Design, Synthesis, in Vitro, and in Vivo Anticancer and Antiangiogenic Activity of Novel 3‑Arylaminobenzofuran Derivatives Targeting the Colchicine Site on Tubulin

A new series of compounds characterized
by the presence of a 2-methoxy/ethoxycarbonyl group, combined with
either no substituent or a methoxy group at each of the four possible
positions of the benzene portion of the 3-(3′,4′,5′-trimethoxyanilino)­benzo­[b]­furan skeleton, were evaluated for antiproliferative activity
against cancer cells in culture and, for selected, highly active compounds,
inhibition of tubulin polymerization, cell cycle effects, and in vivo potency. The greatest antiproliferative
activity occurred with a methoxy group introduced at the C-6 position,
the least with this substituent at C-4. Thus far, the most promising
compound in this series was 2-methoxycarbonyl-3-(3′,4′,5′-trimethoxyanilino)-6-methoxybenzo­[b]­furan (3g), which inhibited cancer cell growth
at nanomolar concentrations (IC50 values of 0.3–27
nM), bound to the colchicine site of tubulin, induced apoptosis, and
showed, both in vitro and in vivo, potent vascular disrupting properties
derived from the effect of this compound on vascular endothelial cells.
Compound 3g had in vivo antitumor activity in a murine
model comparable to the activity obtained with combretastatin A-4
phosphate.

本研究对一系列新型化合物进行了系统评价：该类化合物的结构特征为携带2-甲氧基/乙氧基羰基，且在3-(3',4',5'-三甲氧基苯胺基)苯并[b]呋喃母核的苯环片段四个可取代位点中，要么无取代基，要么带有一个甲氧基。首先针对该系列化合物的体外培养癌细胞抗增殖活性开展了评价；对于筛选得到的高活性化合物，则进一步评估了其微管蛋白(tubulin)聚合抑制活性、细胞周期影响及体内药效学活性。实验结果表明，该系列化合物在苯环片段C-6位引入甲氧基时抗增殖活性最强，而在C-4位引入该取代基时活性最弱。截至目前，该系列中最具开发前景的化合物为2-甲氧基羰基-3-(3',4',5'-三甲氧基苯胺基)-6-甲氧基苯并[b]呋喃（3g），其可在纳摩尔浓度区间内抑制癌细胞增殖（半数抑制浓度IC50值为0.3~27 nM），能够结合微管蛋白的秋水仙碱结合位点，诱导细胞凋亡，并通过作用于血管内皮细胞，在体外及体内均展现出强效的血管破坏活性。化合物3g在小鼠模型中呈现的体内抗肿瘤活性，与康普瑞汀A4磷酸酯(combretastatin A-4 phosphate)的抗肿瘤活性相当。