In-vitro assessment of antimicrobial properties and lymphocytotoxicity assay of benzoisochromanequinones polyketide from Streptomyces sp JRG-04.

The chromanequinone (BIQ) compound produced by the mangrove estuary derived strain, Streptomyces sp. JRG-04 was effective even at low MIC level concentration against Methicillin resistant S. aureus and other clinical pathogens. In this study, we have investigated the antimicrobial potential of chromanequinone compound by using various microscopy and imaging techniques. The flow cytometry (FACS) analysis suggested the BIQ aromatic polyketide compound produced by the Streptomyces sp. JRG-04 has toxic effect on MRSA cell membrane by increased up take of propidium iodide dye. The bacterial imaging analysis by high content screening experiment (HCS) revealed the increased number of dead MRSA cells than the live MRSA populations with chromanequinone treatment. Furthermore, atomic force microscopic study proved the MRSA cell surface ultra-structure changes when the cells exposed to chromanequinone compound at 3 h and 6 h. Further, in-vitro lymphocytotoxicity effect of chromanequinone compound at different concentrations with the combination of complement was performed on human lymphocytes by cell lysis assay. Interestingly, we have found that the higher concentration of BIQ chromanequinone (10 mg/mL) compound without complement induced apoptosis of human lymphocytes. The present investigation reveals that the toxic potential of chromanequinone on human lymphocytes might be associated with the complement dependent. This study strongly suggests that the chromanequinone compound produced by the Streptomyces strain with bioactive property can be developed as a therapeutic leads for various pharmaceutical applications.