Integrated Phytochemical Profiling and Antioxidant Evaluation of Wild Thapsia garganica L. Roots from Western Algeria Using Spectrophotometry, GC–MS and LC–MS/MS

Thapsia garganica L. is a medicinal plant widely used in North African traditional medicine, yet the phytochemical composition and antioxidant potential of its roots remain poorly characterized. This study investigated the phytochemical profile and antioxidant activity of wild T. garganica roots collected from western Algeria. Methanolic and n-hexane extracts were prepared for phytochemical characterization, while the crude methanolic extract and its flavonoid and alkaloid fractions were evaluated for antioxidant activity. Antioxidant activity of the crude methanolic root extract and the isolated flavonoid and alkaloid fractions were evaluated using the 2,2-diphenyl-1-picrylhydrazyl (DPPH) radical-scavenging assay, complemented by kinetic analysis of radical scavenging. Phytochemical characterization was performed using GC–MS and LC–MS/MS. The crude methanolic extract exhibited the strongest DPPH radical-scavenging response among the tested samples, showing a concentration-dependent increase in radical-scavenging activity and time-dependent DPPH radical-scavenging kinetics, with an initial rapid phase followed by a slower reaction. LC–MS/MS identified ferulic acid (90.2 µg/mg), vanillic acid (9.26 µg/mg), and caffeic acid (2.49 µg/mg) as the major quantified phenolic compounds, while GC–MS revealed a diverse chemical profile comprising fatty acid-related, sterol-related, terpenoid-related, and phenolic-related constituents. Overall, these findings demonstrate promising in vitro DPPH radical-scavenging activity of the crude methanolic root extract and reveal a diverse metabolite profile, providing a basis for further investigation of its phytochemical composition and biological properties.