Studies on synthesis and structure-activity relationships against cytoprotective activity of triterpenoidal diglycosides with an acid saccharide, d-glucopyranosuronic acid

Synthesis and anti-HIV activity of triterpene 3-O-galactopyranosides, analogs of glycyrrhizic acid

“…Forming such a bond between GD and sterically hindered 3-OH of triterpene alcohols is a rather complicated problem. Glycosylation of natural triterpenoids by readily available GD such as glycosylhalides is usually carried out using compounds of mercury [Hg(CN) 2 , HgBr 2 ] and silver (Ag 2 O, Ag 2 CO 3 , AgOTf) as promoters [1][2][3][4][5]7]. Use of mercury salts for practical syntheses of triterpene glycosides is limited by their high toxicity whereas silver salts are expensive.…”

“…Use of mercury salts for practical syntheses of triterpene glycosides is limited by their high toxicity whereas silver salts are expensive. As a rule, both methods produce a mixture of D-and E-O-glycosides in 30-70% yields [1][2][3][4].In continuation of our studies of the synthesis of biologically active GA analogs [8], we studied glycosylation of triterpenoids from licorice root using the convenient and inexpensive reagent iodine monobromide (I-Br), which was proposed earlier by Field and Kartha for synthesizing various simple glycosides and disaccharides [9,10]. However, it has not yet been used to synthesize triterpene glycosides.…”

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The synthesis of model triterpene glycosides that are analogs of glycyrrhizic acid (GA) with a modified carbohydrate chain is of great interest for studying the molecular mechanisms of GA biological activity, toxicity, and structure-activity relationships [1][2][3][4][5].The sugar moiety in most natural triterpene glycosides is bonded to the sapogenin 3-OH through a 1,2-trans-glycosidic bond [6]. Therefore, a key step in the synthesis of saponins is 3-O-glycosylation of the corresponding triterpene sapogenins by mono-and disaccharide glycosyl donors (GD).

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“…The synthesis of model triterpene glycosides that are analogs of glycyrrhizic acid (GA) with a modified carbohydrate chain is of great interest for studying the molecular mechanisms of GA biological activity, toxicity, and structure-activity relationships [1][2][3][4][5].…”

“…Use of mercury salts for practical syntheses of triterpene glycosides is limited by their high toxicity whereas silver salts are expensive. As a rule, both methods produce a mixture of D-and E-O-glycosides in 30-70% yields [1][2][3][4].…”