This was to test whether the transfer had worked, because the transplanted biochemical pathway turns caffeine into xanthine, a molecule can make into guanine without the missing gene.

Patients who experience frequent attacks may require continuing treatment with urate-lowering drugs called xanthine oxidase inhibitors, like allopurinol and febuxostat, which reduce the amount of uric acid the body produces.

In 1881-1882 he published papers which established the formulae of uric acid, xanthine, caffeine, theobromine and some other compounds of this group.

The conventional treatments include the drugs allopurinol and febuxostat, both of which inhibit the enzyme xanthine oxidase, which produces uric acid from DNA in food.

To obtain the xanthine we treat the petals of yellow flowering dahlias with alcohol, which quickly dissolves the yellow coloring matter, besides the fat and resin.