Brazilein protects the brain against focal cerebral ischemia reperfusion injury correlating to inflammatory response suppression

Brazilein isolated from Caesalpinia sappan was evaluated for neuroprotection against transient focal cerebral ischemia/reperfusion in rats. The results showed that administration of brazilein after the onset of cerebral ischemia reperfusion can reduce the brain infarction area and improve the neurological score. The mechanisms underlying the action were investigated and attributed to the anti-inflammatory effect of brazilein, because a decrease of the mRNA level of pro-inflammatory cytokines (tumor necrosis factor-α(TNF-α) and interleukin-6 (IL-6)) was found in the ischemic animals with brazilein treatment. To further substantiate the anti-inflammatory effect of brazilein, we examined the mRNA expression of the cytokines in the lipopolysaccharide (LPS) induced microglial cell line BV2 cells; TNF-α and IL-6 mRNA expressions were significantly suppressed by brazilein treatment but the decrease of interleukin-1β (IL-1β) expression was not detected. Nitric oxide (NO) produced by inducible nitric oxide synthase (iNOS), another indicator of the inflammatory response of the immune cells was measured in RAW 264.7 macrophages and BV2 cells; brazilein inhibited its production induced by LPS in both types of cells in a dose-dependent manner. Consistently, the mRNA level of iNOS was also decreased by brazilein. Together, these results illustrate that brazilein can protect the brain against ischemia/reperfusion injury and the anti-inflammatory effect was believed to be one of the contributive mechanisms.