37 アブラナ科植物ファイトアレキシンの生合成研究(ポスター発表の部)

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We have recently isolated and characterized several phytoalexins from cruciferous vegetables: Chinese cabbage, cabbage, and Japanese radish. These phytoalexins(1〜13) are synthesized de novo under stress conditions and structurally unique in possessing an indole or oxindole nucleus linked to a sulfur-containing moiety. Structural features suggest close biosyntheic relationships between these phytoalexins and indole glucosinolates(15〜17) which are known as biologically-active secondary metabolites in cruciferous plants. Time-course studies of cruciferous phytoalexins in UV-irradiated turnip root tissue suggested that brassinin(1) would be transformed into spirobrassinin(6) via cyclobrassinin(4). Feeding experiments with D-labeled brassinin(1) indicated that both cyclobrassinin(4) and spirobrassinin(6) were derived from brassinin(1). However, no incorporation of D-labeled cyclobrassinin(4) or dioxibrassinin(5) into spirobrassinin(6) was observed. Feeding experiments with D-labeled amino acids showed that brassinin(1) was biosynthesized from tryptophan and methionine. Feeding experiment with DL-tryptophan-α-^<13>C revealed the increase of ^<13>C content of the imino carbon atom in 6, suggesting that molecular rearrangement, such as Lossen type, would be involved in a biosynthetic pathway to brassinin(1).
1990-09-25