Positive inotropic action of Solanaceae glycoalkaloids

Six glycoalkaloids and one aglycone were tested for cardiotonic activities and compared with K-strophanthoside by use of the isolated frog heart. The decreasing order of potency was as follows: K-strophanthoside greater than tomatine greater than alpha-chaconine=alpha-solanine greater than demissine=commersonine greater than beta-chaconine greater than solanidine. Cardiotonic activity was directly related to the number of sugars in the molecule in which the glycoalkaloids had a common aglycone. On the other hand, glycoalkaloids with dissimilar aglycones, but with identical sugars, such as tomatine and demissine, differed significantly with respect to cardiotonic potency. Apparently, therefore, the cardiotonic activity of glycoalkaloids on the frog heart is determined by the nature of the aglycone and the number of sugars and not by the kinds of sugars or their stereochemical configuration.