Phenolic compounds as selective antineoplasic agents against multidrug-resistant human cancer cells.

Twelve phenolic compounds, including three stilbenes, two flavonoids, two coumarins, one neolignan, and four lignans, isolated from Euphorbia and Pycnanthus species or obtained by derivatization, were assayed for their potential antineoplastic efficacy in three human cancer cell lines: gastric (EPG85-257), pancreatic (EPP85-181), and colon (HT-29) carcinomas as well as derived multidrug-resistant sublines. In each case, two different multidrug-resistant variants, i.e., cell lines with classical and atypical MDR phenotype, were used. The majority of the MDR cancer sublines showed increased sensitivities to the studied compounds when compared to the parental sublines. The most active compound was the flavonoid naringenin, found to be 15-fold more effective against the atypical MDR subline of gastric carcinoma than in parental drug-sensitive cells. Furthermore, the stilbene trans-3,5,3',4'-tetramethoxypiceatannol and the lignans 4'-hydroxy-3,3',4-trimethoxylignan and heliobuphthalmin also exhibited high antineoplasic activities against the classical MDR subline derived from gastric carcinoma. The results of this study suggest that some phenolic compounds might be valuable for the treatment of multidrug-resistant cancer cells.