Anti-Nematodal Essential Oils with Activity against Anisakis

Anisakiasis is a human parasitic infection caused by the larvae of the Anisakis nematode through the consumption of raw or undercooked seafood, namely fish and cephalopods. To date, no effective drug has been uncovered and common anthelmintic treatments seem to have reduced activity against this parasite. Essential oils (EOs) are an unexplored source of natural products able to counteract Anisakis. The present work reviews the available literature on EOs tested in vitro against Anisakis nematodes and compiles the activity and composition of the most active EOs. Over a dozen plant species were used as sources of EOs, mainly from the Asteraceae, Lamiaceae, Apiaceae and Myrtaceae families. The lowest half maximal effective concentrations (EC50) were reported for Origanum syriacum and O. compactum EOs, both rich in carvacrol (83% and 50%, respectively). The EOs extracted from Tagetes minuta and Nepeta cataria were reported as the fastest acting, with half maximal effective times (ET50) under 4 h, and were rich in geraniol (55%) or β-ocimene (36%) and limonene (27%), respectively. Given their complex chemical composition, additive, synergistic and antagonistic interactions between EO compounds can be responsible for EO activity. A deeper analysis of the chemical structures that are active against Anisakis, and the nature of their interactions, can be unveiled with further studies on this parasitosis.