Methods: The cytotoxicity of FD extract was assessed by MTS solution. BV2 cells were divided into 5 experimental groups, intervened, respectively, by FD (4 mg/mL) and LPS + FD (0, 1, 2, and 4 mg/mL). Besides, a blank control group was set up without any intervention. TNF-α release was assessed by enzyme linked immunosorbent assay (ELISA). The expression of CD40 was examined by flow cytometry. Immunocytochemical staining was used to show the morphology of BV2 cells.

Results: FD extract of different concentrations (1, 2, and 4 mg/mL) had no significant toxic effects on the BV2 cells. FD suppressed the activation of microglia in morphology and reduced TNF-α production and expression of CD40 induced by LPS.

METHODS: BV2 microglial cells c for 24 h, pre-treated with EPA for 24 h prior to LPS induction for another 24 h. Surface expression of CD11b and CD40 on BV2 cells was analyzed by flow cytometry. ELISA was employed to measure the production of pro-inflammatory mediators i.e. nitric oxide (NO) and tumor necrosis factor (TNF)-α. Western blotting technique was used to determine the expression of inducible nitric oxide synthase (iNOS), myeloid differentiation protein 88 (MYD88), nuclear factor kappa B (NF-κB), caspase-1, and mitogen activated protein kinase (MAPK).

RESULTS: Qualitative and quantitative analyses of the EPA using a validated ultra-high pressure liquid chromatography tandem mass spectrometry (UHPLC-MS/MS) method indicated the presence of phyllanthin, hypophyllanthin, niranthin, ellagic acid, corilagin, gallic acid, phyltetralin, isolintetralin and geraniin. EPA suppressed the production of NO and TNFα in LPS-activated BV2 microglial cells. Moreover, EPA attenuated the expression of MyD88, NF-κB and MAPK (p-P38, p-JNK and p-ERK1/2). It also inhibited the expression of CD11b and CD40. EPA protected against LPS-induced microglial activation via MyD88 and NF-κB signaling in BV2 microglial cells.