Trifolium nigrescens was researched for its chemical constituents for the first time. Bioassay-guided isolation of the EtOAc extract from the leaves of T. nigrescens resulted in the purification of a new biflavone, 4''',5,5″,7,7″-pentahydroxy-3',3'''-dimethoxy-3-O-β-d-glucosyl-3″,4'-O-biflavone (1)
Two bischromones, 3,3'-dimethoxy-2'-oxychromone (1), 3,3'-dihydroxy-2,2'-oxychromone (2) and a biflavone, 5,7,4',5″,3'",4″″-hexahydroxy-3″-O-β-glucosyl-3',7″-O-biflavone (3) have been isolated from whole plant of Trifolium echinatum Bieb. together with five known flavonoids. The structures of the