Synthesis and biological activity of some rigid analogues of flavone-8-acetic acid

Some rigid analogues of flavone-8-acetic acid are described. Direct in vitr o toxicity of the synthesised compounds was evaluated towards four tumoral cell lines and the ability of these compounds to stimulate mouse peritoneal macrophages in culture to become tumoricidal (indirect toxicity) was also studied. All compounds were able to induce direct cytotoxicity only at very high concentrations but showed a remarkable indirect activity. In particul ar compound 4d was able to significantly increase macrophage lyric properti es and has been selected for further investigations. (C) 2000 Elsevier Scie nce Ltd. All rights reserved.