Polyphenols Investigation and In Vitro Antioxidant Activity of Romanian Wild-Grown Geranium spp. (Geraniaceae)

Geranium spp. are recognized as rich sources of phenolic metabolites, with potential health benefits, yet comparative evaluations remain limited. We assessed four wild-grown Geranium spp. (G. dissectum – G1, G. lucidum – G2, G. pusillum – G3, and G. robertianum – G4), from southwestern Romanian flora, using complementary antioxidant (DPPH, ABTS and FRAP) and phytochemical (TPC and TFC) assays. Targeted UHPLC/UV–MS quantified eight phenolic acids. FRAP provided the strongest discrimination between species, and mirrored TPC, with the highest values in G4 sample. ABTS and DPPH supported the same ranking, and TFC varied only modestly, but differences were narrower and not significant between species. Caffeic acid was highest in G1 sample, and chlorogenic acid was selectively elevated in G3 sample. Gallic and protocatechuic acids were highest in G4 sample, both tracking the FRAP/TPC gradient. Syringic acid and vanillic acid were enriched in weaker-antioxidant species. Distinctive signatures included high p-coumaric acid in G4 sample and chlorogenic and ferulic acids in G3 sample. Antioxidant potential among Geranium spp. is best explained by TPC, particularly hydroxybenzoic acids, with FRAP emerging as the most sensitive discriminator. These findings provide a comparative benchmark for Geranium spp. phytochemistry and a framework for future pharmacological studies.