Biosynthesis of Isonorargemonine, Eschscholtzidine and 4-Hydroxyeschscholtzidine inThalictrum minus

Abstract

Feeding experiments with (14)C-labelled reticuline have shown that reticuline is an efficient precursor of isonorargemonine, eschscholtzidine, and 4-hydroxyeschscholtzidine in Thalictrum minus (Ranunculaceae). Feeding experiments using (14)C-labelled isonorargemonine and eschscholtzidine led to the conclusion that the substitution pattern of 4-hydroxyeschscholtzidine can be formed at the pavine stage.

Targeted metabolite and transcript profiling for elucidating enzyme function: isolation of novel N‐methyltransferases from three benzylisoquinoline alkaloid‐producing species

“…Mass spectrometry data (Tables S1 and S3) were also consistent with production of the pavine alkaloid N ‐methyleschscholtzidine, although no intermediates downstream of reticuline were present (Figure 4). Eschscholtzidine biosynthesis requires a C–C coupling enzyme to form the pavine skeleton, an O ‐methyltransferase, and a methylenedioxy bridge‐forming enzyme (Sidjimov, 1997). Corresponding genes encoding these enzymes are presently unknown.…”

“…Although TfCNMT N ‐methylated (±)‐pavine with limited efficiency compared with its preferred substrates, TfPavNMT displayed a previously unreported preference for the pavine backbone (Figure 6 and Table 2). Reticuline has been reported to be an efficient precursor for N ‐methylated pavine alkaloids such as eschscholtzine in Thalictrum minus (Sidjimov, 1997), suggesting that the N ‐methyl group in N ‐methylpavine arises from reticuline rather than from the N ‐methylation of pavine. However, N ‐methylpavine could also be derived from pavine via C–C coupling of an N ‐demethylated BIA, such as norreticuline.…”

“…In T. flavum , biosynthesis of the pavine alkaloid eschscholtzidine also requires a bisnorargemonine O ‐methyltransferase, and a methylenedioxy bridge‐forming enzyme (Sidjimov, 1997), which might be represented by the ESTs Tfl_022_D03 and Tfl_002_A03 (Table S2), respectively.…”