Invitro and invivo antioxidant activity of aqueous extract of Carica papaya seed

Abstract

High concentrations of free radicals are hazardous to cells triggering damage of cellular constituents in living organisms. When the rate of free radical production is greater than that of its clearance, the free radical producing sites tend to undergo oxidative stress and damage. Antioxidant molecules play a pivotal role in controlling the free radicals produced during the breakdown of food in the body or through environmental factors, by scavenging excess free radical, thereby maintaining the redox balance. The aim of this study was to determine the invivo and invitro antioxidant activity of the aqueous extract of Carica papaya seed. Antioxidant phytochemicals present in Carica papaya seed were quantified and the invitro antioxidant activity was determined using 1,1-diphenyl-2-picrylhydrazyl (DPPH) and lipid peroxidation inhibition assay. These were carried out using standard analytical methods. The invivo study was carried out using paracetamol to induce oxidative stress in mice. Eighteen mice were divided into 6 groups comprising 3 mice each, group 1 served as normal control, group 2 served as negative control, group 3,4 and 5 received 200 mg/kg, 400 mg/kg, 600 mg/kg body weight aqueous extract of Carica papaya seed respectively while group 5 was treated with standard sylimarin drug, mice in group 2 - 4 were given 2 g/kg paracetamol to induce oxidative at the interval of 72 hours.its median effective dose (EC50) was 402.1±3.0µg/ml, the total phenolic content was 74.1±1.1 mg/100g and the total flavonoid was 117.56±2.1 mg/100 g. The highest DPPH scavenging activity of the aqueous extract was demonstrated at the concentration of 250 µg/ml to be 86.6 ±1.1 %, the highest lipid peroxidation inhibition capacity of the extract was demonstrated at the concentration of 250 µg/ml to be 74.23±2.3 %. The DPPH scavenging capacity and lipid peroxidation inhibition was observed to increase with increase in extract concentration. Carica papaya seed extract as compared to the negative control, showed an increase in the activity of SOD andcatalase in the acute liver damage induced with paracetamol in mice. These results is significantly comparable to the group treated with standard drug sylimarin. The best dose for the invivo study was shown to be 400 mg/kg body weight; it was comparable to the standard drug sylimarin. This study indicates that Carica papaya seed extracts possess antioxidant activity.