Structure-based design of eugenol analogs as potential estrogen receptor antagonists

Eugenol is an essential oil mainly found in the buds and leaves of clove (Syzygium aromaticum (L.) Merrill and Perry), which has been reported to have activity on inhibition of cell proliferation and apoptosis induction in human MCF-7 breast cancer cells. This biological activity is correlated to its activity as an estrogen receptor antagonist. In this article, we present the construction and validation of structure-based virtual screening (SBVS) protocols to identify the potent estrogen receptor α (ER) antagonists. The selected protocol, which gave acceptable enrichment factors as a virtual screening protocol, subsequently used to virtually screen eugenol, its analogs and their dimers. Based on the virtual screening results, dimer eugenol of 4-[4-hydroxy-3-(prop-2-en-1- yl)phenyl]-2-(prop-2-en-1-yl)phenol is recommended to be developed further in order to discover novel and potent ER antagonists.     

Gas chromatographic determination of thymol.

Thymol in biological samples is analyzed by gas chromatography utilizing a 5% OV-25 column, a flame ionization detector, and eugenol as an internal standard. Samples are extracted with diethyl ether and analyzed without derivatization. The lower limit of detection of thymol in a sample is about 0.01 μg and quantitation is satisfactory in plasma at $\text{0.05 μ}\text{g}\text{2}\text{ml}$. Data was recorded digitally on magnetic tape and calculated off-line at a central facility.     

Gas chromatographic determination of meprobamate in human plasma

A simplified and rapid gas chromatographic method has been developed for the determination of meprobamate in human plasma. The procedure includes a single-step extraction of alkalinized sample with chloroform, and chromatography on a non-polar fused-silica capillary column with flame ionization detection. The method is accurate (97.7 ± 5.7% at 20 mg/l) and precise (maximum coefficient of variation of 9.5%). It provides an alternative to existing methods and is particularly suitable for toxicological studies.     

Gas chromatographic determination of zopiclone in plasma after solid-phase extraction

A gas chromatographic technique for determining zopiclone based on a solid-phase extraction procedure with C₁₈ cartridge for sample clean-up is presented. Quantification can be achieved with 1 ml of plasma. The method uses prazepam as internal standard. Zopiclone is separated on a 5% phenyl methyl silicone analytical column and detected with an electron-capture detector, which consequently allows a limit of quantitation of 2 μg/l. It is thus simple, rapid, sensitive and linear over the range 5–2000 μg/l.     

Gas chromatographic method for the determination of testosterone in urine

A method is described for measuring testosterone in the urine using glucuronidase hydrolysis, continuous extraction with methylene dichloride, and chromatography on silica gel column as well as thin-layer and gas chromatography. This method proved to be practical for processing large numbers of samples and gave consistently reproducible results in the more than 600 specimens tested in the course of clinical evaluation of patients.     

Gas chromatographic determination of the hypoglycaemic agent gliclazide in plasma

A gas chromatographic method has been developed that permits the accurate and specific determination of the hypoglycaemic agent gliclazide in plasma. Gliclazide is extracted with chloroform and, after clean-up, derivatized with diazomethane followed by heptafluorobutyric anhydride to form N-methyl-N′-heptafluorobutyrylgliclazide, which is assayed on a gas chromatograph equipped with a flame ionization detector, an electron-capture detector or a nitrogen—phosphorus sensitive detector.Accurate determinations are possible with flame ionization detection over a concentration range of 1–15 μg/ml of gliclazide in plasma with a relative standard deviation of 5.2%. The minimum detectable concentration with electron-capture detection is 0.02 μg per sample. Plasma levels of gliclazide in dogs following single oral administration (40 mg per dog) have also been determined.     

Gas chromatographic determination of malonaldehyde formed by lipid peroxidation

Gas chromatographic (GC) methods for the determination of malonaldehyde (MA) all require formation of a stable derivative of MA since free MA is not suitable for direct GC analysis. Most reported GC methods give a total measure of free MA and its bound forms because their assay conditions are sufficient to hydrolyze or decompose bound MA during sample preparation. In this paper, GC methods that provide a measure of total MA (free plus bound) are reviewed. A recently developed capillary GC method that allows determination of free MA apart from other forms is also discussed. The method involves derivatization of MA to N-methylpyrazole under milder reaction conditions than with other GC methods. The method represents an advantage over existing techniques for free MA determination because capillary GC offers the highest efficiency of separation among chromatographic methods thus allowing a more specific and accurate measure of MA.     

Gas chromatographic method for the determination of urinary acetylpolyamines

A gas chromatographic method was developed for the determination of monoacetylputrescine, monoacetylcadaverine, N¹-acetylspermidine and N⁵-acetylspermidine in human urine. The amines were isolated from urine by silica gel column chromatography. 1, 10-Diaminodecane was used as internal standard. The amines were reacted with ethyl chloroformate in aqueous medium to four ethyloxycarbonyl derivatives prior to application to gas chromatography using a flame ionization detector. Separation and determination of the derivatives were carried out on a Uniport HP column (1.0 m) impregnated with 0.5% SP-1000 under temperature-programmed conditions. The monoacetylpolyamines could be measured accurately at the nanomole level. The method was used for the determination of the monoacetylpolyamines in urine of healthy volunteers. The values obtained were in the range of the published data.     

Gas chromatographic determination of aromatic acid metabolites of phenylalanine in brain

A method for the determination of the aromatic acid metabolites of phenylalanine in brain by gas-liquid chromatography is described. Procedures were developed for the extraction and purification of the metabolites, the preparation of their trimethylsilyl derivatives, the separation and identification of these derivatives by gas-liquid chromatography, and the quantification of the metabolites by employing the internal reference standards phenylvaleric and o-hydroxyphenylacetic acids with the detector molar response factors. The metabolites in the hyperphenylalaninemic brain were identified as the trimethylsilyl ester of phenylacetic, ester-ethers of mandelic and phenyllactic, and the ester-enol ether of the oxime of phenylpyruvic acid.     

Gas chromatographic determination of isosorbide dinitrate in human plasma and urine

A rapid, simple and sensitive method for the specific determination of isosorbide dinitrate concentrations down to 0.5 ng/ml in human plasma and urine is described. Following traction (with or without internal standard) of isosorbide dinitrate into toluene, the compound is determined by gas chromatography using a ⁶³Ni electron-capture detector.