Capsaicinoids from hot pepper (Capsicum annuum L.) and their phytotoxic effect on seedling growth of lettuce (Lactuca sativa L.)

Abstract

One new capsaicinoid, N-vanillyl-4E,6E-dien-8-methylnonanamide (4), along with nine known capsaicinoids, capsaicin (1), dihydrocapsaicin (2), N-vanillyloctanamide (3), nordihydrocapsaicin (5), N-vanillyldecanamide (6), homocapsaicin (7), N-vanillyl-4,8-dimethylnonanamide (8), homodihydrocapsaicin II (9), and homodihydrocapsaicin I (10) were isolated from the fruits of Capsicum annuum using semi-preparative high-performance liquid chromatography. The structural characterizations of the isolated compounds were elucidated by spectroscopic data and comparison with the literatures. Bioassays showed that the isolated capsaicinoids significantly reduced the radical length of Lactuca sativa seedling, this inhibition being dose-dependent.     

Preparation of W1/O/W2 emulsion to limit the diffusion of Fe3+ in the Fricke gel 3D dosimeter

The irradiation of tumors in radiotherapy requires accurate 3D dosimetry. The Fricke 3D dosimeters, which were considered to be high potential of application in 3D dosimetry, suffer from a reduced temporal integrity of dose distribution caused by Fe³⁺ ions diffusion. To overcome the drawback, we firstly synthesized a kind of amphiphilic molecules with critical micelle concentration of 0.45 g/L and hydrophile‐lipophile balance value of 10, then prepared multiple emulsions by self‐assembling those molecules in Fricke solution under liquid paraffin, and finally obtained Fricke hydrogel embedded with the multiple emulsions. The diffusion coefficient of Fe³⁺ ions in the embedded Fricke hydrogel was measured to be 0.17 mm²/h. The hydrogel dosimeter exhibits considerable potential for use in dose verification applications.     

靶向抗肿瘤药N-(N’-苄氧羰基甘氨酰脯氨酰)丙卡巴肼(Z-GP-Pcb)的环境友好合成及其透过血脑屏障活性评价

利用靶向策略设计了抗肿瘤药物N-(N’-苄氧羰基甘氨酰脯氨酰)丙卡巴肼(Z-GP-Pcb),发展了3步法合成丙卡巴肼(Pcb).首先以4-甲基苯甲醛为原料,经二溴异氰脲酸(DBI)转化为N-异丙基-4-甲基苯酰胺.该化合物经2-碘酰基苯甲酸(IBX)直接氧化为N-异丙基-4-甲酰基苯酰胺,随后还原胺化得Pcb.最后与N-苄氧羰基甘氨酰脯氨酸缩合得Z-GP-Pcb,总收率49.9%.另外,本研究还建立了体外平行人造膜渗透测血脑屏障(PAMPA-BBB)方法评价Z-GP-Pcb透过血脑屏障(BBB)活性,发现其透膜常数(Pe)为(19.22±4.25)×10^-6cm·s^-1,大于母药Pcb[(11.14±1.34))×10^-6cm·s^-1],具有较高的透过BBB活性.     

Fast inspection of fruits using nuclear magnetic resonance spectroscopy

High-resolution nuclear magnetic resonance (NMR) spectroscopy is an indispensable technique for obtaining chemical structure information. Its quantitative and noninvasive properties have led to its growing popularity as an analytical tool in many fields, including biology, chemistry, medicine, and food science. During transportation and storage, chemical reactions among the many nutrients lead to a loss of food quality. In these circumstances, portable NMR spectrometers can readily be used for food inspection and quality control. Because of the heterogeneous tissue distribution in food, a high-resolution NMR method is required for detailed food inspection. Therefore, in this study, we demonstrated the feasibility of using an intermolecular double-quantum coherence signal to obtain high-resolution metabolic profiles of several fruits, including grape, cantaloupe, tomato, and watermelon. The resulting high-resolution NMR spectra facilitate the identification of important metabolites, which can be used as biomarkers for food quality control. The method established here may be adapted for food inspection using portable NMR equipment.     

Copper-Catalyzed Defluorinative Hydroarylation of Alkenes with Polyfluoroarenes

A catalytic defluorinative hydroarylation of alkenes with polyfluoroarenes in the presence of dppbz-ligated Cu catalyst and silanes was developed. This method provides a straightforward and alternative avenue to synthetic important polyfluorinated arenes with readily available and bench-stable alkenes as latent nucleophiles, and therefore avoids conventional reliance on stoichiometric quantities of organometallic reagents. This reaction proceeds under very mild conditions and exhibits good functional group compatibility and high level of regioselectivity. The synthetic potential of this method was further demonstrated by a gram-scale synthesis, and an array of experimental studies were also carried out to elaborate the probable mechanism.     

Theoretical tools for predicting optimal cross‐sectional shapes in micro‐gas chromatography

It is meaningful to explore the possibility of improving the micro‐GC column performance by adjusting the column cross‐sectional shape. The objective of this study was to seek the column cross‐sectional shape that results in larger plate number per meter than other shapes with the same cross‐sectional area and the same flow resistance coefficient. We applied a model based on the volume averaging method to derive the expression of plate height for columns with arbitrary cross‐sectional shapes, and conducted the shape optimization by combining the model and an optimization tool. By varying flow resistance coefficient, we obtained a series of optimal shapes. It is found that, the optimal shape with larger flow resistance coefficient is shallower and the related plate number per meter is larger. We predicted and optimized the performance of a micro‐GC column reported in literature. The prediction agrees reasonably with experimental data. More than twice the plate number per meter of the original column was predicted by using a hypothetical column with one optimal cross‐sectional shape.     

11-Nor-9-carboxy-∆9-tetrahydrocannabinol quantification in human oral fluid by liquid chromatography–tandem mass spectrometry

Currently, ?9-tetrahydrocannabinol (THC) is the analyte quantified for oral fluid cannabinoid monitoring. The potential for false-positive oral fluid cannabinoid results from passive exposure to THC-laden cannabis smoke raises concerns for this promising new monitoring technology. Oral fluid 11-nor-9-carboxy-?9-tetrahydrocannabinol (THCCOOH) is proposed as a marker of cannabis intake since it is not present in cannabis smoke and was not measureable in oral fluid collected from subjects passively exposed to cannabis. THCCOOH concentrations are in the picogram per milliliter range in oral fluid and pose considerable analytical challenges. A liquid chromatography–tandem mass spectrometry (LCMSMS) method was developed and validated for quantifying THCCOOH in 1 mL Quantisal-collected oral fluid. After solid phase extraction, chromatography was performed on a Kinetex C18 column with a gradient of 0.01 % acetic acid in water and 0.01 % acetic acid in methanol with a 0.5-mL/min flow rate. THCCOOH was monitored in negative mode electrospray ionization and multiple reaction monitoring mass spectrometry. The THCCOOH linear range was 12–1,020 pg/mL (R ²?>?0.995). Mean extraction efficiencies and matrix effects evaluated at low and high quality control (QC) concentrations were 40.8–65.1 and ?2.4–11.5 %, respectively (n?=?10). Analytical recoveries (bias) and total imprecision at low, mid, and high QCs were 85.0–113.3 and 6.6–8.4 % coefficient of variation, respectively (n?=?20). This is the first oral fluid THCCOOH LCMSMS triple quadrupole method not requiring derivatization to achieve a <15 pg/mL limit of quantification. The assay is applicable for the workplace, driving under the influence of drugs, drug treatment, and pain management testing.

Numerical investigation into the effects of ordered particle packing and slip flow on the performance of chromatography

The pressure drop and the plate height of chromatography columns packed with particles in the face‐centered cubic, the body‐centered cubic and the simple cubic configurations are calculated by a volume averaging method model. It is found that the Kozeny‐Carman equation provides a reasonable prediction of the pressure drop when particles are in the face‐centered cubic configuration, but overestimates the pressure drop when particles are in the body‐centered cubic and the simple cubic configurations. The face‐centered cubic configuration has the advantage to provide a smaller longitudinal dispersion coefficient than the body‐centered cubic, the simple cubic, and the random configurations. The pressure drop and the plate height for slip flow through particles in the face‐centered cubic configuration are lower than that for no‐slip flow. The values of the smallest reduced plate height of columns packed with particles in the face‐centered cubic configuration for no‐slip flow and slip flow are about 0.084 and 0.059, respectively. The plate height of the ordered particle packing structures is smaller and the effect of slip flow on the plate height is less remarkable than results reported in literature.     

Comparison and optimization of strategies for a more profound profiling of the sialylated N-glycoproteomics in human plasma using metal oxide enrichment

Glycosylation is an important posttranslational modification of proteins and plays a crucial role in both cellular functions and secretory pathways. Sialic acids (SAs), a family of nine-carbon-containing acidic monosaccharides, often terminate the glycan structures of cell surface molecules and secreted glycoproteins and perform an important role in many biological processes. Hence, a more profound profiling of the sialylated glycoproteomics may improve our knowledge of this modification and its effects on protein functions. Here, we systematically investigated different strategies to enrich the SA proteins in human plasma using a newly developed technology that utilizes titanium dioxide for sialylated N-glycoproteomics profiling by mass spectrometry. Our results showed that using a combination of a filter-aided sample preparation method, TiO₂ chromatography, multiple enzyme digestion, and two-dimensional reversed-phase peptide fractionation led to a more profound profiling of the SA proteome. In total, 982 glycosylation sites in 413 proteins were identified, among which 37.8 % were newly identified, to establish the largest database of sialic acid containing proteins from human plasma.

Single-molecule monitoring in living cells by use of fluorescence microscopy

Monitoring single molecules in living cells is becoming a powerful tool for study of the location, dynamics, and kinetics of individual biomolecules in real time. In recent decades, several optical imaging techniques, for example epi-fluorescence microscopy, total internal reflection fluorescence microscopy (TIRFM), confocal microscopy, quasi-TIRFM, and single-point edge excitation subdiffraction microscopy (SPEED), have been developed, and their capability of capturing single-molecule dynamics in living cells has been demonstrated. In this review, we briefly summarize recent advances in the use of these imaging techniques for monitoring single-molecules in living cells for a better understanding of important biological processes, and discuss future developments.