Rambutan rind in the management of hyperglycemia

Plant extracts have been suggested as a rich as yet unexplored source of potentially useful anti-diabetic drugs. Recent scientific investigations have confirmed the efficacy of many of these preparations, as effective antioxidants; able to regenerate functional pancreatic beta cells and has a hypoglycemic potential. In this study, the exotic rambutan (Nephelium lappaceum L.) fruit's rind has been shown to be effective in inhibiting the carbohydrate hydrolyzing enzymes. alpha glucosidase (EC50=2.7 mu g/mL) and alpha amylase (EC50 = 70.8 mu g/mL), at a much more significant level than the drug acarbose (EC50 = 3500 mu g/mL; alpha glucosidase; EC50 = 12 mu g/mL.; alpha amylase). In addition, the geraniin-enriched ethanolic extracts were able to inhibit the key enzyme in the polyol pathway, aldol reductase (EC50 = 0.04 mu g/mL) and prevent the formation of advanced glycation end-products (AGE) by 43%. These findings indicate that the geraniin-standardized N. lappaceum rind may be a potential source of an anti-hyperglycemic agent. (C) 2011 Elsevier Ltd. All rights reserved.