In vitro α-glucosidase inhibitory activity of compounds isolated from mangrove Lumnitzera littorea leaves

Introduction: Lumnitzera littorea grown at CanGio Mangrove Forest has been investigated. The present study reports the isolation, characterization and evaluation of the alpha-glucosidase inhibitory activity of isolated compounds from Lumnitzera littorea leaves. Methods: Their structures were elucidated by spectroscopic methods (including MS, 1D and 2D–NMR) and comparison with values from the literature. From the n-hexane extract, nine compounds including lupeol (1), betulin (2), betulinic acid (3), oleanolic acid (4), corosolic acid (5), -sitosterol (6), beta-sitosterol 3-O- beta-D-glucopyranoside (7), stigmast-5-ene-3beta-O-(6-O-hexadecanoyl-beta-D-glucopyranoside) (8), and stigmast-4-ene-3-one (9) were isolated and identified. Results: The results of the alpha-glucosidase inhibitory activity showed thatcorosolic acid (5) and oleanolic acid (4) were the most potent, with IC50 values of 17.86 +/- 0.42 and 18.82 +/- 0.59 ug/mL, respectively. Five of the other seven compounds exhibited inhibitory activity with IC50 values below 100 ug/mL, and higher than the positive control acarbose (127.64 +/- 0.64 ug/mL).