Evaluation of antioxidant, antimicrobial, and cytotoxic activities of Digitalis davisiana Heywood

The genus Digitalis L. (Plantaginaceae), commonly known as foxglove, is a key natural source of cardenolides, with diverse pharmacological properties, particularly in treating cardiovascular diseases [ 1 ]. In Türkiye, Digitalis is represented by eight species and nine taxa, including D. lanata Ehrh. and D. ferruginea L., known for their high cardenolide content. D. davisiana Heywood , an endemic taxon, remains largely unexplored in terms of its phytochemical and biological properties [ 1 ] [ 2 ] [ 3 ]. This study investigates the biological activities of methanol and ethyl acetate extracts from D. davisiana . Antioxidant potential was assessed using DPPH radical scavenging activity, where the methanol extract exhibited 43,56% inhibition at 125 μg/mL, while the ethyl acetate extract showed 69,06% inhibition at 1250 μg/mL. The total phenolic content (TPC) was measured using the Folin-Ciocalteu method. The methanol extract exhibited a higher TPC (60.93±0.05 mg GAE/g) than the ethyl acetate extract (40±0.005 mg GAE/g), suggesting that methanol is more effective in extracting phenolic compounds. Antimicrobial activity was assessed using the microdilution method, revealing that both extracts were active against Bacillus subtilis NRRL B478 , Escherichia coli ATCC 35218 , Pseudomonas aeruginosa ATCC 27853 , Staphylococcus aureus ATCC 29213, Candida albicans ATCC 90028 , and Candida krusei ATCC 6258 at MIC values of 1025-625 μg/mL. Cytotoxicity tests (MTT assay) on NIH3T3 cells showed IC 50 values above 500 μg/mL. These findings suggest that D. davisiana may be a valuable source of bioactive compounds with antioxidant and antimicrobial potential. Further research is needed to evaluate its pharmacological properties and ensure its safe application fully. Publication History Article published online: 05 March 2026 © 2026. Thieme. All rights reserved. Georg Thieme Verlag KG Oswald-Hesse-Straße 50, 70469 Stuttgart, Germany