Effect of cinnamon, clove and some of their constituents on the Na+-K+-ATPase activity and alanine absorption in the rat jejunum

The effect of a water extract of some spices on the in vitro activity of th e rat jejunal Na+-K+-ATPase was investigated. Extracts of nutmeg, cinnamon, clove, cumin, coriander, turmeric and caraway all inhibited the ATPase, wh ile aniseed and white pepper exerted no significant effects. The extracts o f clove and cinnamon had the most potent inhibitory effect on the intestina l ATPase as compared to extracts of other spices. They also inhibited the i n vitro Na+-K+-ATPase activity in a crude kidney homogenate and the activit y of an isolated dog kidney Na+-K+-ATPase. The alcoholic extract of cinnamo n, compared to the aqueous extract, had a stronger inhibitory action on the jejunal enzyme and a lower IC50 value, which was not significantly differe nt from the one observed with cinnamaldehyde, the major volatile oil presen t cinnamon, suggesting that in alcoholic extracts cinnamaldehyde is the maj or inhibitory component. The IC50 values of eugenol, aqueous clove extract and ethanolic clove extract all fell within the same range and were not sig nificantly different from each other, suggesting that eugenol is the major inhibitory component in both alcoholic and aqueous extracts. Based on the I C50 values, the order of sensitivity of the enzyme to the spices extracts i s as follows: isolated dog kidney ATPase > rat kidney ATPase > rat intestin e ATPase. The aqueous extracts of clove and cinnamon also significantly low ered the absorption of alanine from the rat intestine. It was concluded tha t the active principle(s) in clove and cinnamon can permeate the membrane o f the enterocytes and inhibit the Na+-K+-ATPase that provides the driving f orce for many transport processes. (C) 2000 Elsevier Science Ltd. All right s reserved.