EVALUATION OF THE IN VIVO ANTIPLASMODIAL POTENCY OF CRUDE TOAD (ANURA: BUFONIDAE) VENOM IN PLASMODIUM BERGHEI – INFECTED MICE

Abstract

Malaria which is still the most devastating tropical disease causing global health challenge requires an aggressive search for an alternative and non-resistant antimalarial lead compound informed this current study that elucidate the antimalarial potency of the crude venom of toad against Plasmodium berghei infected mice. The toad venom was extracted by manual compression of the large postorbital paratoid gland of the toad. The bioactive compounds of the venom were determined using gas chromatograph mass spectrometry procedure. The acute toxicity of the venom was established using modified Lorke procedure. Thirty mice were randomly shared into six equal groups and five groups were intraperitoneally infected with chloroquine sensitive Plasmodium berghei NK 65 strain. Group one, two and three were administered after establishing infection with 10, 20 and 30 mg/kg/b.wt of the toad venom, group four were not parasitized and not treated, group five were parasitized and not treated and group six were parasitized and treated with 5mg/kg chloroquine (standard control). The LD50 of the toad venom was computed as the geometric mean of the lowest dose that produce mortality and highest dose with no lethal effect. The result of the LD50 of the toad venom was 141.42 mg/kg/b.wt. Zoochemical screen revealed the presence of flavonoids, Tannins, Saponins and Carbohydrates, while GC-MS showed 25 bioactive compounds which includes; Oleic acid, Dencanoic acid and Octadencanoid acid in the toad venom. The group treated with 20 mg/kg b.wt. of the crude toad venom of an independent dose revealed a decrease of the parasitemia level (18.05± 1.01 ml/kg PBS) when compared to the standard group (21.25±0.07 ml/kg PBS). The extract at dose 20 mg/kg b.wt. was significantly (p<0.03) ameliorated the parasite induced decrease in the body weight (31.01 g to 37.05 g) and PCV (44.05 % to 46.28 %) of the mice. The effect of the venom on the hematological parameters was also assessed employing standard procedure. The red blood cells count (10.24±0.62 × 1012/L), hemoglobin (13.08±0.95 g/dL) and total white blood cell (11.05±0.83 × 1012/L) revealed a significant (p< 0.05) decrease in the negative group when compared to the control group (19.01±0.54 × 1012/L), (26.31±0.75 g/dL) and (16.43±0.08 × 1012/L) and the groups treated with 20mg/kgb.wt. of the crude extract (18.12±0.17 × 1012/L), (20.108±0.63 g/dL) and (20.03±0.09 × 1012/L). The survival time of the mice treated with 20 mg/kg b.wt. of the crude toad venom extract showed the highest survival time of over 40 days. Additionally the toad venom ameliorates the parasite induced liver and kidney damage when compared with the negative group. Findings from current study, thus established the antimalarial potency of toad venom and therefore it is suggested to be introduced in the development of antimalarial drugs.