Phenolic compounds characterization, carbohydrate digestive enzyme inhibitory and antioxidant activities of Hieracium pannosum Boiss

Hieracium pannosum Boiss. (Asteraceae) was studied for its antidiabetic and antioxidant activities with the main focus on phenolic compound characterization. The methanol extracts of the flowers, leaves and roots of the plant were examined using in-vitro models for determining the enzyme inhibitory and antioxidant activities. While α-glucosidase enzyme inhibitory activity of the extracts was not promising, α-amylase inhibitory activity of root extract was moderate at 3 mg/mL concentration. Various antioxidant assay techniques, including total antioxidant, free radical scavenging, superoxide anion scavenging, metal chelating activities and ferric reducing antioxidant power were used to present the antioxidant capacity. Root extract having the highest total phenolic content generally showed the highest antioxidant activity. To explain the significant antioxidant potential of the plant, phenolic compounds such as gallic, chlorogenic, caffeic, p-coumaric, ferulic acids, luteolin-7-glucoside, quercetin, luteolin, apigenin and kaempferol were analyzed qualitatively and quantitatively using RP-HPLC-DAD method. Results showed that while chlorogenic acid was the main component of the leaf and root extracts, the flower extract was found to be rich in luteolin, luteolin-7-glucoside, apigenin and chlorogenic acid. The plant could be evaluated as a serious antioxidant source in cosmetic, food and pharmaceutical industries.