The effects of Nerolidol, Allicin and Berenil on the morphology of Trypanosoma evansi in mice: a comparative study using light and electron microscopic approaches

In this study, the effects of nerolidol and allicin respectively extracted from cardamom (Elettaria cardamomum) 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, determined by light and electron microscopes. Male ICR strain mice were subjected to infection: with the parasite or without the infection, treated with nerolidol and allicin, or with berenil or distilled water as control. Blood samples were employed for observation under light and electron microscopes. Parasites had adverse morphological changes due to berenil treatment. Following post-treatments, the parasites stiffened and tapered at both ends, were distorted with fractured flagella and undulating membranes were lost before totally disintegrated and cleared from the blood at 6th – 7th hours post-treatments. The morphological changes in nerolidol-treated group only appeared after 23rd days post-treatment and continued gradually until 26th days post-treatment where the parasite became stiff, lost their undulating membrane but the free flagella remained intact. Total destruction was only observed at 28th days post-treatment. Parasites in the allicin-treated group however, showed marked morphological changes although not as profound as changes due to berenil. Changes occurred only after 18th days post-treatment, and gradually intensified up until 90 days post treatment. However, treatment were terminated on the 30th day. The parasite were also became crescent in shape, lost their undulating membrane and total destruction was only observed in the 95th days post-infection. All mice in the negative group (untreated-infected) succumbed to infection with drastic increased of parasitemia where all the infected and berenil-treated mice survived the infections. Although nerolidol and allicin showed some quite promising and convincing trypanosomatidal activity against the morphology of T. evansi in mice, further study are required to elucidate the mechanism(s) of action of these compounds