Screening of antioxidant activity of vegetables in Thailand

Abstract

The methanolic extracts of ten Thai vegetables from the leaves of Litsea elliptica Blume, Callerya atropurpurea (Wall.) A. M. Schot, Horaphanam (Limnophila sp.), Sesbania grandiflora (L.) Desv. Young, Kaempferia galanga L., Cucurbita moshata Decne, Allophylus cobbe (L) Raeusch and Manihot esculenta (L) Crantz, rhizomes of Alpinia oxy-mitrum K. Schum. and roots of Zingiber zerumbet (L.) Smith were investigated for antioxidant activities and total phenolic contents. The anti-oxidant activities of these extracts were de-termined by 1,1-diphenyl-2-picryl hydrazyl radical scavenging (DPPH) and ferric-reducing antioxidant power (FRAP) assays. Total phenolic content was evaluated according to the Folin-Ciocalteu pro-cedure. Among the investigated Thai vegetables, the extract from leaves of L. elliptica showed the highest free radical scavenging power with IC50 value of 4.2 µg/ml and the most potent reducing power of 2.02 mmol FeSO4 per g of extract as well as the highest amount of phenolic contents of 11.059 g of gallic acid per 100 g of extract. The results indicated that the antioxidant activity was correlated well with the total phenolic contents suggesting that the phenolic compounds might play a major contribution to free radicals sca-venging activity of the studied plants.