Structural revision of periplocosides and periperoxides, natural immunosuppressive agents from the genus Periploca

Abstract

The structures of a series of peroxy function containing pregnane glycosides isolated from Periploca sepium and Periploca forrestii were revised to be orthoester group bearing ones using 2D NMR spectroscopic techniques, as well as chemical transformations and X-ray crystallographic diffraction analysis. The orthoester function appears to be an essential structural feature for immunosuppressive activity.