N-Aryl-N′-(chroman-4-yl)ureas and thioureas display in vitro anticancer activity and selectivity on apoptosis-resistant glioblastoma cells: Screening, synthesis of simplified derivatives, and structure-activity relationship analysis

► Benzopyran-type potassium channel openers were examined in vitro on glioma cells. ► Growth inhibitory activity was observed with nitro-substituted phenylthioureas. ► Phenylureas were less active but more cell selective than phenylthioureas. ► Flow cytometry analyses demonstrated U373 cell cycle arrest in the G0/G1 phase. ► Some benzopyrans displayed cytostatic effects and other cytotoxic effects.