Synthesis of Thiosemicarbazones as Substrates for Xanthine Oxidase Enzyme Activity

摘要

Thiosemicarbazones were synthesized from 7-arylbicyclo[3.2.0]hept-2-en-6-ones (la-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 K_m and V_(max) values for thiosemicarbazone derivatives at different pH values. The derivatives showed better values of Km, V_(max) and V_(max)/K_m than xanthine. Particularly, (Z)-l-((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 K_M and the highest V_(max)/K_M values. K_m and V_(max)/K_M values were 1 x 10~(-4) M and 1.11 x 10~6 min~(-1), respectively. We proposed here a novel substrate for xanthine oxidase which can be used to assess the activity of this enzyme.