Reference standards were used in this study, twenty-eight of them were self-made by our laboratory in the early stage [[16], [17], [18]], including 3′-hydroxy-daidzein, calycosin, trifolirhizin, genistein, maackiain, sophoraflavescenol, noranhydroicaritin, shandougenines B, kushenol C, leachianone G, liquiritigenin, 8-(3-hydroxymethyl-2-butenyl)-5,7,2′,4′-tetrahydroxyflavanone, 2′-hydroxy-isoxanthohumol, (2R)-3β,7,4′-trihydroxy-5-methoxy-8-prenylflavanone, (2R)-3α,7,4′-trihydroxy-5-methoxy-8-prenylflavanone, 4H-1-benzopyran-4-one,2-(4-hydroxyphenyl)-3,7-dihydroxy-5-methoxy-8-[5-methyl-2-(1-methylethenyl)-4-hexenyl], isoxanthohumol, kurarinol, kushenol N, kurarinone, isokurarinone, kushenol U, 2′-methoxykurarinone, norkurarinone, kushenol A, kushenol L, kuraridin, xanthohumol and biochanin A, kushenol B and kushenol M were purchased from Sichuan Weikeqi Biological Technology Co., Ltd (Sichuan China) and Wuhan Tianzhi Biotechnology Co., Ltd. (Wuhan, China), kushenol E and kushenol X were donated by Dr. YY Jiang from Beijing University of Chinese Medicine. The purity of the above standards is greater than 98 %.