Comparison of the Effects of Green and Black Tea Extracts on Na+ /K+ -ATPase Activity in Intestine of Type 1 and Type 2 Diabetic Mice

Abstract

Scope: Na⁺ /K⁺ -ATPase is an important membrane-bound enzyme and high levels of Na⁺ /K⁺ -ATPase activity in intestine result in increased monosaccharide absorption and aggravated undesirable postprandial hyperglycemia in diabetic. The aim is to characterize the effects of green and black tea extracts on the intestinal Na⁺ /K⁺ -ATPase.

Methods and results: The STZ-induced type 1 diabetic mice model and high-fat diet combined with low-dose STZ-induced type 2 diabetic mice model are used in this study and the data indicate that both green and black tea extracts show significant hypoglycemic effect. The Na⁺ /K⁺ -ATPase activities in intestine associated with glucose absorption are increased in type 1 diabetic mice, while those are even normal in type 2 diabetic mice. Green and black tea extracts can attenuate type 1 diabetes-induced intestinal Na⁺ /K⁺ -ATPase disturbance to control postprandial hyperglycemia. Black tea is more effective than green tea in reducing of Na⁺ /K⁺ -ATPase activity and protein expression. Theaflavins are the major functional components of black tea and theaflavine-3,3'-digallate presents the strongest inhibitory effect exhibiting anticompetition with ATP and mixed inhibition with Na⁺ and K⁺ .

Conclusion: Tea, especially black tea, can be considered a potential therapeutic agent against type 1 diabetes-induced intestinal Na⁺ /K⁺ -ATPase disturbance to control postprandial hyperglycemia.

Keywords: black tea; diabetes mellitus; green tea; theaflavines.