Context: Cinnamomum osmophloeum Kaneh. (Lauraceae) is one of the indigenous tree species in Taiwan. This tree species has been of interest to researchers because the chemical constituents of its essential oil are similar to those of Cinnamomum cassia Presl. bark oil, known as cinnamon oil, which is commonly used in foods and beverages. Objective: The anti-inflammatory activities of the leaf essential oils and their major compounds from seven provenances of C. osmophloeum are investigated here for the first time. Materials and methods: Chemical compositions of hydrodistilled essential oils obtained from C. osmophloeum leaves were analyzed by gas chromatography-mass spectrometry (GC-MS), and the effects of essential oils on nitric oxide (NO) production in lipopolysaccharide (LPS)-activated RAW 264.7 macrophages were investigated. Results: The leaf essential oils of cinnamaldehyde type and mixed type strongly inhibited NO production, with IC50 values ranging from 9.7-15.5μg/mL. Furthermore, trans-cinnamaldehyde is responsible for the inhibitory activity of cinnamaldehyde type, and T-cadinol and α-cadinol are responsible for the inhibitory activity of mixed type. Discussion and conclusion: These findings demonstrate that the leaf essential oils and their constituents of C. osmophloeum have excellent anti-inflammatory activities and thus have great potential as a source for natural health products.
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