Purpurogallin is a flavinol obtainable from oak nutgalls. It can inhibit xanthine oxidase, glutathione S-transferase, catechol O-methyltransferase activities, and effectively protects several cell types, also has anti-inflammatory and anti-cancer activities.

In this article, we will introduce the antioxidant,  anti-inflammatory and anti-cancer activities of Purpurogallin.

The first function is the antioxidant effect.

Xanthine oxidase (XO) is the final enzyme in purine catabolism of humans, which catalyzes the oxidation reactions of hypoxanthine and xanthine. The reactions produce uric acid and reactive oxygen species. However, the over-accumulation of these productions will cause disease such as gout.

Purpurogallin has potent XO inhibitory activity with IC₅₀ of 0.2 μM. It potently inhibits urate formation by xanthine oxidase to protect rat aortic endothelial cells. Besides, the formation of superoxide-reduced cytochrome c is also diminished by Purpurogallin.

Secondly, Purpurogallin has anti-inflammatory activity in vitro and in vivo.

In LPS-stimulated BV2 microglial cells, Purpurogallin attenuates the production of pro-inflammatory cytokines, including interleukin-1β (IL-1β) and tumor necrosis factor-α (TNF-α) by suppressing expression. On the other hand, it exhibits anti-inflammatory properties by suppressing the phosphatidylinositol 3-kinase/Akt and mitogen-activated protein kinase signaling pathways.

In subarachnoid hemorrhage (SAH) model SD rats, Purpurogallin (100-400 μg/kg/day) reduces proinflammatory cytokines in the early stage of SAH-induced vascular deformity. In addition, via reducing HMGB1 mRNA activation, it exerts a dual effect on microglia related T-cell transmigration and IL-6 related delayed inflammatory cascade.

Thirdly, Purpurogallin has anti-cancer cells activity.

Polo-like kinase 1 (Plk1) is one of the key regulators of mitotic cell division. And, PBD (polo box domain) is postulated to be essential for Plk1 localization and substrate targeting.

According to previous research, Purpurogallin (50 μM; 16 hours) can prevent kinetochore localization of BubR1 and CENP-E, and the establishment of stable microtubule-kinetochore attachment in HeLa cells. Besides, It inhibits PBD-dependent binding and induces retardation of mitotic progression and apoptosis. In brief, Purpurogallin not only delays the onset of mitosis but also prolongs the progression of mitosis in HeLa cells.

In conclusion, Purpurogallin is a potent xanthine oxidase inhibitor, with antioxidant,  anti-inflammatory, and anti-cancer activities.

Reference:

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