Abstract: This study aimed to elucidate the ameliorative effect and mechanism of quercetagetin, quercetin and lutein, alone and in combination, on acute lung injury. An lipopolysaccharide-induced inflammation model was established based on RAW264.7 cells. The optimal mixture ratios between quercetagetin or quercetin and lutein were determined based on the content of nitric oxide (NO) in RAW264.7 cells using combination index (CI) analysis. The individual and combined effects of quercetagetin, quercetin and lutein on the contents of malondialdehyde (MDA), inflammatory cytokines (including tumor necrosis factor α (TNF-α), interleukin (IL)-1β and IL-6) and the activities of superoxide dismutase (SOD) and glutathione peroxidase (GSH-Px) in LPS-stimulated RAW264.7 cells were investigated. In addition, the relative expression levels of p65, p50, silent information regulator 1 (SIRT1), nuclear factor‑erythroid 2 related factor 2 (Nrf2), and NOD-like receptor thermal protein domain associated protein 3 (NLRP3) were evaluated by Western blot. The results showed that the lowest NO level in RAW264.7 cells was observed by treatment with a mixture of high-dose quercetagetin and lutein of 3:1 (30 μg/mL + 10 μg/mL). Quercetagetin, lutein and their combination all decreased the contents of MDA and inflammatory cytokines, increased the activities of SOD and GSH-Px, down-regulated the expression of nuclear factor kappa-B (NF-κB) p65, p50 and NLRP3, and up-regulated the expression of SIRT1 and Nrf2, the combination being more effective than either treatment alone.

Key words: marigold (Tagetes erecta L.); quercetagetin; lutein; quercetin; RAW264.7 cells; acute lung injury