Interaction of xanthines with khellin

ABSTRACT

The potentiality of interaction of khellin with certain xanthine derivatives, viz, caffeine, theophylline, acepifylline and dyphelline was investigated. Differential ultraviolet spectrophotometry revealed a marked effect of xanthines on the exthinction coefficient of khellin. Applying continuous variation method on spectrophotometric measurements revealed the formation of 1 1 complexes between khellin and caffeine or theophylline, 2 1 khellin- acepifylline as well as 1 2 khellin - dyphelline complexes. The results of determination of the stability constant of the complexes revealed that theophylline and caffeine exhibit the highest tendency to complex with khellin, while acepifylline and dyphelline show a more or less weak tendency. The dissolution of khellin as well as the investigated khellin complexes was found to follow first order kinetics during the first 30 min of the dissolution run. On the other hand, the solublizing power of the investigated xanthine derivatives was also calculated