Pyrimido[4,5-g]quinazoline quinone derivatives were synthesized as anthraquinone-like reductive alkylating agents. Like many naturally-occurring antibiotics, these quinone derivatives are designed to afford an alkylating quinone methide species upon reduction and leaving group elimination. Kinetic studies of pyrimido[4,5-g]quinazoline hydroquinones provided evidence of quinone methide intermediates able to trap nucleophiles (alkylation) and protons. The rate of quinone methide formation is determined by the hydroquinone free energy. Thus, a linear free energy relationship for quinone methide formation was obtained by plotting rates of quinone methide formation, as the log, versus the quinone reduction potential. The pyrimido[4-5-g]quinazoline quinone methides fall on this free energy plot, showing that these species are formed by the same mechanism as the other structurally-diverse quinone methides previously studied in this research group. A drawback of many quinone antibiotics, particularly the anthracyclines, is the formation of toxic oxygen species by quinone/hydroquinone cycling. In the present invention pyrimido[4,5-g]quinazoline hydroquinones are found to be relatively stable toward oxygen, and thus cause little oxygen toxicity. Antitumor screening revealed that the disclosed pyrimid [4,5-g] quinazoline dione and tetione derivatives possess excellent inhibitory activity against selected human cancer cell lines.
嘧啶并[4,5-g]
喹唑啉醌衍
生物被合成为类似
蒽醌的还原烷化剂。与许多
天然存在的
抗生素一样,这些醌衍
生物的设计目的是在还原和离去基团消除时产生一种烷基化的醌
甲醚。对
嘧啶并[4,5-g]
喹唑啉对苯二酚的动力学研究证明,
甲脒醌
中间体能够捕获亲核物(烷基化)和质子。
甲喹酮的形成速率由
对苯二酚自由能决定。因此,通过绘制醌甲
酰胺形成率(对数)与醌还原电位的关系图,可以得出醌甲
酰胺形成的线性自由能关系。
嘧啶并[4-5-g]
喹唑啉醌甲苷就属于这种自由能关系,这表明这些物种的形成机制与本研究小组之前研究的其他结构多样的醌甲苷相同。许多
醌类抗生素,尤其是
蒽环类
抗生素的一个缺点是,醌/
氢醌循环会形成有毒的
氧物种。本发明发现,
嘧啶并[4,5-g]
喹唑啉对
氧相对稳定,因此几乎不会产生
氧毒性。抗肿瘤筛选显示,所公开的
嘧啶并[4,5-g]
喹唑啉二
酮和四
酮衍
生物对选定的人类癌细胞株具有极好的抑制活性。