Bioactive metabolites from the ruminal bacterium Enterobacter amnigenus ZIH

Abstract

Bioassay-guided fractionation and chromatographic purification of the crude extract of ruminal bacterium Enterobacter amnigenus ZIH (isolated from cattle) produce one new microbial product:butyl-a-D-glucopyranoside together with eleven known compounds including (S)-brevinic acid, 3-(hydroxyacetyl)-indole, N_ß-acetyltryptamine, tyrosol, phenol, tryptophol, indole-3-lactic acid, uracil, adenine and two diketopiperazines cyclo-(Phe, Pro) and cyclo-(Leu, Pro). The complete NMR assignments of butyl-a-D-glucopyranoside was done - using different spectroscopic (¹H, ¹³C, ¹H-¹H COSY, HMQC, and HMBC) and spectrometric methods (ESI-MS, HRESI-MS). Compounds 1a and 2 reported for the first time from a natural source. The bacterial extract exhibited high cytotoxicity against brine shrimp and moderate antimicrobial activity against a diverse set of pathogenic bacteria strains.