EXPLORING ANTIBACTERIAL AND CYTOTOXIC POTENTIAL OF ENDOPHYTIC Streptomyces ISOLATED FROM THE MEDICINAL PLANT Litsea cubeba (Lour.) Pers

Abstract

Over the past decades, researchers and scientists have paid more and more attention to the discovery of novel antibiotics and anticancer agents in fighting infection and cancer diseases. It is believed that endophytic actinomycetes from medicinal plants provide abundant resources for new compounds with significant bioactive properties. In the present study, we assessed antibacterial and cytotoxic activities of endophytic actinomycetes associated with Litsea cubeba (Lour.) Pers. A total of 45 endophytic actinomycetes were isolated from Litsea cubeba (Lour.) Pers were collected at Lai Chau province, Viet Nam, with the maximum number of isolates obtained from roots (44.4 %), followed by stems (35.5 %), and leaves (20.1 %). Among them, 3 isolates LCL08, LCL25, LCL28 showed a broad spectrum of antibacterial activity against six tested bacteria, which were subsequently identified as Streptomyces albogriseolus LCL08, S. olivaceus LCL25, and S. cavourensis LCL28 by using 16S rRNA sequence analysis. This is the first report of S. alborgriseolus isolated as endophyte. Ethyl acetate extracted from these 3 strains exhibited strong antibacterial activity against 6 tested pathogens with a minimum inhibitory concentration ranging from 2 to 64 μg/mL. Moreover, these extracts showed remarkable cytotoxic effects against Hep3B human hepatoma, MCF-7 breast cancer, and A549 lung cancer cell lines with the recorded viability of tested cancer cells ranging from 13.87 to 65.69 %. These findings suggest that Streptomyces spp. recovered from Litsea cubeba (Lour.) Pers are an excellent source of natural antibacterial and cancer compounds that could be promising for further research.