Inhibition of NO Production in LPS-Stimulated Primary Rat Glial Cells by Gnidilatimonoein and Extract of Daphne mucronata

In the CNS, glial cells are involved in neuroinflammation and neuropathic pain. The glial cells are activated by a variety of pathological conditions and release pro-inflammatory mediators, including nitric oxide (NO). Overexpression of iNOS (inducible nitric oxide synthase) and extra NO is detrimental to neurophysiology and neuronal viability. This study aimed to examine the effect of Gnidilatimonein isolated from D. mucronata and its leaves extract (as natural phytochemicals) on NO production in the LPS-induced primary glial cells. A preparative HPLC method was used to isolate gnidilatimonoein from leaves ethanolic extract. Various doses of Gnidilatimonoein, the ethanolic extract were applied to primary glial cells inflamed by lipopolysaccharide. A Colorimetric test, an MTT assay, and a RT-PCR analysis were then performed to analyze and compare NO production, cell viability, and iNOS expression. Gnidilatimonoein treatment of pretreated primary glial cells significantly inhibited iNOS expression and decreased NO synthesis. Plant extracts also reduced NO production in inflamed microglial and glial at 0.1-3 mg.mL-1. At these concentrations, none of these compounds exerted a cytotoxic effect, suggesting that their anti-inflammatory effects were not due to the death of cells. This study indicates that D. mucronata and its active compound, Gnidilatimonoein, could have restrained effects on the expression of iNOS on the induced glial cells; however, further investigation is warranted.