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-b-D-glucosaminidase, b-D-glucuronidase, b-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-b-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, b-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. b-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.