Cytotoxic prenylated phenols of false indigo-bush ( Amorpha fruticosa L.)

This study employed the MTT assay to assess the cytotoxicity of one flavan and two stilbene derivatives isolated from the false indigo-bush (Amorpha fruticosa L.) fruits: 5,7-dihydroxy-8-geranylflavanone (1), 2-carboxy-3,5-dihydroxy-4-geranylbibenzyl (2), and 2-carboxy-3-hydroxy-4-prenyl-5-methoxybibenzyl (3). The examined compounds reduced the survival of human cervical and colon tumour cells (HeLa, HT-29, HCT-116, and LS174) with IC50 values ranging from 10.55 to 147.09 μg/mL, except for 1, which did not affect LS174 cells within the tested concentrations. The highest activity was observed for 1 against HeLa cells, and 1 also exhibited the weakest effect against normal foetal lung fibroblasts (IC50 = 166.11 μg/mL), demonstrating good potency and selectivity. Stilbenes 2 and 3 proved efficacious, but lacked selectivity compared to 1. Our findings revealed the cytotoxicity of false indigo-bush constituents, justifying further mechanistic and in vivo investigations, particularly on 5,7-dihydroxy-8-geranylflavanone, which displayed considerable in vitro anticancer capacity and a potentially favourable safety profile.