Valeriana dioscoridis aerial parts' extracts - A new source of phytochemicals with antioxidant and enzyme inhibitory activities

Abstract

Valeriana root extracts are used in herbal medicine for treating sleep disorders. There is a lack of information of phytochemical composition of Valeriana dioscoridis aerial parts’ extracts. The aim of the study was to measure antioxidant activity, determine the phenolic compounds from different groups such as phenolic acids and polyphenolic compounds: verbascoside or eriodictyol, and enzyme inhibitory activities in ethyl acetate, methanol and water extracts. The methanol extract showed the highest antioxidant activity almost in all assays (excluding ferrous ion chelating activity). Moreover, the concentrations of the determined phytochemicals mainly chlorogenic acid content (21.4 ± 0.7 mg/g), hesperidin (2.10 ± 0.05 mg/g) and protocatechuic acid (0.94 ± 0.02 mg/g) were the greatest for this extract. It was also the richest in all determined compounds – 21 phytochemicals were identified and water extract was the second most abundant in analytes (20 phytochemicals). The predominant compounds in water extract were the following: chlorogenic acid (20.3 ± 0.12 mg/g), protocatechuic acid (0.83 ± 0.02 mg/g) and caffeic acid (0.72 ± 0.01 mg/g). Protocatechuic acid was prevailing in ethyl acetate extract (0.59 ± 0.01 mg/g). In addition, in this extract the highest inhibitory activity of α-amylase was found and the highest amount of verbascoside was determined in comparison to other extracts (0.53 ± 0.01 mg/g). The tyrosinase inhibitory effect especially of methanol extract was also shown. Pearson correlation confirmed that the strong biological activity of methanol extract from V. dioscoridis resulted mainly from its high content of chlorogenic acid.