Legume Crops as Sources of Functional Compounds: flavonoids in seeds and sprouts.

The recent development of the nutraceutical market is bringing up an increased demand of crops rich in compounds with beneficial effects on human health. Among these flavonoids, and more generally polyphenols, are an important class of plant secondary metabolites with proven bioactivity. The most appreciable sources of flavonoids in crops are grain legumes (particularly beans, chickpeas, peas), forage legumes (clover and alfalfa) and soybean. Numerous studies about flavonoid content have been performed on different genotypes of soybean, whereas available information about other legume species are quite scarce. In this context a scientific effort aimed at finding a “Mediterranean” alternative to soybean as source of functional compounds is of particular interest. The objective of the present research was to screen a wide germplasm collection, composed of several accessions of grain legumes, for their phytochemical profiles in seeds and seedlings. Results highlighted a broad range of variability in bioactive compounds under both qualitative and quantitative composition. In particular, most of the seeds of investigated accessions contained conjugated forms of the flavonoid kaempferol in the outer layer of the seed. Other bioactive compounds, such as vitexin, were also detected in seeds of adzuki bean accession (Vigna angularis). Beside one common bean accession (Zolfino del Perù) with a flavonoid content (171.3 g/g fresh weight) comparable with that detected in soybean seeds, the total flavonoid content of all other investigated accessions varied from 1.5 to 57.0 g/g fresh weight. As follow-up action, all accessions were analyzed to identify and quantify flavonoids in sprouts. Daidzein, glycitein and genistein, along with kaempferol and quercetin were detected in most of analyzed accessions with amounts ranging from 2.8 to 86.7 g/g fresh weight (approximately 3-10 times lower than isoflavones in soybean sprouts). Results highlighted the possibility of considering some of the investigated legume accessions as a valuable and “Mediterranean” alternative to soybean to obtain plant-derived products with health benefits.