RESUMEN
In this study we developed a sensitive method using high performance liquid chromatography (HPLC) coupled to electrospray ionization (ESI) with high resolution time of flight (TOF) mass spectrometry (MS) for the determination of naturally occurring antioxidant trans-resveratrol (3,5,4'-trihydroxy-trans-stilbene, RES). This method enabled an investigation of a relationship between tumor growth in rats and concentration of RES and its primary metabolites, trans-resveratrol-3-O-sulfate-3-O-sulfate (R3S) and trans-resveratrol-3-O-ß-d-glucuronide (R3G), in rat serum after RES exposure (5 or 25mg/kg/day). RES levels in rat serum were near the limit of detection, showing concentrations of 4±1 and 12±4ng/mL for low and high-dose exposure, respectively. Compared to RES, higher concentrations were found for its metabolites (R3G:4.8±0.3 and 6.8±0.3µg/mL; R3S:0.27±0.09 and 0.34±0.04µg/mL, respectively). Using TOF, for the first time, we measured the matrix affected limits of detection (LODs) in plasma (3.7, 82.4, and 4.7ng/mL for RES, R3G, and R3S, respectively), which were comparable to those reported in previous work using HPLC tandem mass spectrometry, but with a benefit of a full mass spectral profile. The ability to acquire data in full scan mode also revealed other isomers of R3S. The additional novelty of our study is in synthesis and application of deuterated recovery standards enabling accurate and precise quantification. In order to develop a robust method, the ESI conditions were optimized using a multilevel full factorial design of experiments.
Asunto(s)
Antineoplásicos/sangre , Cromatografía Líquida de Alta Presión/métodos , Espectrometría de Masa por Ionización de Electrospray/métodos , Estilbenos/sangre , Animales , Antineoplásicos/síntesis química , Antineoplásicos/aislamiento & purificación , Antineoplásicos/uso terapéutico , Antioxidantes/análisis , Antioxidantes/aislamiento & purificación , Antioxidantes/metabolismo , Antioxidantes/farmacología , Neoplasias de la Mama/tratamiento farmacológico , Medición de Intercambio de Deuterio/normas , Femenino , Glucurónidos/sangre , Glucurónidos/química , Límite de Detección , Ratas , Resveratrol , Estilbenos/síntesis química , Estilbenos/química , Estilbenos/aislamiento & purificación , Estilbenos/uso terapéuticoRESUMEN
Delta-sultones, prepared by C-H insertion, can be oxidatively converted to gamma-lactones by treatment with t-BuOK/t-BuOOH. An intermediate in the synthesis of (-)-eburnamonin was prepared using this approach.
RESUMEN
Intramolecular C-H insertion on diazosulfone and diazosulfonate substrates was used to prepare synthetically useful intermediates from easily available starting materials.
RESUMEN
Investigations were undertaken to utilize flue gas desulfurization (FGD) gypsum for the treatment of leachate from the coal ash (CA) dump sites. Bench-scale investigations consisted of three main steps namely hydrogen sulfide (H(2)S) production by sulfate reducing bacteria (SRB) using sulfate from solubilized FGD gypsum as the electron acceptor, followed by leaching of heavy metals (HMs) from coal bottom ash (CBA) and subsequent precipitation of HMs using biologically produced sulfide. Leaching tests of CBA carried out at acidic pH revealed the existence of several HMs such as Cd, Cr, Hg, Pb, Mn, Cu, Ni and Zn. Molasses was used as the electron donor for the biological sulfate reduction (BSR) process which produced sulfide rich effluent with concentration up to 150 mg/L. Sulfide rich effluent from the sulfate reduction process was used to precipitate HMs as metal sulfides from CBA leachate. HM removal in the range from 40 to 100% was obtained through sulfide precipitation.