Pyridinyl 4-(2-oxoalkylimidazolidin-1-yl)benzenesulfonates and their hydrochloride salts as novel water soluble antimitotic prodrugs bioactivated by cytochrome P450 1A1 in breast cancer cells†

We developed first-in-class antimitotic prodrugs phenyl 4-(2-oxo-alkylimidazolidin-1-yl)benzenesulfonates (PAIB-SOs) bioactivated by cytochrome P450 (CYP) 1A1 that are highly selective toward several breast cancer cells. However, they show sparingly water solubility. Therefore, we replaced their phenyl ring B with a substituted pyridinyl group preparing novel pyridinyl 4-(2-oxo-3-alkylimidazolidin-1-yl)benzenesulfonates (PYRAIB-SOs) and their hydrochloride salts. Our results evidence that PYRAIB-SO hydrochloride salts show higher water solubility compared to their neutral and PAIB-SO counterparts by up to 625-fold. PYRAIB-SOs with a nitrogen atom at position 3 of the pyridinyl ring exhibited strong antiproliferative activity (IC₅₀: 0.03–3.3 μM) and high selectivity (8–>1250) toward sensitive CYP1A1-positive breast cancer cells and cells stably transfected with CYP1A1. They induce cell cycle arrest in the G2/M phase and disrupt microtubule dynamic assembly. Enzymatic assays confirmed that CYP1A1 metabolizes PYRAIB-SOs into their active form with in vitro hepatic half-lives (55–120 min) in rodent and human liver microsomes. Overall, this will allow to increase drug concentration for in vivo studies.