In vitro anti-inflammatory and anti-oxidative effects of Cinnamomum camphora extracts

Cinnamomum camphora Sieb (Lauraceae) has long been prescribed in traditional medicine for the treatment of inflammation-related diseases such as rheumatism, sprains, bronchitis and muscle pains. In this study, therefore, we aimed to investigate the inhibitory effects of Cinnamomum camphora on various inflammatory phenomena to explore its potential anti-inflammatory mechanisms under non-cytotoxic (less than 100 μg/ml) conditions. The total crude extract (100 μg/ml) prepared with 80% methanol (MeOH extract) and its fractions (100 μg/ml) obtained by solvent partition with hexane and ethyl acetate (EtOAc) significantly blocked the production of interleukin (IL)-1β, IL-6 and the tumor necrosis factor (TNF)-α from RAW264.7 cells stimulated by lipopolysaccharide (LPS) up to 20-70%. The hexane and EtOAc extracts (100 μg/ml) also inhibited nitric oxide (NO) production in LPS/interferon (IFN)-γ-activated macrophages by 65%. The MeOH extract (100 μg/ml) as well as two fractions (100 μg/ml) prepared by solvent partition with n-butanol (BuOH) and EtOAc strongly suppressed the prostaglandin E₂ (PGE₂) production in LPS/IFN-γ-activated macrophages up to 70%. It is interesting to note that hexane, BuOH and EtOAc extracts (100 μg/ml) also inhibited the functional activation of β1-integrins (CD29) assessed by U937 homotypic aggregation up to 70-80%. Furthermore, EtOAc and BuOH extracts displayed strong anti-oxidative activity with IC₅₀ values of 14 and 15 μM, respectively, when tested by the 1,1-diphenyl-2-picrylhydrazyl (DPPH) and xanthine oxide (XO) assays. Taken together, these data suggest that the anti-inflammatory actions of Cinnamomum camphora may be due to the modulation of cytokine, NO and PGE₂ production and oxidative stress, and of the subfractions tested, the EtOAc extract may be further studied to isolate the active anti-inflammatory principles.