In Vitro Models on Inhibition of Inflammatory Mediators by Ethanolic Extract of Careya arborea Roxb. Bark in Lipopolysaccharide-Induced RAW 264.7 Cell Lines

Abstract

Inflammation is a normal protective response to tissue injury caused by physical trauma, noxious chemicals, or microbiological agents. When this normal physiological process becomes deregulated, it can become harmful and destructive leading to inflammatory diseases that are a major burden on humanity. Careya arborea Roxb. (F.Lecythidaceae) is a large tree, 30–60 ft high, distributed throughout India up to an altitude of 5000 ft in deciduous forests and grasslands. Bark of C. arborea is antipruritic, astringent, bitter, thermogenic, antipyretic, expectorant, and anthelmintic. Preliminary in vitro anti-inflammatory activity of extract was carried out by protein denaturation and proteinase inhibition methods. Anti-inflammatory studies using lipopolysaccharide-induced RAW 264.7 cell lines were conducted by analyzing inhibition of cyclooxygenase, 5-lipoxygenase, myeloperoxidase, and cellular nitrite levels. Cytotoxicity studies were carried out by MTT assay. Antioxidant activity screening of the extract was found out by iron chelating, DPPH, nitric oxide, ABTS, beta carotene bleaching, and total antioxidant assays. Estimation of flavonoids, phenolics, alkaloids, flavanols, tannins, and carotenoids was conducted. Protein denaturation and proteinase inhibition assays exhibited potent anti-inflammatory activity of the C. arborea extract. IC 50 value of the extract by COX/5-LOX inhibition was found out as 5.30 μg/mL and 26.62 μg/mL, respectively. Diclofenac showed COX inhibition at the IC 50 values of 2.84 and 5-LOX inhibition at IC 50 of 12.14 μg/mL. The extract showed its ability to reduce myeloperoxidase and cellular nitrite levels in a dose-dependent manner. MTT assay showed that extract is not cytotoxic. Antioxidant activity screening and phytochemical estimations showed that the extract is a potent source of antioxidants like flavonoids, phenolics, and carotenoids. Mechanism of action of the traditional claim of C. arborea bark is mainly due to the COX/5-LOX inhibition, and the dual inhibition shows that the extract will not have common adverse effects of NSAIDs. The present study confirms that stem bark of C. arborea is a safe, potent anti-inflammatory agent.