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 ( 1 H 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 evalu- ated 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 (IC 50=4.7μM for MCF-7 and IC 50=9.3μM for MDA-MB-231), II 33 (IC 50=2.4μM for MCF-7 and IC 50=4.2μM for MDA-MB-231) and II 40 (IC 50=3.3μM for MCF-7 and IC 50 =8.6μM for MDA-MB-231) displayed better inhibitory activity than 5-fluorouracil (IC 50=4.8μM for MCF-7 and IC 50=9.6μM 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%).