A bioactive pigment from violet-hued bacteria: a dual approach against prostate cancer and bacterial infections

Given the high potential of microbial metabolites, including pigments, and the desire to utilize them in pharmaceuticals, we decided to isolate the violacein pigment from its producing bacteria and investigate its antioxidant, antimicrobial, and anticancer properties in a PC3 cell line. The bacterium that produces the violacein pigment was isolated from the soil and identified through 16S rRNA sequencing. The pigment was extracted using absolute ethanol. After confirming the pigment, its antimicrobial, antioxidant, and anticancer activities were evaluated using MTT, flow cytometry with apoptosis and cell cycle assays in the PC3 cell line. The violacein-producing bacterium has been identified and named Janthinobacterium lividum strain BAH 1. This pigment was found to have a more significant effect on Gram-positive bacteria; specifically, its highest impact, at a concentration of 1 mg mL^-1, was observed with Streptococcus mutans, which exhibited a growth inhibition zone of 25.5 mm in the disk diffusion method, compared to Gram-negative bacteria. Its highest free radical inhibition was 67%. The IC₅₀ for the PC3 cell line after 48 h was 4.30 µg mL^-1, indicating a more potent lethal effect than on HFF cells. An increase in cells in the sub-G1 phase (48.79%), along with a total apoptosis rate of 75.84% in the treatment group, signifies cell death. Overall, the findings showed that violacein is a promising bioactive compound with potential applications in antibacterial, anticancer, and antioxidant studies.