Synthesis
GENERAL METHODS: 1,1,3,3-Tetramethylguanidine (TMG, 3.5 mmol) was added to a mixture of 5-bromosalicylaldehyde (SA, 1 mmol), ethyl cyanoacetate (MN, 1 mmol), and 2,3-diaminopyridine (DAP, 1 mmol) under pure conditions. The reaction mixture was stirred at room temperature and the reaction process was monitored by thin layer chromatography (TLC). Upon completion of the reaction, distilled water (15 mL) was added to the reaction mixture and stirring was continued until a free-flowing solid was formed. The solid was collected by filtration and washed sequentially with water and hexane. The crude product was purified by recrystallization from ethanol solution: the crude product was dissolved in boiling ethanol to saturation and hot filtered to remove undissolved solid. The hot filtrate was cooled to room temperature to give an elementally analytically pure crystalline product, rel-(αR,4R)-2-amino-6-bromo-4-(1-cyano-2-ethoxy-2-carbonyl)-4H-benzofuran-3-carboxylic acid. Similar experimental procedures were used to synthesize all 2-amino-4H-benzofuran derivatives.
in vivo
Swiss nude mice are challenged with BeGBM cells (104 injected s.c.). HA14-1 (400 nmol) in 100 μL free RPMI 1640-50% DMSO, or the carrier alone, is given at the site of injection once weekly from day 2 following cell injection. HA14-1 treatment does not have any significant effect on the growth of glioblastoma tumors in immunodeficient mice as monitored twice weekly by measuring the volume of the expanding tumors. Moreover, no gross organ toxicity or weight loss can be detected in mice receiving such treatment. To analyze whether HA14-1 treatment might enhance the efficiency of another antitumoral treatment, Swiss nude mice challenged with human glioblastoma multiforme cells are also given i.p. low doses of Etoposide (2.5 mg/kg in 200 μL of 0.9% NaCl 5 days a week from day 2 following cell injection) together with HA14-1 or mock treatment. Whereas Etoposide treatment is insufficient by itself to restrain the growth of glioblastoma cells, its combination with HA14-1 leads to a significant restrain on tumor growth as judged by the ability of the combined treatment to increase the doubling time of the tumor volume[3].
References
[1] Tetrahedron Letters, 2005, vol. 46, # 20, p. 3497 - 3499
[2] RSC Advances, 2015, vol. 5, # 80, p. 65526 - 65531
[3] Tetrahedron, 2013, vol. 69, # 49, p. 10544 - 10551
[4] Tetrahedron Letters, 2006, vol. 47, # 43, p. 7629 - 7633
[5] Russian Chemical Bulletin, 2008, vol. 57, # 3, p. 595 - 600
