Antioxidants and α-glucosidase inhibitors from lactuca serriola l.

Our main objective in the present study was investigation of potential antidiabetic and antioxidant compounds from the methanol extract of Lactuca serriola L. Phytochemical investigation allowed the isolation of seventeen known compounds and their structures were identified based on IR, 1D and 2D NMR techniques and mass spectrometry. Lupeol (1), β-sitosterol (2), taraxast-20-ene-3β,30-diol (3), glycerol monopalmitate (4) (2S,3S,4R,2`R,14E)-2-(2`-hydroxytetracosanoylamino)-14-octadecene-1,3,4-triol (5), lactucopicrin (6), daucosterol (7), (E)-p-coumaric acid (8), 11β,13-dihydrolactucin (9), 4-hydroxybenzoic acid (10), protocatechuic acid (11), kaempferol (12), quercetin (13), lactuside A (14), luteolin-7-O-β-D glucoside (15), lactuside B (16) and cichorioside B (17) were isolated from the species. The antioxidant activity was evaluated using ABTS, DPPH radical scavenging and FRAP assays. The ethyl acetate fraction of the aerial parts of species showed remarkable α-glucosidase inhibitory activity (IC₅₀, 9.16±0.17 µg/mL) and antioxidant activity among the tested fractions. The in vitro α-glucosidase inhibitory assay is reported in this study for the first time for L. serriola L. The results strongly suggest that L. serriola L. can be used as a potential good natural remedy targeting oxidative stress-related diabetes mellitus.