@article {Diaz1150, author = {Gonzalo J. Diaz and Konstantine W. Skordos and Garold S. Yost and E. James Squires}, title = {Identification of Phase I Metabolites of 3-Methylindole Produced by Pig Liver Microsomes}, volume = {27}, number = {10}, pages = {1150--1156}, year = {1999}, publisher = {American Society for Pharmacology and Experimental Therapeutics}, abstract = {A study was conducted to investigate qualitative and quantitative aspects of the phase I metabolism of 3-methylindole (3MI) by porcine liver microsomes. Microsomal suspensions were prepared from the liver of 30 intact (uncastrated) male pigs. Metabolites produced in microsomal incubations were identified and quantitated with HPLC-UV, HPLC-fluorescence, and UV-spectral analysis; liquid chromatography-mass spectrometry (LC-MS) and NMR were used for the identification of a metabolite for which a reference compound was not available. The results showed that seven major metabolites of 3MI are produced by porcine microsomes, three of which had already been identified in pigs (3-OH-3-methyloxindole, 5-OH-3-methylindole, and 6-OH-3-methylindole). The other four major 3MI metabolites identified were 3-OH-3-methylindolenine, 3-methyloxindole, indole-3-carbinol, and 2-aminoacetophenone. On average, the metabolite that was produced in larger amounts was 3-OH-3-methylindolenine (45.1\%), followed by the two oxindoles 3-methyloxindole (27.9\%) and 3-OH-3-methyloxindole (18.5\%). Average percentage of production of 6-OH-3-methylindole was 4.9\%, whereas indole-3-carbinol accounted for 2.7\% of all metabolites produced; 2-amino-acetophenone and 5-OH-3-methylindole were the metabolites produced in lesser amounts (0.5 and 0.3\%, respectively). Large interindividual differences in the rate of production of all metabolites were observed. This variation could be attributed to differences in the activity and/or level of expression of phase I biotransformation enzymes and this issue should be further investigated. The American Society for Pharmacology and Experimental Therapeutics}, issn = {0090-9556}, URL = {https://dmd.aspetjournals.org/content/27/10/1150}, eprint = {https://dmd.aspetjournals.org/content/27/10/1150.full.pdf}, journal = {Drug Metabolism and Disposition} }