Helicase-dependent amplification is effective in distinguishing Asian ginseng from American ginseng

This study describes for the first time the application of helicase-dependent amplification (HDA) to authenticate botanical species and processed products. Asian ginseng (Panax ginseng) and American ginseng (Panax quinquefolius) are consumed worldwide as functional food and health remedies. The two herbs share similar morphological appearance but have different pharmacological effects. In this work, a novel isothermal amplification mediated DNA method was applied to authenticate the two ginseng species. Internal control and P. ginseng specific primers were designed based on the ribosomal external transcribed spacer (ETS) region. The amplification results were confirmed by real-time monitoring, gel electrophoresis and DNA sequencing. The screened retail samples included dried ginseng root, ginseng powder, ginseng tea granules as well as a four-herb formulation. Our HDA protocol worked well on both purified DNA and crude water extract. In conclusion, HDA is a highly sensitive and specific approach for differentiating Asian ginseng from American ginseng and it has the potential for on-site authentication of herbal products.     

The rapid selecting of precursor ions and product ions of thirty-four kinds of pesticide for content determination by GC–EI/MS/MS

Pesticide residues caused great threat to human body health, and all countries protected the health of human body by specifying its upper limit. However, pesticide residues were generally very low, similar to trace analysis and as low as millionth or less, the content determination of pesticide residues was a troublesome problem. With the application and promotion of tandem mass spectrometry, it was able to do trace analysis. GC–EI/MS/MS was a common method for the determination of pesticide residues. The multiple reaction monitoring (MRM) mode was the most common quantitative method used in GC–EI/MS/MS. It has the characteristics of high sensitivity, good reproducibility, high accuracy, strong anti-interference and high ion flux. Multiple-twin precursor ions, product ions and collision energy of thirty-four pesticides were provided for MRM. It could play an important role in developing MRM method for the quantifying of 34 kinds of pesticide. Meanwhile, the development of MRM method for the quantifying of other compounds could also refer to this paper.     

太子参化学成分及生物活性研究进展

太子参为石竹科植物孩儿参的干燥块根,味甘、微苦,性平,归脾肺经,具有益气健脾、生津润肺之功效,常用于气虚津伤的肺虚燥咳,被国家卫生健康委员会批准用于保健食品。现代药理和临床研究表明,太子参中特征性化学成分多糖和环肽具有免疫调节、抗炎、改善记忆等作用。近年来对太子参的化学成分、结构和药理作用的综述仅局限于特征成分,对其他成分还鲜有系统梳理报道。因此本文系统梳理了太子参的化学成分及生物活性研究进展,以期为太子参的开发利用提供参考和依据。     

Molecular parameters controlling the energy storage capability of lithium polyaromatic hydrocarbon intercalation compounds

One route for improving the performance of Li-based batteries is to optimize the carbon-based electrode. In order to find the best carbon-based materials, the specific roles of the molecular and solid-state contributions have to be understood. Here, the molecular contributions are analyzed. A semi-quantitative method is proposed to compare the charge storage capability of polyaromatic hydrocarbon molecules (PAHs). For planar PAHs, the ability to store electrical energy is found to be to a large extend determined by a single parameter, that is the electronic hardness (half the electronic gap) multiplied the number of carbon atom in the molecule. A compilation of results for oligophenyls, oligoacenes and medium-size planar systems suggests trends in the dependence of the energy storage capability on the size and shape of the molecules.     

Nutrient composition and food potential of Parkia roxburghii,a less known tree legume from northeast India

The nutrient compositions of Parkia roxburghii kernels and pods (i.e. tender, immature and mature) were determined. Protein content of the kernel was 29% and that of pods 13–19%. Similarly, fat content was highest (34%) in the kernel and ranged from 1–16% in the pods. Unsaturated acids Oleic, linoleic and linolenic acids made up 63–68% of the total fat in the pods as well as the kernels. The total essential amino acids amounted to 33%, 36% and 39% in the tender, immature, mature pods, respectively, and 42% in the kernels. The essential amino acid pattern of the kernel was comparable to the FAO/WHO/UNU (1985) amino acid requirement for preschoolers. However, the amino acid scores of the tender, immature and mature pods were 64, 84 and 92, respectively, with sulphur amino acids as the limiting amino acids in all the pod samples.     

乌头碱类双酯型二萜生物碱水解反应的电喷雾质谱分析

阐明了乌头碱类双酯型二萜生物碱水解反应过程,确定水解反应的类型以及最佳水解条件。利用电喷雾离子阱质谱分析比较了生川乌提取液,制川乌提取液及其水解反应提取液中生物碱的差异。生川乌炮制后生物碱大多数由双酯型水解转化为单酯型,水解反应最容易发生的位置在C₈位,水解反应的类型是烷氧键发生断裂的酯的碱性水解。     

Fluorescent pH probes based on boron dipyrromethene dyes

Two novel fluorescent pH probes based on 4,4-difluoro-4-bora-3a,4a-diaza-s-indacene dyes were configured as a “fluorophore-spacer-receptor” system. Their absorption and fluorescence properties were investigated in various solvents; in aqueous solution, based on their photo-induced electron transfer, the probes exhibited 3-fold (pH 8.70–4.93) and 14-fold (pH 9.02–3.29) fluorescence enhancement upon increase in the acidity of the solution, respectively. The probes can be used as fluorescent pH probes which are excitable with visible light; the pK_a values of the probes were determined from the fluorescence changes.     

A Single Gene Cluster for Chalcomycins and Aldgamycins: Genetic Basis for Bifurcation of Their Biosynthesis

Aldgamycins are 16‐membered macrolide antibiotics with a rare branched‐chain sugar d ‐aldgarose or decarboxylated d ‐aldgarose at C‐5. In our efforts to clone the gene cluster for aldgamycins from a marine‐derived Streptomyces sp. HK‐2006‐1 capable of producing both aldgamycins and chalcomycins, we found that both are biosynthesized from a single gene cluster. Whole‐genome sequencing combined with gene disruption established the entire gene cluster of aldgamycins: nine new genes are incorporated with the previously identified chalcomycin gene cluster. Functional analysis of these genes revealed that almDI/almDII, (encoding α/β subunits of pyruvate dehydrogenase) triggers the biosynthesis of aldgamycins, whereas almCI (encoding an oxidoreductase) initiates chalcomycins biosynthesis. This is the first report that aldgamycins and chalcomycins are derived from a single gene cluster and of the genetic basis for bifurcation in their biosynthesis.