ABSTRACT
BACKGROUND AND OBJECTIVES: A reliable biomarker for optimal selenium (Se) intake in lactating women is not currently available. METHODS AND STUDY DESIGN: Daily dietary Se intake in lactating women was calculated from a 24-hour meal record survey for over 3 days. Se levels in plasma and breast milk were measured through inductively coupled plasma mass spectrometry. Plasma selenoprotein P 1 levels and glutathione peroxidase 3 activity were measured using an enzyme-linked immunosorbent assay. Ultra-performance liquid chromatography-tandem mass spectrometry was used to analyze proteinaceous Se species in enzymatically digested breast milk. RESULTS: Dietary Se intakes of lactating women from Liangshan, Beijing, and Enshi were 41.6±21.2 ng/d, 51.1±22.6 ng/d, and 615±178 ng/d, respectively (p<0.05). The Se levels in the blood and breast milk were significantly associated with the dietary Se intake (p<0.05). The proteinaceous Se species in breast milk were SeMet and SeCys2. The levels of SeMet in the lactating women from Liangshan, Beijing, and Enshi were 3.31±2.44 ng Se/mL, 7.34±3.70 ng Se/mL, and 8.99±9.64 ng Se/mL, while that of SeCys2 were 13.7±12.0 ng Se/mL, 35.6±20.9 ng Se/mL, and 57.4±13.2 ng Se/mL, respectively. Notably, the concentration of SeCys2, the metabolite of unstable SeCys, reached a saturation platform, whereas no similar phenomenon were found for the total Se SeMet from Secontaining proteins. CONCLUSIONS: SeCys2 in breast milk is a potential biomarker for determining the optimal Se intake in lactating women.
Subject(s)
Breast Feeding , Cystine/analogs & derivatives , Lactation/metabolism , Nutritional Status , Organoselenium Compounds/metabolism , Selenium/deficiency , Adult , Biomarkers/metabolism , China , Cystine/metabolism , Female , Humans , Milk, Human , Risk , Selenium/metabolismABSTRACT
Icaritin (ICT) has distinct bioactivities, especially known for its beneficial effects on bone-related degenerative disorders; however, its pharmacokinetic properties remain unknown. A novel developed UPLC-MS/MS method for the determination of ICT and its main metabolite glucuronidated icaritin (GICT) was firstly applied to pharmacokinetic and metabolism studies of ICT in female rats, which were intraperitoneally given 40 mg/kg ICT. Following the protein precipitation of plasma samples with acetonitrile, ICT and GICT were separated on a C18 column using gradient elution mode and quantified in the multiple reaction monitoring mode. The linearities were acceptable for ICT (r = 0.9960) and GICT (r = 0.9968), and the lower limit of quantification values was 0.5 and 5 ng/ml, respectively. The accuracy fell in the range of 92.0%-103.1% and precisions were within 9.5%. Good linearity, accuracy, precision, and recovery were achieved for the UPLC-MS/MS method. ICT was predominantly and rapidly biotransformed to GICT which was slowly eliminated in vivo with a terminal half-life value of 4.51 hr. Pharmacokinetics of pure ICT eliminated biotransformation interference of Epimedium extract and disclosed genuine pharmacokinetic manner of ICT, as well as firstly elucidated low concentration and bioavailability of ICT in rat plasma.
