Diuretic Effect in Rats of Betulinic Acid, a Pentacyclic Triterpene from Citharexylum myrianthum

The diuretic effect of betulinic acid obtained from the hexane fraction of branches of Citharexylum myrianthum Cham., Verbenaceae, was evaluated in rats. Male Wistar rats were used for the experiments, and the urine volume was recorded for 8 h and further analyzed. Betulinic acid showed an increased diuretic and natriuretic action when orally given to rats (1 mg/kg) without changing the urinary elimination of K + and Cl − . The non-selective cholinergic receptor antagonist, atropine, and the non-selective inhibitor of the cyclooxygenase enzyme indomethacin completely avoided betulinic acid-stimulated diuresis. In addition, indomethacin and atropine could preclude betulinic acid - induced natriuresis. While no rise in the volume of urine was detected when betulinic acid was provided in combination with hydrochlorothiazide or amiloride, K + excretion was considerably enhanced in the hydrochlorothiazide plus betulinic acid and diminished in the amiloride plus betulinic acid association. This study reveals the diuretic effect of the pentacyclic triterpene betulinic acid, an action possibly related to the activation of cholinergic receptors and prostaglandins generation. Graphical Abstract