Bioactive metabolites from the ruminal bacterium <em>Enterobacter amnigenus </em>ZIH

Abstract

Bioassay-guided fractionation and chromatographic purification of the crude extract of ruminal bacterium <em>Enterobacter amnigenus</em> ZIH (isolated from cattle) produce one new microbial product:butyl-α-D-glucopyranoside together with eleven known compounds including (<em>S</em>)-brevinic acid, 3-(hydroxyacetyl)-indole, <em>N_ß</em>-acetyltryptamine, tyrosol, phenol, tryptophol, indole-3-lactic acid, uracil, adenine and two diketopiperazines <em>cyclo</em>-(Phe, Pro) and <em>cyclo</em>-(Leu, Pro). The complete NMR assignments of butyl-α-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.