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

The syntheses of three natural furanoflavonoid glucosides, including two flavone glucosides, pongamosides A ( 1 ) and B ( 2 ), and a flavonol glucoside, pongamoside C ( 3 ), 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 O -glycosidic linkage. The anti-inflammatory activities of compounds 1 - 3 , as well as their aglycones 5a , 5b , and 23 , were determined against NO production in the LPS-stimulated RAW264.7 cells. The results indicated that the O -glycosylation may reduce the anti-inflammatory activity of furanoflavonoid in vitro .