Anti-inflammatory activity of the aerial parts of Platycodon grandiflorum and its constituents in LPS-stimulated RAW264.7 macrophages

Abstract

Platycodon grandiflorum A. DC. (Campanulaceae) grows as a perennial herb, and is widely distributed or cultivated in Korea, Japan and China. Platycodi Radix, the dried root of P. grandiflorum has been used as an antitussive, expectorant and drainage medicine in the traditional herbal medicine [1]. Lipopolysaccharides (LPSs) induce the production of inflammatory mediators such as iNOS, COX-2, TNF-α, IL-1, and IL-6 in macrophages. Therefore, reducing the expression levels of LPS-inducible inflammatory mediators is considered as an effective way to evaluate anti-inflammatory activity [2]. In order to compare the anti-inflammatory activity of solvent fractions from the aerial parts of P. grandiflorum on LPS-stimulated macrophages, the EtOH extract was consecutively partitioned with CH2Cl2, EtOAc and n-BuOH, and the levels of inflammatory mediators such as NO, TNF-α and IL-6 were evaluated. The anti-inflammatory activity potential of the solvent fractions was in the order of n-BuOH>EtOAc>CH2Cl2>H2O. The BuOH fraction strongly regulated NO, TNF-α and IL-6, and especially showed potent inhibition of the production of NO and IL-6 in LPS -stimulated RAW264.7 cells (IC50: 6.7 and 8.1 µg/mL, respectively). Seven known phenolic compounds were isolated from the BuOH and EtOAc fractions, which showed comparatively higher activity than the other fractions. The known compounds were identified as luteolin 7-glucoside, 3'-rhamnoside, apigenin 7-glucoside, 4'-rhamnoside, luteolin 7-(6"-O-acetyl)-glucoside, luteolin 7-glucoside, apigenin 7-glucoside, chlorogenic acid, and luteolin. The isolated compounds revealed inhibitory effects on NO, TNF-α and IL-6 production at concentrations of IC50 below 25, 60 and 38 µg/mL, respectively.