Chebulinic acid is an ellagitannin found in the seeds of Euphoria longana, in the fruits of Terminalia chebula or in the leaves of Terminalia macroptera. The effects of chebulinic acid, which has been shown to elicit blood pressure lowering effect in rats, on aortic vascular contraction as well as cardiac contraction were studied in rats.Chebulinic acid had no effect on KCl-induced aortic contraction, but irreversibly inhibited the contractile responses to phenylephrine in an apparently non-competitive manner. Chebulinic acid also inhibited contractile responses of rat aorta to 5-hydroxytryptamine and angiotensin II.Chebulinic acid inhibited the binding of [3H]-prazosin to dog aortic microsomal membranes in a concentration-dependent manner with an IC50 value of 0.34 mmol/L. hypotensive effect of chebulinic acid is probably mediated via the decrease in cardiac output resulting from reduced left ventricular contraction.
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