Seasonal Phytochemical Variation and Bioactivity of Artemisia herba-alba: Comparative Evaluation of Essential Oils and Phenolic Extracts With Antioxidant, Tyrosinase Inhibitory and In Silico Studies.

This study estimated the effect of seasonal variation on the chemical composition and biological activities of Artemisia herba-alba hydroalcoholic extract and essential oil, focusing on antioxidant and tyrosinase inhibitory activities. Chemical profiling was achieved using LC-MS for the extract and GC-MS for the essential oil. Total phenolic and flavonoid contents were estimated by the Folin-Ciocalteu's and aluminium chloride colorimetric assays. Antioxidant activity was evaluated using DPPH, ABTS, phosphomolybdate, and FRAP methods, while tyrosinase inhibition was expressed as IC50 values using kojic acid as a positive control. Molecular docking was performed to explore the interactions of the main constituents with the tyrosinase enzyme. LC-MS analysis identified naringenin, vanillin, luteolin, quercetin, and trans-cinnamic acid as the major compounds across all samples. GC-MS disclosed seasonal variation in essential oil composition; autumn oil contained several unique ingredients, remarkably davana ether 2, while winter oil was characterized by high carvacrol content. The winter essential oil and summer extract exhibited the strongest antioxidant and tyrosinase inhibitory activities. Molecular docking revealed strong binding affinities of vanillin, kojic acid, and carvacrol within the catalytic pocket of tyrosinase, while thujone isomers exhibited weaker but consistent interactions.