Total Syntheses and Anti-inflammatory Evaluations of Pongamosides A-C, Natural Furanoflavonoid Glucosides from Fruit of (L.) Pierre.

The syntheses of three natural furanoflavonoid glucosides, including two flavone glucosides, pongamosides A () and B (), and a flavonol glucoside, pongamoside C (), were achieved for the first time in 9-15 steps from commercially available materials in overall yields ranging from 2.9% to 29%. The synthetic sequence featured a NaH-promoted BK-VK rearrangement and acid-catalyzed intramolecular cyclization to furnish the furanoflavonoid aglycone. Meanwhile, phase-transfer-catalyzed glycosylation and Schmidt's trichloroacetimidate procedure were employed to establish the pivotal -glycosidic linkage. The anti-inflammatory activities of compounds -, as well as their aglycones , , and , were determined against NO production in the LPS-stimulated RAW264.7 cells. The results indicated that the -glycosylation may reduce the anti-inflammatory activity of furanoflavonoid .