Anti-trypanosomal activity of Carica papaya aqueous seed extracts in mice.

摘要

A study was conducted to evaluate the anti-parasitic effects of the aqueous seed extracts of papaya (Carica papaya) on the infections of parasitic Trypanosoma evansi in mice. Groups of male and 6 weeks old ICR mice (n=5) were infected with 5x103 parasites intraperitoneally (i.p) on day 0. The positive control group was treated with an anti-protozoal drug berenil (0.35 mg/100 g body weight, BW) while the negative control group left untreated. The experimental groups were either treated i.p with 250, 500 or 750 mg/kg BW fresh aqueous seed extracts of papaya prepared in dH₂O. The treatments were given 5 days pre-infection, concurrently with the infection on day 0 or 5 days post-infection and continued daily until the mice succumbed or survived. Giemsa-stained thin blood smears were prepared following the infection for monitoring daily parasitaemia and determining prepatent period. The results showed that there was no significant difference in the prepapent period (2-3 days) between the control and experimental groups (p>0.05). However the patterns of parasitaemias of the control and experimental groups were significantly different (p<0.05). Parasitaemia in negative control group increased drastically until all the mice succumbed within 5 days post-infection while parasitaemia in positive control group was shorted-lived for 3 days and all mice survived. On the other hand, reduction of parasitaemia was observed in all experimental groups which were associated with the regimes of the treatment. The pre-infection and concurrent treatments were more effective than post-infection treatment in reducing parasitaemias and lengthening the survival time of the treated mice. The treatment dose of 750 mg/kg BW was found to be the most effective dose. Results of this study indicated that the aqueous seed extracts of Carica papaya have anti-parasitic activity against T. evansi.