Prenylated Chalcones From Roots of Kidney Vetch (Anthyllis vulneraria L.) With Antiproliferative Activity

Kidney vetch (Anthyllis vulneraria L.) is an old medicinal plant mostly known for ethnomedicine. Nowadays, its herbal parts are only scarcely used in phytotherapy, whereas medicinal applications of roots have not been reported so far. In this study, we investigated ethyl acetate (EtOAc) extracts obtained by solvent partition of an acetone/water crude extract of A. vulneraria roots. Mainly prenylated chalcones, flavones, isoflavones, and cinnamic acid derivatives dominated the compound profile when the extracts were studied by HPLC-ESI-(HR)MSⁿ and GC-MS analysis. Two main chalcones (23 and 24) were isolated from the EtOAc extracts by several consecutive preparative chromatographic steps. Based on 1D- and 2D-NMR data 24 was assigned to the known compound kanzonol C, while 23 was identified as a novel chalcone. Moreover, antiproliferative activities of the EtOAc extract and of isolated chalcones were investigated in different liver, breast, and thyroid carcinoma cell lines. Interestingly, the EtOAc extract and 24 exhibited the most pronounced decrease of cell viability in the MDA-MB468 breast carcinoma cell line with an IC₅₀ value of 5.97 µM. Two synthetic derivatives of 24 (hexahydro- and triacetyl kanzonol, 30, 31, respectively), 23 and isobavachalcone 18 were less active (IC₅₀ > 11.7 µM). Thus, the prenylated chalcones detected in A. vulneraria roots appear to be promising lead structures for further antiproliferative studies.