Separation and evaluation of potential antioxidant, analgesic, and anti-inflammatory activities of limonene-rich essential oils from Citrus sinensis (L.)

The peel of Citrus sinensis (L.) Osbeck is a source of essential oils, particularly limonene, which is this plant's characteristic molecule. The main goal of this study was to test the potential analgesic and anti-inflammatory properties of limonene-rich essential oils derived from the peel of C. sinensis L. (orange) in vivo, as well as their antioxidant activity in vitro. Carrageenan-induced paw edema in Wistar rats and the formalin test in Swiss albino mice were used to examine anti-inflammatory activity. The analgesic activity was assessed using hot plate and acetic acid writhing tests, while the antioxidant activity was assessed using the 1,1-diphenyl-2-picrylhydrazyl and ferric reducing antioxidant power methods. The essential oil (EO) safety was determined using an acute toxicity experiment on mice. The phytochemical analysis confirmed the existence of limonene as the primary molecule (88.94%), and in vivo experiments revealed that the EO had a significant pain and inflammation-relieving effect, especially at the dose of 50 mg/kg, when compared to the used control drugs. The acute toxicity evaluation reported this EO's safety. This study contributes to the pharmacological valorization of the peel of C. sinensis L., confirming that, in addition to its numerous cosmetic and industrial uses, it may be effective in the treatment of inflammatory and pain-related illnesses.