Assessment of antioxidant potential, verbascoside, and sugar composition of the floral parts of verbascum sinuatum

In this study, the antioxidant capacity of the hydromethanolic extract obtained from the floral parts of Verbascum sinuatum was evaluated, and its total phenolic, flavonoid, verbascoside, and sugar contents were determined. The antioxidant capacity of the extract was evaluated using DPPH, ABTS, and FRAP assays. Total phenolic and flavonoid contents were measured spectrophotometrically, while the verbascoside and sugar contents of the extract were quantified by the HPLC-UV and HPLC-RID methods, respectively. According to the results, the DPPH radical scavenging activity of the extract was found to be IC50= 30.70±1.76 µg/mL, and the ABTS value was IC50= 17.31±0.65 µg/mL. The FRAP activity was determined as 63.94±0.98 mg TE/g extract. The total phenolic content was measured as 45.23 0.77 mg GAE/g, and the total flavonoid content as 6.31±0.50 mg QE/g. According to the HPLC-UV analysis, the verbascoside content of the extract was found to be 9.72±0.85 mg/g. Additionally, the results demonstrated that fructose (190.39 mg/g) was the most abundant sugar in the floral extract of V. sinuatum, followed by glucose (132.91 mg/g) and a relatively small amount of sucrose (7.21 mg/g). As a result, the hydromethanolic extract of V. sinuatum floral parts exhibited a considerable level of antioxidant activity, contained significant amounts of phenolic compounds, particularly verbascoside, and was rich in hexose sugars, especially fructose and glucose. These findings suggest that this plant may be considered a promising natural source of antioxidants and bioactive compounds.