BIOTRANSFORMATION, Drug metabolism, detoxification Phase 2 conjugation

sulfation acetylation Glucuronidation (80%) GSH conjugation 12% acetylation Glucuronidation (80%) Conjugation with amino acids glycosylation sulfation su

phase I phase II nucleophilic metabolites glucuronides sulfate esters X electrophilic metabolites GSH conjugates DNA, RNA, protein

Ways of conjugation Glucuronidation – UDP glucuronate – UDP-glucuronosyl transferases

Conjugation of salicylic acid

Enzyme and transporter in the ER membrane

Role of UGT-s in activation of drugs morphin steroids bile acids retinoids policyclic aromatic hydrocarbons heterocyclic aromatic amines

Hyperbilirubinemias unconjugated hyperbilirubinemias Gilbert disease Low UGT activity treatment: inducer phenobarbital benign, 5-6 % of population Crigler Najjar syndr. bilirubin encephalopathia, fatal

Hyperbilirubinemias Conjugated hyperbilirubinemias Transport of conjugates is disturbed Expression of MRP2 is depressed Dubin Johnson syndr. Rotor syndr.

Ways of conjugation Glucuronidation – UDP glucuronate – UDP-glucuronosyl transferases Sulfation – PAPS - sulfotransferases

Sulfate conjugation of coumarine

Ways of conjugation Glucuronidation – UDP glucuronate – UDP-glucuronosyl transferases Sulfation – PAPS – sulfotransferases GSH conjugation - GSH, acetyl CoA - GSH transferases

Biotransformation of acetaminophen

Ways of conjugation Glucuronidation – UDP glucuronate – UDP-glucuronosyl transferases Sulfation – PAPS – sulfotransferases GSH conjugation - GSH, acetyl CoA - GSH transferases Acetylation – acetyl CoA Amino acid conjugation – amino acids Methylation - SAM

Overlapping substrate, inducer specificity Phisiological substrates: steroids Eicosanoids Fatty acids lipids hydroperoxides retinoids aceton (inducers ?) Xenogenic substrates (inducers ?) Ah receptor: aromatic hydrocarbon receptor intracellular receptors: CAR, PXR, VDR, FXR, RXR, HNF4 Overlapping substrate, inducer specificity

Biotranszformation reactions in intermediery metabolism synthesis conjugation Bile acid synthesis conjugation steroid hormones „Maturation” of D vitamin synthesis conjugation prostaglandin, leukotriene Synthesis of cholesterin synthesis conjugation chatecholamines „synthesis” conjugation bilirubin Synthesis of (poly)unsaturated fatty acids Oxidation of aceton

ligand reactivation by deconjugationl 2. phase: ligand inactivation by conjugation sulfo- transferase estron- sulphate estron szteroid szulfatáz Estron-sulphate estron androstane-dion estron P450 aromatase 1. phase: ligand activation by oxygenation

Consequences of Biotransformation actíve inactive drogs, hormones (steroid, prostanoid) inactive active drogs (imipramine) hormones (testosterone) vitamin (D vitamin) chemical carcinogenesis (nitrosamines) biosynthesis aceton glucose Synthesis of leukotrienes inactivation, „detoxification” toxicity Role of induction in regulation

Toxicity 1. dosis 5-10 different drugs/patient Logarythmic increase of adverse drug effects with the number of drugs nutrition Intracellular cofactors NADPH UDPGA PAPS GSH vitamines alkoholism

Toxicity 2. Aspecific enzyme systems Competition of substrates Addition of various drugs Changes in induction e.g. Coumarine Biotransformation enzymes in livers of newborns Treatment of mothers at delivery chloramphenicol morfin gray baby szindróma Hyperbilirubinaemia of newborns low UGT

Toxicity 3. Genetic differences Treatment of populations INH (isoniazid) N acetyl transferase Pathological circumstances diabetes mellitus Liver diseases ageing Gender differences

ethanol acetaldehid acetate ADH alcohol dehydrogenase CYP2E1 catalase cytosol SER peroxisome NADPH ADH alcohol dehydrogenase CYP2E1 catalase NADP KM:8-10 mM H2O2 H2O KM:0,2-2 mM NAD NADH acetaldehid mitokondrium NAD NADH aldehyde dehydrogenase acetate

ethanol acetaldehid acetate ADH alcohol dehydrogenase CYP2E1 catalase → stimulated metabolism of other drugs ethanol cytosol SER peroxisome NADPH ADH alcohol dehydrogenase CYP2E1 catalase NADP KM:8-10 mM H2O2 H2O KM:0,2-2 mM NAD NADH acetaldehid mitokondrium ↓ Fatty liver NAD NADH aldehyde dehydrogenase acetate → acetaldehyde toxicity autoimmune pathology