RESUMO
This study was designed to ascertain/verify whether Sacoglottis gabonensis stem bark extract has biological antioxidant activity in membrane lipid peroxidation using male weanling rats as the experimental animals and, if so, to attempt to establish/deduce the possible mechanism(s) of the antioxidant action of the bark extract. Lipid peroxidation was induced experimentally with a single intraperitoneal 2,4-dinitrophenyl hydrazine (2,4-DNPH) at the end of a 3-day administration with the bark extract in drinking water. Three hours later, the liver and red blood cells were analysed for the three primary antioxidant enzymes, namely catalase, superoxide dismutase (SOD) and glutathione peroxidase, and two nonenzymic antioxidants, namely vitamin E (alpha-tocopherol) and vitamin C (ascorbic acid) levels. Results showed that pretreatment with the bark extract exhibited divergent effects on natural antioxidant enzymes: It impaired the enzyme-inducing action of 2,4-DNPH (and of ethanol) on liver and red blood cell catalase but reduced the SOD depressing effect of the experimental oxidant (2,4-DNPH) and ethanol. Neither 2,4-DNPH nor the extract had any measurable effect on glutathione peroxidase. The bark extract also exerted a sparing effect on tissue antioxidant vitamins, ascorbic acid and vitamin E, effectively inhibiting their depletion by 2,4-DNPH or ethanol in the liver, red blood cells and brain. It is being concluded that the mechanism of antioxidant action of the bark extract against membrane peroxidation is multifactorial/multisystem, involving inhibition of catalase, enhancing the SOD capability of the liver and red blood cells and sparing tissue depletion/utilization of vitamins C (ascorbic acid) and E (alpha-tocopherol).
