Green drugs in the fight against Anisakis simplex-larvicidal activity and acetylcholinesterase inhibition of Origanum compactum essential oil

Abstract

Anisakiasis is a fish-borne parasitic disease caused by the consumption of raw or undercooked fish, as well as cephalopods,contaminated by third instar larvae (L3) of species belonging to the genusAnisakis(Anisakidae).Origanum compactumis asmall herbaceous aromatic plant endemic to Spain and Morocco. In Morocco, the plant is used under infusion to treat heartdiseases and intestinal pains or as preservative for foodstuffs. This is the first time that theO. compactumessential oil is testedagainst the parasitic nematodeAnisakis simplex.The phytochemical analysis by GC-MS revealed carvacrol (50.3%) and thymol(14.8%) as the major oil constituents. The essential oil and its major constituents carvacrol and thymol were tested againstA. simplexL3 larvae isolated from blue whiting fish (Micromesistius poutassou).A. simplexmortality (%) after 24 and 48 h oftreatment at 1μl/ml was 100%, with a low LD50compared with other essential oils and extracts, and the penetration in the agarassay was also reduced, if compared with control wells. The oil, as well as its major constituents, demonstrated a dose-dependentlarvicidal activity. Inhibition of the enzyme acetylcholinesterase through a colorimetric assay in 96-well plates was used toelucidate the pharmacological mechanism as this enzyme plays a key role in nematodes neuromuscular function. Interestingly,O. compactumessential oil, carvacrol and thymol inhibited the enzyme, confirming that this could be one of the mechanismsinvolved in the anthelmintic activity. To the best of our knowledge, this is the first time thatO. compactumessential oil is reportedas a larvicidal agent againstA. simplexL3 larvae