Screening of aromatase inhibitors in traditional Chinese medicines by electrophoretically mediated microanalysis in a partially filled capillary

An electrophoretically mediated microanalysis method with partial filling technique was developed for screening aromatase inhibitors in traditional Chinese medicine. The in‐capillary enzymatic reaction was performed in 20 mM sodium phosphate buffer (pH 7.4), and sodium phosphate buffer (20 mM, pH 8.0) was used as a background electrolyte. A long plug of coenzyme reduced β‐nicotinamide adenine dinucleotide 2′‐phosphate hydrate dissolved in the reaction buffer was hydrodynamically injected into a fused silica capillary followed by the injection of reaction buffer, enzyme, and substrate solution. The reaction was initiated with a voltage of 5 kV applied to the capillary for 40 s. The voltage was turned off for 20 min to increase the product amount and again turned on at a constant voltage of 20 kV to separate all the components. Direct detection was performed at 260 nm. The enzyme activity was directly assayed by measuring the peak area of the produced β‐nicotinamide adenine dinucleotide phosphate and the decreased peak area indicated the aromatase inhibition. Using the Lineweaver–Burk equation, the Michaelis–Menten constant was calculated to be 50 ± 4.5 nM. The method was applied to the screening of aromatase inhibitors from 15 natural products. Seven compounds were found to have potent AR inhibitory activity.     

Qualitative and quantitative analysis in quality control of traditional Chinese medicines

Separation techniques with high efficiency and sensitive detection have been widely used for quality control of traditional Chinese medicines (TCMs). High-performance liquid chromatography, gas chromatography, and capillary electrophoresis are commonly used to separate various components in TCMs. Ultraviolet detection, fluorescence detection, evaporative light-scattering detection, mass spectrometry and nuclear magnetic resonance can be applied to separation techniques for qualitative and quantitative analysis of TCMs. The development of quality control for TCMs based on quantitative and qualitative analysis from 2000 to 2007 are reviewed; the fingerprint technique is also discussed due to its broad application in the quality control of TCMs. Prospects for further research based on our primary results are also discussed.     

Quality evaluation of traditional Chinese medicines based on fingerprinting

The usage of traditional Chinese medicines has expanded globally, but the data about authentication, efficacy, and safety is far from sufficient to meet the criteria supporting their use worldwide due to complexity in the composition. Fingerprinting describes integral characterization and reflects interactive aspects of complex components; therefore, it can offer the possibility of evaluating quality of traditional Chinese medicines following the overall principle. Chemometric techniques introduce multivariate analytical methods into fingerprinting to obtain more information that is useful, which is consistent with the holistic thought and plays an important role in research on the substantial basis. In this review, we will start with three aspects to expound the quality evaluation of traditional Chinese medicines based on fingerprints. The analytical techniques used in developing fingerprints including chromatographic methods, spectroscopic methods, and capillary electrophoresis are introduced. Strategies for fingerprints analysis usually based on chemometric methods including unsupervised and supervised pattern recognition are described. Applications of fingerprints for multi‐component quantification, quality control, screening of bioactive components, and fingerprint‐efficacy relationship study are also outlined. Finally, we propose challenges and future perspectives of fingerprints in quality evaluation to promote the development of modernization and internationalization of traditional Chinese medicines.     

In silico and in vitro identification of candidate SIRT1 activators from Indonesian medicinal plants compounds database

Sirtuin 1 (SIRT1) is a class III family of protein histone deacetylases involved in NAD⁺-dependent deacetylation reactions. It has been suggested that SIRT1 activators may have a protective role against type 2 diabetes, the aging process, and inflammation. This study aimed to explore and identify medicinal plant compounds from Indonesian Herbal Database (HerbalDB) that might potentially become a candidate for SIRT1 activators through a combination of in silico and in vitro methods. Two pharmacophore models were developed using co-crystalized ligands that allosterically bind with SIRT1 similar to the putative ligands used by SIRT1 activators. Then, these were used for the virtual screening of HerbalDB. The identified compounds were subjected to molecular docking and 50 ns molecular dynamics simulation. Molecular dynamics simulation was analyzed using MM-GB(PB)SA methods. The compounds identified by these methods were tested in an in vitro study using a SIRT-Glo™ luminescence assay. Virtual screening using structure-based pharmacophores predicted that mulberrin as the best candidate SIRT1 activator. Virtual screening using ligand-based pharmacophores predicted that gartanin, quinidine, and quinine to be the best candidates as SIRT1 activators. The molecular docking studies showed the important residues involved were Ile223 and Ile227 at the allosteric region. The MM-GB(PB)SA calculations confirmed that mulberrin, gartanin, quinidine, quinine showed activity at allosteric region and their EC₅₀ in vitro values are 2.10; 1.79; 1.71; 1.14 μM, respectively. Based on in silico and in vitro study results, mulberin, gartanin, quinidine, and quinine had good activity as SIRT1 activators.     

中药指纹图谱研究的某些进展与展望

在中药现代化的过程中,中药的质量控制标准直接影响到中药的国际化问题。近年来,国内很多学者对中药指纹图谱用于质量控制的问题进行了深入的研究,取得了很多成果。本文着重就近几年来中药指纹图谱的某些进展进行了综述,内容包括气相色谱指纹图谱、液相色谱指纹图谱以及其他指纹图谱。最后就指纹图谱研究的发展提出了几点看法。共引用文献161篇。     

Molecular docking studies on tetrahydroimidazo-[4,5,1-jk][1,4]-benzodiazepinone (TIBO) derivatives as HIV-1 NNRT inhibitors

At present, chemotherapy seems to be the main weapon in the arsenal of remedies for the ongoing crusade against AIDS. The mode of binding of the TIBO family of inhibitors has been of interest because these compounds do not fit the two-hinged-ring model as generally observed in the NNRTIs. Flexible docking simulations were performed with a series of 53 TIBO derivatives as NNRTIs. Binding preferences as well as the structural and energetic factors associated with them were studied. A good correlation (r ² = 0.849, q ² = 0.843) was observed between the biological activity and binding affinity of the compounds which suggest that the identified binding conformations of these inhibitors are reliable. Further screening of PubChem database yielded novel scaffolds. Our studies suggest that modifications to the TIBO group of inhibitors might enhance their binding efficacy and hence, potentially, their therapeutic utility.     

Discovery of potential inhibitors targeting the kinase domain of polynucleotide kinase/phosphatase (PNKP): Homology modeling,virtual screening based on multiple conformations,and molecular dynamics simulation

In recent years, the level of interest has been increased in developing the DNA-repair inhibitors, to enhance the cytotoxic effects in the treatment of cancers. Polynucleotide kinase/phosphatase (PNKP) is a critical human DNA repair enzyme that repairs DNA strand breaks by catalyzing the restoration of 5’-phosphate and 3’-hydroxyl termini that are required for subsequent processing by DNA ligases and polymerases. PNKP is the only protein that repairs the 3′-hydroxyl group and 5′-phosphate group, which depicts PNKP as a potential therapeutic target. Besides, PNKP is the only DNA-repair enzyme that contains the 5′-kinase activity, therefore, targeting this kinase domain would motivate the development of novel PNKP-specific inhibitors. However, there are neither crystal structures of human PNKP nor the kinase inhibitors reported so far. Thus, in this present study, a sequential molecular docking-based virtual screening with multiple PNKP conformations integrating homology modeling, molecular dynamics simulation, and binding free energy calculation was developed to discover novel PNKP kinase inhibitors, and the top-scored molecule was finally submitted to molecular dynamics simulation to reveal the binding mechanism between the inhibitor and PNKP. Taken together, the current study could provide some guidance for the molecular docking based-virtual screening of novel PNKP kinase inhibitors.     

毛细管电泳指纹图谱及毛细管电泳-质谱联用在中药质量控制中的作用

以作者多年从事毛细管电泳、毛细管电泳-质谱联用及其指纹图谱对中药的研究成果为基础,介绍了毛细管电泳实验条件的优化方法、毛细管电泳指纹图谱的研究方法与评价方法及其在中药质量控制中的作用。     

高效液相色谱法测定降糖中成药中添加的高极性化学降糖药物

建立了测定添加在降糖中成药中高极性的盐酸二甲双胍、盐酸苯乙双胍、阿卡波糖、伏格列波糖等4种化学降糖药物的高效液相色谱方法。采用Thermo氨基色谱柱(4.6 mm×250 mm,5 μm)分离,流动相组成为磷酸盐缓冲溶液(0.06%磷酸二氢钾和0.028%磷酸氢二钠溶液)-乙腈(体积比为30∶70),流速为1 mL/min,紫外检测波长为195 nm,柱温为30 ℃,进样量为20 μL。结果表明,4种化学降糖药能完全分离,中成药基质不干扰测定;检出限为0.1～3 mg/L;4种药物具有宽的线性范围和良好的线性关系(r2≥0.9981);日内、日间测定的相对标准偏差(RSD)分别为0.10%～5.07%和0.19%～6.41%;在中成药中的加标回收率除了添加低浓度的伏格列波糖的回收率较低外,均高于80%,RSD为1.14%～4.82%。该方法用于中成药中高极性的化学降糖药的检测具有特异、快速、简便、高效的特点。     

Comparison of three‐phase hollow fiber liquid‐phase microextraction based on reverse micelle with conventional two‐phase hollow fiber liquid‐phase microextraction and their applications for analysis of cinnamic acids in traditional Chinese medicines

A novel three‐phase hollow fiber liquid‐phase microextraction was developed based on reverse micelle as extraction solvent and acceptor phase, and compared with conventional two‐phase hollow fiber liquid‐phase microextraction. Both procedures were used in the extraction and concentration of four cinnamic acids (caffeic acid, p‐hydroxycinnamic acid, ferulic acid, and cinnamic acid) in traditional Chinese medicines prior to high‐performance liquid chromatography analysis. Parameters affecting the two procedures were investigated and optimized to obtain the optimum enrichment factors. The mechanism of the developed procedure was explored and elucidated by comparison with conventional two‐phase hollow fiber liquid‐phase microextraction. Under the optimized conditions, the analytes’ enrichment factors were between 50 and 118 for the proposed procedure, and 31–96 for conventional two‐phase mode. Satisfactory linear ranges (r² ≥ 0.99), detection limits (0.1–0.6 ng/mL), precisions (<9.2%), and accuracies (recoveries: 80–123.1%) were observed for the two procedures. The results showed that the enrichment capacity of the proposed procedure for the cinnamic acids is better than that of conventional two‐phase procedure, and both are eco‐friendly, simple, and effective for the enrichment and detection of cinnamic acids in traditional Chinese medicines.     

前体离子扫描法在快速筛查中药及保健食品中非法添加的5型磷酸二酯酶抑制剂及其未知衍生物中的应用

改造有明确疗效的药物,合成新的衍生物以避开法定检验方法是目前化学药物非法添加的趋势之一。本文提出将液相色谱-三重四极杆质谱联用仪的质谱前体离子扫描模式应用于中药及保健食品等复杂体系中非法添加药物衍生物的快速筛查策略,以5型磷酸二酯酶抑制剂为实验对象,通过分析该类化合物的结构和质谱特点将其分类,筛选各类共有的子离子碎片,优化质谱参数,建立了前体离子扫描模式的LC-MS筛查方法,讨论了质谱参数和碎片离子的选择对筛选结果的影响,并应用于实际样品的测定。结果表明,该方法既可以满足已知化合物的测定需要,又可以对复杂体系中未知的同类衍生物进行快速筛查,防止未知衍生物的漏检。该方法灵敏、专属、高效,值得进一步研究。