Chemical composition of essential oils of Citrus limon peel from three Moroccan regions and their antioxidant, anti-inflammatory, antidiabetic and dermatoprotective properties

Introduction: The current study aimed to explore the in vitro antioxidant, anti-inflammatory, antidiabetic, and dermatoprotective properties of lemon peel essential oil (EO). Methods: The chemical composition of lemon EOs extracted from the lemon of three cities in Morocco was investigated using gas chromatography-mass spectrometry (GC-MS) analysis. The antioxidant property was estimated by two complementary tests: Ferric ion reducing antioxidant power (FRAP) and 1,1-diphenyl-2-picrylhydrazyl (DPPH). The in vitro anti-inflammatory activity was assessed by the inhibition of albumin denaturation and proteinase. Inhibitory properties of α-glucosidase and α-amylase were used to reveal the antidiabetic activity of lemon peel EOs. Dermatoprotective property was evaluated by the tyrosinase inhibition method. Results: In addition to high amounts of polyphenols and flavonoids, GC-MS analysis of lemon peel EOs demonstrated the presence of D-limonene, β–pinene, and γ-terpinene as the main compounds in the three samples studied. Lemon peel EOs exhibited significant antioxidant activities by IC50 values ranging from 40.57 µg/mL to 100.22 µg/mL and 113.63 µg/mL to 180.90 µg/mL obtained by DPPH and FRAP tests, respectively. in vitro inhibition of enzymes involved in inflammatory response revealed that lemon peel EOs presented remarkable inhibitory activities against albumin denaturation (230.48 µg/mL IC50 341.13 µg/mL) and proteinase (199.70 µg/mL IC50 307.05 µg/mL). Moreover, lemon peel EOs demonstrated powerful inhibition of α-amylase and α-glucosidase with various IC50 values (1689.06 µg/mL IC50 4000 µg/mL and 1021.58 µg/mL C50 2467.62 µg/mL), respectively. These EOs also revealed significant inhibition of tyrosinase with IC50 values ranging from 248.42 μg/mL to 378.02 μg/mL. Conclusion: These results revealed that lemon peel EOs might constitute a new product with beneficial biological abilities against the mentioned complications.