Molluscicidal activity of monoterpenes and their effects on inhibition of acetylcholinesterase activity on Biomphalaria glabrata, an intermediate host of Schistosoma mansoni

• Published in: Acta tropica Vol. 223; p. 106089
• Main Authors: Ribeiro, Edilene Carvalho Gomes, Leite, José Antonio Costa, Luz, Tássio Rômulo Silva Araújo, Silveira, Daniella Patrícia Brandão, Bezerra, Samara Araújo, Frazão, Gleycka Cristine Carvalho Gomes, Pereira, Luciana Patrícia Lima Alves, Guimarães dos Santos, Everton Gomes, Ribeiro Filho, Paulo Roberto Campos Flexa, Soares, Alexandra Martins Santos, Santos, Ricardo Luvizotto, Coutinho, Denise Fernandes
• Format: Journal Article
• Language: English
• Published: Elsevier B.V 01-11-2021
• Subjects: AChE; Danio rerio; Molluscicide; Schistosomiasis; Schistosomiasis; AChE; Molluscicide; Danio rerio
• ISSN: 0001-706X; 1873-6254
• DOI: 10.1016/j.actatropica.2021.106089

•Camphor and 1,8-cineole did not induce the mortality of adult B. glabrata snails.•Thymol and α-pinene are toxic to B. glabrata in concentration recommended by WHO.•Thymol and α-pinene toxicity to snails is concentration dependent.•Thymol and α-pinene are inhibitors of acetylcholinesterase of B. glabrata snails.•Low toxicity of thymol and α-pinene to non-target organisms compared to niclosamide.
The molluscicidal action of essential oils have been attributed to the most prevalent terpene compounds. However, molluscicidal properties, mode of action, and toxicity to non-target organisms remain unclear. In this study, the molluscicidal potential of four monoterpenes (camphor, thymol, α-pinene, and 1,8-cineole) against the snail Biomphalaria glabrata, an intermediate host of Schistosoma mansoni, was analyzed. The molluscicide activity of each monoterpene was assessed by the standardized test of the World Health Organization (WHO) and the monoterpenes considered active against B. glabrata were analyzed as inhibitors of the enzymatic activity of acetylcholinesterase (AChE) extracted from snails. In addition, acute toxicity to non-target organisms was assessed against Danio rerio fish. The results show that camphor and 1,8-cineole monoterpenes did not induce snail mortality. Thymol and α-pinene were active against B. glabrata, inducing mortality in concentration-dependent patterns and showing a lethal effect in concentrations compatible with that recommended by the WHO (LC90 of 7.11 and LC90 10.34 μg ∙ mL−1, respectively). The toxic action of thymol and α-pinene on snails indicates that these monoterpenes may account for or largely contribute to the molluscicidal activity of essential oils that contain them as major compounds. Thymol and α-pinene inhibit the AChE of B. glabrata at concentrations higher than those used in the molluscicide test. These monoterpenes show low toxicity to non-target organisms compared to the commercial molluscicide niclosamide. Knowledge about monoterpene toxicity against B. glabrata contributes to its potential use in molluscicidal formulations and in alternatives to the control of snails that host intermediate S. mansoni, a crucial action in the prevention and transmission of schistosomiasis, a neglected tropical disease.