Compound IQ-1S is a potent, noncytotoxic inhibitor of pro-inflammatory cytokine [interleukin (IL)-1α, IL-1β, IL-6, IL-10, tumor necrosis factor (TNF)-α, interferon-γ, and granulocyte-macrophage colony-stimulating factor] and nitric oxide production by human and murine monocyte/macrophages. The effect of IQ-1S is evaluated on LPS-induced cytokine production in human PBMCs. Among the 12 cytokines analyzed, LPS (200 ng/mL) consistently induces five (IL-1α, IL-1β, IL-6, IL-10, and TNF-α) in PBMCs compared with DMSO-treated control cells. Production of all of these cytokines is significantly inhibited by 20 μM IQ-1S. Among them, TNF-α production is inhibited completely by IQ-1 (>99%), the levels of IL-1α, IL-1β, and IL-10 are decreased by 85%, and IL-6 production is decreased by 33%.