A number of essential oils derived from plants are claimed to have several medicinal functions, including anti-cancer and anti-inflammation effects. However, the chemical composition and biological activities of flower-derived components have not been sufficiently characterized. Therefore, we investigated the composition of essential oils from Hallabong flower [(Citrus unshiu Marcov × Citrus sinensis Osbeck) × Citrus reticulata Blanco] and their anti-inflammatory effects. Hydro-distilled essential oils (HEOs) were analyzed using gas chromatography-mass spectrometry (GC-MS). In total, 21 components were identified, representing more than 98 % of the oils, with sabinene (34.75 %), linalool (14.77 %), β-ocimene (11.07 %), 4-terpineol (9.63 %), l-limonene (5.88 %), and γ-terpinene (4.67 %) as the main components. In the present study, we also investigated the anti-inflammatory effects of HEOs on lipopolysaccharide (LPS)-stimulated RAW 264.7 macrophage cells. HEOs were found to inhibit nitric oxide (NO) and prostaglandin E2 (PGE2) production and to suppress the LPS-induced expression of cyclooxygenase-2 (COX-2) protein. In addition, HEOs downregulated the production of the inflammatory cytokines, tumor necrosis factor (TNF)-α, interleukin (IL)-6, and IL-1β (IC50 values are 0.05 %, 0.02 %, and 0.01 %, respectively). On the basis of these results, we suggest that HEOs can be considered potential anti-inflammatory candidates for therapeutic use in humans.
Keywords: Hallabong; chemical composition; citrus flower; essential oil; inflammation.