Antioxidant Activity and Alpha-glucosidase Inhibitory Activity of Traditional Herbal Extracts in the Blood and Body Nourishing Group from upper Northern Regions of Thailand

This research aims to study phytochemicals, total phenolic content, antioxidant activity and alphaglucosidase inhibitory activity of 10 traditional herbal crude extracts. The medicinal herbs that nourish blood and body from the upper Northeastern of Thailand used in this study included Erycibe paniculata Roxb., Gnetum macrostachyum. Hook. f., Bauhinia sirindhorniae K. Larsen & S. S. Larsen, Knema angustifolia Roxb Warb., Ventilago denticulata Willd., Melastoma malabathricum L., Strychnos axillaris Colebr., Caesalpinia sappan L., Ochna integerrima Lour Merr., and Osyris sp. The results showed that most of the ethanolic herbs extracts contained flavonoids and terpenes. In addition, alkaloids, anthraquinone, coumarin, saponin and tannin were found in some extracts. However, there was no steroids and cardiac glycoside found in the extracts. The extracts of Ventilago denticulata Willd., Bauhinia sirindhorniae K. Larsen & S. S. Larsen, Caesalpinia sappan L., and Osyris sp. showed relatively high antioxidant activity determined by DPPH assay with the value of 147.03 ± 2.72, 127.30 ± 0.99, 104.94 ± 3.84 and 73.72 ±1.46 mg AE/g crude extract, respectively. This is related to the high content of total phenolic compounds in these extracts. Interestingly, all the extracts, except the extract of Erycibe paniculata Roxb., had significantly (p < 0.05) higher alpha-glucosidase inhibitory activity than acarbose. Thus, the traditional blood and body nourishing herbs are good sources of antioxidants and could be further developed to foods or drugs for diabetes prevention.