Antimicrobial compounds were isolated from the secondary metabolites of Gordonia, a resident of intestinal tract of Periplaneta americana

Abstract

Microbial secondary metabolites are one of the main sources of bioactive natural products. It is estimated that around 75% of all antibiotics are derived from secondary metabolites produced by filamentous actinomycete. Gordonia sp. are members of the actinomycete family, their contribution to the environment improvement and environmental protection by their biological degradation ability, but there are few studies on the antimicrobial activity of their secondary metabolites. Our team isolated a Gordonia strain WA 4–31 with anti-Candida albicans activity from the intestinal tract of Periplaneta americana in the early stage. In this study, we firstly identified the strain WA 4–31 by the morphological characteristics and the phylogenetic analyses, and found that it homologous to a strain of Gordonia from the Indian desert by 100%. Then four compounds, Actinomycin D (1), Actinomycin X2 (2), Mojavensin A (3) and cyclic (leucine-leucne) dipeptide (4) were purified from the ethyl acetate extract of the fermented broth of the strain. The compounds 1–4 had activities against Candida albicans, Aspergillus niger, Aspergillus fumigatus and Trichophyton rubrum. They also had activities against methicillin-resistant Staphylococcus aureus (MRSA) and Escherichia coli.coli in different degree. Interestingly, we found that when Mojavensin A was mixed with compound 4 ratio of 1:1, the activity of the mixture on anti-Candida albicans was better than the single. Besides, compounds 1–3 had varying degrees of antiproliferative activity on CNE-2 cells and HepG-2 cells. These indicated that Gordonia rare actinomycete from the intestinal tract of Periplaneta americana possessed a potential as a source of active secondary metabolites.