Action of Carvacrol on Parascaris sp. and Antagonistic Effect on Nicotinic Acetylcholine Receptors

Abstract

Parascaris sp. is the only ascarid parasitic nematode in equids and one of the most threatening infectious organisms in horses. Only a limited number of compounds are available for treatment of horse helminthiasis, and Parascaris sp. worms have developed resistance to the three major anthelmintic families. In order to overcome the appearance of resistance, there is an urgent need for new therapeutic strategies. The active ingredients of herbal essential oils are potentially effective antiparasitic drugs. Carvacrol is one of the principal chemicals of essential oil from Origanum, Thymus, Coridothymus, Thymbra, Satureja and Lippia herbs. However, the antiparasitic mode of action of carvacrol is poorly understood. Here, the objective of the work was to characterize the activity of carvacrol on Parascaris sp. nicotinic acetylcholine receptor (nAChR) function both in vivo with the use of worm neuromuscular flap preparations and in vitro with two-electrode voltage-clamp electrophysiology on nAChRs expressed in Xenopus oocytes. We developed a neuromuscular contraction assay for Parascaris body flaps and obtained acetylcholine concentration-dependent contraction responses. Strikingly, we observed that 300 µM carvacrol fully and irreversibly abolished Parascaris sp. muscle contractions elicited by acetylcholine. Similarly, carvacrol antagonized acetylcholine-induced currents from both the nicotine-sensitive AChR and the morantel-sensitive AChR subtypes. Thus, we show for the first time that body muscle flap preparation is a tractable approach to investigating the pharmacology of Parascaris sp. neuromuscular system. Our results suggest an intriguing mode of action for carvacrol, being a potent antagonist of muscle nAChRs of Parascaris sp. worms, which may account for its antiparasitic potency.

Pharmacological effects of monoterpene carveol on the neuromuscular system of nematodes and mammals

“…Briefly, defolliculated Xenopus laevis oocytes (Ecocyte Bioscience) were micro-injected with 36 nL of Asu-ACR-16 cRNA at 50 ng/μL using the Nanoject II microinjector (Drummond). Two micro-electrode voltage-clamp experiments were performed 3 days after micro-injections as previously described ( Trailović et al, 2021 ). Data were collected and analyzed using the pCLAMP 10.4 package (Molecular Devices).…”

“…In the previous research, we have shown that monoterpenoid carvacrol acts on the neuromuscular system of nematodes and exhibits an inhibitory effect on contractions caused by acetylcholine (ACh) ( Trailović et al, 2015 ). In our following study, carvacrol dominantly exhibited characteristics of a non-competitive antagonist of nicotinic acetylcholine receptor (nAChR) in Ascaris suum ( A. suum ), and enhances the inhibitory effect of monepantel ( Marjanović et al, 2021 ; Trailovic et al, 2021 ).…”

Preliminary screening of plant essential oils from an oceanic climate zone (NW Spain) for the control of equine cyathostomins

“…In addition, some in vivo studies have been carried out on sheep (Štrbac et al 2022). In horses, carvacrol has been studied as the main component derived from EOs of plants for the control of Parascaris (Trailovic et al 2021).…”

Anthelmintic and Hepatoprotective Activities of the Green-Synthesized Zinc Oxide Nanoparticles Against Parascaris equorum Infection in Rats

“…In severe cases, the infection with P. equorum is associated with unthriftiness, respiratory signs, or intestinal impaction. In some cases, ascarids can lead to an obstruction and rupture of the small intestine or the death of foals [ 1 , 2 ]. Infection can be diagnosed by detecting eggs in feces, but this is only possible after the worms are fully mature [ 3 ].…”