The inhibitory effects of Citrus unshiu Markovich extracts on the receptor activator of nuclear factor-kappa-B ligand-mediated osteoclast differentiation and function

Neuroprotective properties of ethanolic extract of Citrus unshiu Markovich peel through NADPH oxidase 2 inhibition in chemotherapy-induced neuropathic pain animal model

The present study aimed to determine the antioxidant effect of Citrus unshiu Markovich (CUM) extract in neuronal cell lines under oxidative stress and to investigate the effect of chemotherapy-induced peripheral neuropathy (CIPN) on the nociceptive response in a preclinical mice model. We tested the inhibition of H₂ O₂ in Neuro2A cells treated with CUM. Experimental animals were treated with oxaliplatin to induce CINP, and then administered oral CUM for 4 weeks in order to observe the effect of CUM. Animals were evaluated weekly for thermal hyperalgesia and digital motor nerve conduction velocity (NCV). Lumbar dorsal root ganglia (DRG) isolated from each animal were evaluated through immunochemical and western blot analysis for nerve damage, inflammatory response, and expression of redox signaling factors. The main mechanisms were determined to be decreased inducible nitric oxide synthase (iNOS) production due to the inhibition of NADPH oxidase 2 (NOX2). To determine the functional role of NOX2 in CINP, we administrated CUM into NOX2-deficient mice with neuropathic pain. Therefore, we suggest that CUM controls the expression levels of inflammatory factors in CINP via NOX2 inactivation. This study demonstrated that a complementary medicine such as CUM might be a potential novel therapeutic agent for the treatment of CINP.

Skin Lightening Effect of the Dietary Intake of Citrus Peel Extract Against UV-Induced Pigmentation

Recent studies revealed that citrus peel has beneficial effects in various disorders associated with nitric oxide and/or oxidative stress. In this study, we investigated the effects of Jeju citrus ( Citrus unshiu) peel using various in vitro and in vivo methods. First, the inhibitory effect of citrus peel extract (CPE) on enzymatic activity of tyrosinase was evaluated. Tyrosinase activity was dose-dependently decreased by CPE. Second, the effect of CPE on melanogenesis was determined by measuring the melanin content in melan-a cells. The inhibitory effect of CPE on melanin synthesis was greater than that of vitamin C. Finally, the effect of long-term supplementation with CPE on ultraviolet B-induced skin pigmentation was examined in guinea pigs. Administration of CPE improved Δ L-value compared with the nontreated ultraviolet control group. As a strong inhibitor of melanogenesis, CPE could be used as a depigmentation agent and a supplement for skin lightening.