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 the rat jejunal Na+-K+-ATPase was investigated. Extracts of nutmeg, cinnamon, clove, cumin, coriander, turmeric and caraway all inhibited the ATPase, while aniseed and white pepper exerted no significant effects. The extracts of clove and cinnamon had the most potent inhibitory effect on the intestinal ATPase as compared to extracts of other spices. They also inhibited the in vitro Na+-K+-ATPase activity in a crude kidney homogenate and the activity of an isolated dog kidney Na+-K+-ATPase. The alcoholic extract of cinnamon, compared to the aqueous extract, had a stronger inhibitory action on the jejunal enzyme and a lower IC50 value, which was not significantly different from the one observed with cinnamaldehyde, the major volatile oil present cinnamon, suggesting that in alcoholic extracts cinnamaldehyde is the major inhibitory component. The IC50 values of eugenol, aqueous clove extract and ethanolic clove extract all fell within the same range and were not significantly different from each other, suggesting that eugenol is the major inhibitory component in both alcoholic and aqueous extracts. Based on the IC50 values, the order of sensitivity of the enzyme to the spices extracts is as follows: isolated dog kidney ATPase > rat kidney ATPase > rat intestine ATPase. The aqueous extracts of clove and cinnamon also significantly lowered the absorption of alanine from the rat intestine. It was concluded that the active principle(s) in clove and cinnamon can permeate the membrane of the enterocytes and inhibit the Na+-K+-ATPase that provides the driving force for many transport processes. (C) 2000 Elsevier Science Ltd. All rights reserved.