Anti-inflammatory effects of essential oil isolated from the buds of Cleistocalyx operculatus (Roxb.) Merr and Perry

Cleistocalyx operculatus (Roxb.) Merr and Perry buds (Myrtaceae) are widely used in folk medicine for the treatment of gastric ailments as well as an antiseptic agent in China, Vietnam and some other tropical countries. However, to be clinically useful, more scientific data are needed. In the present study, we investigated the in vitro and in vivo anti-inflammatory activities of the essential oil of the C. operculatus buds (EO–CO). In the applied tests, EO–CO significantly inhibited lipopolysaccharide (LPS)-induced secretion of pro-inflammatory cytokines, including tumor necrosis factor-α (TNF-α) and interleukin-1β (IL-1β), in RAW 264.7 cells, a mouse macrophage-like cell line. Also the mRNA expression of TNF-α and IL-1β was suppressed by treatment with EO–CO in LPS-stimulated RAW 264.7 cells. Moreover, reporter gene analysis revealed that the EO–CO significantly blocked LPS-induced transcriptional activation of NF-κB in RAW 264.7 cells. Nuclear translocation of p65 subunit was also suppressed by EO–CO treatment. In addition, EO–CO inhibited phorbol ester-induced increase in ear swelling and skin water content in BALB/c mice. These results suggest that EO–CO might exert an anti-inflammatory effect by suppressing the expression of pro-inflammatory cytokines which is mediated, at least in part, by blocking NF-κB activation.