Antioxidant activity of 1-hydroxy-1-norresistomycin derived from Streptomyces variabilis KP149559 and evaluation of its toxicity against zebra fish Danio rerio

Abstract

It is a known fact that marine actinomycetes are potential source of bioactive compounds. However, the toxicity evaluation of these bioactive compounds is lacking in numbers. To emphasize the problem, the present study aims to produce and characterize the bioactive compounds obtained from Streptomyces variabilis and evaluate their toxicity against the human model system Danio rerio. Ethyl acetate was used to extract the bioactive compounds from the culture supernatant of S. variabilis and the antimicrobial activity assessed against human clinical pathogens. Thin layer chromatography of the ethyl acetate extract showed six fractions and all the fractions were purified by column chromatography. Among the six fractions assessed for antimicrobial activity, fraction 4 (F4) has excellent activity and was selected for characterization. Furthermore, F4 was identified as 1-hydroxy-1-norresistomycin (HNM) using FT-IR, GC-MS, ¹H NMR and ¹³C NMR analyses and its chemical structure confirmed with the previous reports. The in vitro antioxidant activity revealed that HNM can act as a potential scavenger of cancer inducing molecules such as DPPH, hydrogen peroxide and hydroxyl radicals. Moreover, the toxicity evaluation against zebra fish showed that HNM induces no toxicity in the major organs of D. rerio such as the heart, liver, kidney, intestine, and gills, and minimal toxicity in the spleen.