Synthesis of thiosemicarbazones as substrates for xanthine oxidase enzyme activity

Abstract

Thiosemicarbazones were synthesized from 7-arylbicyclo[3.2.0]hept-2-en-6-ones (1a-d) and thiosemicarbazide. The compounds were purified on a silica gel column chromatography. The thiosemicarbazone compounds were tested in vitro effect on xanthine oxidase (XO) purified from bovine milk. These compounds exhibited activator effects on xanthine oxidase enzyme activity at low concentration. We examined KM and Vmax values for thiosemicarbazone derivatives at different pH values. The derivatives showed better values of KM, Vmax and Vmax/KM than xanthine. Particularly, (Z)-1-((1R,5S,E)-7-(4-methylbenzylidene)bicyclo[3.2.0]hept-2-en-6-ylidene) thiosemicarbazide (4Mtc) was the most suitable substrate, due to the lowest KM and the highest Vmax/KM values. KM and Vmax/KM values were 1 × 10-4 M and 1.11 × 106 min-1, respectively. We proposed here a novel substrate for xanthine oxidase which can be used to assess the activity of this enzyme.