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Metabolism of selegiline in human Identification, Excretion, and Stereochemistry of Urine Metabolism. เมตาบอลิซึ่มของซิลิจีลีนในมนุษย์ นำเสนอโดย น.ส. อรทัย กฤษณานุวัฒน์ รหัสนักศึกษา 51312336. Introduction. The chemical name is (R)-(-)-N,2-dimethyl-N-2-propynylphenethylamine hydrochloride
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Metabolism of selegiline in humanIdentification, Excretion, and Stereochemistry of Urine Metabolism เมตาบอลิซึ่มของซิลิจีลีนในมนุษย์ นำเสนอโดย น.ส. อรทัย กฤษณานุวัฒน์ รหัสนักศึกษา 51312336
Introduction • The chemical name is (R)-(-)-N,2-dimethyl-N-2-propynylphenethylamine hydrochloride • It is a white to near white crystalline powder, soluble in water, chloroform and methanol • Molecular weight of 223.75 • Boling point 80 °c
Monoamine oxidase, L-dopamin Later, Heinonen et.al Methamphetamine, amphetamine, desmethyl – selegiline urine human p-hydroxyamphetamine, p-hydroxymetamphetamine rat
H2N H H NH2 CH3 CH3 l-Amphetamine d-Amphetamine CH3NH H H NHCH3 CH3 CH3 l-Methamphetamine d-Methamphetamine Material and Method • d-, l-,R-,S-, or(+)- and (-)- systems of naming optical isomers enantiomers of amphetamine and methamphetamine
Materials and Methods Chemical (R)-amphetamine sulfate (S)-amphetamine sulfate sigma (S)- methamphetamine (1R,2R)-norpseudoepedrine · HCl
(1R,2S)-norephedrine·HCl (1S,2R)-norephedrine·HCl Fluka (1S,2R)-ephedrine·HCl (1S,2R)-pseudoephedrine·HCl p- hydroxyamphetamine p- hydroxymethamphetamine Instd. p- hydroxynorephedrine p- chlorphetermine
Drug administration and sample collection • 10, 5, and 2.5 mg of selegiline.HCl • Urine sample collection at various times over 72 hr and stored at 4 °c
Isolation of Unconjugate Metabolism • Urine 3 ml+ 100mg sodium bicarbonate: potassium carbonate (2:1) +150 ng instd. (p- chlorphentamine) • 8 ml of diethylether-tert butanol(7:1) for metabolite extracted • Organic layer was transfer into a 15ml glass centrifuge tube + 0.4ml of 0.06M HCl
Mixing, Centrifuge 5 min at 1200 g • Organic layer was aspirate , dried
Isolation of Conjugate Metabolite • Urine 3 ml adjusted ph 5.2 with 0.2M Sodium acetate buffer • Incubate with 50 µl of arylsulfatase / β - glucolonidase 52 °c • Solution was neutralized with 5 M KOH and adjusted pH 9.6 with 200mg of sodium bicarbonate : potassium carbonate (2:1)
Quantification of Selegiline and Its Metabolite • Dry residue was dissolved in 50 µl of ACN:TFA (60:40) • Titrated with MSTFA until color reaction changes red to yellow • Sample was heated for 10 min at 60°c
Two drops of MSTFA added to the reaction mixture • 2 µl of the solution was injected into the GC/MS
GC/MS, GC-NPD • HP 5890/5971Ainstrument, HP 9144 disk drive,HP Think Jet Printer • HP fused-silica capillary column, 5% phenylmethylsilicon(SE-54) • 17 min length, with 0.2 mm diameter, 0.33 µl film thickness • Temperature and column condition identical for GC/MS
Results and Discussion • Identification of Metabolites by GC-NPD and GC/MS • Comparison of the EI mass spectra and gas chromatographic retention times • GC-NPD gave six peaks (A1-A6) • N-trifluoroacetylation, O- trimethylsilylation showed 10 peaks(B1-B10)
Identification of the Stereoisomer of the Selegiline Metabolites • Applicable to the quantification of trace optical isomer containing more than one reactive functional gr. • The stereochemical identities of the metabolites confirmed by comparison of the GC RT of derivative of the extractd metabolites with of the authentic std.
Urinary excretion of metabolites • Summarized in table 1 • Trifluoroacetylated form, N-trifluoroacetylation-O-trimethlysilation derivative • Detection limit of selegiline was ~ 0.3ng/ml other metabolites were were ~ 0.1ng/ml - Correlation(r) =0.999 between injection amounts and detection response
The major metabolite was (R)-methamphetamine for ~ 37% of dose • β-hydroxylation and aromatic hydroxylation were minor metabolite • Dealkylation, β-hydroxylation of selegiline lead to unconjugate • Most of the p-hydroxylated of selegiline excreted conjugate (57.3-77.3%)
The sum of the amount of urinary metabolite in 2 days • 44-58% dose-independent amount of selegiline • 48.67-48.8% dose of dealkylated metabolites (Asia) • 30.78-34.09% (Europeans) • 4.84-8.77%dose of aromatic hydroxylate metabolites (Asia) • 12.42-17.54% (Europeans)
Kinetic Studies • Quantification of urine concentration of selegiline and the metabolite • The excretion rate for selegiline and metabolite was calculated by division of the total amount via the urine collection interval • Readily absorbed, rapidly distributed
ขอบคุณ อาจารย์ ธงชัย เตโชวิศาล ที่ปรึกษาสัมมนา Quesssion
A2 4.0E Abundance A1 3.0E 2.0E A6 A4 A3 A5 1.0E