Phytochemical Characterisation and Skin-Relevant In Vitro Biological Activity of Leaf Extracts from Selected Geranium Species

In the search for natural compounds with skin-relevant biological activity, the leaves from three species of the Geraniaceae family (Geranium phaeum, Geranium sanguineum, and Geranium macrorrhizum) were investigated. The study combined phytochemical characterisation with a broad evaluation of biological activity. The bioactivity of the tested extracts was assessed using antioxidant assays (DPPH, ABTS, and CUPRAC), metal-chelating tests, and inhibition assays of hyaluronidase, elastase, and tyrosinase. In addition, antimicrobial activity was evaluated against selected Gram-positive and Gram-negative bacteria and Candida spp., while cytocompatibility was assessed using HaCaT keratinocytes and HFF-1 fibroblasts. To support the interpretation of the observed biological effects, qualitative phytochemical profiling of the extracts was performed by LC–MS; selected compounds were quantified by HPLC; and total polyphenol and flavonoid contents (TPC and TFC) were determined. Overall, the extracts exhibited notable antioxidant, antimicrobial, and enzyme-inhibitory activities, while maintaining good cytocompatibility at lower concentrations. Among the tested species, G. sanguineum and G. macrorrhizum showed the most pronounced overall activity, likely associated with their high polyphenol content. These results indicate that selected Geraniaceae species represent promising sources of bioactive compounds with combined antioxidant, antimicrobial, and skin-compatible properties, supporting their further investigation in skin-relevant in vitro and formulation-oriented studies.