Comparative analysis of C-glycosidic flavonoids from Prosopis spp. and Ceratonia siliqua seed germ flour

Seed germ of South American algarrobo (Prosopis species) and European carob (Ceratonia siliqua) contains nutritionally interesting proteins, lipids and phenolics. Using reversed phase-HPLC-diode array detector and nanoflow-HPLC coupled to tandem mass spectrometry (MS/MS), we comparatively characterized and semi-quantified flavonoids from germ of three Argentinean algarrobo (Prosopis alba, Prosopis nigra and Prosopis ruscifolia) and one European carob species. The patterns of glycosylated flavonoids were very similar each other, confirming the taxonomic parentage of the species and supporting their functional similarity on a molecular basis, in view of the use of seed germ flour (SGF) for food applications. The predominant phenolic compounds were apigenin 6,8-C-di-glycoside isomers, namely isoschaftoside and schaftoside, accounting for 3.22-5.18 and 0.41-0.72 mg/g SGF, respectively. C. siliqua germ contained relatively high amounts of further glycosilated derivatives of (iso)schaftoside, which occurred at a lower abundance in Prosopis. Apigenin 6,8-C-di-glycosides have been described as potent ?-glucosidase inhibitors, suggesting that food preparations obtained with Prosopis spp. and C. siliqua SGF might contribute to modulate the digestion of carbohydrates in humans. Chemical compounds Isoschaftoside (PubChem CID: 13644661); Schaftoside (PubChem CID: 442658); Vicenin-2 (PubChem CID: 442664); Isovitexin (PubChem CID: 162350).