Chamaecyparis obtusa (Siebold & Zucc.) Endl. leaf extracts prevent inflammatory responses via inhibition of the JAK/STAT axis in RAW264.7 cells.

Chamaecyparis obtusa (Siebold & Zucc.) Endl. (C. obtusa) has been used as folk medicine in East Asia and has been reported to alleviate inflammatory diseases. However, the detailed mechanisms for the anti-inflammatory effects of C. obtusa remain unclear. Although the anti-inflammatory mechanisms of natural products have been studied for decades, it is still important to identify the potential anti-inflammatory effects of natural sources. In this study, we investigated the anti-inflammatory effects and underlying mechanism of C. obtusa leaf extracts. The cell viability was determined by MTT and crystal violet staining. NO production in the supernatant was measured using Griess reagent. The cell lysates were analyzed by immunoblotting and RT-qPCR. Secreted cytokines were analyzed using ELISA kit and cytokine array kit. mRNA expression from the GSE9632 database set. Z-scores were calculated for each gene and visualized by heat map. Among the extracts of C. obtusa obtained with different extraction methods, the 99% ethanol leaf extract (CO99EL) strongly inhibited lipopolysaccharide (LPS)-induced inducible nitric oxide synthase (iNOS) and cyclooxygenase-2 (COX-2) expression and Janus kinase/signaling transducer and activator of transcription (JAK/STAT) phosphorylation in RAW264.7 cells. In addition, CO99EL strongly inhibited LPS-induced interleukin (IL)-1β, IL-6, IL-27, and C-C motif chemokine ligand (CCL)-1 production and directly inhibited LPS-induced JAK/STAT phosphorylation in RAW264.7 cells. These findings demonstrate that CO99EL significantly prevents LPS-induced macrophage activation by inhibiting the JAK/STAT axis. Therefore, we suggest the use of C. obtusa extracts as therapeutic approach for inflammatory diseases. [Display omitted] • The cytotoxicity of the leaf extracts was lower and the yields were higher than for the other C. obtusa extracts. • CO99EL had remarkably potent anti-inflammatory effects among the C. obtusa leaf extracts in RAW264.7 cells. • CO99EL inhibited LPS-induced JAK/STAT by inhibiting pro-inflammatory secreted molecules in RAW264.7 cells. • CO99EL directly inhibited JAK/STAT activation in RAW264.7 cells. [ABSTRACT FROM AUTHOR]