Further new resin glycosides from Convolvulus tricolor seeds and their neuroprotective activities

Resin glycosides, the characteristic constituents of family Convolvulaceae, are a kind of new and complex glycolipids with diversified biological activities. In the present study, the ethanolic extract of Convolvulus tricolor seeds were purified by various separation methods, leading to the isolation of seven new resin glycosides (1-7). Their structures were established as glycosidic acids methyl esters by extensive spectroscopic analyses and chemical evidences, and were considered to be generated via methyl esterification of natural resin glycosides during the NH₂ silica gel chromatography. Compounds 1 and 2 are rare octasaccharide resin glycosides, while compounds 4-6 restored the viability of H₂O₂-damaged PC12 cells from 62.74 % to 71.79 %-95.39 %, suggesting the neuroprotective effect. Taken together, these findings not only expanded the understanding on the structural diversity of resin glycosides, but also provided potential candidates for further pharmaceutical applications.