Effects of black grape extract on activities of DNA turn-over enzymes in cancerous and non cancerous human colon tissues.

Effects of extract of dried whole black grape including seed on adenosine deaminase (ADA), 5' nucleotidase (5'NT) and xanthine oxidase (XO) enzymes were investigated in cancerous and non-cancerous human colon tissues. Enzyme activities were measured in 20 colon tissues, 10 from cancerous region and 10 from non cancerous region with and without pre incubation with black grape extract. ADA and 5'NT activities were found increased and that of the XO decreased in the cancerous tissues relative to non cancerous ones. After incubation period with black grape extract for 12 h, ADA and 5'NT activities were found to be significantly lowered but that of XO unchanged in both cancerous and non cancerous tissues. Results suggest that ADA and 5'NT activities increase but XO activity decreases in cancerous human colon tissues, which may provide advantage to the cancerous tissues in obtaining new nucleotides for rapid DNA synthesis through accelerated salvage pathway activity. Black grape extract makes significant inhibition on the ADA and 5'NT activities of cancerous and non cancerous colon tissues, thereby eliminating this advantage of cancer cells, which might be the basis for the beneficial effect of black grape in some kinds of human cancers.