(E)-Flavokawain A, a novel chalcone from kava extract, induces apoptosis in bladder cancer cells by involvement of Bax protein-dependent and mitochondria-dependent apoptotic pathway and suppresses tumor growth in mice.

Flavokawain A 对CYP1A2、CYP2D1、CYP2C6和CYP3A2活性表现出显著抑制作用，其IC50值分别为102.23、20.39、69.95、60.22μmol/L。抑制模式分别为竞争性抑制、混合抑制、非竞争性抑制和非竞争性抑制。分子对接研究显示，Flavokawain A 在CYP450亚型活性位点中的配体结合构象。化学抑制实验表明，在酮康唑、磺胺甲噁唑和α-萘黄酮存在下，Flavokawain A的代谢清除率分别降至对照的19.84%、50.38%及67.02%[1]。

Flavokawain A导致侵袭性膀胱癌细胞系T24的线粒体膜电位显著下降及细胞色素c释放到胞质中。Flavokawain A的这些效应伴随着Bcl-x(L)的时间依赖性减少、Bcl-x(L)与Bax结合的减少以及Bax蛋白活性形式的增加。通过使用主要的小鼠胚胎成纤维细胞Bax敲除和野生型细胞以及来源于Ku70的Bax结合域的Bax抑制肽，至少在部分上，Bax蛋白对Flavokawain A的凋亡效应是必需的。此外，Flavokawain A下调X连锁凋亡抑制剂和存活蛋白的表达。因为X连锁凋亡抑制剂和存活蛋白是抵抗凋亡的主要因素，并在膀胱肿瘤中过表达，表明Flavokawain A可能在诱导膀胱肿瘤凋亡方面具有双重效能。

Probe-based assays with rat liver microsome system were used to characterize the inhibitory effects of FLAVOKAVAIN A(P). Molecular docking study was performed to further explore the binding site of FLAVOKAVAIN A(P) on CYP450 isoforms. Chemical inhibition experiments using specific inhibitors (a-naphthoflavone, quinidine, sulfamethoxazde, ketoconazole, omeprazole) were performed to clarify the individual CYP450 isoform that are responsible for the metabolism of FLAVOKAVAIN A(P)[1].

Flavokawain A was formulated in 10% grain alcohol in 0.9% saline and given by gavage. EJ bladder tumor cells were concentrated to 2 × 10^6 per 200 μL and injected s.c. into the right flank of each mouse. Next day, the mice were randomly divided and pair matched into treatment and control groups of 18 mice each, and daily dosing was begun with vehicle or 50 mg/kg flavokawain A. Because there were no in vivo data regarding flavokawain A before this study, the dose of flavokawain A (50 mg/kg/d) was used according to 1:60 of 3,000 mg/kg, a LD50 dose for a similar chemical structure compound, isoliquiritigenin . Body weight, diet, and water consumption were recorded thrice weekly throughout the study. Once xenografts started growing, their sizes were measured every other day. The tumor volume was calculated by the formula: 0.5236 L1(L2)^2, where L1 is the long axis and L2 is the short axis of the tumor. At the end of experiment, tumors were excised, weighed, blood collected, and stored at ?80°C until additional analysis[2].