ANTITRYPANOSOMAL EFFECT OF CRUDE SCORPION VENOM EXTRACT IN TRYPANOSOMA EVANSI INFECTED SWISS ALBINO RATS

ABSTRACT

Despite the control measures against trypanosomiasis over the past few decades, the disease still contributes to the current economic losses and socio-political crises in the sub-Saharan Africa. The recent interest of chemotherapists in aggressive search for novel antitrypanosomal drug agents informed this current investigation to elucidate the acute toxicity and antitrypanosomal efficacy of crude scorpion venom in Trypanosoma evansi infected rats. Eighty (80) medium sized scorpions, brownish in colour with robust metasoma ending in telson were collected from their habitat in Minna metropolis. Venom was collected by electric stimulation of each scorpion telson. Acute toxicity of the venom was established through oral injection of the scorpion venom using graded concentrations (10, 20 and 30 mg/kg body weight) with saline extract of crude venom. The antitrypanosomal bioassay of the venom was performed against established infection in Trypanosoma evansi infected rats. Group 1 was set up as negative control of 0.2ml normal saline /kg/body weight, group 2 as 5mg chloroquine /kg/body weight and group 3 to 5 as 10, 20 and 30 mg/kg/body weight of the scorpion venom. Acute toxicity showed an LD50 extrapolated to be 44.72 mg/kg body weight. Antitrypanosomal bioassay results showed scorpion venom significantly (P˂0.05) reduced the level of parasitemia of the infected rats, with peak activity recorded on the last day of observation, a pattern distinctly different from the positive control and total parasite clearance was recorded on the 5th day in the group treated with 20 and 30 mg/kg body weight venom concentration having 0.00 and 0.00±0. Treatment of infected rats with scorpion venom extract significantly (P˂0.05) ameliorated loss in some body enzymes tested. The crude venom extract also promoted fall in Packed Cell Volume of T. evansi infected rats, promoted body weight loss for the infected untreated group   having 71.23±1 against the initial weight of 123.45±1 and elongated the survival time of T. evansi infected rats. Treatment of the infected rats with scorpion venom at 20 and 30 mg/kg body weight significantly restored the liver and spleen to body weight ratio to a level comparable with the normal rats. Findings from this study suggest that scorpion venom posses a potent and promising source of antitrypanosomal agent.