Chemical Components and Antioxidant Activities of Thai Local Vegetables

Proximate compositions, phenolic compounds and antioxidant activities of five Thai local vegetables were investigated. All studied samples showed the similar proximate profiles, in which moisture and carbohydrate were the major components. However, Tiliacora triandra Diels. also contained high content of fiber and protein. Careya sphaerica Roxb. had the highest total phenolic content (TPC) among all samples tested (p < 0.05). The main phenolic acids found in the vegetables were hydrocinnamic acids, including ferulic acid (1 to 16 mg/g), p-coumaric acid (4 to 7 mg/g), sinapic acid (0.9 to 5 mg/g) and syringic acid (1 to 6 mg/g). Careya sphaerica Roxb. extract exhibited the highest ferric reducing antioxidant power (FRAP) (3355.84 μmol FeSO4/100g sample) (p < 0.05). DPPH radical scavenging activities of Careya sphaerica Roxb.(85.6 %inhibition) and Cratoxylum formosum (Jack) Dyer (82.6 %inhibition) extracts were comparable (p > 0.05). This research provided useful information for screening Thai local vegetables as potential sources of bioactive components for consumers and public health workers.

Keywords: local vegetables, phenolic acids, phenolic compounds, antioxidants

*Corresponding author:  raksakantong.p@gmail.com