Bacground: We aimed to investigate possible effects of aqueous curcuma longa extract on adenosine deaminase (ADA) activity in cancerous and noncancerous human gastric and colon tissues in order to obtain information about anti cancer mechanism of curcuma longa. Methods: Cancerous and noncancerous human gastric and colon tissues were used in the studies. The extracts were prepared in distilled water. Before and after treatment with the extracts, ADA activities in the tissue homogenates were

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... red. Results: ADA activity was found to be higher in gastric tissue compared with colon tissue, but no differences were found between ADA activities of cancerous and noncancerous tissues. In the plant extract studies, it was found that curcuma extract significantly inhibited ADA activity both in cancerous and noncancerous gastric and colon tissues. Conclusion: Our results suggest that aqueous extract from curcuma longa inhibits ADA activities in both gastric and colon tissues significantly. It is suggested that in addition to other proposed mechanisms, accumulated adenosine due to the inhibition of ADA enzyme might also play part in the anticancer properties of curcuma longa.