Antioxidant activity of stem bark methanolic extract of Acacia nilotica in controlling organophosphate pesticides toxicity in mice

Abstract

Organophosphate (OP) pesticides are reported to cause acute poisoning cases because of their ability to inhibit acetyl cholinesterase enzyme (AChE). Available antidotes are atropine sulfur, pralidoxime (2-pyridine aldoxime methyl chloride), and diazepam, which act to recover OP-AChE inhibition. These are controlled drugs hence not easily accessed and very expensive. In this study Acacia nilotica stem bark extract was assessed for its oral acute toxicity, antioxidant activity, and in vivo AChE depression and recovery from OP-AChE inhibition. The mice were exposed in three different OPs including chlorpyrifos 480 g/l (CPF), fenitrothion 10 g/l (FNT) and profenophos 720 g/l (PFP). The extract of had a substantial increase of absorbance readings from 2.895±0.0032 to 3.716±0.0259 compared to standard (ascorbic acid) that had advantage ranging from 0.108±0.0033 to 1.468±0.0297 at P<0.05. In oral acute toxicity, the results did not show significant increase of body weight at P<0.05 from 22.345 ± 0.068 to 24.557 ± 0.410 in control and from 20.493 ± 0.082 to 24.155 ± 0.260 in treating group. This might have been contributed to normal growth. There were no significant changes of hemoglobin concentration observed in control and treated groups. Neither mortality nor toxicity signs were observed during the first 24 h and daily. Recovery effect under crude methanolic extract from A. nilotica, ascorbic acid and normal feeding were compared with the untreated group. There were significant decreases of AChE level from day one to 14 th day in all treated groups of CPF, PFP and FNT which indicate poisoning. The significant of AChE recovery was observed only in male mice in all treatment groups. This is a first study to assess and report the antioxidant activity of stem bark methanolic extracts of A. nilotica in controlling organophosphate pesticide toxicity in mice, hence further studies on isolation of active compounds are recommended.