Suppression of lipopolysaccharide-induced inflammatory responses in RAW 264.7 murine macrophages by aqueous extract of Clinopodium vulgare L. (Lamiaceae)

The wild basil Clinopodium vulgare L. is commonly used in Bulgarian folk medicine for treatment of irritated skin, mastitis- and prostatitis-related swelling, as well as for some disorders accompanied with significant degree of inflammation (e.g. gastric ulcers, diabetes, and cancer). To determine the effect of aqueous extract of Clinopodium vulgare L. on LPS-induced inflammatory responses of murine RAW 264.7 macrophages. Cell cytotoxicity was evaluated by MTT assay. Protein expression levels were monitored by Western blot analysis. Production of NO and PGE 2 was measured by the Griess colorimetric method and enzyme immunoassay, respectively. Activation of MMP-9 was visualized by gelatin zymography. Cytokine levels were determined by BioPlex assay. Intracellular ROS and free radical scavenging potential were measured by DCFH-DA and DPPH method, respectively. Xanthine oxidase activity was evaluated spectrophotometrically. The extract suppresses NF-κB activation by preventing Iκ-B phosphorylation and inhibits the phosphorylation of p38 and SAPK/JNK MAPKs. It down-regulates iNOS expression which manifests as a drastic decrease of NO production, inhibits MMP-9 activation, but does not affect COX-2 protein levels and reduces only slightly the released PGE 2. Secretion of IL-1β and Il-10 is greatly reduced, whereas suppression of TNF-α and GM-CSF production is less dramatic. The extract has strong free radical scavenging properties and exerts inhibitory effect on xanthine oxidase activity, which lowers the levels of intracellular ROS. The study provides evidence for the anti-inflammatory potential of Clinopodium vulgare L. aqueous extract.