Twenty maslinic acid and corosolic acid derivatives were obtained by coupling with l-amino acids at C-28 position. The α-glucosidase inhibitory activities of the present compounds were evaluated in vitro. Results reveal that some of the derivatives exhibit a better α-glucosidase inhibitory activity than that of acarbose in the test conditions of ethanol-water solution and DMSO. It is worth noting that maslinic acid and corosolic acid derivatives coupled aspartic acid (9f: IC50 = 382 μm and 10f: IC50 = 364 μm, respectively) have the best water solubility and thus presented higher inhibitory activity than that of acarbose (IC50 = 484 μm). Unfortunately, all of the derivatives possess lower inhibitory properties of α-glucosidase than those of the parent compounds in the measurement system of DMSO solution, even if the derivatives exhibit better water solubility than that of the parent compounds.
Keywords: Corosolic acid; Maslinic acid; Water solubility; l-amino acids; α-Glucosidase inhibitory activities.
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