Phytochemical characterization and bioactive potential of Stachys germanica L.: LC-MS/MS profiling and multi-target biological activities

Abstract

Stachys germanica L. is a member of the Lamiaceae family traditionally recognized for its bioactive secondary metabolites. The present study aimed to investigate the phytochemical composition and biological potential of the 80% ethanolic extract of S. germanica using spectrophotometric assays and liquid chromatography–tandem mass spectrometry (LC–MS/MS) analysis. The extract exhibited a high phenolic content (59.80 ± 0.84 mg GAE/g) and flavonoid content (20.50 ± 0.24 mg RE/g), with notable antioxidant activity, particularly in CUPRAC (445.26 ± 6.11 mg TE/g), ABTS (387.12 ± 3.03 mg TE/g), FRAP (360.89 ± 5.19 mg TE/g), and DPPH (333.96 ± 1.61 mg TE/g) assays. Enzyme inhibition assays revealed a selective inhibitory profile, with pro nounced activity against tyrosinase (62.23 ± 0.06 mg KAE/g) and α- glucosidase (1.05 ± 0.24 mmol ACAE/g), suggesting poten tial relevance in dermatological and metabolic applications. Notably, antimicrobial evaluation demonstrated significant activity against Acinetobacter baumannii ATCC 19606 (MIC: 97 μg/mL), highlighting a selective antibacterial effect against a clinically relevant Gram- negative pathogen. LC–MS/MS analysis revealed a chemically diverse metabolite profile largely composed of phe nolic acids and flavonoids, with chlorogenic acid (1024 ± 20.54 μg/g), naringin (196.10 ± 4.65 μg/g), luteolin (82.46 ± 1.88 μg/g), and kaempferol (70.99 ± 1.71 μg/g) identified as the main components. Overall, this study provides a multi- dimensional char acterization of S. germanica, linking its phenolic- rich composition to antioxidant, enzyme- modulating, and selective antimi crobial activities. These findings highlight the potential of S. germanica as a natural source of bioactive compounds for food, nutraceutical, and functional product applications.