[Comparative assessment of antioxidant activity of para-aminobenzoic acid and emoxipin in retina].

Effect of para-aminobenzoic acid (PABA) on lipid peroxidation (LPO) in rat and guinea pig retina exposed to hypoxic hypoxia is studied. PABA was injected intraperitoneally and parabulbarly before and after hypoxic exposure. Antioxidant activities of PABA and emoxipin were compared. An intraperitoneal injection of PABA in a dose of 10 mg/kg 24 h before hypoxia virtually completely prevented accumulation of lipid peroxides and preserved catalase activity in the retina. Parabulbar injection of 0.01% PABA solution 1 h before hypoxia prevented LPO intensification, stabilized catalase activity in hypoxia, and protected the retina starting from the moment immediately after hypoxic exposure. The efficacy of 0.01% PABA is comparable with that of 1% emoxipin, and a 0.01% solution of emoxipin is less effective than PABA in the same concentration. PABA exerts an antioxidant effect after hypoxia by decreasing the abnormally high level of lipid peroxides and reducing catalase activity in the retina after parabulbar injection of the drug. All the studied concentrations of the drug (from 0.007 to 0.08%) are active, but the optimal dose for the retina is 0.04%. By its efficacy this concentration is equivalent to 1% emoxipin.