Bioactive metabolites produced by Streptomyces Cheonanensis VUK-A from Coringa mangrove sediments: isolation, structure elucidation and bioactivity

Abstract

The strain VUK-A was isolated from a sediment sample of the Coringa mangrove ecosystem was identified as Streptomyces cheonanensis based on morphological, physiological, biochemical and molecular properties. Chemical investigation of the secondary metabolites of the strain Streptomyces cheonanensis VUK-A has led to the segregation of two bioactive compounds, namely 2-Methyl butyl propyl phthalate (1) and Diethyl phthalate (2) using column chromatography. The chemical structure of the active compounds was established on the basis of spectroscopic analysis, including ¹H NMR and ¹³C NMR spectroscopies, FTIR and EIMS. The antimicrobial activity of the bioactive compounds produced by the strain was tested against a wide variety of bacteria and fungi and expressed in terms of minimum inhibitory concentration. The compounds (1&2) were active against all the bacteria tested, and the best activity of compound 1 was recorded against Proteus vulgaris (4 µg/ml). Compounds (1&2) were active against dermatophytes and fungi but compound 1 displayed high antifungal activity against Candida albicans (8 µg/ml) and Fusarium solani (16 µg/ml) compared to standard antifungal agents. The cytotoxicity of the bioactive compound 1 was tested against MDA-MB-231, OAW-42, HeLa, and MCF-7 cell lines. The highest activity of 100 µM by compound 1 was recorded against HeLa cancer cell lines. In fact, this is the first report of 2-Methyl butyl propyl phthalate from the genus Streptomyces.

Keywords: Antimicrobial activity; Bioactive compounds; Cytotoxicity; Mangrove ecosystem; Streptomyces cheonanensis.

Fig.1

Molecular structures of a 2-Methyl butyl propyl phthalate (1) b Diethyl phthalate (2)

Fig. 2

Dose response curve of compound 1 on the growth of a MDA-MB-231, b HeLa, c MCF-7, d OAW-42 cancer cell lines