IN SILICO IDENTIFICATION OF SECONDARY METABOLITES FROM AQUATIC STREPTOMYCES ISOLATE WITH ANTIYEAST AND ANTICANCER ACTIVITIES

This study explored the potential of bioactive metabolites from Streptomyces strain WHD3007-4. Isolated from a Nile tilapia pond, aquatic Streptomyces sp. WHD3007-4 was cultured in four media (International Streptomyces Project-2 Medium (ISP2), 301, Starch Casein Broth (SCB), and Bennet’s Broth (BN). Its secondary metabolites were extracted using ethyl acetate and acetone at a ratio of 15:2 (v/v). The cytotoxicity of all crude extracts on the human colorectal cancer cell line HCT-116 was assessed using the MTT assay. The percentage of viable HCT-116 cells was lowest with Streptomyces sp. WHD3007-4 in the SCB medium (36.20%). The antiyeast activity of the crude extract from Streptomyces sp. WHD3007-4 in SCB medium was assessed against Candida tropicalis (TISTR No. 5136) using the disk diffusion method. The crude extract effectively inhibited C. tropicalis growth at 2 mg. Known compounds in the crude extract from Streptomyces sp. WHD3007-4 in different media were identified using liquid chromatography-tandem mass spectrometry, with the data processed using MZmine 3 for molecular networking and spectral library searching on the Global Natural Products Social Molecular Networking (GNPS) web platform. Several candidate anticancer molecules were identified: kynurenic acid, brevianamide F, N-(2-hydroxyphenyl) acetamide, and decumbenone A. These results suggest that Streptomyces sp. WHD3007-4 is a potential source of antiyeast and anticancer agents.