Abstract
The photolysis of riboflavine with a low-intensity light source was investigated. Biphasic rate curves were obtained ; that is, an induction period was observed before the reaction rate reached its maximum value. The duration of the initial phase depended on the temperature and the concentration of riboflavine. The molecular associations of isoalloxazine nuclei may be responsible for such biphasic photolysis. The addition of xanthine derivatives to an aqueous solution of riboflavine reduced the rate of photolysis. Although the rate was reduced most effectively by theophylline, it appears that the interaction between riboflavine and theophylline differs considerably from that in other systems, i.e., caffeine, theobromine, and hypoxanthine systems.
