Pedras M Soledade C, Park Myung Ryeol
Department of Chemistry, University of Saskatchewan, 110 Science Place, Saskatoon, SK, S7N 5C9, Canada.
Department of Chemistry, University of Saskatchewan, 110 Science Place, Saskatoon, SK, S7N 5C9, Canada.
Phytochemistry. 2016 Dec;132:26-32. doi: 10.1016/j.phytochem.2016.09.009. Epub 2016 Sep 22.
Alternaria brassicicola (Schwein.) Wiltshire is a phytopathogenic fungus that together with A. brassicae causes Alternaria black spot disease in Brassica species. Brassicicolin A is the major host-selective phytotoxin produced in cultures of A. brassicicola. Biosynthetic studies to establish the metabolic precursors of brassicicolin A were carried out with isotopically labeled compounds. Incorporation of D-[C]glucose, L-[N]valine, or L-[H]valine into brassicicolin A was established using H, C, N NMR and INADEQUATE spectroscopy and HPLC-ESI-MS spectrometry. Based on analyses of the spectroscopic data, the labeling patterns of brassicicolin A isolated from cultures incubated with the labeled precursors are found to be consistent with both the glycolytic and the valine pathways. That is, the carbons of mannitol and acetyl units and the isocyanide carbon atoms are derived from D-[C]glucose whereas the hydroxyisopentanoyl and isocyanoisopentanoyl units are derived from L-valine, including the nitrogen atoms of both isocyanide groups.
链格孢（Alternaria brassicicola (Schwein.) Wiltshire）是一种植物致病真菌，它与芸苔链格孢（A. brassicae）共同引发十字花科植物的链格孢黑斑病。油菜毒素A是链格孢在培养过程中产生的主要宿主选择性植物毒素。利用同位素标记化合物对油菜毒素A的代谢前体进行了生物合成研究。通过氢、碳、氮核磁共振、异核单量子相干谱以及高效液相色谱 - 电喷雾质谱法，确定了D-[C]葡萄糖、L-[N]缬氨酸或L-[H]缬氨酸掺入油菜毒素A的情况。基于光谱数据分析，发现从用标记前体培养的培养物中分离出的油菜毒素A的标记模式与糖酵解途径和缬氨酸途径均一致。也就是说，甘露醇和乙酰基单元的碳以及异氰化物碳原子源自D-[C]葡萄糖，而羟基异戊酰基和异氰基异戊酰基单元源自L-缬氨酸，包括两个异氰基的氮原子。
