Isolation, identification, and bioactivity evaluation of secondary metabolites from Blaps rynchopetera gut-derived Streptomyces sp. BPA71

Abstract:

[Background] Insects are the animal group with the most species and the most abundant gut microbiota resources in the world. The microorganisms in insect gut have the ability to produce active secondary metabolites, which is an important source of active natural products.[Objective] To identify the secondary metabolites produced by Streptomyces sp. BPA71 isolated from the gut of the medicinal insect Blaps rynchopetera and determine their biological activities. [Methods] The crude fermentation extract of the strain was separated and purified by column chromatography with silica gel and Sephadex LH-20. Oxford cup method was employed to determine the antimicrobial activity, and the antimicrobial active part was determined. The compound structure was identified by comparison of data from ESI-MS, ¹H NMR, and ¹³C NMR. The minimum inhibitory concentration (MIC) and antitumor activity were determined by microbroth dilution method and MTS method, respectively.[Results] Four known compounds were purified from the crude fermentation extract of BPA71 and identified as methyl 2-furoate (1), pyrroloformamide A (2), pyrroloformamide B (3), and methyl 2-(1H-indol-3-yl) acetate (4). Compound 2 had broad-spectrum antimicrobial activity. In addition, it demonstrated significant inhibitory activities on five tumor cell lines, including cervical cancer cell line HeLa, lung cancer cell line A549, liver cancer cell line SMMC-7721, breast cancer cell line MDA-MB-231, and colon cancer cell line SW480. [Conclusion] Streptomyces sp. BPA71 from the gut of B. rynchopetera can produce rich bioactive substances. The findings of this study lay a foundation for further mining the active natural products of Streptomyces from the gut of B. rynchopetera and enriched our understanding of the gut microbiota of B. rynchopetera.