Bromisoval (BU) suppresses nitric oxide (NO) releasing and proinflammatory cytokine expression in lipopolysaccharide (LPS)-treat BV2 cells, a murine microglial cell line. Bromisoval suppresses LPS-inducing phosphorylation of signal transducer and activator of transcription 1 (STAT1) and expression of interferon regulatory factor 1 (IRF1). The Janus kinase 1 (JAK1) inhibitor filgotinib suppresses the NO release much more weakly than that of Bromisoval, although filgotinib almost completely prevents LPS-inducing STAT1 phosphorylation. Knockdown of JAK1, STAT1, or IRF1 does not affect the suppressive effects of Bromisoval on LPS-inducing NO. A combination of Bromisoval and filgotinib synergistically suppress the NO releasing. The mitochondrial complex I inhibitor rotenone, which does not prevent STAT1 phosphorylation or IRF1 expression, suppresses proinflammatory mediator expression less significantly than Bromisoval. Bromisoval and rotenone reduce intracellular ATP (iATP) levels to a similar extent. A combination of rotenone and filgotinib suppress NO release in LPS-treated BV2 cells as strongly as Bromisoval.