Dihydroaurones and Isoflavan Derivatives from the Roots of Glycyrrhiza asymmetrica

As a continuation of our pharmacognostic studies on different Glycyrrhiza species growing in Türkiye, the phytochemical investigation of the roots of Glycyrrhiza asymmetrica Hub.-Mor., a licorice species endemic to Türkiye, was carried out. This study yielded twenty-three secondary metabolites (1–23) including nine previously unreported compounds: two dihydroaurone-3-enoic acids, licoaurone A (1) and licoaurone B (2), isoflavan hydroxypreglabridin (3), isoflavanone cyclodeoxykievitone (4), flavanone-3-ol glycyasymmetrol (5), and four bi-isoflavans, glycyasymmetrica A–D (6–9). The structures of isolated compounds were established by NMR and MS experiments. The relative configurations (6–9) were assigned by a combined quantum mechanical/NMR approach, comparing the experimental ¹³C/¹H NMR chemical shift data and the related predicted values. The absolute configurations of compounds 1–9 were assigned by comparison of their experimental electronic circular dichroism curves with the TDDFT-predicted curves. All isolated compounds were also evaluated for their cytotoxic activity against MCF-7, HeLa, HepG2, and A549 cancer cell lines by using MTT assay.