Agronomy and Plant Breeding Department, Agriculture Faculty of Bu-Ali Sina University, 6517833131, Hamedan, Iran.
Br J Nutr. 2011 Jan;105(1):62-70. doi: 10.1017/S0007114510003120. Epub 2010 Sep 28.
Biochemical components in alfalfa (Medicago sativa L.), such as saponins, can act as protecting factors against bio-stresses. Saponins are also antifeedants and show oral toxicity towards higher and lower animals. Changes in saponins, such as variation in the carbon skeleton, or hydrolysis of saponin glycosides and other conjugates, may change their biological effects. The aims of this research were to study saponin variation in different growth stages of alfalfa and to investigate the biological role of saponins in the spotted alfalfa aphid, Therioaphis maculata. Saponins from alfalfa shoots in different growth stages were extracted, chemically purified and analysed by TLC. Specific saponins such as soyasaponin1 from root and shoot and two bisdesmosides of medicagenic acid, one from shoot and another from root tissues, were identified using reference compounds allowing changes in saponin composition during plant development in different shoot tissues of alfalfa to be assessed. The response of the alfalfa aphid to feeding on alfalfa in different growth stages was studied. No significant difference in the survival of aphids, from neonate to adult, was observed, but due to the antibiotic effects of saponins, two differences were found in the onset of nymph production and cumulative nymph production. The results show that the saponin composition in alfalfa changes with plant development and this, in turn, can often negatively affect the development of specific insect pests such as the spotted alfalfa aphid, suggesting a possible biological role of alfalfa saponins.
紫花苜蓿（Medicago sativa L.）中的生化成分，如皂角苷，可以作为生物胁迫的保护因子。皂角苷也是抗营养物质，对高等和低等动物具有口服毒性。皂角苷的变化，如碳骨架的变异，或皂角苷糖苷和其他缀合物的水解，可能会改变它们的生物学效应。本研究的目的是研究不同生长阶段紫花苜蓿中皂角苷的变化，并研究皂角苷在斑叶苜蓿蚜（Therioaphis maculata）中的生物学作用。从不同生长阶段的紫花苜蓿嫩枝中提取、化学纯化并通过 TLC 进行分析。使用参考化合物鉴定了特定的皂角苷，如来自根和嫩枝的大豆皂角苷 1 以及两种羽扇豆酸的双糖苷，一种来自嫩枝，另一种来自根组织，从而可以评估皂角苷组成在不同嫩枝组织中植物发育过程中的变化。研究了斑叶苜蓿蚜在不同生长阶段取食紫花苜蓿时的反应。未观察到从幼蚜到成虫的蚜虫存活率有显著差异，但由于皂角苷的抗生素作用，在若虫产生和累计若虫产生方面发现了两个差异。结果表明，紫花苜蓿中的皂角苷组成随植物发育而变化，这反过来又会对特定害虫如斑叶苜蓿蚜的发育产生负面影响，这表明紫花苜蓿皂角苷可能具有生物学作用。
