| Popis: |
For many years the biotransformation of digitoxin or β-methyldigitoxin to digoxin or β-methyldigoxin (Fig. 1) by cell cultures of Digitalis lanata has been studied (Reinhard 1974). This reaction is of pharmaceutical interest, since cardiac glycosides, mainly of the C-series, are among the most frequently used drugs against congestive heart failure. The enzyme catalyzing the 12β-hydroxylation was described for the first time by Petersen and Seitz (1985). It could be shown that this enzyme is another cytochrome P-450-dependent monooxygenase from higher plants. Among the best-studied cytochrome P-450-containing enzymes from plants are the cinnamic acid 4-hydroxylase (Russell 1971; Benveniste et al. 1977, and many others), the flavonoid 3′-hydroxylase (Formann et al. 1980; Larson and Bussard 1986) or the monoterpene hydroxylase (Meehan and Coscia 1973; Mady-astha et al. 1976). |
