Antispasmodic effects of essential oil of Pterodon polygalaeflorus and its main constituent β-caryophyllene on rat isolated ileum

This study investigates the effects of essential oil of Pterodon polygalaeflorus (EOPP) and β-caryophyllene (β-CAR). EOPP and β-CAR relaxed the basal tone of ileum smooth muscle in a concentration-dependent manner (IC₅₀s = 394.35 ± 62.12 and 68.65 ± 9.51 μg/mL respectively), an effect that was unaltered by hexamethonium, L-nitroarginine methyl ester or indomethacin. Both EOPP and β-CAR evoked a concentration-dependent relaxation of ileum pre-contracted with KCl with an IC₅₀ value of 107.78 ± 10.47 and 17.35 ± 0.75 μg/mL, respectively. EOPP and β-CAR inhibited the contractions induced by acetylcholine (ACh) and by KCl. In ileal preparations, the CaCl₂-induced contractions were reduced by EOPP (300 μg/mL) and β-CAR (100 μg/mL). Furthermore, CaCl₂-induced contractions were also reduced by EOPP (300 μg/mL) and β-CAR (100 μg/mL) in ileal preparations pretreated with ACh under Ca²⁺-free condition and in the presence of verapamil. EOPP (100 and 300 μg/mL) and β-CAR (30 and 100 μg/mL) reduced the ACh-induced contractions of isolated rat ileum under Ca²⁺-free conditions. In the presence of high KCl and Ca²⁺-free conditions, EOPP (300 μg/mL) and β-CAR (100 μg/mL) reduced the contractions induced by barium. A similar effect was also observed with verapamil. It is concluded that (i) β-CAR is an important constituent involved in the myorelaxant and antispasmodic effects induced by EOPP; (ii) the inhibitory effect on intestinal contractility is myogenic and seems mainly mediated through an intracellular mechanism. However, the ability of EOPP and β-CAR to decrease Ca²⁺ influx through cytoplasmic membrane could not be discounted.