Anticancer Activity of Microbial Biosurfactants Amphisin and Viscosinamide Against Melanoma Cells

The anticancer activity of two novel microbial lipopeptide biosurfactants, amphisin and viscosinamide, was evaluated against human (A375) and murine (B16 4A5) melanoma cells. Normal human dermal fibroblasts (NHDFs) were used as a control. Cell viability was assessed using the MTT assay, while membrane integrity was analysed by the lactate dehydrogenase (LDH) release test. Early and late stages of apoptosis were investigated using Annexin V-FITC and Hoechst 33342 staining, respectively. In addition, the expression of apoptosis-related genes bax and bcl-2 was quantified by RT-qPCR. Finally, the wound healing (scratch) assay was performed to evaluate the effect of the tested lipopeptides on the migratory ability of melanoma cells. Both lipopeptides inhibited melanoma cell proliferation in a concentration- and time-dependent manner and exhibited significantly lower cytotoxicity toward NHDF cells, indicating selective antitumor activity. Viscosinamide exhibited stronger cytotoxic activity than amphisin. LDH release and fluorescence microscopy confirmed that the main mechanism of cytotoxicity was cell membrane damage and induction of apoptosis, including phosphatidylserine externalization and characteristic changes in the cell nucleus, such as chromatin condensation and cell nucleus fragmentation. Gene expression analysis demonstrated increased levels of bax and decreased levels of bcl-2, indicating activation of the intrinsic mitochondrial pathway of apoptosis. In addition, tested compounds effectively inhibited cell migration. The studies show that amphisin and viscosinamide exhibit selective anticancer potential related to the cell membrane and are promising molecules for further development as melanoma treatments.