The insulin-sensitising properties of the ellagitannin geraniin and its metabolites from Nephelium lappaceum rind in 3T3-L1 cells.

In this study, the insulin-like and insulin sensitising effects of the ellagitannins geraniin, corilagin, ellagic acid, gallic acid and Nephelium lappaceum rind extract in 3T3-L1 adipocytes was investigated. It was observed that non-toxic concentrations of geraniin and its metabolites (0.2-20 μM) and N. lappaceum extract (0.2-20 μg/mL) exhibited insulin-like properties in the absence of insulin and insulin-sensitising properties in the presence of insulin particularly with regards to glucose uptake in 3T3-L1 adipocytes. The compounds were further able to promote adipocyte differentiation and may be involved in the inhibition of lipolysis in 3T3-L1 adipocytes in the presence of insulin. However further study into the molecular mechanisms of action of these compounds need to be carried out to better understand the potential of these compounds/extracts to act as therapeutic agents for hyperglycaemia associated with diabetes mellitus and obesity.