Synthesis, Structure, Chemical Stability, and In Vitro Cytotoxic Properties of Novel Quinoline-3-Carbaldehyde Hydrazones Bearing a 1,2,4-Triazole or Benzotriazole Moiety.

A small library of novel quinoline-3-carbaldehyde hydrazones (Series 1), acylhydrazones (Series 2), and arylsulfonylhydrazones (Series 3) bearing either a 1,2,4-triazole or benzotriazole ring at position 2 was prepared, characterized by elemental analyses and IR, NMR, and MS spectra, and then subjected to in vitro cytotoxicity studies on three human tumor cell lines: DAN-G, LCLC-103H, and SISO. In general, compounds 4 , 6 , and 8 substituted with a 1,2,4-triazole ring proved to be inactive, whereas the benzotriazole-containing quinolines 5 , 7 , and 9 elicited pronounced cancer cell growth inhibitory effects with IC50 values in the range of 1.23⁻7.39 µM. The most potent 2-(1 H -benzotriazol-1-yl)-3-[2-(pyridin-2-yl)hydrazonomethyl]quinoline ( 5e ) showed a cytostatic effect on the cancer cell lines, whereas N ′-[(2-(1 H -benzotriazol-1-yl)quinolin-3-yl)methylene]-benzohydrazide ( 7a ) and N ′-[(2-1 H -benzotriazol-1-yl)quinolin-3-yl)methylene]-naphthalene-2-sulfonohydrazide ( 9h ) exhibited selective activity against the pancreas cancer DAN-G and cervical cancer SISO cell lines. Based on the determined IC50 values, the compound 5e seems to be leading compound for further development as anticancer agent.