Determination of some biological properties and phenolic components of Verbascum napifolium extracts

Although the health benefits of increased consumption of herbal products have been known since ancient times, it is not known which specific ingredients are responsible for this beneficial effect. However, today, many herbal products are attracting more attention, and the number of studies on their benefits and uses is increasing day by day. Plants are a good source of fats, simple and complex carbohydrates, proteins, minerals and secondary metabolites important for human nutrition. In addition, the health benefits of some substances such as phytochemicals in the chemical composition of plants have recently attracted a lot of attention. This study investigated antioxidant, toxic, anthelmintic activities and phenolic component compositions of methanol, acetone, and distilled water extracts of the endemic Verbascum napifolium species distributed in Turkey. The antioxidant activity of the extracts was determined by DPPH, ABTS, phosphomolybdenum, β-carotene/linoleic acid, copper (CUPRAC), and iron reduction (FRAP) methods. The free radical scavenging activities of leaf and flower extracts prepared with methanol, acetone, and water solvents at 1 mg/mL concentration ranged from 44.92±1.16/92.83±0.26% in the DPPH method. In the DPPH study, the highest scavenging activity was the leaf methanol extract with a value of 92.83±0.26% (0.29±0.01 mg/mL, IC50). The lowest activity was found in the flower water extract with a value of 44.92±1.16% (1.18±0.05 mg/mL, IC50). In terms of the best antioxidant activity value, it was observed that the leaf methanol, acetone, and water extracts exhibited an activity close to the value of the synthetic antioxidant BHA (0.01±0.002 mg/mL, IC50). In addition, the total amount of phenolic, flavonoid, and tannin substances was determined using Folin-Ciocalteu, aluminum chloride, and vanillin reagent. The phenolic component contents of the plant extracts were determined by the HPLC assay. Leaf water extracts of Verbascum napifolium plant had the highest phenolic content value (20.11±1.24 mg GAE/g). Leaf acetone extract has the highest value (9.21±0.12 mg QE/g, 75.55±0.29 mg CE/g) in terms of flavonoid and tannin content. Flower water extracts showed the weakest effect in terms of phenolic substance, flavonoid, and tannin. Quercetin was the highest phenolic component in HPLC content identification. The possible toxic effects of the extracts were investigated by the lethality test of Brine shrimp (Artemia salina L.). The methanol extract showed the highest toxic effect with an LC50 value of 0,033±0,015 mg/mL. The anthelmintic activity test was found by recording the lethal times of plant extracts at different concentrations on Tubifex tubifex. Flower methanol extracts (4 min) showed the highest anthelmintic activity. It is believed that the data obtained from this study will contribute to the development of research on the use of products obtained from plants in many fields such as medicine and alternative medicine. Keywords: Anthelminthic, Antioxidant, Artemia salina, HPLC, Verbascum napifolium