Transcript mGST1
Drug discovery Virtual screening Phase I CYP Phase II Computational model Oxidation Conjugation * Bioactivation for CYP prediction. * Uncoupling * Inhibition Clinical trials Where Do New Potential drug candidates Come From? Natural Sources Acquisition Compounds From other Pharmaceutical companies Endogenous Ligand e.g. Natural peptide, hormone, etc. Random Screening of Existing Compounds Drug Newly Synthesized Combinatorial Chemistry Libraries Hepatic microsomal enzymes (oxidation, conjugation) Adverse drug interactions are unpredictable from routine laboratory test in human. Despite rigorous testing, approximately 75,000-135,000 deaths due to adverse drug reactions occur annually in the United States, making it the sixth leading cause of death. ► In Smooth Endoplasmic Reticulum (microsome) - detoxification (cytochrome P-450s) - toxins, drugs and xenobiotics - O2 + RH R-OH and H2O - leakage of O2-. (Uncoupling) - metabolic activation - X. (Bioactivation) P450 Bioactivation Detoxification Oxidative stress is caused by an imbalance between the production of reactive oxygen and a biological system's ability to readily detoxify the reactive intermediates or easily repair the resulting damage. One of the enzyme known to protect the cell from reactive oxygen species consequently from oxidative stress. Transferase Peroxidase mGST1 is involved in cellular. defense against toxic, carcinogenic, and pharmacologically active electrophilic compounds e.g: SH mGST1 Activation of mGST1 via cystein 49 It is possible that activation is an alternative rapid response to toxic conditions in the cell. SX mGST1 Activity increased several fold. -mGST1 is activated by most alkylating agents, Cysteine 49, which is the target for electrophile activation. Short lived Spin trapping Sensors detect modification of macromolecules Looking for easy methods for predicting drug bioactivation! Oxidative Damage Short half life Difficult to detect Proteins (-SH) Free Radicals and Reactive metabolites Modification of enzyme function e.g. mGST1 Scientific Question?? Utilize it as a marker !!! DNA/RNA (-OH.) Lipids (R-OO.) The relationship between drug metabolism and drug toxicity. P450 SH SX Activity increased several fold. J. L.Walgren, M. D. Mitchell, & D. C. Thompson (2005) Crit. Rev. Toxicol. 35, 325-361 ► Drugs with reactive metabolites that have warnings of precautions for hepatoxicity Acetaminophen Carbamazepine Clozapine Diclofenac Disulfiram Halothane Leflunomide Methyldopa Rifampin Tacrin Tamoxifen Terbinafine Ticlopidine Zileuton ► Drugs with reactive metabolites & never approved in US Alpidem Amineptine Amodiaquine Cinchophen Dihydralazine Dilevaolo Ebrotidine Glafenine Ibufenac Isoxanine Niperotidien Perhexiline Pirprofen Tilbroquinol Sensing Scheme: Especially for the novel series of chemical entities under investigation. Biosensor with immobilized P450 and mGST1 mGST1 modified Covalantaly Transferase Enhanced activity of mGST1 Peroxidase Biological monitor for reactive intermediates will be helpful in sorting out harmful compounds without prior knowledge of the intermediate structure of that particular compound. Support i-e Aluminium oxized Key benefit : high surface to volume Immobilization Fixation of Endoplasmic reticulum membranes Biomedical device mGST1 Detection marker In the case of reactive metabolites formation SH SX mGST1 P450-b5-reductase Enhanced activities of mGST1 Expected outcomes Development of the biosensor using mGST1 activation as a surrogate detection marker which will be highly valuable technology for the prediction and testing of new drug entries that form reactive intermediates.