EFFECTS OF THE ESSENTIAL OIL OF CROTON ZEHNTNERI, AND ITS CONSTITUENTESTRAGOLE ON INTESTINAL SMOOTH-MUSCLE

The effects on isolated guinea-pig ileum of the essential oil of Croto n zehntneri (CZEO) and of its main constituent estragole (57% of CZEO by weight) were studied. CZEO and estragole (0.1-100 mu g/mL) decrease d the tonus in 56% and 61.5%, respectively, of the muscles, At concent rations above 10 mu g/mL, they induced spontaneous rhythmic movements of small amplitude (less than 11% of the potassium contraction peak to peak), At concentrations from 1 to 100 mu g/mL and with similar poten cies, these agents blocked the contractions induced by acetylcholine, histamine and 50 mM K+ and caused relaxation of already established po tassium contractures, Tested separately, CZEO, estragole and anethole (28% of CZEO by weight) blocked the contraction induced by Ca++ in the presence of 50 mM K+, but CZEO was more potent than estragole or anet hole in blocking the Ca++ induced contractions than those induced by K +, With large increases in the agonist concentration, the action of th e oils on the contractions induced by Ca++ was reversible; however, th eir effect on contractions induced by histamine or ACh was not, The da ta show that the essential oil of Croton zehntneri has an effect on in testinal smooth muscle that is predominantly antispasmodic, and attrib utable in part to the effect of estragole, a major constituent. (C) 19 97 by John Wiley & Sons, Ltd.