[Comparative evaluation of the antioxidant activity of para-aminobenzoic acid and emoxipin in the cornea and crystalline lens (an experimental study)].

Antioxidant effect of paraaminobenzoic acid (PABA) in the retina upon different routes of its administration has been revealed previously. In this study we investigated the antioxidant effect of PABA in the cornea and lens of rats after its parabulbar injection. Antioxidant activity of PABA was compared to that of emoxipin. One hour after hypoxic hypoxia the animals were parabulbarly injected with PABA solutions (0.007-0.08%) and 1% emoxipin. The eyes of intact animals and rats exposed to hypoxia alone served as the control. The levels of lipid peroxidation products (hydroperoxide, malonic dialdehyde) and catalase activity in the cornea and lens were measured 1, 3, 6, and 11 h after injections. PABA in all studied concentrations essentially decreased the elevated levels of hydroperoxides and malonic dialdehyde and normalized catalase activity. The level of lipid peroxidation products and catalase activity normalized 24-28 h after hypoxia, while after PABA it normalized within 2-11 h. Antioxidant activity of emoxipin in the lens and cornea was the same as that of optimal antioxidant concentrations of PABA (0.02% for the cornea and 0.06% for the lens). Hence, PABA in a wide range of concentrations (0.007-0.06%) is characterized by sufficiently high antioxidant activity in tissues of the anterior segment of the eye (cornea and lens) upon local administration.