SciCombinator

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Journal: Journal of pharmaceutical and biomedical analysis

38

Extracts of Acacia rigidula leaves are used in weight-loss products sold in vitamin shops and over the internet with little or no published data about their potential biological effects. In our chemical investigations on authenticated A. rigidula plant material, we established a rapid and sensitive LC-MS/MS method for the quantitative determination of several phenethylamine, tyramine and tryptamine derivatives. Stable isotopically labeled compounds were used as internal standards for quantitative analysis. We found total calculated contents of 6 biogenic amines in A. rigidula leaf of 18.6 and 32.9μg/g. The content of selected amines in 21 dietary supplements labeled as containing A. rigidula was determined by a second LC-MS/MS method. Our study revealed significant differences in the amine profiles of authenticated plant materials and dietary supplements. β-Methylphenethylamine, a non-natural compound, was found in 9 of the 21 dietary supplement products. β-Methylphenethylamine was found at levels of 960-60,500μg/g while phenethylamine was found at levels of 710-171,620μg/g. β-Methylphenethylamine is a positional isomer of amphetamine and our results showed that it can be misidentified as amphetamine during LC-MS analysis. An independent GC-MS analysis was used to confirm the presence of β-methylphenethylamine and the absence of amphetamine in dietary supplements labeled as containing A. rigidula. This study demonstrates that confirmations by independent analytical methods are essential to verify findings of unusual or unexpected compounds in dietary supplements.

Concepts: Amine, Vitamin, Dietary supplement, Chemical compound, Leaf, Biogenic amine, Acacia, Acacia berlandieri

28

In recent years, amorphous formulations and other special dosage forms of drug products have been investigated to achieve adequate solubility and disintegration. We have evaluated the distribution of crystalline and amorphous states of a drug product using Nanothermal analysis (Nano-TA) and Raman imaging methods. Compared to conventional differential scanning calorimetry, Nano-TA can be used to more rapidly characterize the crystalline and amorphous states of model formulations, including their ingredient distributions, without any sample preparation. In the current study, imaging maps obtained for specific model formulations were evaluated on the basis of their visual appearance and the physicochemical properties of the active pharmaceutical ingredient (API). In addition, the crystalline and amorphous states of the model formulations were distinguished by Raman mapping. Nano-TA was found to be useful for the characterization of crystalline and amorphous states of APIs and the distribution of other ingredients. This technology could be used to monitor the changes in crystalline forms of drug substances and dosage forms during processing. In addition, Nano-TA can be used to characterize amorphous states.

Concepts: Pharmacology, Physical chemistry, Materials science, Differential scanning calorimetry, Pharmaceutical drug, Glass transition, Active ingredient, Isothermal titration calorimetry

28

Gamma-hydroxybutyric acid (GHB) and its “pro-drugs”, gamma-butyrolactone (GBL) and 1,4 butanediol (1,4-BD), are drugs of abuse with depressant effects on the central nervous system. Many analytical methods have been proposed for the quantitative determination of these compounds mainly in biological matrices but only few have been addressed to dietary supplements and foods. Facile synthesis of the GBL and 1,4-BD isotopologues are available by “one pot” Ru-catalyzed homogeneous deuteration of dicarboxylic acids. In this work we propose a new method for determination of GHB, GBL and 1,4-BD in commercially available dietary supplements, based on isotope dilution mass spectrometry (ID-MS). The procedure involves a simple extraction of sample with acidic acetonitrile and direct analysis by GC-ID-MS method without any purification or derivatization. Indeed, the proposed method takes advantage of the complete conversion of GHB (free acid or its salts) to GBL, allowing the quantification of GHB and its pro-drugs. Five levels for each calibration curve have been prepared by diluting working solutions of the analytes to obtain concentrations ranging from 1 to 20mg/mL. The validation procedures have shown an accuracy between 88% and 99% and a precision between 7.3% and 2.9% of each analyte in the sample matrix. Positive ions chemical ionization (PICI) have been employed to preserve the information on molecular ions and to improve specificity and sensitivity of quantitative determination.

Concepts: Nervous system, Acid, Ammonia, Mass spectrometry, Molecule, Chemistry, Analytical chemistry, Ion source

28

Polygonum multiflorum is one of the most commonly used Chinese medicines. In this study, an effective pressurized water extraction and HPLC method was developed for first simultaneous determination of 8 hydrophilic compounds, including gallic acid, Hypaphorine, Catechin, Proanthocyanidin B1, Epicatechin, Proanthocyanidin B2, Emodin-8-O-β-d-glucopyranoside, stilbene glycosides, in P. multiflorum. The analysis was performed on a Zorbax SB-AQ column with gradient elution of 0.05% phosphoric acid aqueous solution and acetonitrile in 45min. All calibration curves showed good linearity (R(2)>0.9994) within test ranges. The LOD and LOQ were lower than 0.2 and 1.0μg/mL on column, respectively. RSD for intra- and inter-day of 8 analytes were less than 4.1% and 4.0%, respectively, and the overall recovery was 96.0-100.7%. The validated method was successfully applied to quantification of 8 hydrophilic compounds in samples of P. multiflorum from different locations of China. Chemometrics such as principal component analysis (PCA) and hierarchical clustering analysis (HCA) were used to evaluate homogeneity of P. multiflorum in China, which suggested that their quality homogeneity was good.

Concepts: High performance liquid chromatography, Phosphoric acid, Principal component analysis, Catechin, Tannin, Polygonum multiflorum, Proanthocyanidins, B type proanthocyanidin

28

In this study, a total of 20 elements (essential, non-essential and toxic): lithium (Li), sodium (Na), potassium (K), gallium (Ga), magnesium (Mg), zinc (Zn), iron (Fe), copper (Cu), manganese (Mn), vanadium (V), chromium (Cr), nickel (Ni), cobalt (Co), molybdenum (Mo), selenium (Se), barium (Ba), tin (Sn), arsenic (As), lead (Pb) cadmium (Cd) and mercury (Hg) in natural and cultured Cordyceps kyushuensis have been determined by means of inductively coupled plasma mass spectrometry (ICP-MS). Cultured stroma, natural stroma and natural worm were digested by microwave-assisted method before analysis. The proposed ICP-MS method was validated by analyzing a certified reference material (CRM) GBW10015 (spinach). The results of one-way analysis of variance (ANOVA) revealed that the element concentrations in the three kinds of samples were significantly different (p<0.05). Except for Mg, Zn, Cu, the values of other elemental contents were the highest in the stroma of natural C. kyushuensis. In comparison with the worm, the concentrations of determined elements in wild stroma were higher. The remarkable difference of elemental contents between cultured and natural stroma may be caused by distinct growing environment. This finding highlighted the usefulness of ICP-MS elemental analysis and enhanced the value of C. kyushuensis as a candidate for nourishing food based on its composition.

Concepts: Iron, Chemical element, Metal, Zinc, Copper, Analysis of variance, Chemical elements, Biology and pharmacology of chemical elements

28

A serum metabonomic profiling method based on ultra-performance liquid chromatography/time-of-flight mass spectrometry (UHPLC/TOF-MS) was applied to investigate the metabolic changes in hypothyroid rats induced by propylthiouracil (PTU). With Significance Analysis of Microarray (SAM) for classification and selection of biomarkers, 13 potential biomarkers in rat serum were screened out. Furthermore, Ingenuity Pathway Analysis (IPA) was introduced to deeply analyze unique pathways of hypothyroidism that were primarily involved in sphingolipid metabolism, fatty acid transportation, phospholipid metabolism and phenylalanine metabolism. Our results demonstrated that the metabonomic approach integrating with IPA was a promising tool for providing a novel methodological clue to systemically dissect the underlying molecular mechanism of hypothyroidism.

Concepts: Amino acid, Nutrition, Fatty acid, Triglyceride, Fat, Lipid, Hyperthyroidism, Fatty acid synthase

28

Olive leaves, an easily available natural low-cost material, constitute a source of extracts with significant antitumor activity that inhibits cell proliferation in several breast-cancer-cell models. In this work, a metabolite-profiling approach has been used to assess the uptake and metabolism of phenolic compounds from an olive-leaf extract in the breast-cancer-cell line SKBR3 to evaluate the compound or compounds responsible for the cytotoxic activity. For this, the extract was firstly characterized quantitatively by high-performance liquid chromatography coupled to electrospray ionization-quadrupole time-of-flight mass spectrometry (HPLC-ESI-QTOF-MS). Then, SKBR3 cells were incubated with 200μg/mL of the olive-leaf extract at different times (15min, 1, 2, 24, and 48h). A metabolite-profiling approach based on HPLC-ESI-QTOF-MS was used to determine the intracellular phenolic compounds, enabling the identification of 16 intact phenolic compounds from the extract and four metabolites derived from these compounds in the cell cytoplasm. The major compounds found within the cells were oleuropein, luteolin-7-O-glucoside and its metabolites luteolin aglycone and methyl-luteolin glucoside, as well as apigenin, and verbascoside. Neither hydroxytyrosol nor any of its metabolites were found within the cells at any incubation time. It is proposed that the major compounds responsible for the cytotoxic activity of the olive-leaf extract in SKBR3 cells are oleuropein and the flavones luteolin and apigenin, since these compounds showed high uptake and their antitumor activity has been previously reported.

Concepts: Protein, Chromatography, High performance liquid chromatography, Olive oil, Hydroxytyrosol, Oleuropein, Oleocanthal, Olive leaf

28

A new sildenafil analogue was found to be added illegally to a energy drink marketed for the enhancement of sexual function. The structure was determined as 1-[4-propoxy-3-(6,7-dihydro-1-methyl-7-oxo-3-propyl-1H-pyrazolo[4,3-d]pyrimidin-5-yl)phenylsulfonyl]-4-methylpiperazine. Owing to the inclusion of one more methyl group to sildenafil (on C-21), the detected compound was called “propoxyphenyl sildenafil”. The sample was purified with column chromatography. The UV, IR, LC/MS (ESI) and completely assigned NMR data of propoxyphenyl sildenafil is reported. Having compared the structure with sildenafil, the results showed that the 2-ethoxy group (at the position on C-19) has been replaced by propoxy group.

Concepts: Sociology, Chromatography, High performance liquid chromatography, Group, Set, Ring, Expanded bed adsorption, Silica gel

28

Ion mobility spectrometry (IMS) served as a rapid, qualitative screening tool for the analysis of adulterated weight-loss products. We have previously shown that sibutramine extracted into methanol from dietary supplements can be detected at low levels (2ng) using a portable IMS spectrometer, and have adapted a similar method for the analysis of additional weight-loss product adulterants. An FDA collaborative study helped to define the limits for fluoxetine with a limit of detection of 2ng. We also evaluated more readily available, less toxic extraction solvents and found isopropanol and water were comparable to methanol. Isopropanol was favored over water for two reasons: (1) water increases the analysis time and (2) aqueous solutions were more susceptible to pH change, which affected the detection of sibutramine. In addition to sibutamine and fluoxetine, we surveyed 11 weight-loss adulterants; bumetanide, fenfluramine, furosemide, orlistat, phenolphthalein, phentermine, phenytoin, rimonabant, sertraline and two sibutramine analogs, desmethylsibutramine and didesmethylsibutramine, using portable and benchtop ion mobility spectrometers. Out of these 13 active pharmaceutical ingredients (APIs), portable and benchtop ion mobility spectrometers were capable of screening products for 10 of these APIs. The developed procedure was applied to two weight-loss dietary supplements using both portable and benchtop instruments. One product contained didesmethylsibutramine while the other contained didesmethylsibutramine and phenolphthalein.

Concepts: Mass spectrometry, Obesity, Ethanol, Chemistry, Pharmaceutical drug, Active ingredient, Monoamine oxidase inhibitor, Ion mobility spectrometry

27

With the worldwide rapid increasing interest in the use of natural products as dietary supplements, medical remedies and functional foods, it has been accepted that omitting the plant constituents with potential adverse effects was a huge fault of the past. Several countries developed regulations to limit the consumption of such products in the markets. Among these natural products, butterbur (Petasites) has been used for years as herbal supplement for its anti-spasmodic and anti-inflammatory effects. However, its hepatotoxic alkaloid content limits the direct usage. In this study, investigation of sesquiterpenes and pyrrolizidine alkaloids (PAs) together with their N-oxide forms has been conducted with an offline 2D-combination using high-performance liquid chromatography with UV detection (HPLC-UV) and liquid chromatography - multi mode ionization - time-of-flight mass spectrometry (LC-MMI-ToF-MS) for plant screening. The content has been qualitatively investigated to provide information on the constituents of the plant rhizomes extracted using ethanol. Besides the reported hepatotoxic and medically bio-active plant constituents, a strategy has been suggested for estimating the retention order and retention times with respect to calculated logD (distribution coefficient) and hydrophobicity distributions on C18 reversed-phase column when all standard compounds are not available in laboratory. In this sense, the influence of calculated logD and hydrophobicity distributions on retention time has been clarified via available PA and PA-N-oxide standards. The ethanolic extract of Petasites hybridus has been used for examination of the strategy in a real-sample model. Additionally, the advantages of the developed HPLC-UV and LC-MMI-ToF-MS combination have been discussed with respect to the presented results.

Concepts: Protein, Mass spectrometry, Chromatography, High performance liquid chromatography, Analytical chemistry, Alkaloid, Petasites japonicus, Petasites