Antioxidant activity and bioactive phytochemical contents of traditional medicinal plants in northeast Thailand

Abstract

Traditional medicinal plants are efficacious for many ailments, but most of them still lacked the supportive scientific information for their therapeutic properties. We collected 31 medicinal plant species from 19 families commonly used as traditional medicine in northeast Thailand and classified into digestive tonic, diarrheal relief, anti-tussive and anti-inflammation groups. Their total antioxidant activity, free radical scavenging activity, total phenolic and ascorbic acid contents were determined. The results showed that these biological parameters were highly variable among plants examined. Stronger total antioxidant activity and higher amount of total phenolics and ascorbic acid were shown in anti-tussive than diarrheal relief and anti-inflammation plants, but digestive tonic group possessed strong free radical scavenging activity. When the top three plants with relatively high phenolics were selected from each group, alkaloids contents were found at high level in digestive tonic and anti-tussive plants, whereas tannins were high in digestive tonic and diarrheal relief plants. Our data provided significant scientific data on biological activities and phytochemical compositions of Thai medicinal plants consumed by local people in relation to their therapeutic activities. Key words: Thai medicinal plants, 1,1-diphenyl-2-picryl hydrazyl (DPPH), 2,2′-azinobis (3-ethylbenzothiazoline-6-sulfonic acid (ABTS), antioxidant activity, phenolic compounds, alkaloids, ascorbic acid.