| Abstract
| - Chemical investigation of a red-type Cuban propolis sample has led to the isolation of 11 isoflavonoids(2 isoflavones, 3 isoflavans, and 6 pterocarpans), together with gallic acid, isoliquiritigenin, and (−)-liquiritigenin. Structural determination, including the absolute stereochemistry, was accomplished byspectroscopic analysis, particularly CD and 2D NMR techniques. The fragmentation behavior ofpterocarpans was studied by electrospray ionization (ESI) tandem mass spectrometry (MS/MS) usingan ion-trap analyzer, and a generalized fragmentation pathway, useful in the identification and structuralcharacterization of pterocarpans, is proposed. Isoflavonoids are reported for the first time from propolissamples. Keywords: Propolis; isoflavonoids; isoflavans; pterocarpans; isoliquiritigenin; (−)-liquiritigenin; 1Dand 2D NMR spectroscopy; CD; ESI-MS/MS
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