Systematic Reviews
Copyright ©The Author(s) 2016.
World J Gastroenterol. Oct 28, 2016; 22(40): 9012-9021
Published online Oct 28, 2016. doi: 10.3748/wjg.v22.i40.9012
Figure 1
Figure 1 Simplified scheme of thiopurine metabolism. Azathioprine is non-enzymatically converted to 6-mercaptopurine by separating the imidazole-group. 6-Mercaptopurine is converted into 6-methylmercaptopurine (6-MMP) by thiopurine S-methyl transferase (TPMT) and into 6-thioguaninenucleotides (6-TGN) by an extensive enzymatic pathway using hypoxanthine-guanine phosphoribosyl transferase (HGPRT), inosine monophosphate dehydrogenase (IMPDH) and guanosine monophosphate synthetase (GMPS). 6-Thioguanine is converted directly into 6-TGN using HGPRT without producing the potentially toxic metabolite 6-MMP. Squared abbreviations display enzymatic conversions[46].
Figure 2
Figure 2 Flowchart of article selection procedure[22].