Department of Physiology, China Medical University, Taichung 40402, Taiwan.
Eur J Pharmacol. 2012 May 5;682(1-3):73-8. doi: 10.1016/j.ejphar.2012.02.013. Epub 2012 Feb 21.
Magnolol, a polyphenolic compound isolated from Houpu, a Chinese herb from the bark of Magnolia officinalis, has been reported to have in vitro and in vivo neuroprotective effects. In spite of these reported beneficial effects, studies on the direct impact of magnolol on neuronal ion channels have been scarce. Whether magnolol affects voltage-gated Na(+) channels (VGSC) and voltage-gated K(+) (Kv) channels is unknown. Using the whole-cell voltage-clamp method, we studied the effects of magnolol on voltage-gated ion channels in neuronal NG108-15 cells. Magnolol inhibited VGSC channels with mild state-dependence (IC(50) of 15 and 30 μM, at holding potentials of -70 and -100 mV, respectively). No frequency-dependence was observed in magnolol block. Magnolol caused a left-shift of 18 mV in the steady-state inactivation curve but did not affect the voltage-dependence of activation. Magnolol inhibited Kv channels with an IC(50) of 21 μM, and it caused a 20-mV left-shift in the steady-state inactivation curve without affecting the voltage-dependence of activation. In conclusion, magnolol is an inhibitor of both VGSC and Kv channels and these inhibitory effects may in part contribute to some of the reported neuroprotective effects of magnolol.
厚朴酚是从厚朴中分离得到的一种多酚类化合物，厚朴是木兰科植物的树皮。已有研究报道厚朴酚具有体外和体内的神经保护作用。尽管有这些有益作用的报道，但关于厚朴酚对神经元离子通道的直接影响的研究却很少。厚朴酚是否影响电压门控钠离子通道（VGSC）和电压门控钾离子通道（Kv）尚不清楚。本研究采用全细胞膜片钳技术，研究了厚朴酚对神经元 NG108-15 细胞电压门控离子通道的影响。结果表明，厚朴酚对 VGSC 通道具有轻度的状态依赖性抑制作用（在 -70 和 -100 mV 的钳制电位下，IC50 分别为 15 和 30 μM）。厚朴酚的抑制作用无频率依赖性。厚朴酚使稳态失活曲线向左移动 18 mV，而不影响激活的电压依赖性。厚朴酚对 Kv 通道的抑制作用的 IC50 为 21 μM，使稳态失活曲线向左移动 20 mV，而不影响激活的电压依赖性。总之，厚朴酚是 VGSC 和 Kv 通道的抑制剂，这些抑制作用可能部分解释了厚朴酚的一些神经保护作用。
