evaluation of the anti-inflammatory properties of d-limonene compared with dexamethasone and ibuprofen in bovine synoviocyte

Introduction: osteoarthritis is a public health concern that leads to disability due to chronic pain, stiffness, sleep disturbance, and depression. d-limonene    is a racemic mixture of limonene, a natural cyclic monoterpene, and the major component of the oil extracted from the citrus rind with chemo-preventive and anti-inflammatory activities. the purpose of this study was to investigate the anti-inflammatory properties of d-limonene   compared with dexamethasone and ibuprofen in bovine fibroblast-like synoviocyte cells (bflsc) as well as human thp-1 monocyte/macrophage-like cells.materials and methods: bflsc was isolated from the synovial membrane of the metacarpal joint cartilage of an 8-month-old holstein. thp-1 cells were prepared by the pasteur institute of iran. cells were cultivated and exposed to 20 ng/ml lipopolysaccharide (lps) stimulation without, or in the presence of, ibuprofen, dexamethasone, or d-limonene (7.5µg/ml). the gene expressions of cyclooxygenase-2 (cox-2), interleukin-1β (il-1β), inducible nitric oxide synthase (inos), and tumor necrosis factor alpha (tnf-α) were evaluated by real-time pcr. concentrations of nitric oxide (no), and prostaglandin-e2 (pge2) were measured by elisa methods. results: the inhibitory effects of d-limonene   included dose-dependent decreases in the expression of inos and cox-2 proteins (p < 0.05). the treated cells secreted increased amounts of cox-2, il-1β, inos, tnf-α, no, and pge2 in response to lps stimulation in all conditions. d-limonene quenched the gene expression of cox-2, il-1β, inos, and tnf-α, in bflsc, and the production of pge2 and no in monocyte/macrophage cells alike dexamethasone, and ibuprofen. conclusion: the results obtained in this study show that d-limonene   probably exerts anti-inflammatory effects through the suppression of tnf-α, il-1β, cox-2, and inos and no, pge2 production.