Saponins contained in alfalfa act on the cardiovascular, nervous, and digestive systems (1). The hypocholesterolemic and hemolytic activity of the leaves and sprouts of alfalfa are attributed to a steroidal saponin fraction which, along with fiber contained within the plant, binds to cholesterol in vitro. Alkaloids such as stachydrine and l-homo-stachydrine found in the seed are thought responsible for alfalfa's ability to promote menstrual discharge and for its lactogenic activity (2).
Biochanin-A, an isoflavonoid constituent, blocks NF-κB activation by preventing phosphorylation and degradation of IκBα, leading to decreased expression of inducible nitric oxide synthase, thus preventing proliferation and inflammation (17).
Extracts from alfalfa preferentially served as agonists for estrogen receptor beta, and alfalfa increased estrogen-dependent MCF-7 breast cancer cell proliferation even more than did estradiol (9).
The non-protein amino acid constituent, L-canavanine, constitutes 1.5% of the dry weight of alfalfa seeds and alfalfa sprouts. It has been shown to affect human T cells in vitro and induce hematologic and serologic abnormalities characteristic of systemic lupus erythematosus in monkeys (13). This is the proposed mechanism by which systemic lupus erythematosus relapse occurs in humans as well (7), although some researchers question whether L-canavanine concentrations in alfalfa are sufficient to cause this effect (8).