Unsaturated fatty acids and a prenylated tryptophan derivative from a rare actinomycete of the genus <i>Couchioplanes</i>
Shun Saito, Kanji Indo, Naoya Oku, Hisayuki Komaki, M. Kawasaki, Yasuhiro Igarashi
Abstract
A genome mining survey combined with metabolome analysis of publicly available strains identified Couchioplanes sp. RD010705, a strain belonging to an underexplored genus of rare actinomycetes, as a producer of new metabolites. HPLC-DAD-guided fractionation of its fermentation extracts resulted in the isolation of five new methyl-branched unsaturated fatty acids, (2 E ,4 E )-2,4-dimethyl-2,4-octadienoic acid ( 1 ), (2 E ,4 E )-2,4,7-trimethyl-2,4-octadienoic acid ( 2 ), ( R )-(−)-phialomustin B ( 3 ), (2 E ,4 E )-7-hydroxy-2,4-dimethyl-2,4-octadienoic acid ( 4 ), (2 E ,4 E )-7-hydroxy-2,4,7-trimethyl-2,4-octadienoic acid ( 5 ), and one prenylated tryptophan derivative, 6-(3,3-dimethylallyl)- N -acetyl-ʟ-tryptophan ( 6 ). The enantiomer ratio of 4 was determined to be approximately S / R = 56:44 by a recursive application of Trost’s chiral anisotropy analysis and chiral HPLC analysis of its methyl ester. Compounds 1 – 5 were weakly inhibitory against Kocuria rhizophila at MIC 100 μg/mL and none were cytotoxic against P388 at the same concentration.