The lack of effectiveness of (−)-epicatechin against alloxan induced diabetes in Wistar rats

(−)-Epicatechin, a naturally occurring flavonoid, has been reported to protect pancreatic beta cells from alloxan-induced diabetes (1) and to stimulate beta cell regeneration when given after alloxan administration (2,3). However, in the present study, we have not been able to confirm these findings. Administration of (−)-epicatechin (100 mg/kg/day for 15 days) beginning three days after alloxan administration (140 mg/kg) had no significant effect on blood glucose levels when compared to alloxan control animals. Another study which failed to demonstrate an antidiabetic effect of (−)-epicatechin (4) has been criticized for not using fresh solutions of (−)-epicatechin because of its instability in aqueous solution (5). We have found, however, that (−)-epicatechin is stable for at least five days based on thin-layer chromatographic analysis and optical rotation measurements.