Inhibition of xanthine oxidase by some Chinese medicinal plants used to treat gout

• Published in: Journal of ethnopharmacology 2000-11, Vol.73 (1), p.199-207
• Main Authors: Kong, L.D., Cai, Y., Huang, W.W., Cheng, Christopher H.K., Tan, R.X.
• Format: Article
• Language: English
• Subjects: Biological and medical sciences; Enzyme Inhibitors - isolation & purification; Enzyme Inhibitors - therapeutic use; Ethnobotany; General pharmacology; Gout - drug therapy; Gout treatment; Humans; Medical sciences; Medicinal plants; Medicine, Chinese Traditional; Pharmacognosy. Homeopathy. Health food; Pharmacology. Drug treatments; Plant Extracts - isolation & purification; Plant Extracts - therapeutic use; Plants, Medicinal - chemistry; Plants, Medicinal - enzymology; Traditional Chinese medicine; Xanthine Oxidase - antagonists & inhibitors; Xanthine oxidase inhibition
• ISSN: 0378-8741; 1872-7573
• DOI: 10.1016/S0378-8741(00)00305-6

The enzyme xanthine oxidase catalyses the oxidation of hypoxanthine to xanthine and then to uric acid, which plays a crucial role in gout. A total of 122 traditional Chinese medicinal plants, selected according to the clinical efficacy and prescription frequency for the treatment of gout and other hyperuricemia-related disorders, have been evaluated for the enzyme inhibitory activity. Among the 122 methanol extracts derived from these species, 69 were shown to be inhibitory at 100 μg/ml, with 29 having greater than 50% inhibition. As to the equal amount of water extracts, 40 were disclosed to be active at 100 μg/ml, with 13 possessing more than 50% inhibition. At 50 μg/ml, 58 methanol and 24 water extracts exhibited inhibitory activity, with 15 of the former and two of the latter showing greater than 50% inhibition. The most active was the methanol extract of the twig of Cinnamomum cassia (Lauraceae) (IC 50, 18 μg/ml), which was followed immediately by those of the flower of Chrysanthemum indicum (Asteraceae) (IC 50, 22 μg/ml) and the leaves of Lycopus europaeus (Lamiatae) (IC 50, 26 μg/ml). Among the water extracts, the strongest inhibition of the enzyme was observed with that of the rhizome of Polygonum cuspidatum (Polygonaceae) (IC 50, 38 μg/ml). The IC 50 value of allopurinol used as a positive control was 1.06 μg/ml. The study demonstrated that the effects for these medicinal plants used for the gout treatment were based, at least in part, on the xanthine oxidase inhibitory action.