Solvent-Driven Variation in Phytochemical Profile and Antioxidant Activity of Melissa officinalis from Tabasco, Mexico, Revealed by UPLC-QtoF.

Melissa officinalis is recognized as a rich source of phenolic compounds with antioxidant properties. However, although its phytochemical composition has been extensively investigated, comparative studies integrating phytochemical characterization, antioxidant properties, and LC-MS metabolite profiling across commonly used extraction systems remain limited. This study comparatively evaluated aqueous, hydroacetonic, and hydroethanolic extracts of M. officinalis leaves by determining total phenolic (TPC), flavonoid (TFC), and tannin (TTC) contents, antioxidant activity (DPPH, ABTS, and FRAP assays), and metabolite profiling using UPLC-QToF-MS. The hydroethanolic extract exhibited the highest TPC (442.17 mg GAE/g DE), TTC (221.17 mg TAE/g DE), and antioxidant activity, whereas the hydroacetonic extract showed the highest TFC (178.52 mg CE/g DE). UPLC-QToF-MS-based metabolite profiling aided in the tentative annotation of 15 metabolites, including phenolic acids (rosmarinic, gallic, and ellagic acids) and flavonoids (catechin, rutin, quercetin, and apigenin). Among the evaluated conditions, the hydroethanolic and aqueous extracts yielded a higher number of metabolites than the hydroacetonic extract. Our findings demonstrate that solvent selection substantially influences phytochemical recovery, metabolite coverage, and antioxidant properties, providing an integrated framework for selecting extraction systems for phytochemical characterization and antioxidant-oriented applications.