Design, synthesis and in vitro cytotoxicity studies of novel pyrrolo[2,1][1,4] benzodiazepine-glycosylated pyrrole and imidazole polyamide conjugates

The design, synthesis and biological evaluation of novel pyrrolo [2,1][1,4] benzodiazepine-water insoluble 31 - 38 and water soluble 39 - 46 glycosylated pyrrole and imidazole polyamide conjugates are described that involved mercuric chloride mediated cyclization of the corresponding amino diethyl thioacetals. The compounds were prepared with varying numbers of pyrrole and imidazole containing polyamides and incorporating glucose moieties in order to improve the water solubility of PBD-polyamide conjugates and probe the structural requirements for optimal in vitro antitumor activity. These compounds were tested against a panel of 60 human cancer cells by the National Cancer Institute, and demonstrated that the water soluble PBD-polyamide compounds exhibited a higher level of cytotoxic activity than the existing natural and synthetic pyrrolo [2,1-c][ 1,4] benzodiazepines. The cytotoxic activities of these compounds dramatically increase after hydrolysis of their acetylated counterparts. The activity data summarized in Table 1 and Table 2 show that the solubility of the PBD-polyamides and also the type of heterocycle play important roles influencing the cytotoxic activity of the PBD-polyamide conjugates. The PBD-glycosylated polyamide ( water soluble) conjugates 39 - 46 are highly cytotoxic against many human cancer cell lines in comparison with the PBD-polyamide (water insoluble version) conjugates.