Perisesaccharides A-E, new oligosaccharides from the root barks of Periploca sepium

Five new oligosaccharides, named perisesaccharides A-E (1- 5), were isolated from the root barks of Periploca sepium. Their structures were elucidated by NMR and HRESIMS data. The absolute configurations of these compounds were determined by a combination of X-ray diffraction analysis, modified Mosher's method, circular dichroism spectroscopy, and acid hydrolysis. The boat conformation of oleandronic acid delta-lactone was reported for the first time.