title: An LC/MS method for the quantitative determination of 7alpha-OH DHEA and 7beta-OH DHEA: an application for the study of the metabolism of DHEA in rat brain.
abstract: Dehydroepiandrosterone (DHEA) is an important neurosteroid with neuronal protection and memory enhancement functions. 7alpha-OH DHEA and 7beta-OH DHEA are the two important metabolites of DHEA in the brain. We have developed an LC/MS method to quantitatively analyze 7alpha-OH DHEA and 7beta-OH DHEA. Chromatographic separation was carried out on a C18 column with gradient elution using mobile phases of formic acid in acetonitrile and in water formic acid. Mass spectral detection was performed with a ThermoFinnigan LCQ advantage quadruple ion trap mass spectrometer with electrospray ionization. Positive ion chromatograms were acquired using single ion monitoring. The protonated molecule was 305 m/z, but the most abundant ion (269 m/z) was used for quantification. This method was validated and applied to investigate the 7-hydroxylation of DHEA. When incubating DHEA with rat brain microsomes, both 7alpha-OH DHEA and 7beta-OH DHEA were observed, but 7alpha-OH DHEA was the major metabolite.
authors.affiliation: Department of Biomedical and Pharmaceutical Sciences, College of Pharmacy, Idaho State University, Pocatello, ID 83209-8334, USA.
authors.forename: Aiqun
authors.initials: A
authors.lastname: Li
authors.forename: Matthew P
authors.initials: MP
authors.lastname: May
authors.forename: James C
authors.initials: JC
authors.lastname: Bigelow
mesh_terms: D000818:Animals; D001921:Brain / Q000378:metabolism*; D001923:Brain Chemistry; D002853:Chromatography, Liquid / Q000379:methods*; D003687:Dehydroepiandrosterone / Q000031:analogs & derivatives / Q000032:analysis* / Q000378:metabolism*; D005260:Female; D008297:Male; D013058:Mass Spectrometry / Q000379:methods*; D008861:Microsomes / Q000737:chemistry / Q000378:metabolism; D051381:Rats; D017207:Rats, Sprague-Dawley
chemical_list: D003687:Dehydroepiandrosterone