Synthesis of novel heterocycles as anticancer agents -

Abstract

Cancer is as old as mankind and its treatment history reveals slow progression, but it has peaked in the 20th century due to modern technology and ongoing research worldwide, and has been progressing ever since. Chemotherapy showed to be effective in arresting the progress and development of the disease in metastatic patients. However, selectivity is still a major issue in most chemotherapeutic drugs. Meanwhile, quinones have emerged in this field as promising anticancer agents and proved their worth. Heterocyclic compounds have gained much importance recently, especially those including nitrogen atoms such as2-benzoyl-3-phenyl-6,7-dichloroquinoxaline 1,4-dioxide (DCQ, synthesized by the Beirut reaction). Based on this perspective, the aim of this study was to synthesize heterocyclic compounds having similarity in structure with that of quinone systems where nitrogen atoms replace the oxygens, trying to mimic and possibly enhance their activity against cancerous cells. Indeed, seven novel isoquinolino[3,4-b]quinoxaline analogues were synthesized in four steps each (28 steps in total, a sample of these syntheses is depicted below), whereby after each step the product was isolated and characterized by spectroscopic analyses (IR, ¹H NMR, ¹³C NMR, ¹³C NMR DEPT 135, MS).In addition, the X-Ray of 20a was determined by Dr. James Fettinger of the University of California at Davis, CA, USA. Four of the seven isoquinolino[3,4-b]quinoxaline systems were subjected to biological evaluation, by Ms. Monzer with the supervision of Dr. Hala Muhtasib, against colon cancer stem cells (HCT116 cell lines) and normal colon cells (FHs74Int cells). The results revealed that theseheterocycles (20a-d) possess anticancer activity against HCT116 at various concentrations the lowest of which was 4μM, whereby they show no significant cytotoxicity on the normal FHs74Int cells.