Bioactive Potential of The Endemic Verbascum bellum: Cytotoxicity Against Cancer Cells and Antimicrobial Effects

Natural products remain a major source for the discovery of novel therapeutic agents, particularly in cancer treatment and the fight against antimicrobial resistance. Verbascum bellum, an endemic Turkish species, was evaluated for its cytotoxic and antimicrobial potential using methanolic extracts prepared from its leaves and flowers. Cytotoxic activity was assessed in three human cancer cell lines (Huh-7, Caco-2, and PC-3) using the MTT assay, while antibacterial activity was determined against two Gram-positive (Staphylococcus aureus and Bacillus subtilis) and two Gram-negative (Escherichia coli and Pseudomonas aeruginosa) bacterial strains using the agar well diffusion method. Among the tested extracts, the leaf extract demonstrated significant and selective cytotoxicity, particularly against Huh-7 hepatocellular carcinoma cells after 72 hours of exposure (IC₅₀ = 24.6 ± 5.1 µg/mL). Both extracts also exhibited notable antimicrobial activity, with strong inhibition observed against B. subtilis (up to 19 mm) and E. coli (up to 23 mm). To our knowledge, this is the first report describing the cytotoxic activity of V. bellum. These findings highlight the potential of this endemic species as a promising source of bioactive compounds for further pharmacological investigation.