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

 The current study aimed to explore the in vitro antioxidant, anti-inflammatory, antidiabetic, and dermatoprotective properties of lemon peel essential oil (EO).

 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.

 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.

 These results revealed that lemon peel EOs might constitute a new product with beneficial biological abilities against the mentioned complications.