Brusatol (NSC-172924) is a natural product isolated from the Brucea javanica plant. It inhibits Nrf2.

Brusatol 通过一种不依赖于 Keap1、蛋白酶体和自噬蛋白降解系统的机制，引发 Nrf2 的消耗。在小鼠 Hepa-1c1c7 肝癌细胞中，Brusatol 通过一种转录后机制迅速且短暂地引起 Nrf2 蛋白的消耗。Brusatol 也能抑制新鲜分离的原代人肝细胞中的 Nrf2 [1]。CT-26 细胞分别单独或联合应用不同浓度的 Brusatol（0.05、0.15、0.45、1.35、4.05 和 12.15 μg/mL）和 CDDP（0.05、0.15、0.45、1.35、4.05 和 12.15 μg/mL）处理 48 小时。经 Brusatol 和 CDDP 处理 48 小时后，CT-26 细胞的存活率呈剂量依赖性降低，其 IC50 值分别为 0.27±0.01 和 1.44±0.22 μg/mL。当 Brusatol 与 CDDP 以 1:1 的恒定浓度比联合应用时，细胞生长抑制明显增强，合用治疗的 IC50 值为 0.19±0.02 μg/mL [2]。

裸鼠被注射A549细胞以诱导肿瘤生长，随后进行一次每千克体重2 mg的Brusatol腹腔注射。在注射后24小时或48小时，将肿瘤组织分离出来。发现Nrf2蛋白水平在注射后24小时或48小时显著降低，表明Brusatol能够达到肿瘤组织并抑制Nrf2途径。在第一次实验中，一旦肿瘤体积达到平均230 mm3，将DMSO、Brusatol（每千克体重2 mg）、Cisplatin（每千克体重2 mg）或Cisplatin（每千克体重2 mg）与Brusatol（每千克体重2 mg）联合治疗通过腹腔注射，每隔一天一次，共五次。Cisplatin或Brusatol单独使用未能显著抑制肿瘤生长，而在联合治疗组中，肿瘤体积显著减小[3]。

CT-26 cells in logarithmic growth are seeded onto a 96-well plate at a density of 4×10^3 cells/well. After 24 h of incubation at 37°C, fresh medium containing a series of concentrations of Brusatol (0.05, 0.15, 0.45, 1.35, 4.05 and 12.15 μg/mL) and CDDP (0.05, 0.15, 0.45, 1.35, 4.05 and 12.15 μg/mL) is added at 100 μL/well; each concentration is used to treat six replicate wells. After 48 h of incubation at 37°C, the cells are further incubated with MTT (10 mg/mL) at 37°C for 4 h. The supernatant is then removed and the precipitate is dissolved with 100 μL DMSO. Absorbance is measured using a microplate reader at a wavelength of 490 nm. Cytotoxicity is expressed as the concentration of Brusatol and CDDP that inhibit cell growth by 50% (IC50 value). The inhibitory rate is calculated. The possible synergistic effect of Brusatol combined with CDDP is investigated by exposing CT-26 cells to various concentrations of each agent alone or in combination for 48 h [2].

Athymic nude mice are used. Mice 4-6 wk old are injected with A549 cells. Once the tumors reached 80 mm3 (for the two times five-time Cisplatin treatment regimen) or 280 mm3 (for the single five-time Cisplatin treatment regime), mice are randomly allocated into four groups and treated i.p. with DMSO, Cisplatin (2 mg/kg), Brusatol (2 mg/kg), or in combination every other day for a total of five times. After the initial five-time Cisplatin treatment regimen, treatment stops for 1 wk to allow mice to recover before the second five-time Cisplatin treatment regimen is repeated [3].