Antiparasitic assessment of nerolidol against the growth and survival of Haemoflagellate protozoa, Trypanosoma Evansi in mice

Cell morphological changes are frequently used as indirect indicators of the effect of studied materials on targeted cells. In this study, antiparasitic effects of active compound, namely nerolidol or 3,7,11-trimethyl-1,6,10-dodecatrien-3-ol (C12H26O), in which extracted from cardamom seeds (Eiettaria cardamomum) was in-vivo compared with commercial anti-trypanosomal drug, Berenil, on the growth and survival of the haemoflagellate protozoa Trypanosoma evansi in mice. Groups of male ICR strain mice aged 6 – 8 weeks with 20 – 25g body weight (bw) were administered with the parasite (5.0 × 103 T. evansi per mouse) and orally given pre-, concurrent- or post-infection treatments with nerolidol (0.1 ml 8.8 µg/ml nerolidol per mouse). Stained blood slides were prepared and examined under the light (Zeiss Primo Starr attached with Canon LA-DC58F digital camera) and electron (Phillips XL30) microscopes for the evaluation of specified parameters. The results showed that the mice in negative control group (untreated but infected mice) succumbed to the T. evansi infections with rapid increase of parasitaemia and survived in a short period of time. Mice in the pre-infection treatments with nerolidol not only demonstrated longer pre-patent periods but also exhibited the longest survival times (61.58 ± 0.2 days) as compared to those of the mice in the groups receiving concurrently or post-infection treatments. There was also a positive relationship (p ≤ 0.05, n = 6) between the mice survival time and the ability to inhibit the parasites growth in this group. The morphological changes of T. evansi cells were observed where the undulating membrane was destroyed and the cell became crescent-shaped. Finally, both of the posterior and anterior ends were tapered before the flagellum destroyed and disintegrated in which lead to death of the cells. The cell morphological changes in berenil-treated mice was occurred much earlier (2nd - 3rd hour post-treatment) and totally disappeared from the blood circulation within 5 - 6 hour later. The destruction of these parasite cells allowed the mice survived more than 300 days of observation. The results from this study suggest that nerolidol has a stronger anti-parasitic activity against T. evansi by causing the destruction of the cells. Further studies are required to elucidate the mechanism of action of nerolidol on these cell structures