Xanthosine is produced by guanine-free mutants of bacteria e.g. Bacillus subtilis Aerobacter aerogenes. Xanthosine monophosphate is an intermediate in purine metabolism formed from IMP and forming GMP.

1-O-Gentiobiosyl-3,7-dimethoxy-8-hydroxyxanthone (Compound 18) is a natural product that can be isolated from Swertia mussotii.

(-)-Epiafzelechin exhibits significant anti-inflammatory activity on carrageenin-induced mouse paw edema, it exhibits a dose-dependent inhibition on the COX activity with an IC50 value of 15 microM, it exhibits about 3-fold weaker inhibitory potency on the enzyme activity than indomethacin as a positive control.