Inhibition of the pro-inflammatory mediators in rat neutrophils by shanzhiside methyl ester and its acetyl derivative isolated from Barleria prionitis.

Abstract

The aerial parts of Barleria prionitis Linn. (BP) (Acanthaceae) plant has long been used to treat inflammatory disorders such as toothache, swellings, arthritis and gout. The purpose of this study was to evaluate the effects of shanzhiside methyl ester (SME), 8-O-acetyl shanzhiside methyl ester (ASME) and iridoid glycosides rich monoterpenoidal fraction (IFBp), isolated from the aerial part of BP, on the pro-inflammatory mediators in stimulated rat neutrophils. Rat neutrophils were incubated with or without test drugs. The influence of laboratory isolated and identified SME, ASME and IFBp on the production and release of pro-inflammatory mediators i.e. myeloperoxidase (MPO), elastase, matrix metalloproteinase-9 (MMP-9), interleukin 8 (IL-8), tumor necrosis factor alpha (TNF-α) and leukotriene B4 (LTB4) was evaluated in the formyl-met-leu-phenylalanine (f-MLP) and lipopolysaccharide (LPS) stimulated rat neutrophils using enzyme-linked immunosorbent assay (ELISA) methods. IFBp was also standardized with the high performance thin layer chromatography by simultaneous determination of SME and ASME marker compounds. SME, ASME and IFBp displayed concentration-dependent inhibitory effects on the MPO, elastase and MMP-9 enzymes release, and IL-8, TNF-α and LTB4 cytokines production in the f-MLP and LPS stimulated rat neutrophils. The content of SME and ASME was found to be 17.32 ± 1.98 and 11.30 ± 1.06% w/w, respectively, in IFBp by HPTLC method. Altogether, the present results suggest that the iridoidal glycosides of BP may be considered as therapeutic strategy against neutrophil-mediated inflammatory diseases. Developed and validated HPTLC method for the standardization of IFBp of BP can be used as a quality control tool for the routine qualitative and quantitative analysis of Barleria species containing SME and/or ASME.