Effect of pomegranate juice, punicalagin and ellagic acid on fructose mediated glycation of albumin

Non-enzymatic glycation of proteins results in the formation of advanced glycation endproducts (AGE), leading to the crosslinking of proteins. The process is believed to be responsible for the mobidity and mortality associated with the diabetic state. Currently, there is no FDA approved therapeutic agent to inhibit protein glycation, however numerous natural products have been shown to inhibit this process. In this study, we examined the effect of pomegranate juice and its constituents (punicalagin and ellagic acid) on protein glycation and compared them to other commercially available fruit juices. Bovine serum albumin (10mg/ml) was incubated with 250 mM fructose for 72 hours and the extent of glycation determined fluorometrically at the wavelength pair of 370/440nm.

Pomegranate juice, at 10µL/ml, inhibited protein glycation by 98%; this inhibition was much greater than that observed with other juices. The greater inhibition by pomegranate juice was also observed when the juices were added at the same phenolic concentration and the same FRAP (antioxidant capacity) values. Both punicalagin and ellagic acid inhibited protein glycation by approximately

90% when present at a concentration of 5µg/ml. These results demonstrate that pomegranate juice and its constituents are robust inhibitors of fructose mediated protein glycation.