Anti-inflammatory Effects of Quercetin and Vitexin on Activated Human Peripheral Blood Neutrophils: - The effects of quercetin and vitexin on human neutrophils -

OBJECTIVES: Polymorphonuclear neutrophils (PMNs) constitute the first line of defense against invading microbial pathogens. Early events in inflammation involve the recruitment of neutrophils to the site of injury or damage where changes in intracellular calcium can cause the activation of pro-inflammatory mediators from neutrophils including superoxide generation, degranulation and release of myeloperoxidase (MPO), productions of interleukin (IL)-8 and tumor necrosis factor α (TNF-α), and adhesion to the vascular endothelium. To address the anti-inflammatory role of flavonoids, in the present study, we investigated the effects of the flavonoids quercetin and vitexin on the stimulus-induced nitric oxide (NO), TNF-α, and MPO productions in human neutrophils. METHODS: Human peripheral blood neutrophils were isolated, and their viabilities were determined by using the Trypan Blue exclusion test. The polymorphonuclear leukocyte (PMNL) preparations contained more than 98% neutrophils as determined by morphological examination with Giemsa staining. The viabilities of cultured neutrophils with various concentrations of quercetin and vitexin (1 – 100 μM) were studied using 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyl tetrazolium bromide (MTT) assays. Neutrophils were cultured in complete Roswell Park Memorial Institute (RPMI) medium, pre-incubated with or without quercetin and vitexin (25 μM) for 45 min, and stimulated with phorbol 12-myristate 13-acetate (PMA) (10(−7) M). NO production was carried out through nitrite determination by using the Griess method. Also, the TNF-α and the MPO productions were measured using enzyme-linked immunosorbent assay (ELISA) kits and MPO assay kits. RESULTS: Neutrophil viability was not affected up to a concentration of 100 μM of quercetin or vitexin. Both quercetin and vitexin significantly inhibited TNF-α, NO, and MPO productions in human neutrophils (P < 0.001). CONCLUSION: The present study showed that both quercetin and vitexin had significant anti-inflammatory effects. Thus, treatment with either quercetin or vitexin may be considered as a therapeutic strategy for treating patients with neutrophil-mediated inflammatory diseases.