Xanthone-2-carboxylic acid effect on lens growth, hydration and proteins during diabetic cataract development

The concomitant protective effects of the aldose reductase inhibitor, 7-dimethylsulfamoyl-xanthone-2-carboxylic acid, were established by three lens parameters (soluble crystallin proteins, growth and cell hydration) because their quantitation provided a comprehensive index of lens physiology during sugar cataractogenesis in the rat neonate. Their fused eyelids provided the orbital pouch for topical administration of inhibitor to the treated lens; the contralateral pouch served as an untreated control. Protein preservation was determined by gel filtration chromatography. In galactose-maintained neonates, untreated lenses exhibited only 50% of the normal Fraction II protein whereas xanthone-treatment maintained 73% of this component. Quantitative analysis of scanning electron micrographs indicated that xanthone-treatment partially protected lenses against both intra and extracellular fluid accumulation as determined by measurements of individual fiber cell thickness, density (the number of cells/10 micron cortex), and interdigitation. In addition, xanthone-treatment improved lens growth as evidenced by radius and dry weight measurements. Our results suggest that topically applied xanthone partially inhibited sugar cataractogenesis.