• Archives of Pharmacal Research
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• v.20 no.3
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• pp.247-252
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• 1997

Perfluorotolyl (PFT)-ether and perfluorotoly-trimethylsilyl (PFT-TMS) ether derivatives of oestrone, $17{\alpha}$- and $17{\beta}$oestradiol were prepared under phase transfer conditons. The former derivatives under negative ion chemical ionization conditions gave significant ions in the mass spectrometer but $17{\alpha}$- and $17{\beta}$ -oestradiol gave poor resolution. However, the PFT-TMS derivatives of 17.${\alpha}$- and$17{\beta}$-oestradiol showed good resolution. These derivatives were used for the analysis of oestrogens in bovine aqueous humour, vitreous humour and retina. The mean $({\pm}SEM)$ concentrations of oestrone in bovine aqueous humour (n=18), vitreous humour (n=18) and bovine retina (n=4) were $0.47{\pm}0.11$, $0.46{\pm}0.14$ and $1.10{\pm}0.24 ng.ml^{-1}$, respectively. $17{\alpha}$-Oestradiol was detected in 16 out of 18 samples of bovine aqueous humour and vitreous humour and the mean $({\pm}SEM)$ concentrations were $0.30{\pm}0.10$ and $0.08{\pm}0.02 ng.ml^{-1}$, respectively. The mean $({\pm}SEM)$ concentration of 17.betha.-oestradiol in aqueous humour (n=7) and vitreous homour (n=11) $0.83{\pm}0.26 ng ml^{-1}$ and $0.39{\pm}0.09 ng ml^-1$, respectively. In retina the concentrations of both steroids were below the detection limit.

• Journal of Photoscience
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• v.9 no.1
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• pp.17-22
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• 2002

Studies have been conducted to explore photoaddition reactions of N-methylthiophthalimide with $\alpha$-silyl-n-electron donors Et$_2$NCH$_2$SiMe$_3$, n-PrSCH$_2$SiMe$_3$ and EtOCH$_2$SiMe$_3$. Photoaddition of $\alpha$-silyl amine Et$_2$NCH$_2$SiMe$_3$ to N-methylthiophthalimide occurs in $CH_3$CN and benzene to produce non-silicon containing adduct in which thiophthalimide thione carbon is bonded to $\alpha$-carbon of $\alpha$-silyl amine in place of the trimethylsilyl group. In contrast, photoaddition of EtOCH$_2$SiMe$_3$ to N-methylthiophthalimide generates two diastereomeric adducts in which thiophthalimide thione carbon is connected to $\alpha$-carbon of $\alpha$-silyl ether in place of u-hydrogen. Based on a consideration of the oxidation potentials of u-silyl-n-electron donors and the nature of photoadducts, mechanism for these photoadditions involving single electron transfer(SET) -desilylation and H atom abstraction pathways are proposed.

• Mass Spectrometry Letters
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• v.1 no.1
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• pp.29-32
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• 2010

Cross reacting antibodies can cause an overestimation of the results of immunoassays. Therefore, alternative methods are needed for the accurate quantification of steroids. Gas chromatography combined with isotope-dilution mass spectrometry (GC-IDMS) is developed to quantify urinary active androgens, testosterone, epitestosterone and dihydrotestosterone, which are clinically relevant androgens to both hair-loss and prostate diseases. The method devised involves enzymatic hydrolysis with $\beta$-glucuronidase, solid-phase extraction, liquid-liquid extraction using methyl tert-butyl ether and subsequent conversion to pentafluorophenyldimethylsilyl-trimethylsilyl (flophemesyl-TMS) derivatives for sensitive and selective analysis in selected-ion monitoring mode. Flophemesyl-TMS derivatization not only eliminates matrix interference but also has a good peak resolution within a 6 min-run. A selective and sensitive GC technique with flophemesyl-TMS derivatives also allows accurate quantitative analysis of three active androgens when combined with IDMS. The limit of quantification of the three analytes was <50 pg/mL, and extraction recoveries ranged from 91.9 to 102.1%. The precision and accuracy were 1.2~6.5% and 89.0~106.7%, respectively. This GC-IDMS method can be useful for evaluating the drug efficacy and monitoring the biological processes responsible for male-pattern baldness and prostate diseases.

• Bulletin of the Korean Chemical Society
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• v.26 no.1
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• pp.97-102
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• 2005

The addition reactions of $\alpha$,$\alpha$-difluoroiodomethyl n-butyl ketone, α,α-difluoroiodomethyl cyclohexyl ketone, or $\alpha$,$\alpha$-difluoroiodomethyl phenyl ketone to alkenes were successfully accomplished in good yields in the presence of copper powder. The reaction was also applicable to alkenes containing a variety of functional groups such as ester, trimethylsilyl, or ether group. Acetonitrile was determined to be the best solvent in the present study and the reaction was performed at 55 ${^{\circ}C}$ for 15-22 h. This reaction provides a new, efficient and general method for the synthesis of $\alpha$,$\alpha$-difluoro functionalized ketones.

• Journal of the Korean Chemical Society
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• v.36 no.3
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• pp.453-459
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• 1992

3-Aryl-3-bromopropanoyl chloride in either ether or carbon tetrachloride reacted with 2 equiv. of hydroxylamine in the absence of trimethylsilyl chloride at ambient temperature to give directly 2,5-diarylisoxazolidin-3-ones in good yields. However, when 3-benzylhydroxylamine at $0^{\circ}C$, N-benzyl-3-bromo-3-phenylpropanohydroxamic acid (72%) and N-benzyl-C-phenylnitrone (12%) were obtained. On the contrary, 3-phenylisoxazolidin-5-one (41%) and 2-benzyl-S-phenyl-isoxzolidin-3-one (38%) were obtained when 3 equiv. of benzylhydroxylamine was used under the same conditions.

• Analytical Science and Technology
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• v.11 no.5
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• pp.374-385
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• 1998

Phytoestrogens are biologically active compounds derived from plants foods. It had been suggested that phytoestrogens, by inhibiting aromatase in peripheral and/or cancer cells and lowering estrogen levels, may play a protective role as antipromotional compounds during growth of estrogen-dependent cancers. Therefore, simultaneous analysis of estrogens and phytoestrogens is necessary to elucidate the possible involvement of phytoestrogens in estrogen metabolism. In this view, we developed a simple and reproducible procedure to quantitatively determine estrogen and phytoestrogen metabolites. The proposed method consisted of solid phase extraction using preconditioned Serdolit AD-2 resin, enzyme hydrolysis with ${\beta}$-glucuronidase/arylsulfatase from Helix pomatia, liquid-liquid extraction and TMS-ether derivatization. And the final determination was carried out by gas chromatography/mass spectrometry (GC/MS) in selected ion monitoring mode (SIM). The precision and accuracy of this method was evaluated through within-a-day and day-to-day test. Recovery range and detection limit were 71.96~105.66%, 2~4 ng/mL, respectively. Using this method, 17 estrogen and 5 phytoestrogen compositions in urine of normal subjects were analyzed. It was found that amounts and relative distribution of urinary phytoestrigens and estrogens showed different pattern in male and female subjects.

• Journal of the Korean Chemical Society
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• v.42 no.3
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• pp.266-276
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• 1998

Cholesterol supersaturation in bile, which causes gallstone formation, is the result of low bile acid secretion or high cholesterol secretion. The quantitative analysis of cholesterol, bile acids and sterols which are precursors of cholesterol have been used to examine the changes in bile component. We described a simple, sensitive and reproducible method for simultaneous determination of cholesterol, five bile acids and seven sterols in human bile juices and gallstones by capillary column gas chromatography-mass spectrometry (GC/MS). Clinical samples were hydrolyzed by alcoholic KOH, extracted twice (pH 14 and 1) and derivatized to trimethylsilyl (TMS) ether with $MSTFA/NH_4I$ (N-methyl-N-trimethylsilyltrifluoroacetamide/ammonium iodide) mixture in order to be detected on the GC/MS. The good quality control data were obtained through within-a-day and day-to-day test (RSD values were 1.72-13.79, 0.68-14.10, respectively) and the recovery range of them was 73.56-96. 95 Using this method, biliary and gallstone compositions in the patients with intrahepatic stones were analyzed. The amounts and its relative distribution of cholesterol, bile acids and sterols showed different pattern in bile juices and gallstones.

• Journal of Food Hygiene and Safety
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• v.33 no.4
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• pp.266-271
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• 2018

The Ministry of Food and Drug Safety (MFDS) is amending its test methods for health-functional foods (dietary food supplements) to establish regulatory standards and specifications in Korea. In this regard, we continue our research on developing analytical methods for the items. Octacosanol is the major component of polycosanol and is a high-molecular-mass primary fatty alcohol, obtained from sugar cane wax. Previous researchers have shown that octacosanol can lower cholesterol and has antiaggregatory properties, cytoprotective uses, and ergogenic properties for human health. Recently, octacosanol products have been actively introduced into the domestic market because of their functional biological activity. We have developed a sensitive and selective test method for octacosanol that the TMS derivatives by means of gas-chromatographic-tandem mass spectrometry (GC-MS). The trimethylsilyl ether derivative of the target analyte showed excellent chromatographic properties. The procedure was validated in the range of $12.5{\sim}200{\mu}g/L$. Standard calibration curves presented linearity with the correlation coefficient ($r^2$) > 0.999, and the limits of detection (LOD) and limits of quantitation (LOQ) were $4.5{\mu}g/L$ and $13.8{\mu}g/L$, respectively. The high recoveries (92.5 to 108.8%) and precision (1.8 to 2.4%) obtained are in accordance with the established validation criteria. Our research can provide scientific evidence to amend the octacosanol test method for the Health-Functional Food Code.