O-methylation of (+)-(R)- and (−)-(S)-6,7-dihydroxy-1-methyl-1,2,3,4-tetra-hydroisoquinoline (salsolinol) in the presence of pig brain catechol-o-methyltransferase
✍ Scribed by Beate K. Hötzl; Helmut Thomas
- Publisher
- John Wiley and Sons
- Year
- 1997
- Tongue
- English
- Weight
- 243 KB
- Volume
- 9
- Category
- Article
- ISSN
- 0899-0042
No coin nor oath required. For personal study only.
✦ Synopsis
(+)-(R)- and (-)-(S)-salsolinol, dopamine-derived tetrahydroisoquinolines, were tested as substrates of pig brain soluble and membrane-bound catechol-O-methyltransferase (COMT) and as inhibitors of O-methylation of dopamine by soluble COMT in vitro. Methylation products were separated by high-performance liquid chromatography with electrochemical detection. Quantification of the products showed that O-methylation of (+)-(R)-salsolinol by soluble COMT afforded the 7-O-methylated product salsoline preferentially, whereas (-)-(s)-salsolinol yielded almost equivalent amounts of the 6- and 7-methyl ethers. Unlike O-methylation by soluble COMT, 7-O/6-O-methylation ratio produced by membrane-bound COMT varied with (+)-(R)-salsolinol concentration. As to the O-methylation of dopamine by soluble COMT, comparable competitive inhibition was observed with both (+)-(R)- and (-)-(S)-salsolinol.