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Biogenesis and function of macrocyclic spermine alkaloids

“…The MS/MS showed the fragmentation pattern corresponding to aphelandrine (26), fully deuterated in its putrescine C 4 H 8 chain. The fragment ions of 9 (m/z 493) and labelled enzymatically formed 26 (m/z 501) were identical or differed by 8 amu (Fig.…”

“…2). Thus, it was shown that the labelled precursor (S)-(D 8 )-dihydroxyverbacine (25) was enzymatically transformed by the microsomal fraction into (D 8 )-labelled aphelandrine (26). 20 That aphelandrine synthase, the enzyme catalyzing the last phenol oxidative coupling step, is a membrane bound cytochrome P-450 enzyme was proven by several key criteria.…”

“…The data obtained by HPLC-UV (DAD)/APCI-MS and MS/MS measurements show the identity between the synthetic and the natural products. 26 The MS/MS experiment showed an identical fragmentation pattern for the synthetic and the natural compound (Fig.1). Since (−)-(S)-4′-hy-droxyprotoverbine (7) is a natural product it was named prelandrine (7) (Scheme 1).…”

“…The microsomal fraction of young Aphelandra roots was therefore tested for its capacity to hydroxylate protoverbine (6) to form prelandrine (7). After microsomes were incubated with the synthetically prepared (−)-(S)-protoverbine (6) in the presence of NADPH the hydroxylated derivative prelandrine (7) was detected by on-line coupled HPLC/UV (DAD)/APCI-MS. 26 The structure was proven using the synthetically prepared prelandrine (7) as reference. The enzyme catalyzing this aromatic hydroxylation was identified as a membrane-bound cytochrome P-450 enzyme, requiring NADPH and O 2 by the same key criteria as for the aphelandrine synthase.…”

The Asymmetric Synthesis of the [D8]-Labeled (−)-(S)-Dihydroxyverbacine, the Terminal Precursor in the Biogenesis of the Macrobicyclic Spermine Alkaloids Aphelandrine and Orantine

“…Compound 3 was recently detected in the roots of A. squarrosa and named prelandrine [3]. The presence of 3 in Aphelandra plants supports its possible key role in the biogenetic pathway of aphelandrine (5) and strongly favors the second pathway mentioned above [3].…”