title: Comparative efficacy and toxic effects of carvacryl acetate and carvacrol on sheep gastrointestinal nematodes and mice.
abstract: Carvacrol is a compound isolated from some essential oils. It has been reported to possess anthelmintic activity. Acetylation of this monoterpene has been proposed as a potential way to reduce the toxicity and enhance the pharmacological effects of carvacrol. This study aimed to evaluate the effect of carvacryl acetate (CA) using in vitro and in vivo assays with gastrointestinal nematodes of small ruminants. The egg hatching test (EHT), larval development test (LDT) and adult worm motility (AWM) assessment were conducted to evaluate the effect of the acetylated product and pure carvacrol on Haemonchus contortus eggs, larvae and adults. The structural changes induced in adult H. contortus were assessed using scanning electron microscopy (SEM). CA and carvacrol acute toxicity was evaluated in mice. Finally, the efficacy of 250 mg/kg CA and 2.5mg/kg monepantel (positive control) were evaluated in 30 sheep naturally infected with gastrointestinal nematodes by the fecal egg count reduction test (FECRT). In vitro tests were analyzed by analysis of variance (ANOVA) followed by comparison with Tukey's test. The efficacy was calculated by the Boot Street program using the arithmetic average. The number of eggs in feces (epg) of the groups were transformed to log (x+1) and subjected to ANOVA to compare differences among the groups by Tukey's test. The level of significance was P<0.05. CA and carvacrol inhibited larval hatching by 89.3 and 97.7% at doses of 8.0 and 1.0mg/ml, respectively. At the concentration of 2mg/ml, CA and carvacrol inhibited 100% of larval development. At a concentration of 200 μg/ml, CA and carvacrol inhibited the motility of adult worms by 100% and 58.3% at 24h post-exposure, respectively. CA caused cuticle and vulvar flap wrinkling and bubbles to emerge from the tegument. Carvacrol caused more discreet effects on the cuticle and vulvar flap. The LD10 and LD50 of CA were 566.7 mg/kg and 1544.5mg/kg, respectively. The LD10 and LD50 of carvacrol were 546.8 mg/kg and 919 mg/kg, respectively. CA and monepantel reduced the epg of sheep by 65.9 and 96.4%, respectively, at 16 days post-treatment. CA showed in vitro and in vivo anthelmintic activity and was less toxic than carvacrol.
authors.affiliation: Programa de Pós-Graduação em Ciências Veterinárias, Universidade Estadual do Ceará, Brazil.
authors.forename: Weibson P P
authors.initials: WP
authors.lastname: Andre
authors.affiliation: Programa de Pós-Graduação em Ciências Veterinárias, Universidade Estadual do Ceará, Brazil.
authors.forename: Wesley L C
authors.initials: WL
authors.lastname: Ribeiro
authors.affiliation: Programa de Pós-Graduação em Ciências Veterinárias, Universidade Estadual do Ceará, Brazil.
authors.forename: Géssica S
authors.initials: GS
authors.lastname: Cavalcante
authors.affiliation: Programa de Pós-Graduação em Ciências Veterinárias, Universidade Estadual do Ceará, Brazil.
authors.forename: Jessica M L
authors.initials: JM
authors.lastname: dos Santos
authors.affiliation: Programa de Pós-Graduação em Ciências Veterinárias, Universidade Estadual do Ceará, Brazil.
authors.forename: Iara T F
authors.initials: IT
authors.lastname: Macedo
authors.affiliation: Departamento de Química Analítica e Físico-Química, Universidade Federal do Ceará, Brazil.
authors.forename: Haroldo C B
authors.initials: HC
authors.lastname: de Paula
authors.affiliation: Programa de Pós-Graduação em Ciência Farmacêutica, Universidade Federal do Piauí, Brazil.
authors.forename: Rivelilson M
authors.initials: RM
authors.lastname: de Freitas
authors.affiliation: Programa de Pós-Graduação em Ciências Veterinárias, Universidade Estadual do Ceará, Brazil.
authors.forename: Selene M
authors.initials: SM
authors.lastname: de Morais
authors.affiliation: Centro Estratégico de Tecnologia do Nordeste, Brazil.
authors.forename: Janaina V
authors.initials: JV
authors.lastname: de Melo
authors.affiliation: Programa de Pós-Graduação em Ciências Veterinárias, Universidade Estadual do Ceará, Brazil. Electronic address: bevilaqua.uece@gmail.com.
authors.forename: Claudia M L
authors.initials: CM
authors.lastname: Bevilaqua
mesh_terms: D000818:Animals; D000871:Anthelmintics / Q000494:pharmacology / Q000627:therapeutic use / Q000633:toxicity; D001522:Behavior, Animal / Q000187:drug effects*; D000081007:Cymenes; D005243:Feces / Q000469:parasitology; D005260:Female; D007814:Larva / Q000187:drug effects; D007928:Lethal Dose 50; D008297:Male; D051379:Mice; D008855:Microscopy, Electron, Scanning; D039821:Monoterpenes / Q000494:pharmacology* / Q000627:therapeutic use / Q000633:toxicity*; D009043:Motor Activity / Q000187:drug effects; D009348:Nematoda / Q000187:drug effects* / Q000648:ultrastructure; D009349:Nematode Infections / Q000188:drug therapy / Q000662:veterinary; D010063:Ovum / Q000187:drug effects; D010270:Parasite Egg Count; D011897:Random Allocation; D012756:Sheep; D012757:Sheep Diseases / Q000188:drug therapy
chemical_list: D000871:Anthelmintics; D000081007:Cymenes; D039821:Monoterpenes; C586464:carvacryl acetate; C073316:carvacrol
keywords: Acetylation; Carvacrol; Haemonchus contortus; Sheep