Novel 2H-pyrazolo[4,3-c]hexahydropyridine derivatives: Synthesis, crystal structure, fluorescence properties and cytotoxicity evaluation against human breast cancer cells

A series of novel 2H-pyrazolo[4,3-c]hexahydropyridine derivatives (II) have been designed and synthesized. The target compounds have been identified by elemental analysis and spectral (1H NMR, IR, and MS) data and the absolute configuration of compound (II 1 ) was confirmed by single crystal X-ray diffraction. The cytotoxicity of the target compounds have been evaluated in vitro against two human breast cancer cell lines MCF-7 and MDA-MB-231 by MTT assay. Most compounds exhibited good inhibition, and compounds II 21 (IC50 = 4.7 μM for MCF-7 and IC50 = 9.3 μM for MDA-MB-231), II 33 (IC50 = 2.4 μM for MCF-7 and IC50 = 4.2 μM for MDA-MB-231) and II 40 (IC50 = 3.3 μM for MCF-7 and IC50 =8.6 μM for MDA-MB-231) displayed better inhibitory activity than 5-fluorouracil (IC50 = 4.8 μM for MCF-7 and IC50 = 9.6 μM for MDA-MB-231, respectively). Flow cytometric analysis and DNA fragmentation suggest that II 33 is cytotoxic and able to induce the apoptosis of MCF-7 cells. The fluorescence properties of compounds II 1 , II 6 , II 11 , II 16 , II 23 , II 28 , and II 35 were also studied and compound II 28 afforded the highest photoluminescence quantum yield (38%).