ABSTRACT
Plant-based anti-helminthics have been reported for their safety and eco-friendly properties. They are used as alternatives for toxic chemical drugs. Allium sativum [garlic] has shown antihelminthic action in vitro and in vivo against many helminthes. The present study was designed to evaluate the in vitro antihelminthic activity of A. sativum in comparison with two commonly used antihelminthic drugs; albendazole and niclosamide against the cattle amphistome, Cotylophoron cotylophorum. Live adult C. cotylophorum worms were collected from the rumen and reticulum of slaughtered cattle. Twelve media [natural calf serum, RPMI 1640 in ten formulas and normal saline] were evaluated to choose the most favorable one for incubation of worms during the study. Different concentrations of albendazole, niclosamide and alcoholic extract of A. sativum were tested in vitro against C. cotylophorum. Treated worms were examined after 2, 4, 8, 12 and 24 hours and the mortality rate was calculated in all experiments. The effect of the sub-lethal concentrations of albendazole and A. sativum on the tegument of the worm was evaluated by scanning electron microscopy [SEM]. Albendazole was highly effective against adult C. cotylophorum, where it exhibited dose-dependent lethal activity at different concentrations. Niclosamide was less effective, with high mortality rates recorded at relatively higher concentrations than albendazole. SEM revealed remarkable changes in the tegument and muscles of adult C. cotylophorum treated with a sub-lethal concentration of albendazole [1.5 mg/L] for eight hours. The whole tegument was deformed and papillae were hardly seen as swollen bodies. Numerous blebs and crater-like structures covered the whole tegument. A. sativum alcoholic extract gave high mortality rate at a relatively low concentration. SEM of adult worms treated with a sub-lethal concentration of A. sativum alcoholic extract [1.0 mg/L] revealed moderate changes in the tegument and a more severe effect on the muscle integrity. The mouth appeared flaccid and slightly retracted and the tegument surrounding it appeared feebly damaged and corrugated. The papillae lost their uniform structure. The acetabulum appeared retracted and lost its specific shape. The present study revealed that A. sativum alcoholic extract has an antihelminthic effect against adult C. cotylophorum at low concentrations. Garlic-based antihelminthic product may be used against rumen cattle amphistomes as an alternative for the commonly used chemical drugs