7-METHYLXANTHINE IS NOT INVOLVED IN CAFFEINE CATABOLISM IN COFFEA-DEWEVREI

To investigate the role of 7-methylxanthine as an intermediary compound in the degradation of theobromine to xanthine in coffee, leaves and immature fruits of Coffea dewevrei were incubated with [8-H-3]caffeine plus allopurinol. In vivo inhibition of xanthine degradation occurred in fruits and leaves fed with allopurinol since marked incorporation of radioactivity in xanthine and 3-methylxanthine was observed. Nevertheless, HPLC analysis did not reveal any radioactivity in 7-methylxanthine. The results suggest that in coffee theobromine is degraded to xanthine via 3-methylxanthine and 7-methylxanthine is exclusively involved in the caffeine biosynthesis pathway.