Anti-Inflammatory Activities of Isogosferol, a Furanocoumarin Isolated from Citrus junos Seed Shells through Bioactivity-Guided Fractionation

Citrus junos Tanaka is a traditional medicine for treating coughs, dyspepsia, diabetes, asthma, neuralgia, and inflammatory disorders, and is distributed in Asia, especially in Korea, Japan, and China. This study aimed to use bioactivity-guided fractionation to find therapeutic phytochemicals from C. junos seeds, which can attenuate inflammatory responses. Nine coumarins (1–9) were isolated from the methanolic extract of C. junos seed shells and the inhibitory effects against inflammatory mediators were investigated using murine macrophages. Among the coumarins, compound 3, isogosferol (ISO), more potently attenuated the production of nitric oxide (NO) in lipopolysaccharide (LPS)-induced RAW 264.7 cells. ISO also inhibited the expression of inducible nitric oxide (iNOS) and cyclooxygenase-2 (COX-2) in LPS-stimulated macrophages. Additionally, the phosphorylation of extracellular-regulated kinases (pERK)1/2 was reduced by ISO. We confirmed that ISO attenuated the release of interleukin-1 beta (IL-1β), which is a central mediator of the inflammatory response. These results demonstrate that ISO from C. junos seed shells may be a potent therapeutic candidate for the treatment of inflammatory diseases.