Marler Thomas E, Shaw Christopher A
CNAS-Western Pacific Tropical Research Center, University of Guam, UOG Station, University Drive, Mangilao, GU 96923, USA.
Sci Hortic. 2010 Feb 2;123(4):537. doi: 10.1016/j.scienta.2009.11.009.
Flour derived from Cycas micronesica seeds was once the dominant source of starch for Guam's residents. Cycad consumption has been linked to high incidence of human neurodegenerative diseases. We determined the distribution of the sterols stigmasterol and β-sitosterol and their derived glucosides stigmasterol β-d-glucoside and β-sitosterol β-d-glucoside among various plant parts because they have been identified in cycad flour and have been shown to elicit neurodegenerative outcomes. All four compounds were common in seeds, sporophylls, pollen, leaves, stems, and roots. Roots contained the greatest concentration of both free sterols, and photosynthetic leaflet tissue contained the greatest concentration of both steryl glucosides. Concentration within the three stem tissue categories was low compared to other organs. Reproductive sporophyll tissue contained free sterols similar to seeds, but greater concentration of steryl glucosides than seeds. One of the glucosides was absent from pollen. Concentration in young seeds was higher than old seeds as reported earlier, but concentration did not differ among age categories of leaf, sporophyll, or vascular tissue. The profile differences among the various tissues within these organs may help clarify the physiological role of these compounds.
来自密克罗尼西亚苏铁种子的面粉曾是关岛居民淀粉的主要来源。食用苏铁与人类神经退行性疾病的高发病率有关。我们确定了甾醇豆甾醇和β-谷甾醇及其衍生的糖苷豆甾醇β-D-葡萄糖苷和β-谷甾醇β-D-葡萄糖苷在各种植物部位中的分布，因为它们已在苏铁面粉中被鉴定出来，并已被证明会引发神经退行性病变。这四种化合物在种子、孢子叶、花粉、叶子、茎和根中都很常见。根中游离甾醇的浓度最高，光合小叶组织中甾醇糖苷的浓度最高。与其他器官相比，三种茎组织类型中的浓度较低。生殖孢子叶组织中的游离甾醇与种子相似，但甾醇糖苷的浓度比种子高。花粉中缺少一种糖苷。如先前报道，幼种子中的浓度高于老种子，但在叶、孢子叶或维管组织的不同年龄类别中浓度没有差异。这些器官内不同组织之间的分布差异可能有助于阐明这些化合物的生理作用。
