Effect of Laurus nobilis L. Essential Oil and its Main Components on α-glucosidase and Reactive Oxygen Species Scavenging Activity

The present study was designed to determine the effects of the essential oil of Laurusnobilis L. (Lauraceae) and its three main components on α-glucosidase and reactive oxygenspecies scavenging activity. The chemical composition of the essential oil from Laurus nobilisL. leaves was analyzed by GC/GC-MS and resulted in the identification of 29 compounds,representing 99.18% of the total oil. 1,8-cineole (68.82%), 1-(S)-α-pinene (6.94%), and R-(+)-limonene (3.04%) were determined to be the main components. The antioxidant features of theessential oil and its three main components were evaluated using inhibition of 2,2-diphenyl-1-picrylhydrazyl, hydroxyl, and superoxide radicals, inhibition of hydrogen peroxide and lipidperoxidation assays. The results show that the DPPH, hydroxyl, and superoxide radical as wellas hydrogen peroxide scavenging activities of the essential oil are greater than the positivecontrols and the three main components of the oil when tested independently. The inhibitionof lipid peroxidation by the oil occurred less frequently than with 1,8-cineole and R-(+)-limonene alone, but the effects were more pronounced than those seen with 1-(S)-α-pineneand the positive controls. An α-glucosidase inhibition assay was applied to evaluate the in-vitroantidiabetic activity of the essential oil. IC50-values were obtained for laurel essential oil, 1,8-cineole, 1-(S)-α-pinene, and R-(+)-limonene: 1.748 μL/mL, 1.118 μL/mL, 1.420 μL/mL and1.300 μL/mL, respectively. We also found that laurel essential oil and 1, 8-cineole inhibitedthe α-glucosidase competitively while 1-(S)-α-pinene and R-(+)-limonene were uncompetitiveinhibitors.