Isolation, chemical and free radical scavenging characterization of phenolics from Trifolium scabrum L. aerial parts.

For the first time Trifolium scabrum L. was researched for its phenolic profile. Sixteen phenolics (isoflavones and flavonoids) were isolated and identified in the aerial parts of T. scabrum L. Their structures were established by electrospray ionization-mass spectrometry (ESI-MS) and nuclear magnetic resonance (NMR) techniques. Quantitative analysis of individual phenolics performed by means of ultraperformance liquid chromatography-mass spectrometry (UPLC-MS) was based on calibration curves obtained for previously isolated standard compounds. Additionally, the free radical scavenging potential of these substances was assessed by means of a simple benchtop thin-layer chromatography-2,2-diphenyl-1-picrylhydrazyl radical (TLC-DPPH(•)) bioassay. Thus, T. scabrum L. can be regarded as a potential source of estrogenic and antioxidant compounds, both of significance in the pharmaceutical as well as the food industry. The results show that T. scabrum L. can be considered as a natural and very good commercial source of phenolic compounds (mainly isoflavones).