:sec><jats:sec><jats:title>Conclusions</jats:title><jats:p> The results suggested sterols 1–6 could be potential antimicrobial agents against Gram-( + ) bacteria. </jats:p></jats:sec>