Suppression of LPS-induced inflammatory activities by Rosmarinus officinalis L.

Rosemary (Rosmarinus officinalis L.) has been used in folk medicine to treat headaches, epilepsy, poor circulation, and many other ailments. It was found that rosemary could act as a stimulant and mild analgesic and could reduce inflammation. However, the mechanisms underlying the anti-inflammatory effects of rosemary need more study to be established. Therefore, in this study, the effects of rosemary on the activation of nuclear factor kappa beta (NF-kB) and mitogen-activated protein kinases (MAPKs), the expression of inducible nitric oxide synthase (iNOS) and cyclooxygenase-2 (COX-2), and the production of nitric oxide (NO), prostaglandin E2 (PGE2), and cytokine in lipopolysaccharide (LPS)-stimulated RAW 264.7 cells were investigated. A methanol extract of rosemary and its hexane fraction reduced NO generation with an IC50 of 2.75 and 2.83 μg/ml, respectively. Also, the methanol extract and the hexane fraction inhibited LPS-induced MAPKs and NF-kB activation associated with the inhibition of iNOS or COX-2 expression. LPS-induced production of PGE2 and tumour necrosis factor-alpha (TNF-α) were blocked by rosemary. Rosemary extract and its hexane fraction are important for the prevention of phosphorylation of MAPKs, thereby blocking NF-kB activation, which in turn leads to decreased expression of iNOS and COX-2, thus preventing inflammation.