Purpose: To evaluate the protective effects of purple sweet potato (Ipomoea batatas Linn, Convolvulaceae) extract (IBE) in stimulated BV-2 microglial cells and its anti-oxidant properties.

Methods: Cell viability assessment was performed by 3-(4, 5-dimethylthiazol-2-yl)-2, 5- diphenyl-tetrazolium bromide (MTT) assay. Lipopolysaccharide (LPS) was used to activate BV-2 microglia. Nitric oxide (NO) levels were measured using Griess assay. Inducible NO synthase (iNOS) and cyclooxygenase (COX)-2 expressional levels were measured by Western blot analysis. Tumor necrosis factor-alpha (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 by IBE (p<0.001 at 100 μg/mL). Increased production of inflammatory mediators such as iNOS, COX-2 and TNF-α (p < 0.01 and p < 0.001 at 100 and 200 μg/ml, respectively) was attenuated by IBE concentration-dependently. IBE also scavenged DPPH radicals in a dose-dependent manner (p < 0.05 at 10 μg/ml and p < 0.001 at 20 - 200 μg/ml).

Conclusion: These results indicate that IBE attenuated neuroinflammatory responses in LPS-activated BV-2 microglia by inhibiting excessive production of pro-inflammatory mediators such as NO, iNOS, COX-2 and TNF-α. The anti-neuroinflammatory potential of IBE may be related to its strong antioxidant properties.