An on-line high-performance liquid chromatography−diode-array detector−multi-stage mass spectrometry−deoxyribonucleic acid−4′,6-diamidino-2-phenylindole−fluorescence detector system for screening the DNA-binding active compounds in Fufang Banbianlian Injection

3, 5-Dihydroxy 4', 7-dimethoxyflavone-DNA interaction study for nucleic acid detection and differential cell staining

The present study is focused on application of a natural compound, 3, 5-dihydroxy 4', 7-dimethoxyflavone (DHDM) from a medicinal plant Alpinia nigra for nucleic acid detection and differential cell staining. DHDM was found to interact with nucleic acid and forms complex, which was investigated for various applications. It was successfully utilized to visualize plasmid, genomic, and ds-linear DNA in agarose gel electrophoresis without affecting the DNA mobility in the gel. Fluorescence of DHDM increased several fold upon binding to dsDNA. Photostability of the compound was assessed and showed photobleaching effect that decreased gradually over time. Application of the compound was further extended to differential cell staining. When observed in fluorescence microscope, DHDM stained the dead cells and differentiated them from live cells in the case of bacterial, yeast, and mammalian cells. Higher concentration of the compound was found to be less cytotoxic to cancerous cells. Nucleic acid staining dyes like Ethidium bromide (EtBr), Propidium iodide (PI), etc. are carcinogens and environmental pollutants and therefore DHDM a natural compound, is a major benefit and thus can serve as an alternative to the current dyes.

Metabolic profiling of Qi-Yu-San-Long decoction in rat feces by ultraperformance liquid chromatography-quadrupole time-of-flight mass spectrometry combined with a post-targeted screening strategy

Research into traditional Chinese medicine metabolism in feces is one of the key avenues to understanding the fate of traditional Chinese medicines in vivo. In this study, we used ultraperformance liquid chromatography-quadrupole time-of-flight MS in combination with a post-targeted screening strategy to identify the prototype components and metabolites in rat feces after oral administration. Based on our group's previous research, the component database of Qi-Yu-San-Long decoction (QYSLD) was established. Prototype components were screened from the fecal samples based on summarized chromatographic and MS behaviors. According to the chemical structure characteristics of related compounds, the possible metabolic pathways were inferred, and the metabolites related to QYSLD were predicted. We extracted ion chromatograms by predicting the m/z values of metabolite excimer ions and identified related metabolites based on their retention time and fragmentation behavior. A total of 93 QYSLD-related xenobiotics were confirmed or tentatively identified in rat fecal samples, and the results indicated that the main metabolic pathways of QYSLD were hydrolysis, deglycosylation, oxidation, reduction, decarboxylation, methylation and acetylation. This study presents a rapid method for identifying the prototype components and metabolites, and offers valuable insights into the biotransformation profiling of QYSLD in rat feces.

Advances in analytical techniques and quality control of traditional Chinese medicine injections

Traditional Chinese medicine injections (TCMIs) are a new pharmaceutical form in the modernization of traditional Chinese medicines (TCMs). Its efficacy is rapid, the curative effect is improved, and is widely used in critical and acute diseases, complicated and severe diseases, and other treatment. However, with the broad applications of TCMIs, clinical adverse reactions frequently occur, and safety problems become more prominent. Therefore, the quality control of TCMIs is essential. Chemical analysis methods and biological analysis methods are widely used in the quality control of TCMIs. This article describes the current status of TCMIs, the analytical techniques, and methods currently used, and the quality control of TCMIs. A summary of the advantages and disadvantages of the current analysis methods is presented. An overview of the quality control of TCMIs is introduced. In addition, emerging techniques of the quality control of TCMIs are introduced.

[Rapid identification of chemical components in Qi-Yu-San-Long decoction by ultra high performance liquid chromatography-quadrupole time-of-flight mass spectrometry]

Qi-Yu-San-Long decoction (QYSLD) is a classic traditional Chinese medicine prescription consisting of ten types of herbal medicines, including Astragali Radix, Polygonati Odorati Rhizoma, Scolopendra, Pheretima, Solanum nigrum L., Hedyotis diffusa Willd., Coicis Semen, Euphorbia helioscopia L., Curcumae Rhizoma, and Fritillariae Cirrhosae Bulbus, combined in a ratio of 15∶5∶3∶3∶10∶10∶10∶3∶5∶3 by weight. QYSLD has been used to treat non-small cell lung cancer (NSCLC) for over 20 years in clinical practice, and its curative effect is considered credible. However, the chemical constituents of QYSLD have not been revealed because of their complexity, which has significantly hindered the systematic clarification of the efficacy of the materials and quality evaluation. In this study, a reliable strategy based on the data-independent acquisition (DIA) technology of ultra high performance liquid chromatography-quadrupole time-of-flight mass spectrometry (UPLC-QTOF-MS) combined with a targeted screening method was established to investigate the chemical components of QYSLD. A 2-μL aliquot from each vial was injected into a Waters ACQUITY UPLC BEH C18 column (100 mm×2.1 mm, 1.7 μm) to separate complex components. The temperature of the column was 35 ℃, and the flow rate was set at 0.2 mL/min. The mobile phase consisted of 0.1% formic acid aqueous solution and acetonitrile. Detection was conducted using an Xevo G2-XS QTOF-MS with a LockSpray capable-electrospray interface. The data for complex components in QYSLD were collected by full-information tandem mass spectrometry (MS E) in the positive and negative ion modes. In the MSE mode, data acquisition was performed using a mass spectrometer by rapidly switching from a low-collision-energy (CE) scan to a high-CE scan during a single LC run. Thus, accurate precursor and fragment ions were collected in a single run, which was helpful for the structural elucidation of multiple components in QYSLD. In addition, systematic information on isolated chemical compounds was collected and distinguished from the ten individual herbs in QYSLD using databases such as China Academic Journals Full-text database (CNKI), PubMed, Web of Science, Medline, and ChemSpider. Accordingly, a self-building library of QYSLD, including the component name, molecular formula, and structure of the components from the herbs, was established. Subsequently, the raw MSE data of the collected samples and the self-building chemical composition library were imported into a natural product post-processing screening (UNIFI) platform for targeted screening of the chemical components in QYSLD. The parameters for UNIFI platform were as follows: the retention time deviation was ±0.1 min; an error margin of no more than 5×10 -6 for the identified compounds was allowed; positive adducts, including [M+H]+and [M+Na]+, were selected; and negative adducts, including [M-H]- and [M+HCOO]-, were selected. The results showed that a total of 166 compounds were initially identified, including 22 saponins, 13 alkaloids, 27 flavonoids, 32 terpenes, 20 amino acids, 16 phenylpropanoids, 9 organic acids, 6 sterols, 6 anthraquinones, and 15 other components. Among them, sixteen components were confirmed unambiguously with the reference substances. To better understand the chemical contribution of individual herbs to the entire decoction, the attributes of each component were summarized. This study provides a foundation for exploring the pharmacodynamic substances of QYSLD.

Layer-by-layer assembly strategy for fabrication of polydopamine-polyethyleneimine hybrid modified fibers and their application to solid-phase microextraction of bioactive molecules from medicinal plant samples followed by surface plasmon resonance biosensor validation

A solid-phase microextraction method is introduced to overcome limitations of classical phytochemical pattern of identifying bioactive compounds, including tedious and time-consuming separation and purification step and consumption of large amounts of organic solvents, which was non-environmentally- friendly. In this proposed method for solid-phase microextraction, polyvinylidene fluoride fibers@polydopamine@polyethyleneimine@receptor as a solid part of the extractors were pushed into sample solution of medicinal plants, and the procedure was followed by stirring and easily dissociation of receptor binding ligands in organic solvent through pulling out of the functionalized fibers. Xanthine oxidase was chosen as the model receptor, while isoacteoside was selected as the model inhibitor. Several effecting parameters were optimized by experimental design, including temperature, ion strength and pH. Nine bioactive components were obtained from extract of Plantago depressa by using the established solid-phase micro-extraction method. The limit of detection and limit of quantification of the nine components ranged from 0.0008 to 0.03 mg mL^-1 and from 0.001 to 0.016 mg mL^-1, respectively. The RSD values of intra-day and inter-day precisions ranged from 0.24% to 2.19% and 0.62%-2.84%, respectively. The average recoveries of the nine components were from 95.06 to 104.03% with relative standard deviation (RSD) values from 1.02 to 2.90% for Plantago depressa. The RSD values of stability of the nine components ranged from 1.36% to 2.74%, which satisfied the requirements of an analytical method. In addition, surface plasmon resonance biosensor was utilized to corroborate the binding affinity between these compounds and receptor. The avidity values of these ligands corresponded well with their IC₅₀ values. The results confirmed that polydopamine and polyethyleneimine hybrid modified polyvinylidene fluoride fibers based solid-phase microextraction method was successfully utilized for locating bioactive compounds of medicinal plants.

Characterization and quantitative analysis of phenolic derivatives in Longxuetongluo Capsule by HPLC-DAD-IT-TOF-MS

Longxuetongluo Capsule (LTC), which is derived from the total phenolic extract of Chinese dragon's blood, has been proved to be safe as well as effective towards ischemic stroke. However, the effective material basis remains unclear. The present study thereby focused on the clarification of the qualitative and quantitative properties for the phenolic derivatives in LTC. Regarding homolog-focused chemical profiling, the mass fragmentation patterns of the primary subtypes of phenolic compounds such as homoisoflavanones, flavanes, chalcones, and flavonoid oligomers were summarized by assaying authentic references with hybrid ion trap time-of-flight mass spectrometry, and the chemical structures of 124 phenolic compounds, in total, were unambiguously or tentatively annotated in LTC by matching the accurate mass spectral profiles with the proposed mass cracking rules and those reference substances. Afterwards, simultaneous determination of 12 primary phenolic compounds was carried out in different batches of LTC using HPLC-DAD, after that the method was proved to be accurate, precise, and reproducible according to diverse method validation assays. The obtained findings are expected to be meaningful for clarifying the effective substances and quality assessment of LTC.

Rapid Screening of Potential Phosphodiesterase Inhibitors from the Roots of Ilex pubescens Hook. et Arn. Using a Combination of Ultrafiltration and LC-MS

The cyclic nucleotide phosphodiesterase (PDE) plays an important role in regulating the levels of second messenger molecules cAMP and cGMP. Various PDE inhibitors have been successfully developed into drugs for targeted diseases. In addition, PDE inhibitors can also be found in different foods and natural medicines. In this study, ultrafiltration liquid chromatography-diode-array detector-electrospray ionization-ion-trap-time-of-flight-mass spectrometry (ultrafiltration LC-DAD-ESI-IT-TOF-MS) was applied to screen PDE inhibitors from the roots of Ilex pubescens Hook. et Arn. As a result, 11 major compounds were identified in I. pubescens roots, with nine compounds as potential PDE inhibitors, among which five were further confirmed to be active against PDEI and PDE5A dose-dependently in vitro, with ilexsaponin A1 and ilexsaponin B2 being the strongest. HPLC quantification of these bioactive compounds suggested that they are major components in the plant. The results demonstrate that ultrafiltration LC-DAD-ESI-IT-TOF-MS is an efficient method for rapid screening of PDE inhibitors from natural medicines.

Fluorescent natural products as probes and tracers in biology

Fluorescence is a remarkable property of many natural products in addition to their medicinal and biological value. Herein, we provide a review of these peculiar secondary metabolites to stimulate prospecting of them as original fluorescent tracers, endowed with unique photophysical properties and with applications in most fields of biology.