Evaluation of Antioxidant, Antimicrobial and Cytotoxic Activities of Endemic Verbascum diversifolium, which has Medical and Economic Value

Background

Verbascum diversifolium, an endemic medicinal plant native to Türkiye, is recognized for its potential therapeutic and economic value. This study aimed to evaluate the antimicrobial, antioxidant, total phenolic, and cytotoxic activities of its leaf and flower extracts.

Materials and Methods

Antimicrobial activity was determined using the broth microdilution assay against three Gram-positive bacteria, three Gram-negative bacteria, and two fungal strains. Antioxidant activity was assessed by DPPH radical scavenging, ferric reducing power, and metal-chelating assays. Total phenolic content was measured using the Folin-Ciocalteu colorimetric method and expressed as Gallic Acid Equivalents (GAE). Cytotoxic activity was evaluated in MCF-7, A549, C6, and HUVEC cell lines using the MTT assay.

Results

The leaf extract exhibited the strongest antimicrobial activity against Escherichia coli (MIC=0.079 mg/mL) and moderate activity against Candida tropicalis (MIC=0.207 mg/mL), whereas the flower extract showed moderate inhibition of E. coli (MIC=0.319 mg/mL). The flower extract demonstrated the highest DPPH radical scavenging activity (93.90%), while the leaf extract showed superior ferric reducing power and metal-chelating capacity. Total phenolic contents were 11.673 mg GAE/g and 10.782 mg GAE/g extract for the leaf and flower extracts, respectively. Both extracts exhibited limited cytotoxicity toward the tested cancer cell lines; however, low toxicity toward HUVEC cells and relatively greater responsiveness in MCF-7 cells indicated modest selectivity.

Conclusion

The findings suggest that Verbascum diversifolium is a promising natural source of antioxidant and antimicrobial compounds. Further phytochemical isolation, mechanistic studies, and in vivo investigations are required to identify the bioactive constituents responsible for its biological activities and to validate its therapeutic potential.