Evaluation of Microbial Purity and Acute and Sub-acute Toxicities of a Nigerian Commercial Polyherbal Formulation Used in the Treatment of Diabetes Mellitus

Abstract

Objective: This study evaluated acute and sub-acute toxicities in rodents and microbial purity of a polyherbal formulation, Bobwell® popular among the natives for the management of diabetes mellitus (DM). It was prepared with unspecified quantities of the following plant materials viz. Gongronema latifolium. Garcinia kola, Vernonia amgydalina, Sphenocentrum jollyanum and Kigelia africana leaves. Materials and Methods: Microbial purity was evaluated on some bacterial and fungal organisms using appropriate diagnostic media. Toxicity of the polyherbal preparation was evaluated in Swiss albino mice by administering to the animals graded oral doses of the lyophilized preparation in the ranges of 1.0 to 20.0 g/kg body weight (bwt) and observed for changes. Wistar rats were also fed with different doses of the lyophilized formulation for 30 days and the effects on the biochemical profiles and haematological parameters were evaluated. Results: The purity evaluation test revealed presence of some bacterial organisms with the load within officially acceptable limits except Escherichia coli having a load of 1.50x102 cfu/ml while no fungal organisms were observed. The median acute toxicity value (LD50) of the polyherbal medicine was determined to be 15.2 g/kg bwt. There was significant increase (P ≤0.05) in the body weight of the animals treated with the highest dose of the formulation compared to the control. The biochemical parameters showed marked decrease in the plasma glucose level compared to the control. Increase in creatinine level was observed only in the animals that received the highest dose of the formulation while aspartate aminotransferase (AST) decreased significantly. On the other hand, alanine aminotransferase (ALT) exhibited significant increased (P ≤0.05) at the highest dose. The photomicrograph of hepatic tissue showed focal necro-inflammation around the portal hepatics. There was marked increase in the haemoglobin level and in the red blood cell (RBC) count at the highest doses. There was also significant increase in white blood cells (WBC). Conclusion: The high LD50 value indicated that the polyherbal preparations could be safe for use but its safety was negated by high presence of E coli load. Although the formulation showed good hypoglycaemic activity and beneficial effects on cardiovascular risk factors, at the highest dose, the formulation exhibited deleterious effect on the hepatic tissue.