Synthesis and SAR studies of phenanthroindolizidine and phenanthroquinolizidine alkaloids as potent anti-tumor agents

A series of phenanthroindolizidine and phenanthroquinolizidine alkaloids and their 14-amino-derivatives (1–44) were prepared and systematically evaluated for their anti-tumor activities against A549 and HL60 cell lines. The bioassay results showed that most of these alkaloids possess good anti-tumor activities. Especially, compounds 15, 22, 28, 33–36, 40 and 42 displayed low nanomolar or subnanomolar levels of anti-tumor activity. The configuration of (13aS,14S)-14-hydroxyphenanthroindolizidines and (14aR,15R)-15-hydroxyphenanthroquinolizidines was confirmed to be optimal. 14-Amino-phenanthroindolizidines with increased polarity possess good anti-tumor activity, especially for compounds 26 and 28. Most of the phenanthroquinolizidine alkaloids exhibited higher anti-tumor activity than that of phenanthroindolizidine alkaloids. Our present study provides fundamental support for development and optimization of phenanthroindolizidine and phenanthroquinolizidine alkaloids as potential anti-tumor drugs.

Graphical abstractA series of phenanthroindolizidine and phenanthroquinolizidine alkaloids and their 14-amino-derivatives (1–44) were prepared and systematically evaluated for their anti-tumor activities against A549 and HL60 cell lines.Figure optionsDownload full-size imageDownload as PowerPoint slideHighlights► A series of phenanthroindolizidine and phenanthroquinolizidine alkaloids and their 14-amino-derivatives were prepared. ► We systematically evaluated their anti-tumor activities against A549 and HL60 cell lines. ► Most of these alkaloids possess good anti-tumor activities. ► Compounds 15, 22, 28, 33–36, 40 and 42 display low nanomolar or subnanomolar levels of anti-tumor activity.