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 ۱,۱-diphenyl-۲-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 IC۵۰ values ranging from ۴۰.۵۷ μg/mL to ۱۰۰.۲۲ μg/mL and ۱۱۳.۶۳ μg/mL to ۱۸۰.۹۰ 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 (۲۳۰.۴۸ μg/mL > IC۵۰ < ۳۴۱.۱۳ μg/mL) and proteinase (۱۹۹.۷۰ μg/mL > IC۵۰ < ۳۰۷.۰۵ μg/mL). Moreover, lemon peel EOs demonstrated powerful inhibition of α-amylase and α-glucosidase with various IC۵۰ values (۱۶۸۹.۰۶ μg/mL > IC۵۰ > ۴۰۰۰ μg/mL and ۱۰۲۱.۵۸ μg/mL > C۵۰ < ۲۴۶۷.۶۲ μg/mL), respectively. These EOs also revealed significant inhibition of tyrosinase with IC۵۰ values ranging from ۲۴۸.۴۲ μg/mL to ۳۷۸.۰۲ μg/mL. Conclusion: These results revealed that lemon peel EOs might constitute a new product with beneficial biological abilities against the mentioned complications.

Keywords:

Lemon , Digestive enzymes , Monoterpene compounds Proteinase , Tyrosinase