Anti-parasitic effects if nerolidol, gingerol and allicin on the morphology of trypanosoma evansi in mice

Abstract

Cell morphological changes are normally considered as the indirect evidence of the effect of test materials on targeted cells. fn this study, the anti-parasitic activities of nerolidol (C1]Hz60), gingerol (C'5H2504) and allicin (C3H5SS(O)C3H5), respectively extracted from cardamon (Eiettaria cardamomum), ginger (Zingiber ojjicinale) and garlic (Allium sativum), were compared with the effect of berenil (standard anti-trypanosomal drug) on the morphological changes of a protozoan parasite Trypanosoma evansi in mice. Group of male feR strain mice were subjected to infections with the parasite (5.0 x io' t: evansi per mouse) or without infection or treated with nerolidol (0.1 ml 8.8 ug/ml per mouse), gingerol (0.1 ml 20 mglml per mouse) and allicin (0.1 ml of 15 ug/ml per mouse) or with berenil (0.01 ml per mouse) or distilled water (0.1 ml per mouse) as a control. Blood samples were collected and prepared both for the observation under light and electron microscopes. All mice in the negative group (untreated-infected) succumbed to infection with drastic increase of parasitaemia while all the infected and berenil-treated mice survived from the infections. Parasites had adverse morphological changes due to berenil treatment and after 2nd - 3rd hours post-treatment, the parasites became stiffened and tapered at both ends and distorted with fractured flagella and lost of undulating membranes before totally disintegrated and cleared from the blood at 61h - ill hours post- treatment. The morphological changes in the nerolidol-treated group only appeared after 23'cI days post-treatment and continued gradually until 26111 days post-treatment where the parasites became stiff, lost their undulating membrane but the free flagella remained intact. Total destruction was only observed at 28111 days post-treatment but it was too late 10 save the mice. However, there were no convincing morphological changes of the parasite in the gingerol-treated group as the mice in this group had the shortest survival time and died on zs" days post-treatment. Parasites in the allicin-treated group on the other hand also showed marked morphological changes, although not as profound as changes due to berenil. Changes started to occur only after 18111 days post treatment, and gradually intensified up until 90lh days post treatment although the treatments were terminated on day 301h. The parasite also became crescent in shape and lost their undulating membranes and cytoplasm where total destruction was only observed in the 95111 days post-infection. These observations seem to indicate that, to a certain extent, although nerolidol and allicin showed some anti-trypanosomatidal activity against T evansi in mice, but further studies are required to elucidate the mechanism(s) of action of these compounds.