[Enzymatic conversion of tegafur in human tumor tissue].
Enzymatic conversion of tegafur was studied using a thymidine phosphorylase preparation purified from human liver cancer. Tegafur dissolved in water slowly decomposed to 5-FU upon storage at 37 degrees C and this conversion was further activated with an addition of a thymidine phosphorylase preparation. Analysis of Tegafur and 5-FU was performed on a high performance liquid chromatograph. The Km value was in agreement with Michaelis-Menten Kinetics and 2.44 X 10(-2) M without thymidine phosphorylase preparation. When the preparation was added, it was 2.53 X 10(-4) M and 1.75 X 10(-3) M, respectively. Determination of 5-FU concentrations in blood, normal and tumor tissues following a long term administration of Tegafur was performed. The highest concentration of 5-FU was detected in tumor tissue followed by normal tissue and blood, suggesting a human liver thymidine phosphorylase was capable of converting Tegafur to 5-FU more actively in tumor tissue than in normal tissue.
D000328:Adult; D005260:Female; D005472:Fluorouracil / Q000031:analogs & derivatives* / Q000378:metabolism; D006801:Humans; D066298:In Vitro Techniques; D008113:Liver Neoplasms / Q000201:enzymology; D008875:Middle Aged; D013274:Stomach Neoplasms / Q000378:metabolism*; D005641:Tegafur / Q000378:metabolism*; D013939:Thymidine Phosphorylase / Q000378:metabolism
D005641:Tegafur; D013939:Thymidine Phosphorylase; D005472:Fluorouracil