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To study the difference in the contents of phenolics and the antioxidant activities between two kinds of Hawk tea of different maturity levels, and to evaluate their qualities, the contents of 15 phenolic compounds were determined using LC-MS/MS method. Then, the antioxidant activities of two types of tea were evaluated using DPPH radical scavenging rate, ABTS+ radical scavenging rate, and Fe3+ ferric reducing antioxidant power (FRAP). And then, the contents of 15 phenolic compounds and the antioxidant activities between two kinds of Hawk tea of different maturity levels were analyzed by analysis of variance (ANOVA). Based on the contents of 15 phenolic compounds, hierarchical cluster analysis (HCA), principal component analysis (PCA), and orthogonal partial least square-discriminant analysis (OPLS-DA) were used to classify two kinds of Hawk tea. Finally, the contribution of different phenolic compounds in Hawk tea to antioxidation was discussed by partial least square regression analysis (PLSR). The results were as follows: (1) The contents of catechin, p-coumaric acid, isoquercitrin, hyperoside, nicotiflorin, astragalin, kaempferol, quercetin, and afzelin in tender leaf tea were significantly higher than those in old leaf tea, among which the average contents of catechin, isoquercitrin, and astragalin were higher than those in old leaf tea by 1 039.43, 169.12 and 257.35 mg·100 g-1, respectively. The results of HCA, PCA, and OPLS-DA could distinguish two kinds of Hawk tea. (2) The ANOVA showed significant differences in DPPH radical scavenging rate, ABTS+ radical scavenging rate, and FRAP between two kinds of tea, with the tender leaf tea superior to the old leaf tea. (3) The PLSR suggested that isoquercitrin, catechin, astragalin, chlorogenic acid, hyperoside, p-coumaric acid, and kaempferol were the main phenolic compounds those contributed to the antioxidant activity of Hawk tea. This study can provide a reference for Hawk tea's quality control and application promotion.

ABSTRACT A formal [3 + 3] cycloaddition of 4‐hydroxycoumarins with propargylicalcohols was established under mild conditions. This strategy utilizes diazonium tetrafluoroborate as the Lewis acid catalyst and provides a practical approach for delivering pyranocoumarin derivatives in moderate to high yield. The structure of the cycloadduct was unequivocally confirmed by single‐crystal x‐ray diffraction. The potential synthetic applications of this strategy were also highlighted by the scale‐up experiment and further synthetic transformation. [ABSTRACT FROM AUTHOR]

Substrate-controlled divergent reactions of between salicylaldehydes and acrylates have been developed. By using methyl acrylate as the substrate with salicylaldehydes, a domino reaction was established, delivering coumarins with good yield (up to 81% yields) and high chemoselectivity under mild conditions. Whereas the methyl acrylate was changed to tert-butyl acrylate or iso-propyl acrylate, the classical Morita − Baylis − Hillman adducts were produced in good yields (up to 75% yields) under near exclusivity under the otherwise identical reaction conditions, without any other competitive products. Additionally, the synthetic utility of the present methodology was further demonstrated by synthetic transformation. The structure of the typical product was unambiguously established by single crystal X-ray diffraction analysis. [ABSTRACT FROM AUTHOR]

A simple and efficient three‐component coupling reaction of carboxylic acids, diazo compounds, and tertiary amines catalyzed by manganese has been described. This reaction proceeds smoothly under mild conditions to afford various β‐amino esters in moderate to good yields by using O2 as the terminal oxidant. In this process, Mn‐based carbene radical, single‐electron transfer, and nucleophilic attack were fused into a reaction system. [ABSTRACT FROM AUTHOR]

In this work, the antioxidant components in persimmon (Diospyros kaki) leaves were separated by offline two‐dimensional liquid chromatography‐electrochemical detection (LC×LC‐ECD) and identified by LC‐tandem mass spectrometry (LC‐MS/MS). A total of 33 antioxidants, mainly proanthocyanidins, and glycosides of kaempferol and quercetin, were identified. The antioxidant assays demonstrated that the fractions collected from the first‐dimension LC (1D‐LC) possessed considerable radical scavenging capabilities, with correlation coefficients of peak area versus radical scavenging capability of 1,1‐diphenyl‐2‐picrylhydrazyl and 2,2′‐azino‐bis(3‐ethylbenzothiazoline‐6‐sulfonic acid) being 0.9335 and 0.9116, respectively. The fingerprinting showed that 37 peaks were present in all samples. The major antioxidant components of persimmon leaves were the glycosides of kaempferol and quercetin. Finally, fourteen antioxidants were quantitatively assessed. Offline LC×LC provided high peak capacity and separation; ECD enabled specific screening and detection of antioxidant components; and MS/MS provided excellent identification capability. In this study, the combination of the three approaches was utilized to screen for antioxidant components in persimmon leaves, with satisfactory findings. In conclusion, this technique is an effective means for rapid analysis of antioxidant components and quality control of medicinal plants, achieving rapid separation of congeners and facilitating more accurate qualitative and quantitative analyses. [ABSTRACT FROM AUTHOR]

Though the specialty of the public affair management has been developed for ten years, but it is still facing the actuality that the orientation and development are difficult. Only by confirming the cultivation target and the development orientation, the development of the specialty could find the development approach and method. According to the actuality of the public affair management of China and the public management education, this specialty should orientate to cultivate public management and service personnel for the establishment units, and cultivate startup and service personnel for the non-governmental organizations, and cultivate the modern citizens with public thought, public responsibility, and public ability, and cultivate the builders with modern public spirit for the local economy and the social development. Based on that, to fully perfect the course system and the teaching mode, and enhance the power of teachers, could really develop and stably enhance the specialty of the public affair management.

A dearomative [4 + 2] cycloaddition of 3‐nitroindoles ortho‐amino Morita−Baylis−Hillman carbonates was established under mild conditions. This method provides an efficient and practical approach for delivering tetrahydro‐5H‐indolo[2,3‐b]quinolines containing three contiguous stereocenters, two tertiary and one quaternary, in high yield (up to 95%) with excellent diastereoselectivity (all cases >25:1 dr). The potential synthetic applications of this strategy were also highlighted by the scale‐up experiment and further synthetic transformation. Moreover, the structure and relative configuration of the cycloadduct was unequivocally confirmed by single‐crystal X‐ray diffraction. [ABSTRACT FROM AUTHOR]

High performance liquid chromatography-electrochemical detection (HPLC-ECD) fingerprints of Cichorium intybus L. (chicory) of different origins were established. The antioxidant activities of chicory were evaluated in vitro by 1,1-diphenyl-2-picrylhydrazyl (DPPH), [2,2'-azino-bis-(3-ethylbenzothiazoline-6-sulfonic acid)] (ABTS+) radical scavenging assays and ferric reducing antioxidant power (FRAP) assays. The "spectrum-effect" relationship between the fingerprint and antioxidant activities of chicory was analyzed using Pearson correlation analysis, partial least squares regression (PLSR) analysis, and gray correlation analysis (GRA) to identify the active antioxidant compounds. In total, 13 phenolic compounds were identified from the fingerprint of 21 batches of chicory from different regions. The total phenol content of chicory extract was up to 30.76 mg GAE/g, and the correlation coefficient between peak areas and antioxidant activity was >0.92. According to "spectrum-effect" relationship analyses, chicoric acid, caftaric acid, isochlorogenic acid B, isochlorogenic acid A, 1,5-dicaffeoylquinic acid, and isochlorogenic acid C comprised the components primarily contributing to the antioxidant activity of chicory, indicating significant correlations between these chemical compounds and antioxidant activity (P<0.01). The HPLC-ECD fingerprint of chicory established in this study combined with the statistical analysis method exploring the "spectrum-effect"not only indicate the differences in chemical compounds between samples but also directly demonstrate the antioxidant activity of samples. This method is simple and reliable, providing a reference for improving the quality evaluation and product development of chicory. [ABSTRACT FROM AUTHOR]

A simple and convenient strategy for the synthesis of N‐acyl protected 2‐aminoacrylates via PPh3‐catalyzed reaction of alkyl propiolates with amides has been developed. This protocol is rapid and highly regioselective to provide various N‐acyl protected 2‐aminoacrylates in high yields (up to 95 %). The chemical structure of the product was determined by X‐ray single‐crystal structure analysis. In contrast, 3‐sulfonamidoacrylates were obtained by Cs2CO3‐catalyzed reactions of alkyl propiolates with secondary sulfamides. Moreover, synthetic utility of this method was further highlighted in the late‐stage modification of drug molecules. [ABSTRACT FROM AUTHOR]

Arginine and its metabolites play important roles in pain and analgesia. This study aimed to develop a comprehensive quantification method for amino acids and metabolites related to arginine metabolism in rat plasma by hydrophilic interaction chromatography–tandem mass spectrometry (HILIC–MS/MS). Rat plasma was diluted to reduce the matrix effect and deproteinized with acetonitrile. The analytes were separated on a Syncronis HILIC column with a gradient elution. MS analysis was performed in positive ion mode with an electrospray ionization source using multiple reaction monitoring technology. All calibration curves for the 10 analytes showed good linear regression (R 2 > 0.99). The limits of detection (LODs) were in the range of 0.9–13.4 μg/L. The established method was validated for intra-day and inter-day precisions (relative standard deviation [RSDs] < 6.21%) and accuracy (average recovery ranged from 87.34% to 100.35% with the RSD values less than 11.41%). This method was successfully applied to characterize dynamic alterations in the plasma of rats with neuropathic pain and thus provide service to explore the mechanism of action between metabolite changes and clinical disease. [ABSTRACT FROM AUTHOR]