Molyneux R J, Roitman J N, Dunnheim G, Szumilo T, Elbein A D
Arch Biochem Biophys. 1986 Dec;251(2):450-7. doi: 10.1016/0003-9861(86)90351-6.
A second indolizidine alkaloid, epimeric with castanospermine, has been isolated from seeds of the Australian tree Castanospermum australe. The structure was established as 6-epicastanospermine by proton and carbon-13 nuclear magnetic resonance spectroscopy and mass spectrometry. 6-Epicastanospermine was found to be a potent inhibitor of amyloglucosidase, (an exo-1,4-alpha-glucosidase), a weak inhibitor of beta-galactosidase, and not to inhibit beta-glucosidase and alpha-mannosidase. These results indicate that glycosidase inhibitory activity cannot be predicted by comparison of the structure and stereochemistry with the appropriate sugars, since 6-epicastanospermine is an analog of mannose and not of glucose. The inhibition of amyloglucosidase was found to be competitive and to be more effective at higher pH values. Castanospermine and 6-epicastanospermine differed in their effect upon the mung bean processing enzymes, glucosidase I and II, in that the former is a potent inhibitor whereas the latter is a very poor inhibitor. Subtle alterations in stereochemistry of these alkaloids can therefore produce significant changes in their biological activity.
从澳大利亚树木栗豆树（Castanospermum australe）的种子中分离出了第二种与栗精胺呈差向异构体的中氮茚生物碱。通过质子和碳-13核磁共振光谱以及质谱分析确定其结构为6-表栗精胺。研究发现，6-表栗精胺是一种有效的淀粉葡萄糖苷酶（一种外切-1,4-α-葡萄糖苷酶）抑制剂，是β-半乳糖苷酶的弱抑制剂，对β-葡萄糖苷酶和α-甘露糖苷酶没有抑制作用。这些结果表明，糖苷酶抑制活性无法通过与相应糖类的结构和立体化学比较来预测，因为6-表栗精胺是甘露糖而非葡萄糖的类似物。研究发现，淀粉葡萄糖苷酶的抑制作用具有竞争性，且在较高pH值下更有效。栗精胺和6-表栗精胺对绿豆加工酶葡萄糖苷酶I和II的作用不同，前者是一种有效的抑制剂，而后者是一种非常弱的抑制剂。因此，这些生物碱立体化学的细微变化会导致其生物活性发生显著改变。
