-
Organic Letters 04/2013; · 5.86 Impact Factor
-
[show abstract]
[hide abstract]
ABSTRACT: Marine bacteria are a potential source of structurally diversified bioactive secondary metabolites that are not found in terrestrial sources. In our continuous effort to search for new antimicrobial agents from marine-derived bacteria, we isolated a bacterial strain 109GGC020 from a marine sediment sample collected from Gageocho, Republic of Korea. The strain was identified as Bacillus subtilis based on a 16s rRNA sequence analysis. After a 7 day fermentation of the B. subtilis strain under optimum growth conditions three new and four known secondary metabolites were discovered using chromatographic procedures and their biological activities were evaluated against both bacteria and crop devastating fungi. The discovered metabolites were confirmed by extensive 2D NMR and high-resolution ESI-MS data analyses to have the structures of new macrolactin derivatives, gageomacrolactins 1-3 and known macrolactins A (4), B (5), F (6) and W (7). The stereoconfigurations of 1-3 were assigned based on coupling constant values, chemical derivatization studies, and a literature review. The coupling constants were very crucial to determine the relative geometries of olefins in 1-3 because of overlap of the 1H NMR signals. The NMR data of these compounds were recorded in different solvents to overcome this problem and obtain accurate coupling constant values. The new macrolactin derivatives 1-3 displayed good antibiotic properties against both Gram-positive (S. aureus, B. subtilis, and B. cereus) and Gram-negative (E. coli, S. typhi and P. aeruginosa) bacteria with minimum inhibitory concentration (MIC) values of 0.02-0.05 μM. Additionally, the antifungal activities of 1-7 were evaluated against pathogenic fungi and found to inhibit mycelial growth of A. niger, B. cinerea, C. acutatum, C. albicans and R. solani with MIC values of 0.04-0.3 μM, demonstrating that these compounds were good fungicides.
Journal of Agricultural and Food Chemistry 03/2013; · 2.82 Impact Factor
-
[show abstract]
[hide abstract]
ABSTRACT: In the course of our ongoing research for antimicrobial agents, we isolated five new compounds, three 24-membered macrolactones, macrolactins X-Z (1-3) and two hydroxy unsaturated fatty acids, linieodolides A (5) and B (6), together with a known metabolite, macrolactinic acid (4), from the culture broth of a marine Bacillus sp. The structures of these metabolites were determined on the basis of their spectroscopic data interpretation. Their absolute configurations were addressed by modified Mosher's method and literature data review. Compounds 1-6 showed moderate to potent inhibitory activities (8∼128 μg ml(-1)) against selected pathogenic microorganisms.The Journal of Antibiotics advance online publication, 5 December 2012; doi:10.1038/ja.2012.102.
The Journal of Antibiotics 12/2012; · 1.65 Impact Factor
-
[show abstract]
[hide abstract]
ABSTRACT: Ieodoglucomides A (1) and B (2), unique glycolipopeptides consisting of an amino acid, a new fatty acid, a succinic acid, and a sugar, were isolated from a Marine-derived bacterium Bacillus licheniformis. The absolute stereochemistry of 1 and 2 was determined by deploying coupling constants, Marfey's and Mosher's methods, and literature reviews. Compounds 1 and 2 displayed moderate in vitro antimicrobial activity. Furthermore, ieodoglucomide B (2) exhibited cytotoxic activity against lung cancer and stomach cancer cell lines with GI(50) values of 25.18 and 17.78 μg/mL, respectively.
Organic Letters 02/2012; 14(6):1464-7. · 5.86 Impact Factor
-
[show abstract]
[hide abstract]
ABSTRACT: Bioassay-guided isolation of bioactive metabolites from the ethyl acetate extract of a marine Bacillus sp. fermentation broth has led to the discovery of three new 24-membered macrolactones, macrolactins 1-3, which contain an oxetane, an epoxide, and a tetrahydropyran ring, respectively. The configurations of 1-3 were assigned by a combination of coupling constants, ROESY data analysis, and application of the modified Mosher's method. Compounds 1-3 showed in vitro antimicrobial activity.
Journal of Natural Products 12/2011; 74(12):2582-7. · 3.13 Impact Factor
-
[show abstract]
[hide abstract]
ABSTRACT: Bioassay-guided isolation of the EtOAc extract of a marine Bacillus sp., cultured in modified Bennett's broth medium, yielded four new antimicrobial fatty acids, named ieodomycins A-D. The planar structures of these new compounds were determined by extensive 1D and 2D NMR and HRESIMS spectroscopic data analysis. Their absolute configurations were elucidated by modified Mosher's method and literature data review. All four new compounds demonstrated antimicrobial activities in vitro.
Journal of Natural Products 06/2011; 74(7):1606-12. · 3.13 Impact Factor
-
[show abstract]
[hide abstract]
ABSTRACT: Bioactivity-guided isolation for the new/novel metabolites from the EtOAc extract obtained from the culture broth of a marine Bacillus sp. 09ID194 followed by chromatographic fractionations and subsequently HPLC purifications led to the isolation of two known macrolides, macrolactins A (1) and Q (2), together with a new glycosylated marcrolide, macrolactin W (3). The chemical structures of compounds 1-3 were assigned based on extensive MS and NMR spectral data analysis and literature review. Compound 3 showed potent antibacterial activity against both Gram-positive and Gram-negative pathogenic bacteria.
Bioorganic & medicinal chemistry letters 06/2011; 21(12):3832-5. · 2.65 Impact Factor
