Development of rapid method for detection of isomiroestrol in Pueraria candollei using immunochromatographic strip test

Pueraria candollei is a traditional herb widely used in Thailand as a source of phytoestrogen and was considered to be the standard herbal estrogen replacement therapy because of its highly estrogenic activity [1]. Isomiroestrol was a compound found in P. candollei. It has estrogenic activity the same as another miroestrol, deoxymiroestrol, and isoflavonoids thus isomiroestrol was used as an identical marker for P. candollei [2]. To date, LC-MS-MS, LC-Q-Orbitrap/MS and enzyme-link immunoassay (ELISA) have been used to quantify isomiroestrol levels in plant samples which has several limitation such as long time-consuming and needed for expensive equipment [2 – 3]. Therefore, lateral-flow immunoassay using a colloidal gold-antibody probe was developed for the analysis of isomiroestrol in plant and product obtained from P. candollei. The competitive immunoassay was based on anti-isomiroestrol monoclonal antibody conjugated with colloidal gold-antibody (detection reagent). Secondary antibody was immobilized on one end of a nitrocellulose membrane (control line) and isomiroestrol-bovine serum albumin conjugate was immobilized on the other end (test line). Then eighteen different plant and products were tested using developed and validated method. The detection limit of isomiroestrol was 7 µg/mL. Detection time was 15 min. Our results demonstrated that the applied method was effective to detect isomiroestrol in P. candollei and its product.

[1] Chansakaow S, Ishikawa T, Seki H, Sekine K, Okada M, Chaichantipyuth C. J Nat Prod 2000; 63: 173 – 175.

[2] Kitisripanya T, Jutathis K, Inyai C, Komaikul J, Udomsin O, Tanaka H, Putalun W. J Pharm Biomed Anal 2017; 137:229 – 234.

[3] Lee JH, Kim JY, Cho SH, Jeong JH, Cho S, Park HJ, Baek SY. J Chromatogr Sci 2017; 55: 214 – 221.