Context Murraya paniculata (L.) Jack (Rutaceae), Qianlixiang in Chinese, is distributed in China. As an important traditional Chinese medicine (TCM), it demonstrates many bioactivities, such as febrifuge, astringent, anti-dysenteric, and tonic.
Objective: The objective of this study is to evaluate the anti-inflammatory effect of three flavonoids isolated from M. paniculata in lipopolysaccharide (LPS)-activated murine macrophage cell line and ethanol-induced gastric damage on gastric epithelial cell (GES-1). Materials and methods Three identified flavonoids were isolated from stems and leaves of M. paniculata using ultra performance liquid chromatography (UPLC). Cell viability was measured with MTT, mouse peritoneal macrophages and GES-1 cells were incubated with 0, 0.01, 0.1, 1, 10, and 100 μM P1, P3 and P8 for 24, 48, and 72 h. The inhibitory effect of pretreatment with various concentrations of 5,7,3',4',5'-pentamethoxyflavone (P1), 5,7,3',4'-tetramethoxyflavone (P3), or 5-desmethylnobiletin 5-hydroxy-6,7,8,3',4'-pentameth-oxyflavone (P8) ranging from 0.03 to 30 μM on nitric oxide (NO) secretion was quantified by the Griess assay for 24 and 48 h, while interleukin-6 (IL-6) was measured by ELISA for 24 and 48 h. Results The effects of P1, P3, and P8 on mouse peritoneal macrophages and GES-1 cells were not attributable to cytotoxic effects at the doses of 0-10 μM. The IC50 value of P1 is 53.40 μM, P3 is 120.98 μM, and P8 is 10.73 μM. The concentration of the three flavonoids had the best effects of anti-inflammation upon NO inhibition at the dose of 3 μM. P3 had the highest inhibition on IL-6 production. The GES-1 cells pretreated with three flavonoids showed a significant increase in the level of NO (P1: 7.94 ± 0.0635 μM, P3: 8.81 ± 0.0159 μM, and P8: 8.51 ± 0.0522 μM) at 24 h and a more significant increase at 48 h (P1: 9.34 ± 0.0975 μM, P3: 11.9 ± 0.0672 μM, and P8: 9.34 ± 0.0454 μM). Discussion and conclusion The current results suggested that the anti-inflammatory activity of three flavonoids was mainly manifested in the reduction of production of NO and IL-6 production. Analysis of the structure-activity relationship indicated that the double bond at C2-C3 and the position of the B ring at C2/C3 seemed to be indispensable for the anti-inflammatory activity.
Keywords: Anti-inflammation activity; flavonoid; gastritis; interleukin-6; nitric oxide; structure–activity relationship.