Quantitative Analysis of Estrogenic Xenobiotics in Humans Using Liquid Chromatography-Mass Spectrometry
thesisposted on 11.06.2014 by Yang Yuan
In order to distinguish essays and pre-prints from academic theses, we have a separate category. These are often much longer text based documents than a paper.
Women are trying botanical dietary supplements for the possible relief of menopausal symptoms as alternatives to conventional HRT. Standardization of a botanical dietary supplement is an essential step to achieve a safe and reliable product. Typically, chemical standardization is used to provide consistent levels of active constituents and predictable pharmacological effects to consumers. Humulus lupulus L. (hops) is a source of prenylated flavonoids, and hop dietary supplements are often standardized to the phytoestrogen 8-prenylnaringenin. In this dissertation, a HPLC-MS-MS method is described and validated for the standardization of a hop extract, which was used for a Phase I clinical trial. To determine if prenylflavonoids from a standardized hop extract are orally bioavailable, a Phase I clinical trial was carried out. Five menopausal women subjects were recruited and received 3 escalating dosages of the hop extract with a one-month washout period between each dosage. Using a newly developed and validated UHPLC-MS-MS method that was approximately 10-fold faster than the HPLC-MS-MS method used to standardize the hop extract, serum and urine levels of prenylflavonoids from hops were determined. These prenylflavonoids included xanthohumol, isoxanthohumol, 8-prenylnaringenin, and 6-prenylnaringenin. These data suggest that hop prenylflavonoids are absorbed rapidly after oral administration and that the major circulating forms are glucuronic acid conjugates. Bisphenol A (BPA) is used as a material for the production of epoxy resins and polycarbonate plastics. BPA has been reported to migrate from can surface coatings and polycarbonate plastics into food and water. A sensitive, selective and rapid analytical method based on UHPLC-MS-MS was developed and validated for the measurement of BPA and its primary metabolite, BPA-glucuronide, in human serum.