Antioxidant, Anti-inflammatory, and Analgesic Activities of Citrus reticulata Blanco Leaves Extracts: An In Vivo and In Vitro Study

Abstract

Citrus species are cultivated and consumed widely. Citrus have been investigated for their pharmacological activity and human health. Their beneficial effects include antibacterial, analgesic, anti-inflammatory, and antitumoral effects. This studywas designed to evaluate the analgesic effect and the antioxidant and anti-inflammatory activities of Citrus reticulata Blanco leaves extracts (ECR) in cell and animal models. Antioxidant, anti-inflammatory, and antinociceptive activities were evaluated in mice using 1,1-diphenyl-2-picrylhydrazyl (DPPH) radical inhibition, xylene-induced ear edema, formalin assay and acetic acid-writhing response. Expression of antiinflammatory genes was measured in lipopolysaccharide (LPS)-treated Huh7 cells. ECR showed a significant DPPH radical scavenging activity. No behavioral changes or deaths were observed in mice at doses less than 2,000 mg/kg body weight. Different concentrations of methanolic and aqueous extracts (100–500 mg/kg body wt.) reduced the duration of linking behavior in the second phase of the formalin chemical nociception assay and decreased the number of acetic acidinduced writhing responses in mice, indicating significant analgesic activity. ECR also diminished xylene-induced ear swelling in mice, suggesting an In Vivo anti-inflammatory action. No toxicity of ECR in the range of 0.1–10 μg/ml was observed by 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide. Cell treatment with LPS-induced oxidative/ nitrosative stress as assessed by flow cytometry as the fluorescence of 2′,7′-dichlorofluorescein. This effect was significantly inhibited in a dose-dependent manner by ECR. Administration of ECR caused a dose-dependent inhibition of cytochrome P450 2E1, inducible nitric oxide synthase, tumor necrosis factor α, and interleukin-6 expression in LPS-treated cells. The present study demonstrates that extracts of Citrus reticulata leaves are safe, having antioxidant, anti-inflammatory, and analgesic effects both In Vivo and In Vitro.