Insights into the inhibition of xanthine oxidase by curcumin

As a natural pigment, curcumin exhibits multiple biological activities. Previous studies have investigated the inhibition of xanthine oxidase (XO) by curcumin. In the present work, based on the molecular docking simulations, it is interesting to find that parent curcumin binds weakly to XO, while its degradation products, for example, trans-6-(4'-hydroxy-3'-methoxyphenyl)-2,4-dioxo-5-hexenal, exhibit effective inhibitory activities against XO. The findings shed new light on the underlying mechanisms of curcumin in inhibiting XO and also have potential implication that both parent curcumin and its degradation products should be taken into account when exploring the mechanisms of curcumin's biological activities.