Cardiotonic action of a new glycoside (bipindogenin D-xylosy1-D-alloside, R-16) aqueously extracted from Rhodea japonica ROTH.

Abstract

A new glycoside (R-16) was aqueously extracted from Rhodea japonica ROTH, and its chemical structure was determined as bi-pindogenin D-xylosyl-D-alloside by Miyahara et al.(1979). As the structure of R-16 is similar to that of ouabain (ouabagenin L-rhamnose), the pharmacological action of R-16 was compared with that of ouabain. On the contractions of isolated guinea-pig papillary muscle driven by electrical stimulation (twice of threshold intensity, 10 msec, and 2 Hz) kept in a Locke’s solution at 30°C, R-16 (3 μM) arrested the contraction at 34.4±2.2 min after application, and ouabain (3 μM) did it at 31.5±2.1 min, i.e., at almost the same time. However, the increase in contractile force induced by R-16 was by about 20% greater than that of ouabain. As it is a characteristic action of ouabain to inhibit Na, K-ATPase activity, this kind of action was examined on R-16. R-16 (1.0 μM to 1.0 mM) decreased the activity in microsome rat brain tissue to almost the same degree as ouabain at the same dose. From the results, it is assumed that the new glycoside, R-16, has a cardiotonic action, and the potency is slightly greater than that of ouabain.