title: Reduction of hydrogen peroxide-induced erythrocyte damage by Carica papaya leaf extract.
abstract: OBJECTIVE
  To investigate the in vitro antioxidant potential of Carica papaya (C. papaya) leaf extract and its effect on hydrogen peroxide-induced erythrocyte damage assessed by haemolysis and lipid peroxidation.
  
  
  METHODS
  Hydroxyl radical scavenging activities, hydrogen ion scavenging activity, metal chelating activity, and the ferrous ion reducing ability were assessed as antioxidant indices. In the other experiment, human erythrocytes were treated with hydrogen peroxide to induce erythrocyte damage. The extract (at various concentrations) was subsequently incubated with the erythrocytes and later analysed for haemolysis and lipid peroxidation as indices for erythrocyte damage.
  
  
  RESULTS
  Preliminary investigation of the extract showed that the leaf possessed significant antioxidant and free radical scavenging abilities using in vitro models in a concentration dependent manner (P<0.05). The extract also reduced hydrogen peroxide induced erythrocyte haemolysis and lipid peroxidation significantly when compared with ascorbic acid (P<0.05). The IC50 values were 7.33 mg/mL and 1.58 mg/mL for inhibition of haemolysis and lipid peroxidation, respectively. In all cases, ascorbic acid (the reference antioxidant) possessed higher activity than the extract.
  
  
  CONCLUSIONS
  The findings show that C. papaya leaves possess significant bioactive potential which is attributed to the phytochemicals which act in synergy. Thus, the leaves can be exploited for pharmaceutical and nutritional purposes.
authors.affiliation: Biochemistry Programme, Department of Chemical Sciences, Niger Delta University, PMB 71, Wilberforce Island, Bayelsa State, Nigeria.
authors.forename: Tebekeme
authors.initials: T
authors.lastname: Okoko
authors.forename: Diepreye
authors.initials: D
authors.lastname: Ere
mesh_terms: D000975:Antioxidants / Q000302:isolation & purification / Q000494:pharmacology*; D029441:Carica / Q000737:chemistry*; D004912:Erythrocytes / Q000187:drug effects*; D006461:Hemolysis; D006801:Humans; D006861:Hydrogen Peroxide / Q000633:toxicity*; D064209:Phytochemicals / Q000302:isolation & purification / Q000494:pharmacology*; D010936:Plant Extracts / Q000302:isolation & purification / Q000494:pharmacology*; D018515:Plant Leaves / Q000737:chemistry
chemical_list: D000975:Antioxidants; D064209:Phytochemicals; D010936:Plant Extracts; D006861:Hydrogen Peroxide
keywords: Antioxidant; Bioactive potential; Carica papaya; Erythrocyte; Free radical scavenging ability; Haemolysis; Hydrogen peroxide; Lipid peroxidation