Antinematodal Efficacy of Citrullus colocynthis Fruit Extract to Control Benzimidazole-Resistant Gastrointestinal Nematodes: Haemonchus contortus as a Paradigm
SUMMARY
The current study was intended to assess crude aqueous methanol extract (CAME) of the native plant, Citrullus colocynthis Schrad (bitter apple) fruit to hamper the rampancy of antinematodal-resistant gastrointestinal roundworms utilizing the highly pathogenic abomasal nematode of sheep; Haemonchus contortus as a key model. The field trials were conducted on private sheep ranches in Khabat district-Erbil governorate, whilst the laboratory techniques were carried out at the Department of Biology, College of Science, Salahaddin University from March 2018 to January 2019.
The cardinal objectives of this research work were diagnosing the emergence and rampancy of resistance among the alimentary tract trichostrongylid roundworms in sheep against the renowned synthetic dewormers which are employed recurrently in the area to fight parasitic gastrointestinal nematodes. The other major purpose was to assess the activity of the bitter apple fruit CAME as an efficient substitute to orthodox or allopathic synthetic drugs in controlling resistant H. contortus individuals.
For detection of the antinematodal resistance and efficacy evaluation of the C. colocynthis fruit CAME against the antinematodal-resistant helminths, reliable parasitological assays such as faecal egg count reduction test (FECRT) and egg hatch assay (EHA) were used. The computer RESO program was utilized to determine antinematodal resistance precisely.
To meet the required steps of the present study, the experimental animals (lambs having 3-6 months age) infested naturally with various roundworms, were divided into six groups (n=15) followed by the detection of haemonchosis proportion (more than 90%) among other nematode infections. One group was allocated for detection of resistance against albendazole (benzimidazole drug family) and one group for control. According to the RESO Computer Program, the calculated FECR% was 70.77%, whilst the lower confidence interval was 49.7%. The EC50 value for albendazole, calculated via probit analysis, was 2.046 μg/ml after conducting egg hatch assay (EHA). The aforementioned data were reckoned as salient indications for emergence of resistance among the parasite populations.
Antinematodal efficacy of C. colocynthis fruit CAME was evaluated in vivo through drenching four doses (50, 100, 150, and 200 mg/kg B.W) using FECRT as an evidence for their effectiveness. There was a dose- dependent antinematodal activity of C. colocynthis fruit CAME. The ovicidal potency of the plant extract was also trialed in vitro via conducting EHA. The estimated EC50 value was 0.3422 μg/ml after performing EHA, whilst the calculated mean FECR% for the highest dose of CAME was 95.57%, which is deemed effectual. Furthermore, oral administration of C. colocynthis fruit CAME at 200 mg/kg B.W did not reveal untoward consequences in animals; accordingly, could be employed as an alternative therapy in combating antinematodal-resistant populations of gastrointestinal nematodes.