Isolation of pentasaccharide resin glycosides from the whole plants of Ipomoea biflora and their cytotoxic activities.

A total of eight previously undescribed pentasaccharide resin glycosides, named ipomofins I-VIII (1-8), along with five known ones (9-13), were isolated from the whole plants of Ipomoea biflora. Their structural elucidation was achieved through a comprehensive application of spectroscopic and chemical techniques. All these resin glycosides were characterized as partially acylated pentasaccharides, originating from operculinic acids A or D, containing l-rhamnose, d-glucose, d-xylose or d-fucose units, and 11S-hydroxyhexadecanoic acid serving as the aglycone. Notably, compounds 1 and 2 represent the first resin glycosides with operculinic acid D as their core structure, while compounds 3 and 4 are the first derivatives of operculinic acid A featuring a 23-membered ring. Compounds 1, 2, and 4-6 exhibited apparent cytotoxic effects against certain cancer cell lines. Particularly, compound 5 demonstrated the ability to impair colony formation, reduce the proportion of EdU-positive cells, and enhance the expression of proteins related to endoplasmic reticulum stress (ERS) in HCT-15 cells, indicating that its cytotoxicity might be driven by the activation of ERS pathways. Collectively, this research identified 13 resin glycosides from I. biflora, including eight previously undescribed compounds, with compound 5 emerging as a potential anticancer agent due to its induction of ERS.