中药知母有效组分——知母皂甙元“滋阴”作用的研究

本工作以~(123)I-心得静结合分析法及环核苷酸RIA法观察了知母中提取得到的知母皂甙元对甲亢模型(模拟“阴虚”)βAR-cAMP系统的作和,结果表现,知母皂甙元明显降低甲亢小鼠脑β受体的RT值,显著降低甲亢小鼠β受体-cAMP系统的反应性,重现了知母水煎剂的下调作用。体外竞争抑制实验表明,知母皂甙元和知母皂甙元半琥珀酸都不能抑制~(125)I-心得静与β受体的结合。

A study on the "Yin-tonic" component of the Chinese herb Zhimu: Sarsasapogenin

Sarsasapogenin was extracted from the Chinese herb Zhimu and its pharmacological action was compared with ZM decoction (ZM) in "Hyperthyroid" mice. 125I-Pindoiol binding assay revealed that the maximum binding capacity (RT) of brain beta-adrenoceptors of the models was significantly higher than normal and that repeated oral administrations of either ZM or SAR reduced the elevated RT to nearly normal. The peak value of plasma cAMP after a single dose of isoproterenol (ISO) was also significantly higher in the models than in control. Again oral administrations of either ZM or SAR reduced the response of plasma cAMP to ISO to nearly normal. However, in vitro competitive binding assay indicated that neither SAR nor its succinyl derivative had any direct binding reaction with beta adrenoceptors. It is therefore concluded that SAR is an important component of Zhimu and the mechanism of its "Yin-tonic" action is probably a down-regulation of the beta-adrenoceptors rather than direct occupation of receptor binding sites.