Inhibitory effects of plant growth regulators on xanthine oxidase

Shiow Yunn Sheu, Hsüch Ching Chiang

Research output: Contribution to journalArticlepeer-review

16 Citations (Scopus)


Several plant hormones and analogues were tested for their inhibitory effects on xanthine oxidase. The flavoprotein enzyme, xanthine oxidase, catalyses the oxidation of hypoxanthine to xanthine and then xanthine to uric acid which has λmax 295 nm. Uric acid was thus the basis for a spectrophotometric assay of the activity of xanthine oxidase. The results showed that trans-zeatin displayed the strongest activity (IC50= 23.5 μM) on xanthine oxidase inhibition, followed by indole-3-acrylic acid (IC50= 136.0 μM) and then by the mixed isomers of zeatin (trans-zeatin and cis-zeatin) (IC50= 198.65 μM). Trans-zeatin induced an uncompetitive inhibition of the enzyme with respect to the substrate xanthine and the apparent inhibition constant (Ki) was 5.09 μM. However, zeatin riboside was inactive. Since xanthine oxidase serum levels are increased in hepatitis, mild hepatic intoxication, tumours brain tissues, and DNA damage induced by cytotoxic agents, it is expected that trans-zeatin may be useful for the treatment of these diseases as well as gout which is caused by deposition of uric acid in the joints and oxidative damage of tissue caused by generation of superoxide union radical.

Original languageEnglish
Pages (from-to)311-316
Number of pages6
JournalAnticancer Research
Issue number1
Publication statusPublished - Jan 1996


  • Brain tumours
  • Cytokinins
  • DNA damage
  • Gout
  • Hepatitis
  • Plant growth regulator
  • Trans-zeatin
  • Xanthine oxidase inhibitor

ASJC Scopus subject areas

  • Oncology
  • Cancer Research


Dive into the research topics of 'Inhibitory effects of plant growth regulators on xanthine oxidase'. Together they form a unique fingerprint.

Cite this