Essential oil of Sicilian Prangos ferulacea (L.) Lindl. and its major component, β-ocimen, affect contractility in rat small and large intestine

Ethnopharmacological relevance: Prangos ferulacea (L.) Lindl is an Apiaceae plant, widely used in traditional medicine. Recently, chemical composition and biological activities of its essential oil (Prangroil) have been reported, but there are no studies on possible effects on intestinal contractility. Aims of the study: We investigated the effects of essential oil Sicilian Prangoil on the contractility of rat small (duodenum) and large (colon) intestine and the related action mechanism. Materials and methods: Responses to Prangoil and to its major component β-ocimen in intestinal segments were assessed in vitro as changes in isometric tension. Results: Prangoil, induced in duodenum, depending upon doses, contraction and/or muscular relaxation. Instead, in colon Prangoil only reduced the phasic contractions and induced muscular relaxation. β-ocimen, in both segments, produced only reduction of the spontaneous contractions without affecting basal tone. Prangoil contractile effects were abolished by ω-conotoxin, neural N-type Ca2+ channels blocker, atropine, muscarinic receptor antagonist, neostigmine, acetylcholinesterase (AChE) inhibitor, suggesting that Prangoil-induced contraction would be the result of an increase in neuronal cholinergic activity. Prangoil and β-ocimen inhibitory effects were unaffected by ω-conotoxin, L-NAME, blocker of the NO synthase, ODQ, soluble guanylate cyclase inhibitor, excluding involvement of neurotransmitter release or NO synthesis in the inhibitory effects. Potassium channel blocker did not affect Prangoil or β-οcimen inhibitory responses. Prangoil or β-οcimen inhibited the Ca2+ and high-KCl solution -induced contractions and the Carbachol-induced contractions in calcium free solution. Conclusion: Prangoil affects the contractility of small and large intestine in rat, with regional differences, via potentiation of neural cholinergic activity, blockade of L-type voltage-gated calcium channel and reduction of Ca2+ release from the intracellular store. The Prangroil main components, β-ocimen, contributes to the inhibitory effects.