【转帖】Kava肝毒成分新突破

The FASEB Journal doi: 10.1096/fj.10-163311

Flavokawain B, the hepatotoxic constituent from kava root, induces GSH-sensitive oxidative stress through modulation of IKK/NF-κB and MAPK signaling pathways

Ping Zhou*§,1, Shimon Gross??,1, Ji-Hua Liu‖,1, Bo-Yang Yu‖, Ling-Ling Feng?, Jan Nolta*§, Vijay Sharma?, David Piwnica-Worms?? and Samuel X. Qiu?,2

Abstract

Kava (Piper methysticum Foster, Piperaceae) organic solvent-extract has been used to treat mild to moderate anxiety, insomnia, and muscle fatigue in Western countries, leading to its emergence as one of the 10 best-selling herbal preparations. However, several reports of severe hepatotoxicity in kava consumers led the U.S. Food and Drug Administration and authorities in Europe to restrict sales of kava-containing products. Herein we demonstrate that flavokawain B (FKB), a chalcone from kava root, is a potent hepatocellular toxin, inducing cell death in HepG2 (LD50=15.3±0.2 μM) and L-02 (LD50=32 μM) cells. Hepatocellular toxicity of FKB is mediated by induction of oxidative stress, depletion of reduced glutathione (GSH), inhibition of IKK activity leading to NF-κB transcriptional blockade, and constitutive TNF-α-independent activation of mitogen-activated protein kinase (MAPK) signaling pathways, namely, ERK, p38, and JNK. We further demonstrate by noninvasive bioluminescence imaging that oral consumption of FKB leads to inhibition of hepatic NF-κB transcriptional activity in vivo and severe liver damage. Surprisingly, replenishment with exogenous GSH normalizes both TNF-α-dependent NF-κB as well as MAPK signaling and rescues hepatocytes from FKB-induced death. Our data identify FKB as a potent GSH-sensitive hepatotoxin, levels of which should be specifically monitored and controlled in kava-containing herb products.—Zhou, P., Gross, S., Liu, J.-H., Yu, B.-Y., Feng, L.-L., Nolta, J., Sharma, V., Piwnica-Worms, D., Qiu, S. X. Flavokawain B, the hepatotoxic constituent from kava root, induces GSH-sensitive oxidative stress through modulation of IKK/NF-κB and MAPK signaling pathways.

看来人类的水平越来越高了。