Anti-inflammatory Potential of Quercetin-3-O-β-D-("2"-galloyl)-glucopyranoside and Quercetin Isolated from Diospyros kaki calyx via Suppression of MAP Signaling Molecules in LPS-induced RAW 264.7 Macrophages

Abstract

Diospyros kaki (DK) contains an abundance of flavonoids and has been used in folk medicine in Korea for centuries. Here, we report for the first time the anti-inflammatory activities of Quercetin (QCT) and Quercetin 3-O-β-("2"-galloyl)-glucopyranoside (Q32G) isolated from DK. We have determine the no cytotoxicity of Q32G and QCT against RAW 264.7 cells up to concentration of 50 μM. QCT and Q32G demonstrated potent anti-inflammatory activities by reducing expression of nitric oxide (NO), tumor necrosis factor (TNF)-α, interleukin (IL)-1β, IL-6 inducible NO synthase (iNOS), cyclooxygenase (COX)-2, and mitogen-activated protein kinase (MAPKs) in mouse RAW 264.7 macrophages activated with lipopolysaccharide (LPS). Both QCT or Q32G could decrease cellular protein levels of COX-2 and iNOS as well as secreted protein levels of NO, PGE₂ , and cytokines (TNF-α, IL-1β, and IL-6) in culture medium of LPS-stimulated RAW 264.7 macrophages. Immunoblot analysis showed that QCT and Q32G suppressed LPS-induced MAP kinase pathway proteins p-p38, ERK, and JNK. This study revealed that QCT and Q32G have anti-inflammatory potential, however Q32G possess comparable activity as that of QCT and could be use as adjuvant to treat inflammatory diseases.

Keywords: Diospyros kaki; Q32G; QCT; anti-inflammation.