A novel, highly-water-soluble apigenin derivative provides neuroprotection following ischemia in male rats by regulating the ERK/Nrf2/HO-1 pathway.

6"-O-succinylapigenin [apigenin-7-O-(6'-O-succinyl)-glucoside], a novel compound, is identified in chamomile. Although it is highly produced by Bacillus amyloliquefaciens FJ18, its bioactivity remains unknown. The neuroprotective effects and antioxidative mechanism of 6''-O-succcinylapigenin in the middle cerebral artery occlusion model in male rats was investigated in this study. The structure of this compound was determined by spectroscopic data analysis. After 2 h of occlusion and 24 h of reperfusion, magnetic resonance imaging and assessed neurological scores following middle cerebral artery occlusion (MCAO) in male rats to determine the infarction size and neurological deficits, respectively. In addition, we tested protein levels of the nuclear factor E2-related factor 2 (Nrf2), Kelch-like ECH-associated protein1 (Keap1), heme oxygenase-1 (HO-1), and extracellular-signal-regulated kinase (ERK), to investigate the mechanism of antioxidative action of 6''-O-succcinylapigenin. Finally, we employed immunofluorescence to determine the location of Nrf2 and Keap1 in HT22 cells cultured in vitro. Our results revealed that administration of 6''-O-succcinylapigenin induced a decrease in both infarct volume and neurological scores following MCAO, and significantly increased the activity of HO-1 and nuclear Nrf2 in vivo. Similarly, immunofluorescence assays indicated that Nrf2 is highly expressed in the nucleus following treatment with 6''-O-succcinylapigenin in vitro. Our study suggests that 6''-O-succcinylapigenin exerts an anti-ischemic effect by activating the ERK/Nrf2/HO-1 pathway.