Integrated Phytochemical Profiling and Bioactivity Evaluation of Micromeria nervosa, with Emphasis on Antimicrobial and Antiviral Properties.

Background/Objectives: Lamiaceae species are valuable sources of bioactive natural products, often associated with anti-infective properties. This study investigated chemical composition and bioactivities of dry hydroethanolic extracts and essential oils from Micromeria nervosa (Desf.) Benth. aerial parts from two localities. Methods: Extracts and essential oils were analyzed using LC-DAD-QTOF-MS/MS and GC-FID/MS, respectively. Antimicrobial activity was assessed against 14 strains (microdilution method), and antiviral activity against three viruses by determining cytopathic effects, viral titers (end-point dilution assay) and viral loads (qPCR/RT-qPCR). Cytotoxicity was evaluated on three cancer cell lines (MTT assay) and antioxidant potential using three colorimetric tests. Composition-activity correlation was statistically analyzed; in silico molecular docking/dynamics simulations were performed. Results: Thirty-five compounds were annotated in extracts, including 30 reported for the first time in this species, with rosmarinic acid as the main component. Essential oils contained 31 constituents, dominated by carvacrol. Newly detected phenolics included lithospermic acid and several salvianolic and clinopodic acids. Extracts and oils exhibited notable antibacterial activity, especially against five Gram-positive strains (MIC = 0.313-2.5 mg/mL), and oils showed marked anticandidal effects (MIC = 0.313-0.625 mg/mL) and enhanced cytotoxicity against colon, gastric and hypopharyngeal cancer cells (selectivity indices ≥ 1.66). Extracts displayed potent antiviral activity against human herpesvirus 1 (HHV-1) and adenovirus Ad5, reducing cytopathic effects and viral titers, with qPCR revealing decreased HHV-1 load. In silico analysis suggested HHV-1 glycoprotein D binding. Extracts also showed strong antioxidant potential. Conclusions: These findings demonstrate that M. nervosa is a rich source of compounds with antimicrobial/antiviral, cytotoxic and antioxidant activities, warranting further research.