The Association of the Double Bond with the Lactone Group in the Cardiac Aglucones

By way of introduction a brief summary of the conclusions of a previous communication1 may be given. Strophanthidin and all of its derivatives which possess both the la&one group and the double bond of the parent substance reduce Tollens’ reagent and also give a positive nitroprusside reaction. The same has been found to be true of ouabain, gitoxin, and digitoxin. On saponification or hydrogenation these substances in general no longer give these reactions. On relactonization of the saponified substances a reaction will be again obtained where regeneration of the original substance is possible. In the case of strophanthidin the nature of this apparent association of the double bond with the lactone group appeared to be definitely established by the fact that the ethylal of oxidodianhydrostrophanthidin2 yielded a keto acid on saponification which formed an oxime, thus characterizing it as a substituted crotonic lactone. It was therefore inferred that the unsaturated lactone group is present not only in strophanthidin but is in all likelihood a structural characteristic of all of the above ‘(genins.” The possible pharmacodynamic significance of this group was also considered in view of the fact that hydrogenation of the double bond had been shown to produce a marked effect upon the physiological behaviors of several of these substances.3 It was necessary however to carry