We also evaluated the effects of KRG extract on Aβ-induced intracellular ROS generation using DCFH-DA as a fluorescent probe. As shown in Fig. 4B, exposure of cells to Aβ(25–35) increased intracellular ROS levels, which was significantly inhibited by the co-treatment with KRG extract at 0.3 and 1 mg/mL. In contrast, memantine had no effect on the Aβ(25–35)-induced injury or ROS at the concentration tested (data not shown).
KRG Extract Protects from Aβ(25–35)-Induced Neuronal Damage through the Inhibition of Apoptosis
We then evaluated the effects of KRG extract on the Aβ-induced alterations of apoptotic signaling molecules including Bad, Bax, caspase 3 and PARP proteins. The phosphorylation of Bad at Ser 112 was markedly increased by KRG extract (Fig. 5A). In addition, KRG extract almost completely blocked the Aβ-induced cleavages of caspase 3 and PARP (Fig. 5A). However, the enhanced Bax expression in Aβ-treated cells was only slightly inhibited by KRG extract (Fig. 5A).