Integrated Chemical Profiling and Biological Assessment of Melittis melissophyllum L. (Lamiaceae): Antioxidant, Antimicrobial and Cytotoxic Activities.

Background/Objectives: Melittis melissophyllum L. (bastard balm) is a perennial herb belonging to the Lamiaceae family. This study investigated the phytochemical composition, antioxidant properties, antimicrobial activity, and cytotoxic effects of a 50% (v/v) ethanol-water extract of M. melissophyllum. Methods: The phytochemical profiles were characterized by spectrophotometric analysis, while individual polyphenolic compounds were identified and quantified using LC-MS. Antioxidant activity was assessed using the DPPH radical scavenging and FRAP assays. The cytotoxic effects were evaluated in normal human foreskin fibroblasts (BJ) and two human cancer cell lines, HCT-116 (colorectal carcinoma) and OVCAR-3 (ovarian adenocarcinoma). The antimicrobial efficacy of M. melissophyllum extracts was assessed against a panel of Gram-positive and Gram-negative bacterial strains, as well as a representative yeast species. Results: The results revealed a high content of polyphenolic compounds in the tested extract. Cytotoxicity assays demonstrated good tolerability toward normal cells while indicating inhibitory effects on tumor-derived cell lines. In addition, the extract exhibited limited but measurable strain-dependent antimicrobial activity. Conclusions: Collectively, these findings suggest that M. melissophyllum represents a promising source of bioactive compounds with potential medicinal applications.