Metabolomic Profile and Antioxidant Capacity of Methanolic Extracts of Mentha pulegium L. and Lavandula stoechas L. from the Portuguese Flora

This study assessed the phenolic content, antioxidant capacity, and phytochemical composition of methanolic extracts from Portuguese Mentha pulegium L. and Lavandula stoechas L. Through spectrophotometric methods (TPC, FRAP, and DPPH), high-resolution techniques (HPLC-ESI(-)-HRMS/MS), along with multivariate techniques (PCA and cluster analysis). A total of 24 to 26 metabolites were identified across the analyzed plant species, including flavonoids, phenolic acids, terpenoids, jasmonates, and fatty acids. M. pulegium was primarily composed of diosmin and hesperidin, whereas L. stoechas exhibited amounts of rosmarinic acid and associated phenolic compounds. Multivariate and correlation analyses demonstrated variability within species and emphasized connections among metabolite categories, biosynthetic routes and environmental influences like altitude. Inland accessions of M. pulegium from Beja, Portalegre and Évora showed elevated TPC and FRAP levels while DPPH activity fluctuated according to distinct metabolite profiles. Despite these variations, phytochemical diversity did not adhere to a geographic trend, indicating that genetic and biosynthetic elements are more influential. The interplay between flavonoids and phenolic acids seemed crucial in determining antioxidant activity. Overall, the Portuguese germplasm of both species demonstrates substantial bioactive potential and chemical diversity, underscoring its value for food, nutraceutical, and pharmaceutical applications. These findings provide a scientific basis for selecting promising accessions and developing future biotechnological strategies.