Four new hydroxyl fatty acids, gambaoic acids A-C and gambaoic B methyl ester, from Shrimp Jeotgal-derived Bacillus sp. SNB-066.

Four new hydroxyl fatty acids (HFAs), gambaoic acids A - C (1 - 3) and gambaoic B methyl ester (4), were isolated from Bacillus sp. SNB-066, a bacterium derived from shrimp jeotgal. The chemical structures of these HFAs were elucidated through extensive spectroscopic data analysis, including mass spectrometry (MS), ultraviolet (UV), and nuclear magnetic resonance (NMR) spectroscopy data. The relative configurations of compounds 2 and 3 were determined using quantum mechanics-based computational analysis with DP4 statistical calculations. Further specific rotation analyses revealed the absolute configurations of both compounds 2 and 4 as 14 R and 15 R, while compound 3 was assigned as 14S and 15S. Antibacterial activity evaluated by the minimal inhibitory concentration (MIC) assay indicated that only compound 4 exhibited weak activity against the Gram-positive bacteria B. subtilis KCTC 1021 and K. rhizophila KCTC 1915, with MIC values of 64 μg/mL. Further, gambaoic acids B (2) and C (3) exhibited dose-dependent cytotoxicity toward Caco-2 cells, with gambaoic acid C (3) demonstrating a pronounced anti-invasive effect. These findings highlight the diverse bioactivities of the isolated hydroxyl fatty acids and reveal structural features underlying their antimicrobial and anticancer properties.