Anti-inflammatory effects of Eucommia ulmoides Oliv. male flower extract on lipopolysaccharide-induced inflammation

Abstract. Background:. Eucommia ulmoides Oliv. is a medicinal plant native to China, with its bark (Eucommiae Cortex) traditionally being used for medicinal purposes. Previous research has shown that Eucommia male flowers can exert anti-inflammatory, analgesic, antibacterial, and other pharmacological effects, including immune regulation. This study explored the anti-inflammatory effects of the 70% ethanol extract of male flowers (EF) of E. ulmoides in lipopolysaccharide (LPS)-stimulated RAW 264.7 cells and LPS-administered mice. Methods:. Cytotoxicity of EF for RAW 264.7 cells was investigated using Cell Counting Kit-8. The production of proinflammatory mediators, nitric oxide (NO), tumor necrosis factor (TNF)-α, interleukin (IL)-1β, and IL-6 was determined using enzyme-linked immunosorbent assays. IL-17, IL-23, and IL-10 mRNA levels were determined using quantitative real-time polymerase chain reaction. Activation of the nuclear factor (NF)-κB pathway in RAW 264.7 cells was investigated via Western blotting. In vivo anti-inflammatory effects of EF were studied in an LPS-induced acute inflammation mouse model by analyzing lung tissue histopathology, serum TNF-α and IL-6 levels, and myeloperoxidase (MPO) activity in lung tissue. Results:. EF showed no significant cytotoxicity at concentrations from 10 to 60 μg/mL (cell viability > 80%) in the CCK-8 cell viability assay. EF inhibited the RAW 264.7 cell proliferation (EF 60 μg/mL, 120 μg/mL, and 250 μg/mL vs. negative control: 87.31 ± 2.39% vs. 100.00 ± 2.50%, P = 0.001; 79.01 ± 2.56 vs. 100.00 ± 2.50%, P