In Silico Identification of Secondary Metabolites from Aquatic Streptomyces Isolate with Antiyeast and Anticancer Activities

Our objective is to explore the potential of bioactive metabolites from our Streptomyces strain WHD3007-4. The aquatic Streptomyces sp. WHD3007-4, isolated from a Nile tilapia pond, was cultured in four different media (ISP2, 301, SCB, and BN). Secondary metabolite extraction was performed using ethyl acetate and acetone at a ratio of 15:2 (v/v). The cytotoxicity of all crude extracts on the human colorectal cancer cells line (HCT-116) was determined by the MTT assay. The lowest percentage of human colorectal cancer cells line viability observed was 36.20% with WHD3007-4 in SCB medium. Furthermore, the antiyeast activity of the crude extract from WHD3007-4 in SCB medium was tested against C. tropicalis TISTR 5136 using the disk diffusion method. The results showed that the crude extract, at concentrations ranging from 0.1 to 100 mg/mL, effectively inhibiting yeast growth. To identify known compounds, the crude extract from WHD3007-4 in different media was analyzed by LC-MS/MS. MS data were processed using MZmine 3 for molecular networking and spectral library search on the GNPS web platform. Several candidates anticancer molecules; kynurenic acid, brevianamide F, N-(2-hydroxyphenyl)acetamide, and decumbenone A were annotated. These results suggest that Streptomyces sp. WHD3007-4 is a potential source of antiyeast and anticancer agents.