Abstract
The crude methanol extract of the dried aerial parts of Siegesbeckia glabrescens (Compositae) showed antibacterial activity against the foodborne pathogen Staphylococcus aureus. Bioactivity-guided separation led to the isolation of 3-(dodecanoyloxy)-2-(isobutyryloxy)-4-methylpentanoic acid from nature for the first time.The structure was determined by spectroscopic data analysis (UV, MS, and NMR). The minimal inhibitory concentration (MIC) of 3-(dodecanoyloxy)-2-(isobutyryloxy)-4-methylpentanoic acid against S. aureus was found to be 3.12 μg/mL. In addition, in a further antimicrobial activity assay against Gram-positive (B. subtilis, E. faecalis, P. acnes, S. epidermidis, S. schleiferi subsp. coagulans, S. agalactiae and S. pyrogens), and Gram-negative bacteria (E. coli and P. aeruginosa), and yeast strains (C. alibicans and F. neoformans), the antimicrobial activity of the compound was found to be specific for Gram-positive bacteria. The MIC values of the compound for Gram-positive bacteria ranged from 3.12 to 25 μg/mL. Furthermore, it was found that the 2-(isobutyryloxy)-4-methylpentanoic acid substituent may operate as a key factor in the antibacterial activity of the compound, together with the laurate group.
Highlights
Antimicrobial resistance among Gram-positive bacteria has become increasingly prevalent and has resulted in serious infections worldwide over the past two decades [1,2]
We further examined the antibacterial activities of 3-(dodecanoyloxy)-2-(isobutyryloxy)-4methylpentanoic acid against Gram-positive bacteria (S. aureus, B. subtilis, E. faecalis, P. acnes, S. epidermidis, S. schleiferi subsp. coagulans, S. agalactiae and S. pyrogens), Gram-negative bacteria (E. coli and P. aeruginosa) and yeast strains (C. alibicans and F. neoformans) by measuring the minimal inhibitory concentration (MIC), which is the lowest concentration yielding no growth
It was demonstrated that a new compound, 3-(dodecanoyloxy)-2-(isobutyryloxy)-4-methylpentanoic acid isolated from S. glabrescens has antibacterial activities against Gram-positive bacteria
Summary
Young-Soo Kim 1,†, Hyungil Kim 1,†, Eunsun Jung 1, Jang-Hyun Kim 2, Wangtaek Hwang 1, Eun-Ju Kang 1, Sanghyun Lee 3, Byung-Jo Ha 4, Jongsung Lee 4 and Deokhoon Park 1,*. Biospectrum Life Science Institute, Eines Platz 11th FL, #442-13 Sangdaewon Dong, Seongnam City, Gyunggi Do 462-120, Korea. 44-9 Chongho Ri, Jinwi Myeon, Pyeongtaek City, Gyunggi Do 451-862, Korea. Received: 15 August 2012; in revised form: October 2012 / Accepted: October 2012 /
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