(-)-Epicatechin protects hemorrhagic brain via synergistic Nrf2 pathways

In the wake of intracerebral hemorrhage (ICH), a devastating stroke with no effective treatment, hemoglobin/iron-induced oxidative injury leads to neuronal loss and poor neurologic outcomes. (-)-Epicatechin (EC), a brain-permeable flavanol that modulates redox/oxidative stress via the NF-E2-related factor (Nrf) 2 pathway, has been shown to be beneficial for vascular and cognitive function in humans. Here, we examined whether EC can reduce early brain injury in ICH mouse models and investigated the underlying mechanisms.

ICH was induced by injecting collagenase, autologous blood, or thrombin into mouse striatum. EC was administered orally at 3 h after ICH and then every 24 h. Lesion volume, neurologic deficits, brain edema, reactive oxygen species, and protein expression and activity were evaluated.

EC significantly reduced lesion volume and ameliorated neurologic deficits in both male and female ICH mice. Cell death and neuronal degeneration were decreased in the perihematomal area and were associated with reductions in caspase-3 activity and HMGB-1 level. These changes were accompanied by attenuation of oxidative insults, increased phase II enzyme expression, and increased Nrf2 nuclear accumulation. Interestingly, in addition to providing neuroprotection via Nrf2 signaling, EC diminished heme oxygenase-1 induction and brain iron deposition via an Nrf2-independent pathway that downregulated ICH-induced activating protein-1 activation and decreased matrix metalloproteinase 9 activity, lipocalin-2 levels, iron-dependent cell death, and ferroptosis-related gene expression.

Collectively, our data show that EC protects against ICH by activation of Nrf2-dependent and -independent pathways and may serve as a potential intervention for patients with ICH.