BIOLOGICAL-ACTIVITIES OF 4 STEREOISOMERS OF YCLOHEPTA[B]PYRIDIN-9-YLSULFINYL)-1H-BENZIMIDAZOLE SODIUM-SALT AND ACID-INDUCED TRANSFORMATIONS- NOVEL PROTON PUMP INHIBITOR

The sodium salts (5) of four stereoisomeric benzimidazolylsulfoxides, (Ss,9R)-(-)-4, (Rs,9S)-(+)-4, (Ss,9S)-(-)-4 and (Rs,9R)-(+)-4, were pr epared from optically pure sulfides, (+)-8 and (-)-8. The sulfoxides ( 4) were transformed into sulfenamides (6) and symmetric disulfides (9) under acidic conditions, without any change of stererochemical config uration at the alpha-carbon bearing the sulfinyl group. No significant difference was observed among the four stereoisomers in inhibitory ac tivity towards (H+ + K+)-ATPase in vitro. However, (Ss,9R)-(-)-5 showe d more long-lasting antisecretion activity in vivo than that of anothe r enantiomer, (Rs,9S)-(+)-5.