Carob is a resilient plant with ecological and nutritional significance. A comprehensive study of Ceratonia siliqua leaves (CSL) was conducted to explore its chemical composition and health-promoting potential, aiming at improving the carob-crop sustainability through valorization of this untapped co-product. UHPLC-DAD-HRMS/MS quali-quantitative profiling of CSL revealed high levels of n-galloylated glucoses (129-196mgg-1) and flavonol-glycosides (36-42mgg-1), with siliquapyranone (39-56mgg-1), 1,2,3,6-tetragalloylglusose (47-69mgg-1) and myricitrin (27-33mgg-1) as main markers. Highest bioactive content and antioxidant capacity (5.0 and 3.1 TEAC) was obtained during pods harvesting. Besides significant antioxidant potential, CSL exhibited strong-high inhibitory activity against α-glucosidase, acetylcholinesterase and butyrylcholinesterase (IC50, 0.51, 13.5 and 58.0μgmL-1, respectively). 1,2,3,6-tetragalloylglusose and siliquapyranone are the main contributors to antioxidant and α-glucosidase inhibitory capacities. Excellent ability of extract and 1,2,3,6-tetragalloylglusose (IC50, 0.05μM) in selectively inhibiting α-glucosidase, make them promising candidates to manage hyperglycemia with fewer side effects.
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