Suppression of inducible nitric oxide synthase (iNOS) and cyclooxygenase II (Cox-2) by fermented product of Citrus sunki peel in lipopolysaccharide-activated RAW264.7 cells

Peel of Citrus sunki traditionally has been considered to have a potential anti-inflammatory activity and used to alleviate respiratory symptoms in Korea. However, little is known about the pharmacological activities of C. sunki peel. The present study aimed to investigate whether the extract of C. sunki peel and its fermented product may have any anti-inflammatory activities such as scavenging of reactive oxygen species (ROS), suppression of nitric oxide synthase (iNOS) and cyclooxygenase II (Cox-2) in various cellular systems. Ethanol extract of C. sunki peel showed a potent ROS-scavenging activity from experiments using 2',7'-dichlorofluorescin diacetate as a fluorescent ROS probe in HepG2 cells. In addition, fermented product of extract of C. sunki peel markedly suppressed the production of nitric oxide in lipopolysaccharide (LPS)-activated RAW264.7 murine macrophage cells. Intracellular protein levels of iNOS and Cox-2 stimulated by LPS were also decreased by treatment with fermented product of extract of C. sunki peel. Stepwise fractionation is being performed to isolate more effective constituents with less toxic and less side effects to develop potent anti-inflammatory medicines.