INTESTINAL MYORELAXANT AND ANTISPASMODIC EFFECTS OF THE ESSENTIAL OILOF CROTON NEPETAEFOLIUS AND ITS CONSTITUENTS CINEOLE, METHYL-EUGENOL AND TERPINEOL

The effects of the essential oil of Croton nepetaefolius (EOCN), a med icinal plant from the north-east of Brazil, and its constituents cineo le, methyl-eugenol and terpineol were studied on intestinal motility i n vivo and on in vitro mechanical activity of intestinal smooth muscle . In mice, EOCN (10-100 mg/kg body weight, intragastrically) increased the intestinal transit of charcoal marker delivered to the stomach. T his was also observed in animals pretreated with castor oil. In segmen ts of guinea-pig ileum and cardial, pyloral and ileo-caecal sphincters , EOCN preferentially decreased basal tonus compared with the amplitud e of spontaneous contractions with EC50 values in the range 0.9 - 16 a nd 8 - 150 mu g/mL respectively. In ileum, EOCN, cineole, methyl-eugen ol and terpineol decreased tonus with EC50 values of 16, 322, 9 and 71 mu g/mL, respectively, and blocked 60 mM [K+]-induced contraction wit h IC50 values of 18, 419, 12 and 95 mu g/mL. The data show that EOCN p ossesses myorelaxant and antispasmodic properties in vitro, consistent with the use of Croton nepetaefolius in folk medicine as an intestina l antispasmodic, EOCN-induced stimulation of intestinal transit in viv o appears consistent with its in vitro effects, since a preferential d ecrease in tonus may reduce luminal resistance to bulk Bow of intestin al contents. (C) 1998 John Wiley & Sons, Ltd.