ABSTRACT

This study evaluated the in-vivo analgesic and in-vitro antioxidant activities of methanol extact of Anacardium occidentalis leaf, healthy wistar albino rats weighing 80-100g was used to determine the analgesic activity of Anacardium occidentalis. Following the analgesic study, twenty (20) female wistar albino rats were grouped into five (5) and each group consists of four rats. Group I (control): received normal saline and feed, Group II (standard): received O.Olml/kg body weight of morphine, Group III, IV and V received 250mg/kg, 500mg/kg, 750mg/kg body weight of the plant extract respectively. Two methods were used to determine the in vivo analgesic activity: acetic acid induced writhing and tail flick methods. Comparison was made between control and the different concentrations oftire extract which includes 250mg/kg, 500mg/kg and 750mg/kg, the values are represented as mean ± S.E.M and showed an increase in latency in a dose dependent manner. The extract significantly (p<0.05) reduced the number of writhing and the highest analgesic effect was seen in 750mg/kg extract which inhibited by 83.30% but less inhibition was observed in 250mg/kg by 44.40%. Analgesia was shown in the inhibition of nociception induced by tail immersion in 55°C hot water. The extract prolonged the latency of tail withdrawal to a similar degree as morphine with the highest reached at 90 minutes in 750mg/kg by (5.35-1:0.15). The antioxidant activity was assessed using various in vitro systems such as DPPH scavenging activity, anti-lipid peroxidation activity and nitric oxide scavenging activity. The result revealed that methanol leave extract of Anacardium occidentalis exerted antioxidant activity in a concentration dependent manner, it scavenged DPPH radical by ( 83.72 ± 1.08)%, Nitric oxide radical by ( 87.40i0.44 )% and lipid peroxidation by ( 88.65-10.67)% at a concentration of 500mg/ml which is the maximum concentration and shows significant (p<0.05) different when compared with the contol group. The result clearly indicates that the methanol leaf extract of Anacardium occidentalis exhibit analgesic activity and also shows that the extract has the potential to scavenge free radicals.