Multi-component analysis is one of the key techniques for the overall quality control of traditional Chinese medicines. However, the shortage and high cost of reference substances are the greatest obstacles. The substitute method is an alternative solution. In the present study, 11 compounds of rhubarb were simultaneously determined by a method named "two reference substances for determination of multiple components", which includes a qualitative method with linear calibration using two reference substances and a quantitative method with a relative correction factor combined with ultra high performance liquid chromatography. Using aloe-emodin-8-O-β-D-glucopyranoside and chrysophanol as reference compounds, chromatographic peak identification was performed. The results demonstrated that linear calibration using two reference substances method showed higher accuracy, less deviation, and better column adaptability compared to the relative retention time method. Using chrysophanol as a reference compound, the relative correction factors were determined and showed good reproducibility and stability in different laboratories with different instruments, columns, and wavelength fluctuations. The results had no significant difference compared with the external standard method. The strategy of two reference substances for determination of multiple components coupled with ultra high performance liquid chromatography is economical, efficient, accurate, reliable, and environmentally friendly and is suitable for the quality control of traditional Chinese medicines.
An l-phenylalanine-based Zn-MOF, namely [Zn2(l-Phe)2(bpe)2]n, was designed for experimentally revealing the chiral recognition mechanism to alanine and leucine by means of 13C CP MAS NMR spectroscopy, XPS and control experiment.
An effective quality control system is the key to ensuring the quality, safety and efficacy of traditional Chinese medicines (TCMs). However, the current quality standard research lacks the top-design and systematic design, mostly based on specific technologies or evaluation methods. To resolve the challenges and questions of quality control of TCMs, a brand-new quality standard system, named “iVarious”, was proposed. The system comprises eight elements in a modular format. Meaning of every element was specifically illustrated via corresponding research instances. Furthermore, frankincense study was taken as an example for demonstrating standards and research process, based on the “iVarious” system. This system highlighted a holistic strategy for effectiveness, security, integrity and systematization of quality and safety control standards of TCMs. The establishment of “iVarious” integrates multi-disciplinary technologies and progressive methods, basis elements and key points of standard construction. The system provides a novel idea and technological demonstration for regulation establishment of TCMs quality standards.
Density functional theory calculations have been carried out on Pd-catalyzed phosphoryl-directed ortho-olefination to probe the origin of the significant reactivity difference between methyl hydrogen benzylphosphonates and dimethyl benzylphosphonates. The overall catalytic cycle is found to include four basic steps: C-H bond activation, transmetalation, reductive elimination, and recycling of catalyst, each of which is constituted from different steps. Our calculations reveal that the hydroxy group of phosphoryl plays a crucial role almost in all steps, which can not only stabilize the intermediates and transition states by intramolecular hydrogen bonds but also act as a proton donor so that the η(1)-CH3COO(-) ligand could be protonated to form a neutral acetic acid for easy removal. These findings explain why only the methyl hydrogen benzylphosphonates and methyl hydrogen phenylphosphates were found to be suitable reaction partners. Our mechanistic findings are further supported by theoretical prediction of Pd-catalyzed ortho-olefination using methyl hydrogen phenylphosphonate, which is verified by experimental observations that the desired product was formed in a moderate yield.
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