Bossaller C, Schmoldt A
Naunyn Schmiedebergs Arch Pharmacol. 1979 Jan;306(1):11-5. doi: 10.1007/BF00515587.
Dehydro-digitoxosides are metabolites of digitalis glycosides. In order to study their possible biological activity their affinity to (Na+ + K+)-activated ATPase was determined and compared with unchanged glycosides. Based on the dissociation constants of glycoside-enzyme-complexes, the affinity of the dehydro-digitoxosides ranged in the same order of magnitude as that of the native glycosides. Comparing mono-, bis-, and tris-digitoxosides of digitoxigenin (dt-1, dt-2, dt-3) and of digoxin (dg-1, dg-2, dg-3) with the corresponding dehydrodigitoxosides (3'-dehydro-dt-1, 9'-dehydro-dt-2, 15'-dehydro-dt3, 3'-dehydro-dg-1 and 9'-dehydro-dg-2, respectively) the dehydro-digitoxosides had lower affinities to the enzyme. The highest dissociation constants (KD) were found for 3'-dehydro-dt-1 and 3'-dehydro-dg-1. The half maximal inhibition of (Na+ + K+)-ATPase activity (I50) coresponded to affinity measurements in all but two cases: dehydro-dt-3 and dehydro-dt-2 showed very low I50 values.
去氢洋地黄毒苷是洋地黄糖苷的代谢产物。为了研究它们可能的生物活性，测定了它们对（Na⁺ + K⁺）激活的ATP酶的亲和力，并与未变化的糖苷进行了比较。根据糖苷 - 酶复合物的解离常数，去氢洋地黄毒苷的亲和力与天然糖苷处于相同的数量级。将洋地黄毒苷元的单、双、三洋地黄毒苷（dt - 1、dt - 2、dt - 3）和地高辛的（dg - 1、dg - 2、dg - 3）与相应的去氢洋地黄毒苷（分别为3'-去氢 - dt - 1、9'-去氢 - dt - 2、15'-去氢 - dt3、3'-去氢 - dg - 1和9'-去氢 - dg - 2）进行比较，去氢洋地黄毒苷对该酶的亲和力较低。3'-去氢 - dt - 1和3'-去氢 - dg - 1的解离常数（KD）最高。除了两例情况外，（Na⁺ + K⁺）-ATP酶活性的半数最大抑制（I50）与亲和力测量结果相符：去氢 - dt - 3和去氢 - dt - 2显示出非常低的I50值。
