Pueraria mirifica, the rejuvenating herb and its unique phytoestrogenic constituents Miroestrol, its isomers and derivatives

Pueraria candollei var. mirifica (Airy Shaw & Suvat.) Niyomdham (for simplicity, Pueraria mirifica) is native to Thailand and known locally as “White Kwao Kuer”. Its tuberous root has been used locally for centuries due to its profound anti-ageing properties and is considered a “fountain of youth” for aged men and women. The rejuvenating properties of the root are correlated to several different classes of phytoestrogens, namely isoflavonoids, coumestans and chromenes (comprising miroestrol, its isomers and derivatives). Among more than thirteen species of Pueraria (P.) in Thailand, P. mirifica possesses the most distinct phytoestrogenic activity due to its uniquely high content of chromene compounds and its naturally balanced ratio of phytoestrogens. The complex mixture of phytoestrogens in P. mirifica is important for identification, as well as biological activity. Therefore, a simple, accurate and reproducible method to qualitatively and quantitatively describe the chemical constituents of P. mirifica is desirable. For this purpose authentic reference standards were made available, viz, miroestrol, deoxymiroestrol, kwakhurim, puerarin, daidzin, genistin, daidzein, genistein and coumestrol. The captioned characteristic constituents were determined in different P. mirifica herb samples using UPLC/MS/MS. This, together with fingerprinting showing the ideal mixture of phytoestrogenic components, serves as a novel approach for quality control purposes to ensure proper identification of genuine P. mirifica.