Investigation into the species-specific deacylation of penta-acetyl-gitoxin

Penta-acetyl-gitoxin (PAG) shows species-specific deacylation to 16-acetyl-gitoxin (16 AG; I and III) or gitoxin (II and IV) by homogenates of liver and intestinal mucosa of man (I), rabbit (II), guinea-pig (III) and rat (IV), whereas it is degraded into tri- and tetra-acetates by homogenates of guinea-pig myocardium as well as by human blood and serum. The identity of the principal and chloroform-extractable metabolities in human urine after PAG administration with 16-AG has been demonstrated by mass spectrometry.