Efficacy of essential oils from plants cultivated in the Amazonian Biome against gastrointestinal nematodes in sheep

Abstract

The excessive use of anthelmintics to control nematodes has resulted in anthelminthic resistance. Essential oils (EOs) are a rich source of bioactive molecules that can be assessed for their ability to control resistant parasite populations. The aims of this study were to screen EOs from 10 plant species in vitro for anthelmintic activity against , evaluate the cytotoxicity of those EOs in a human immortalized keratinocyte cell line (HaCaT), and test the most promising EO candidate in vivo in Santa Inês sheep. The efficacy was investigated in vitro using an egg hatch test (EHT) and a larval development test (LDT). EO cytotoxicity was evaluated with the sulforhodamine-B assay. In the in vivo experiment, 28 Santa Inês sheep naturally infected were distributed into groups: G1- (EO), 200 mg kg; G2-menthol, 160 mg kg; G3-negative control; and G4-positive control (monepantel). EO, from (86.7% menthol), had the lowest LC and LC values in the EHT (0.10, 0.27 mg mL, respectively), good performance in the LDT (0.015, 0.072 mg mL, respectively), and the lowest cytotoxicity (190.9 µg mL) in HaCaT cells. In the in vivo test, a single dose of the EO (200 mg kg BW) had an efficacy of approximately 50% on days 1, 14, and 21; however, values were not significantly from day 0. Conversely, pure menthol at a dose of 160 mg kg BW showed no in vivo efficacy. This can be attributed to key factors related to bioavailability and pharmacology of terpenes in the host organism, as well as to the fact that menthol is mainly excreted as glucuronides in urine. Thus, further studies should be conducted with formulation systems that deliver bioactives directly to the abomasum, focusing on terpenes, whose excretion route is mainly via faeces.

The Use of Essential Oils Against Sheep Gastrointestinal Nematodes

“…showed anthelmintic potential against sheep GINs (mostly against H. contortus), but it differed depending on the oil used. The highest ovicidal activity, expressed as IC50 values, was recorded for Cymbopogon schoenanthus and Cymbopogon martinii (0.04 and 0.1 mg/mL, respectively, Katiki et al 2011), Thymus vulgaris (0.098 mg/mL, Štrbac et al 2021a), Ruta chalepensis (0.1 mg/mL, Akkari et al 2015), and Mentha arvensis (0.1 mg/mL, Chagas et al 2018). Different EOs of Lippia spp.…”

“…Some of them showed a high effect on the reduction of FEC, such as carvacrol-acetate and thymol-acetate with the efficacy of 65.9 % and 76.2 % on Day 14 a.t., respectively (doses of 250 mg/kG) (André et al 2016;. In a study of Chagas et al (2018), pure menthol, at the dose of 160 mg/Kg, did not express in vivo efficacy unlike the whole oil whose main ingredient is, i.e. Mentha arvensis that reduced FEC by approximately 50% on Days 1, 7 and 14 at a similar dose tested, 200 mg/Kg.…”

“…Different EOs of Lippia spp. showed great larvicidal activity with IC50 less than 0.01 mg/mL (Chagas et al 2018), followed by Thymus vulgaris with IC50 as 0.062 mg/mL (Ferreira et al 2016), Hesperozygis myrtoides with IC50 as 0.07 mg/mL (Castilho et al 2017), Piper aduncum with IC50 as 0.1 mg/mL (Gaínza et al 2016) and Mentha piperita with IC50 as 0.2 mg/mL (Katiki et al 2011). Cymbopogon schoenanthus exhibited a very high activity on the larval motility with IC50 as 0.009 mg/mL (Katiki et al 2012), whereby Ruta chalepensis induced 87.5% inhibition of motility of adults 8 h after exposure at the dose of 1 mg/mL (Akkari et al 2015).…”

“…In a study of Ribeiro et al (2014), the EO of Eucalyptus citriodora was classified as safe with an LD50 value of 2653.0 mg/Kg for mice. Some EO compounds such as menthol are of very low acute oral toxicity (LD50 > 2000 mg/Kg) (Chagas et al 2018). Oral administration of the EO of Origanum majorana at different doses of 1000-5000 mg/Kg displayed no signs of toxicity, nor caused fatal effects in any of the treated mice during an observation period of 24 hours (Abidi et al 2020).…”

Different Variations of Using Essential Oils in Several Animal Species: Treatment and Supplementation

“…A study conducted on Santa Ines sheep reports that the essential oil extracted from the field cache (Aphanes arvensis L.) has been proved effective in fighting the parasite Haemonchus contortus. In the in vivo test, a single dose of the oil (200 mg • kg -1 body weight) had an efficacy of about 50% on days 1, 14 and 21 [Chagas et al 2018]. In the studies carried out by Lima et al [2013], the bactericidal ability of rosemary oil against 18 S. pseudintermedius isolates recovered from dogs with bacterial skin infection has been checked.…”