| Summary: | The aim of the study was to evaluate the antioxidant and antidiabetic potential of five Malaysian Uncaria species namely U. lucida, U. acida, U. cordata, U. callophylla and U. longiflora var. pteropoda, find any correlation between these two activities and relate them to their phytochemical content. Measurement of antioxidant activities employed ferric thiocyanate (FTC), thiobarbituric (TBA) and 1,1-diphenyl-2-picrylhydrazyl (DPPH) assays while evaluation of total phenolic contents employed Folin Ciocalteau methods. Antidiabetic potential was evaluated by a-glucosidase inhibitory assays. All tested extracts exhibited very strong antioxidant potential in the FTC and TBA assays. U. longiflora v.p. (stems and leaves) and U. calophylla (stems) exhibited strong DPPH free radical scavenging activity with IC50 values of 8-20 μg mL-1 compared to 8 μg mL-1 for vitamin C and 7 jig mL-1 BHT. In the a-glucosidase inhibitory assay, the stem extracts of the two plants showed strong a-glucosidase inhibition (>99%). The anti-diabetic activity exhibited by the two plants correlated well with its radical scavenging activities and its phytochemical content. This study has found Malaysian Uncaria to be potentially important sources of antioxidants and anti-diabetic agents, which may be used in prevention and control of type II diabetes. © 2011 Academic Journals Inc.
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