title: Biotin-avidin amplified enzyme-linked immunosorbent assay for determination of isoflavone daidzein.
abstract: A biotin-avidin amplified enzyme-linked immunosorbent assay (BA-ELISA) method was developed and optimized for the determination of a weakly estrogenic isoflavone daidzein in serum, urine and Puerariae radix. Specific polyclonal antibody was produced against daidzein by immunization of rabbits with a conjugate of 7-O-(carboxymethyl)-daidzein and bovine serum albumin (BSA). The polyclonal antibody showed specific recognition of daidzein, while cross-reactivities to coumarin, 4-hydroxycoumarin, phenol, and other isoflavones such as puerarin and rutin were all lower than 1%. The linear range of daidzein calibration curve was 0.1-1000ngmL(-1). The detection limit was found to be 0.04ngmL(-1), and the intra-assay and inter-assay coefficients of variation were 7 and 16%, respectively. Human serum and urine samples were spiked with known amounts of daidzein and measured by the established BA-ELISA. Recoveries were between 91 and 107%. Daidzein in P. radix was determined by the BA-ELISA method and HPLC method, and the content of daidzein was determined to be 0.0219 and 0.0194%, respectively. The results indicated that there was a good agreement between the two methods. The established method is very useful for monitoring daidzein in biological samples and traditional Chinese medicine.
authors.affiliation: The Key Laboratory of Bioorganic Chemistry and Molecular Engineering, College of Chemistry and Molecular Engineering, Peking University, Beijing 100871, PR China.
authors.forename: Jian-Tao
authors.initials: JT
authors.lastname: He
authors.forename: Zhi-Hong
authors.initials: ZH
authors.lastname: Shi
authors.forename: Jin
authors.initials: J
authors.lastname: Yan
authors.forename: Mei-Ping
authors.initials: MP
authors.lastname: Zhao
authors.forename: Zhen-Quan
authors.initials: ZQ
authors.lastname: Guo
authors.forename: Wen-Bao
authors.initials: WB
authors.lastname: Chang