Inhibition of Lipopolysaccharide-Induced Neuroinflammatory Events in Bv-2 Microglia by Chestnut Peel Extract

Purpose: To evaluate the protective effects of chestnut (Castenea cranata Siebold & Zucc., Fagaceae) peel extract on stimulated BV-2 microglial cells as well as its anti-oxidant properties.
Methods: The ethyl acetate fraction of C. cranata peel (CCP) extract was used in the study to evaluate the anti-neuroinflammatory effects in BV-2 microglial cells. Cell viability was performed by 3-(4, 5- dimethylthiazol-2-yl)-2, 5- diphenyl-tetrazolium bromide (MTT) assay. Lipopolysaccharide (LPS) is used to activate BV-2 microglia. Nitric oxide (NO) levels were measured using Griess assay. Inducible NO synthase (iNOS) expressional levels were measured by Western blot analysis. Tumor necrosis factoralpha (TNF-α) production was evaluated by enzyme-linked immunosorbent assay (ELISA). Anti-oxidant properties were evaluated by 1, 1-diphenyl-2-picryl-hydrazyl (DPPH) radical scavenging assay.
Results: LPS-activated excessive release of NO in BV-2 cells was significantly inhibited (p < 0.001 at 100 μg/mL) by CCP extract. LPS-induced excessive production of inflammatory mediator such as iNOS was also significantly attenuated by CCP extract. Further, CCP extract significantly and dose dependently inhibited the TNF-α levels in LPS-induced BV-2 microglial cells (p < 0.05 at 20 μg/mL, p < 0.01 at 40 μg/mL and p < 0.001 at 80 and 100 μg/mL). CCP extract also scavenged DPPH radicals in a dose-dependent fashion (p < 0.05 at 0.01 mg/mL and p < 0.001 at 0.1 and 1 mg/mL) with an IC50 value of 0.08 μg/mL.
Conclusion: Data from this study indicate that CCP extract attenuates neuroinflammatory responses in LPS-activated BV-2 microglia by inhibiting excessive production of pro-inflammatory mediators such as NO, iNOS and TNF-α. The strong anti-oxidant effect of CCP extract suggests that it possesses antineuroinflammatory properties.

Keywords
Castenea cranata; Chestnut peel extract; DPPH radicals; Anti-oxidant; Neuroinflammation; BV-2 microglia