Effect of curcumin and quercetin on lysosomal enzyme activities in streptozotocin-induced diabetic rats

Background & aims: Diabetes causes impairment of various enzyme activities in the physiological system, including lysosomal enzymes. The effect of feeding curcumin, quercetin and aminoguanidine on lysosomal enzyme activities viz., N-acetyl-beta-D-glucosaminidase. beta-D-glucuronidase, beta-D-galactosidase and acid phosphatase were studied in different tissues of streptozotocin-induced diabetic rats. Method: Rats were divided into four control groups and four diabetic groups. Experimental groups were fed with diet supplemented with curcumin (0.5%) or quercetin (0.1%) or aminoguanidine (0.05%). Lysosomal enzyme activities were determined in various tissues. Results: The specific activity of N-acetyl-beta-D-glucosaminidase in liver of diabetic rats was decreased when compared to control rats and was ameliorated with curcumin and quercetin treatment by 67% and 78%, respectively. On the other hand, beta-D-glucuronidase activity was higher in the brain of diabetic rats (0.90 +/- 0.04 nmol/mg protein/min), when compared to control rats (0.45 +/- 0.02 nmol/mg protein/min) and was decreased in curcumin (0.75 +/- 0.05 nmol/mg protein/min) and quercetin (0.74 +/- 0.11 nmol/mg protein/min) treated rats. beta-D-galactosidase activity in spleen of curcumin and quercetin fed diabetic group rats was ameliorated by 68% and 58%, respectively, in comparison to diabetic rats. Acid phosphatase activity in diabetic rats decreased in testis when compared to control. Conclusion: Curcumin and quercetin feeding modulated lysosomal enzyme activities in different tissues during diabetes and the effect was comparable to well-known anti-glycative agent - aminoguanidine. (C) 2012 Elsevier Ltd and European Society for Clinical Nutrition and Metabolism. All rights reserved.