NO and cell viability assays were performed as described during our previous work [18] (link). Briefly, RAW264.7 cells (1×106 cells/mL) were pre-incubated with RGSF (25, 50, 100, and 200 μg/mL) or vehicle for 30 min and then stimulated with LPS (100 ng/mL) for 18 h. One-hundred microliter of cell supernatant from each well were transferred into 96-well microplates and mixed with an equal volume of Griess reagent at room temperature. The absorbance at 540 nm was determined by a Spectramax 250 microplate reader. For cell viability test, 30 μL of 5 mg/mL 3-(4, 5-dimethylthiazol-2-yl)-2, 5-diphenyltetrazolium bromide (MTT) reagent was added to the culture plates and cell viability test was performed based on the reduction of MTT reagent into an insoluble, dark purple formazan product in viable cells.