The chalcone-flavanone isomerization affects in vitro bio-assays as exemplified with isoliquiritigenin from licorice

Although well-studied from a chemical perspective, the real-time biological impact of the chalcone-flavanone isomerization, e.g., under cell-based bioassay conditions is not fully understood yet. Among the principal polyphenols of licorice roots ( Glycyrrhiza sp. Fabaceae) are glycosides of the f lavanone, li quiriti g enin (LigF), and the c halcone, iso li quiriti g enin (LigC). Their isomerization in two widely used culture media, DMEM and RPMI, was analyzed over 4 days by LC-UV-MS. In both media, 50% of LigC were converted into LigF within 24 hrs. A steady state with 80/20% of LigF/LigC was reached at 72 hrs. The influence of the media on chalcone glycoside isomerization and flavanone racemization will be discussed. The findings indicate that flavanone rearrangement products play a role in observed in vitro and possibly in vivo biological activities of LigC and related plant chalcones.