Efficacy of Origanum syriacum Essential Oil against the Mosquito Vector Culex quinquefasciatus and the Gastrointestinal Parasite Anisakis simplex, with Insights on Acetylcholinesterase Inhibition

Abstract

Developing effective and eco-friendly antiparasitic drugs and insecticides is an issue of high importance nowadays. In this study, we evaluated the anthelminthic and insecticidal potential of the leaf essential oil obtained from Origanum syriacum against the L3 larvae of the parasitic nematode Anisakis simplex and larvae and adults of the mosquito Culex quinquefasciatus. Tests on A. simplex were performed by standard larvicidal and penetration assays, while mosquito toxicity was assessed relying on larvicidal, tarsal contact, and fumigation tests. To shed light on the possible mode of action, we analyzed the oil impact as acetylcholinesterase (AChE) inhibitor. This oil was particularly active on L3 larvae of A. simplex, showing a LC50 of 0.087 and 0.067 mg mL−1 after 24 and 48 h treatment, respectively. O. syriacum essential oil was highly effective on both larvae and adults of C. quinquefasciatus, showing LC50 values of 32.4 mg L−1 and 28.1 µg cm−2, respectively. Its main constituent, carvacrol, achieved larvicidal LC50(90) of 29.5 and 39.2 mg L−1, while contact toxicity assays on adults had an LC50(90) of 25.5 and 35.8 µg cm−2, respectively. In fumigation assays, the LC50 was 12.1 µL L−1 after 1 h and decreased to 1.3 µL L−1 in 24 h of exposure. Similarly, the fumigation LC50 of carvacrol was 8.2 µL L−1 after 1 h of exposure, strongly decreasing to 0.8 µL L−1 after 24 h of exposure. These results support the folk usage of Lebanese oregano as an antiparasitic agent, providing new insights about its utilization for developing new effective and eco-friendly nematocidal and insecticidal products.

Origanum syriacum Phytochemistry and Pharmacological Properties: A Comprehensive Review

“…The methanolic extract and essential oil of Origanum syriacum were shown to have a strong anti-parasitic activity against Acanthamoeba castellanii cysts and trophozoites [52]. The essential oil was also active against gastrointestinal Anisakis simplex larvae [53] in vitro, presenting O. syriacum as a potential therapeutic antiparasitic agent.…”

An updated and comprehensive review of the antiviral potential of essential oils and their chemical constituents with special focus on their mechanism of action against various influenza and coronaviruses

“…In a similar study, essential oil derived from Origanum compactum was reported to induce 100% mortality in Anisakis simplex L 3 larvae isolated from Micromesistius poutassou [ 98 ]. In an another study Origanum syriacum essential oil was reported to induce protective effects against the gastrointestinal parasite Anisakis simplex and mosquito vector Culex quinquefasciatus [ 99 ]. Gómez-Rincón and coworkers have shown that essential oils of Melaleuca alternifolia (tea tree) inhibit the growth of L 3 larvae of Anisakis simplex [ 100 ].…”

Anti-Nematodal Essential Oils with Activity against Anisakis

“…Eight publications reported on assays using EOs against Anisakis L3 larvae, from 2012 to 2019 [12][13][14][15][16][17][18][19]. These works were published in journals mainly covering areas of parasitology (38%), tropical medicine (38%), and public environmental and occupational health (25%).…”