Abstract
The objectives of this work were to determine the phytochemical composition and antioxidant, anti-diabetic, antibacterial, anti-inflammatory, and anti-acetylcholinesterase properties of Arbutus unedo L. and Laurus nobilis L. EOs. The antioxidant effects were estimated using four complementary methods. In addition, the anti-diabetic activity was assessed by targeting three carbohydrate-hydrolyzing enzymes, namely alpha-amylase, alpha-glucosidase, and lipase. The anti-inflammatory and anti-acetylcholinesterase effects were evaluated by testing the inhibitory potential of both plants on lipo-oxygenase and acetylcholinesterase (AChE), respectively. The antimicrobial activity of these oils was evaluated using disc-diffusion, minimum inhibitory concentration (MIC), and minimum lethal concentration (MLC) tests. The chemical composition of L. nobilis essential oil (EO) was dominated by eucalyptol (36.40%), followed by alpha-terpineole (13.05%), alpha-terpinyl acetate (10.61%), linalool (10.34%), and northujane (5.74%). The main volatile compounds of A. unedo EOs were decenal (13.47%), alpha-terpineol (7.8%), and palmitic acid (6.00%). L. nobilis and A. unedo EOs inhibited alpha-amylase with IC50 values of 42.51 +/- 0.012 and 102 +/- 0.06 mu g/mL, respectively. Moreover, both oils inhibited the activity of alpha-glucosidase (IC50 = 1.347 +/- 0.021 mu g/mL and IC50 = 76 +/- 0.021 mu g/mL) and lipase (IC50 = 21.23 +/- 0.021 mu g/mL and IC50 = 97.018 +/- 0.012 mu g/mL, respectively). In addition, L. nobilis EO showed an anti-AChE activity (IC50 = 89.44 +/- 0.07 mu g/mL) higher than that of A. unedo EO (IC50 = 378.57 +/- 0.05 mu g/mL). Regarding anti-inflammatory activity, in vitro assays showed that L. nobilis significantly inhibits (IC50 = 48.31 +/- 0.07 mu g/mL) 5-lipoxygenase compared to A. unedo (IC50 = 86.14 +/- 0.05 mu g/mL). This was confirmed in vivo via a notable inhibition of inflammation recorded after 6 h of treatment in both plants at a dose of 50 mg/kg. The microbiological results revealed that EOs from both plants inhibited the growth of all tested organisms except P. aeruginosa, with the highest antimicrobial effect for L. nobilis. The results of these tests showed that these two plants possess remarkable biological and pharmacological properties, explaining their medicinal effects and suggesting them as promising sources of natural drugs.