Young herbaceous legumes – a natural reserve of bioactive compounds and antioxidants for healthy food and supplements

Young plants of clover (Trifolium pratense L. and T. medium L.), medick (Medicago sativa L. and M. lupulina L.), sainfoin (Onobrychis viciifolia Scop.) and milkvetch (Astragalus glycyphyllos L. and A. cicer L.), were investigated for total contents of phenolics, flavonoids, isoflavones, condensed tannins and triterpene saponins as well as their extracts for antiradical and ferrous ion chelating activity. The impact of two sample drying methods on the aforementioned characters was compared. The phytochemical concentrations were higher in the freeze-dried legumes; however, antioxidant activities were generally higher of oven-dried samples. Both the composition of health promoting phytochemicals and antioxidant properties were strongly species-dependent. Among the species tested, Trifolium spp. were most abundant in isoflavones, Medicago spp. – in saponins and O. viciifolia – in tannins. Plants of T. medium and O. viciifolia were rich in TPC. The extracts of T. pratense, O. viciifolia and A. cicer possessed significant antiradical activity; the extracts from Astragalus spp. proved to be promising chelators of ferrous ion. We concluded that young perennial legumes could be considered as potential candidates for the development of nutraceuticals and functional food ingredients to accommodate the need for a particular bioactive component or property.