Formic Acid Aqueous Solution Research Articles

Control of retention mechanisms on an octadecyl-bonded silica column using ionic liquid-based mobile phase in analysis of cytostatic drugs by liquid chromatography

This study assesses the potential of using ionic liquids (ILs) as mobile phase additives to control the retention mechanism of four cytostatic drugs: doxorubicin hydrochloride (DOX), epirubicin hydrochloride (EPI), daunorubicin hydrochloride (DAU) and idarubicin hydrochloride (IDA). Chromatographic separations were performed on a C18 analytical column (Discovery C18 150 × 4.6 mm, 5 µm) using six IL anions and four methyl-substituted IL cations with different alkyl chain lengths (alone or with the additional methyl group on the aromatic ring), or with an allyl group added as a cationic substituent. Thus, a total of 17 different ILs were assessed. The aqueous formic acid solution and phosphate buffer were used to compare how mobile phase composition affected the behavior of the analyzed cytostatic agents in the presence of ILs. In addition, the impacts of IL concentration, phosphate buffer concentration, and phosphate buffer pH on the final results were also considered. The ability to change analyte retention without negatively impacting peak shape or analytical efficiency was also controlled via the tailing factor and number of theoretical plates. Based on the results, the tested ILs were classified as either effective or ineffective mobile phase additives for separation of anthracyclines and identification by LC-FL technique.

Establishment of quantitative methodology for sophoridine analysis and determination of its pharmacokinetics and bioavailability in rat

Objective The aim of this study is to develop a rapid and sensitive UPLC–MS/MS approach to determine the sophoridine (SOP) level in rat plasma and the pharmacokinetics of the substance. Significance Sophoridine is used as an anti-inflammatory, anti-virus, anti-microbial, and anti-tumor alkaloid. It is essential to explore specific detection methods for the quantitative analysis of SOP in the blood circulation. Methods The rat plasma samples were prepared by one-step protein precipitation with acetonitrile. Subsequently, the samples were separated by chromatography using a UPLC BEH C18 reversed-phase with an initial mobile phase of methanol and 0.1% formic acid aqueous solution. The gradient elution was performed at a fixed flow rate of 0.4 mL/min, and multiple reaction monitoring (MRM) mode with an electrospray positive ionization source was employed to detect the transitions of m/z 249.1 → 84.2 for SOP and m/z 264.3 → 69.8 for dendrobine (IS). The entire process required 3.5 min for each sample. Results A linear correlation was established over the range of 2–2000 ng/mL (r 2≥0.9954) for SOP in rat plasma with a lower limit of quantification (LLOQ) at 2 ng/mL. The range of accuracy was tested between 94.90% and 100.80%, and the relative standard deviations (RSDs) toward both intra- and inter-day precision were <10%. Thus, this method was successfully applied to a pharmacokinetic study, and the subsequent results demonstrated a low absolute bioavailability of 2.32%. Conclusion The present study established a reliable method that quantified the SOP concentration in rat plasma after administering a dose of 2 mg/kg intravenously or 20 mg/kg orally.

Chemome profiling of Pien-Tze-Huang by online pressurized liquid extraction-ultra-high performance liquid chromatography-ion trap-time-of-flight mass spectrometry

片仔癀(Pien-Tze-Huang)是由三七、牛黄、蛇胆、麝香等名贵中药经加工精制而成的中药制剂。片仔癀中的三七皂苷、胆汁酸以及麝香酮等主要化学成分已被深入研究,然而其全方化学成分组成尚未被整体阐明。该文建立了在线加压溶剂提取-超高效液相色谱-离子阱-飞行时间质谱(online PLE-UHPLC-IT-TOF-MS)法,快速、直接分析片仔癀化学成分组。将少量片仔癀粉末(0.3 mg)均匀地平铺于预柱芯尾端,之后用正相硅胶填充预柱芯,滤膜密封后构成提取池。提取池装入预柱套后置于70 ℃的柱温箱内,连接于UHPLC-IT-TOF-MS分析系统。通过引入一个二位六通电子阀,将整个分析过程自动在提取相和洗脱相间切换。提取相用时3 min,以0.1%(v/v)甲酸水为提取溶剂,流速为0.2 mL/min;洗脱相以0.1%(v/v)甲酸水和乙腈为流动相进行梯度洗脱,IT-TOF-MS检测。通过与对照品、相关文献和自建中药数据库对照,并总结相关质谱裂解规律,从片仔癀中共检测到73个化学成分,初步鉴定并归属了其中71个,36个来源于三七,15个来源于蛇胆,9个来源于牛黄,11个可能来源于牛黄与蛇胆,另有2个结构无法确定。该研究深入解析了片仔癀的化学成分组,为其质量分析提供了丰富的信息。同时,该文构建的online PLE-UHPLC-IT-TOF-MS分析系统为中药复杂体系快速、直接分析提供了可靠的工具。

Doubly or triply protonated? Complexes of cucurbit[n]urils (n = 6–8) with a tripodal ligand tris(2-aminoethyl)amine (TREN)

Binding interactions between a tripodal ligand tris(2-aminoethyl)amine (TREN) and a series of cucurbit[n]urils (n = 6–8) in aqueous (H2O or D2O) formic acid solutions were investigated by electrospray mass spectrometry (ESI MS), isothermal titration calorimetry (ITC) and NMR titration. DFT calculations were also performed to rationalize the experimental findings. ESI MS data indicate that the studied cucurbiturils bind TREN amine forming two types of adducts of a 1:1 stoichiometry. Dipositive adducts are formed by CB6 and CB7 homologues, while tripositive adducts are formed by CB7 and CB8 homologues. DFT calculations show that the type of the formed adduct is connected with the dimensions of the cucurbituril portal. The results of NMR and ITC measurements confirm that all three CBn homologues (n = 6–8) bind TREN ligands spontaneously in the liquid phase. According ITC results the CB7 homologue binds this amine more strongly than the CB6 and CB8 homologues.

Quantitative analysis of tryptophan and its metabolites in urine by ultra performance liquid chromatography-tandem mass spectrometry

基于超高效液相色谱-串联质谱(UPLC-MS/MS)建立定量分析色氨酸(Trp)及代谢产物3-OH-犬尿氨酸(3-OH-Kyn)、3-OH-邻氨基苯甲酸(3-OH-AA)、黄尿酸(XA)、犬尿氨酸(Kyn)、5-羟基吲哚乙酸(5-HIAA)、犬尿喹啉酸(KA)和5-羟色胺(5-HT)的方法,应用该方法分析其在尿样中的含量,探讨排泄规律。将尿样稀释、离心后,加入丹磺酰氯(DNS-Cl)衍生,经Thermo C18色谱柱(50 mm×3 mm, 2.7 μm)分离和0.1%甲酸和甲醇梯度洗脱后,采用电喷雾电离(ESI)源,在正离子扫描和多反应监测(MRM)模式下检测。以咖啡酸(CA)为内标,定量分析。结果显示,8种目标化合物的线性关系良好,相关系数(R 2)≥0.9740,检测灵敏(LOD为0.005~0.5 ng/mL),回收率高(93.24%~107.65%)。采用本方法检测分析了健康志愿者70个尿液样本,在尿样中检测到Trp原型及其7种代谢产物。结果表明,体内的Trp是通过原型和代谢两种方式排泄:Trp原型的含量为5.22~20.88 μg/mL;尿液中经代谢后排泄的Trp量是原型的124%~268%,即体内的Trp主要经代谢后排出体外。方法主要研究了Trp-5-HT和Trp-Kyn两条途径的代谢产物含量,Trp经Kyn降解生成的3-OH-AA和3-OH-Kyn含量较多,即Trp-Kyn是体内Trp的主要代谢途径。方法通过UPLC-MS/MS实现了尿液中Trp及其代谢产物含量的检测,能为临床检查提供技术和理论支持。

Characterization and identification of flavonoids from Bambusa chungii leaves extract by UPLC-ESI-Q-TOF-MS/MS

AbstractBamboo leaves extract (BLE) has a variety of physiological functions such as antitumour, anti-inflammatory, antioxidant and blood fat reduction activities and the flavonoids of bamboo leaves are the major active constituents. To profile the flavonoids in the complex BLE, a rapid and sensitive analytical method based on ultra-high-performance liquid chromatography coupled with electrospray ionization quadrupole time-of-flight tandem mass spectrometry (UPLC-ESI-Q-TOF-MS/MS) was developed for the structural identification of the flavonoids in Bambusa chungii leaves extract using accurate mass measurements and characteristic fragmentation patterns. After separation on an Agilent SB-C18 Rapid Resolution High Definition (RRHD) column (2.1 mm × 150 mm, 1.8 μm) by gradient elution with 0.1% formic acid aqueous solution and acetonitrile as the mobile phase, the sample was analysed by ESI-QTOF-MS/MS in the negative mode. A total of 22 flavonoids were detected, and eight of these were identified by comparison with reference standards, while the other fourteen were tentatively identified according to their MS/MS data. The main fragmentation pathways of flavonoid C-glycosides (compounds 1, 5 and 10), flavonoid di-C,O-glycosides (compound 4), flavonoid di-C-glycosides (compound 7) and flavonoid C,O-di-glycosides (compounds 2 and 14) are shown in this article. This is the first report on the analysis of the flavonoids in the extract of B. chungii leaves. The present work demonstrates that UPLC-ESI-Q-TOF-MS/MS is an efficient technique for identifying multiple flavonoids of BLE.

Comprehensive Quality Assessment of Kaixin Powder by HPLC-DAD Quantification and HPLC-QTOF-MS/MS Confirmation.

Kaixin Powder (KXP) is a classic formula for treating morbid forgetfulness in ancient China. To guarantee the efficacy and safety of KXP, a simple and accurate HPLC–DAD method has been established and validated for the quantitative analysis of seven bioactive compounds in KXP. Dehydrotumulosic acid (DTU) and dehydrotrametenolic acid (DTR) were quantified in KXP for the first time. Good chromatographic separation was conducted on a Kromasil 100-5 C18 column (250 mm × 4.6 mm, 5 μm) by gradient elution using mobile phases containing acetonitrile and 0.1% formic acid aqueous solution at different detection wavelengths. The calibration curves of each compound showed good linearity (r ≥ 0.9990), and the LOD and LOQ were in the ranges of 0.01–0.10 and 0.03–0.40 μg/mL, respectively. The relative standard deviations (RSDs) of intra-day and inter-day precisions were in the ranges of 0.45–1.74% and 0.56–2.32%, respectively. All recoveries were in the range of 93.6–105.5% with an RSD no more than 2.77%. These quantification results of seven compounds determined in the samples were further confirmed by HPLC–QTOF-MS/MS. This study provides a useful and simple method for analyzing the major bioactive compounds and improves the quality assessment research of KXP.

Authenticity Assessment and Fraud Quantitation of Coffee Adulterated with Chicory, Barley, and Flours by Untargeted HPLC-UV-FLD Fingerprinting and Chemometrics.

Coffee, one of the most popular drinks around the world, is also one of the beverages most susceptible of being adulterated. Untargeted high-performance liquid chromatography with ultraviolet and fluorescence detection (HPLC-UV-FLD) fingerprinting strategies in combination with chemometrics were employed for the authenticity assessment and fraud quantitation of adulterated coffees involving three different and common adulterants: chicory, barley, and flours. The methodologies were applied after a solid–liquid extraction procedure with a methanol:water 50:50 (v/v) solution as extracting solvent. Chromatographic fingerprints were obtained using a Kinetex® C18 reversed-phase column under gradient elution conditions using 0.1% formic acid aqueous solution and methanol as mobile phase components. The obtained coffee and adulterants extract HPLC-UV-FLD fingerprints were evaluated by partial least squares regression-discriminants analysis (PLS-DA) resulting to be excellent chemical descriptors for sample discrimination. One hundred percent classification rates for both PLS-DA calibration and prediction models were obtained. In addition, Arabica and Robusta coffee samples were adulterated with chicory, barley, and flours, and the obtained HPLC-UV-FLD fingerprints subjected to partial least squares (PLS) regression, demonstrating the feasibility of the proposed methodologies to assess coffee authenticity and to quantify adulteration levels (down to 15%), showing both calibration and prediction errors below 1.3% and 2.4%, respectively.

Simultaneous determination of 11 prohibited and restricted veterinary drugs and their metabolites in animal-derived foods by ultra performance liquid chromatography-tandem mass spectrometry coupled with solid phase extraction

建立了固相萃取-超高效液相色谱-串联质谱(SPE-UPLC-MS/MS)同时检测鸡蛋、液态奶、鸡肉及淡水鱼中4类(氯霉素类、硝基咪唑类、林可酰胺类与大环内酯类)8种禁限兽药与3种代谢物残留的分析方法。对样品前处理及色谱条件进行优化,样品经0.1 mol/L pH 9.0的磷酸盐缓冲液水解分散,乙腈提取,提取液经乙酸乙酯萃取后浓缩至近干,残留物用0.3 mL甲醇溶解,再加入5.7 mL磷酸盐缓冲液,混匀,溶解液经Oasis HLB固相萃取柱净化后上机分析,以甲醇与0.1%甲酸水溶液作为流动相进行梯度洗脱,经ACQUITY UPLC BEH C18色谱柱(100 mm×2.1 mm, 1.7 μm)分离,采用ESI+和ESI-电离,在多反应监测模式下采集,同位素内标法定量。结果表明,11种待测物在色谱柱上完全基线分离,在各自范围内线性关系良好,相关系数(R2)>0.99,方法的检出限(LOD)为0.050~0.50 μg/kg,定量限(LOQ)为0.20~1.5 μg/kg。各待测物的平均回收率为65.3%~108%,相对标准偏差(RSD)为0.40%~21%。将该方法应用于市售样品中上述4类兽药残留的常规监测,其阳性样本的检测结果与标准方法测定结果无显著性差异。该方法灵敏度高,稳定性好,定量准确,适用于动物源性食品中多种禁限兽药及代谢物残留的同时快速测定。

Enantioselective Detection, Bioactivity, and Degradation of the Novel Chiral Fungicide Oxathiapiprolin

Oxathiapiprolin is a novel chiral piperidine thiazole isooxazoline fungicide that contains a pair of enantiomers. An effective analytical method was established for the enantioselective detection of oxathiapiprolin in fruit, vegetable, and soil samples using ultraperformance liquid chromatography-tandem triple quadrupole mass spectrometry. The optimal enantioseparation was achieved on a Chiralpak IG column at 35 °C using acetonitrile and 0.1% formic acid aqueous solution (90:10, v/v) as the mobile phase. The absolute configuration of the oxathiapiprolin enantiomers was identified with the elution order of R-(-)-oxathiapiprolin and S-(+)-oxathiapiprolin by electron circular dichroism spectra. The bioactivity of R-(-)-oxathiapiprolin was 2.49 to 13.30-fold higher than that of S-(+)-oxathiapiprolin against six kinds of oomycetes. The molecular docking result illuminated the mechanism of enantioselectivity in bioactivity. The glide score (-8.00 kcal/mol) for the R-enantiomer was better with the binding site in Phytophthora capsici than the S-enantiomer (-7.50 kcal/mol). Enantioselective degradation in tomato and pepper under the field condition was investigated and indicated that R-(-)-oxathiapiprolin was preferentially degraded. The present study determines the enantioselectivity of oxathiapiprolin about enantioselective detection, bioactivity, and degradation for the first time. The R-enantiomer will be a better choice than racemic oxathiapiprolin to enhance the bioactivity and reduce the pesticide residues at a lower application rate.

Pharmacokinetic studies of ginsenosides Rk1 and Rg5 in rats by UFLC–MS/MS

A rapid ultra-fast liquid chromatography tandem mass spectrometry method was developed and validated to determine ginsenosides Rk1 and Rg5, a pair of isomers, in rat plasma, which was successfully applied to their pharmacokinetic studies. Two ginsenosides were given to male Sprague-Dawley rats via intragastrical and intravenous routes, respectively, and the impact of double bond position on the pharmacokinetic features of the two ginsenosides was elucidated in rats. Ginsenoside Rg3 was used as internal standard and ethyl acetate was applied to extract analytes and internal standard. Chromatographic separation was carried out on a reverse-phase UPLC HSS T3 column (100 × 2.1 mm, 1.8 μm). The flow rate was set to 0.4 ml/min. The fragmentation transition was m/z 765.4 → m/z 101.1 for two ginsenosides. The mobile phases were composed of 0.1% formic acid aqueous solution and acetonitrile. The linear range was 2-1,000 ng/ml for the two ginsenosides. Intra- and inter-day precisions were <11.67%, and accuracy fluctuated from -7.44 to 6.78%. The extraction recovery, matrix effect and stability were within acceptable levels. After treatment with ginsenosides Rk1 and Rg5, some differences were found in their pharmacokinetic profiles in rats. The maximum plasma drug concentration and the area under the plasma drug concentration-time curve of ginsenoside Rg5 were about 5 times bigger than those of ginsenoside Rk1 after oral administration, and 3 times higher after intravenous administration. The oral bioavailabilities of ginsenosides Rk1 and Rg5 were 0.67 and 0.97%, respectively. The results indicated that ∆20(22) -ginsenosides showed better pharmacokinetic features than ∆20(21) -ginsenosides with the same glycosylation.

Analysis of chemical constituents of Ginseng-Douchi compound fermentation products based on UPLC-Q-TOF-MS

In this experiment, ultra high performance liquid chromatography-quadrupole time-of-flight mass spectrometry(UPLC-Q-TOF-MS) was used to analyze and identify chemical constituents of Ginseng-Douchi(GD) compound fermentation, and explore the conversion rules of ginsenosides and soybean isoflavones after compound fermentation. Waters Acquity UPLC BEH C_(18) column(2.1 mm×100 mm, 1.7 μm) was adopted, with 0.1% formic acid aqueous solution(A)-0.1% formic acid acetonitrile solution(B) as mobile phase for gradient elution; electrospray ion source(ESI) was used to collect data in positive and negative ion modes; according to the exact mass number, the secondary spectrum comparison of the database and the existing literature reports, Peakview 2.0/masterview 1.0 software was used to determine the common ion structure formula. Finally, a total of 133 chemical constituents were analyzed and identified from the GD. Ginseng saponins and isoflavone glycosides were significantly converted after fermentation. Among them, peak areas of prototype ginsenosides Rk_3, Rh_1, Rh_2, Rh_3, daidzin, glycitin and genistin decreased significantly; whereas peak areas of se-condary ginsenoside Rb_1, Rb_2, Rk_1, glycitein, genistein and daidzein increased significantly. In this experiment, liquid-mass spectrometry technique was used to investigate the conversion of active ingredients of GD compound fermented products after co-fermentation, so as to provide a scientific basis for elucidating pharmacodynamics material basis and quality control.

Correlation study on non-volatile ingredients of Menthae Haplocalycis Herba formula granules and traditional herbal pieces by UPLC-MS/MS

To establish the method for determining non-volatile ingredients of neochlorogenic acid, chlorogenic acid, cryptochlorogenic acid, caffeic acid, isochlorogenic acid A, rosmarinic acid, ferulic acid, rutin, luteoloside, isoquercitrin, hesperidin, diosmin, diosmetin, luteolin, acacetin and linarin in Menthae Haplocalycis Herba formula granules and traditional herbal pieces by UPLC-MS/MS, and analyze the correlation of non-volatile ingredients in Menthae Haplocalycis Herba formula granules and traditional herbal pieces. Shim-pack GIST C_(18) column(2.1 mm×100 mm, 2 μm) was adopted with acetonitrile-0.1% formic acid aqueous solution as the mobile phase for gradient elution at the flow rate of 0.4 mL·min~(-1). The column temperature was set at 35 ℃. The quantitative analysis was performed using the electrospray ionization source and the multiple reaction monitoring. The linear relationship, resolution, repeatability and recovery of the 16 chemical components all met the requirements. The 16 non-volatile ingredients in traditional herbal pieces of Menthae Haplocalycis Herba could be tracked in formula granules. There were certain differences of the 16 chemical components among Menthae Haplocalycis Herba formula granules of different manufacturers and traditional herbal pieces of different producing areas. The UPLC-MS/MS method was simple, rapid and accurate, and could be used for the quality control of non-volatile ingredients in Menthae Haplocalycis Herba formula granules and traditional herbal pieces.

Rapid screening and confirmation of 415 pesticide residues in red cabbages by liquid chromatography-quadrupole-time of flight-mass spectrometry

应用液相色谱-四极杆-飞行时间质谱(LC-QTOF/MS)建立了一次进样可同时对紫甘蓝中415种农药残留进行快速筛查和准确确证的分析方法。实验采用1%(v/v)醋酸乙腈溶液提取,无水硫酸镁和氯化钠进行盐析,ZORBAX SB-C18色谱柱(100 mm×2.1 mm, 3.5 μm)分离,以0.1%(v/v)甲酸水溶液(含5 mmol/L乙酸铵)-乙腈为二元流动相进行梯度洗脱,应用LC-QTOF/MS在电喷雾电离、全离子MS/MS(All Ions MS/MS)扫描正模式下进行检测,基质匹配外标法定量分析。通过优化全自动MS/MS采集模式(Auto MS/MS)和全离子MS/MS采集模式下的不同参数,得到每种采集模式下的最佳条件。然后在2种不同采集模式的最佳条件下对比,最终选取All Ions MS/MS采集模式。实验结果表明,采用所建立的分析方法可以准确定性和定量筛查紫甘蓝中415种农药残留,所有415种农药在各自的范围内线性相关系数(r2)均大于0.990,其中411种农药的筛查限(SDL)≤5 μg/kg, 413种农药的定量限(LOQ)≤10 μg/kg。在1倍、2倍和10倍LOQ添加水平下,农药的回收率分别为65.7%~118.4%、72.0%~118.8%和70.2%~111.2%,相对标准偏差分别为0.9%~19.7%、0.2%~19.9%和0.6%~19.9%。将该方法应用于2019年欧盟能力验证项目的紫甘蓝样品中未知农药残留筛查方法和定量方法考核样的检测,所有添加农药均被准确定性筛查和定量检测,没有假阳性和假阴性。结果表明,该方法快速、准确、可靠,适用于对紫甘蓝中多种农药残留的高通量定性筛查和准确定量,可以扩展到其他果蔬基质中多农残的高通量筛查。

Solvothermal fusion of Ag‐ and N‐doped LiTaO3 perovskite nanospheres for improved photocatalytic hydrogen production

Tantalate semiconductor photocatalyst has received significant attention as an alternative promising material to mitigate the globally increasing energy demand with the course of action of the produced hydrogen. In this report, an efficient enhancement in the hydrogen production under ultraviolet (UV) light by Ag‐ and N‐doped LiTaO3 via solvothermal strategy is proposed. The structural appearance and the spherical morphology are affirmed from the X‐ray diffraction and field emission scanning electron microscopy (FESEM) analysis. The bandgap of the prepared photocatalysts is calculated as 5.12, 4.92, and 4.82 eV for undoped LiTaO3, Ag, and N‐doped LiTaO3 nanoparticles using Tauc's plot. Moreover, the band position of the synthesized LiTaO3 and also with its dopants is calculated by the Mulliken electro negativity method. The elemental composition of the synthesized photocatalyst is confirmed from the energy dispersive analysis (EDS). Photocatalytic water splitting results over Ag‐ and N‐doped LiTaO3 photocatalyst showed that the rate of H2 evolution from formic acid aqueous solution was 240 and 123 μmolh−1 with an apparent quantum yield of 3.11% and 1.59%, whereas for undoped LiTaO3, the rate is quite lower to be 71 μmolh−1. The reason behind the high catalytic activity of Ag‐doped LiTaO3 is explained by the fact that the higher electronegativity of Ag (1.93) as compared with Ta (1.5) resulted in quite transfer of photoexcited electrons from the conduction band of LiTaO3 to the Ag species. Interestingly, up to the best of our knowledge, this is the first study regarding the photocatalytic hydrogen evolution for Ag‐ and N‐doped LiTaO3.

A Rapid UPLC Method for the Simultaneous Quantitation of Caffeic Acid Derivatives in Dried Extracts of Echinacea Purpurea.

Echinacea purpurea is a traditional medicinal plant widely used as adjuvant for the treatment of respiratory and urinary infections. Caffeic acid derivatives are considered the main active markers, such as chicoric acid, caftaric acid and chlorogenic acid. An analytical method using ultra performance liquid chromatography (UPLC) and diode array detector was developed and validated, to quantify caffeic acid derivatives in commercial dried extracts of EP. UPLC method was developed using a C18 column (50× 2.1mm, 1.8μm), at 30°C. Mobile phase was composed of acetonitrile and 0.05% (v/v) formic acid aqueous solution (10:90), flow rate 0.2mL/min. Injection volume was 10μL and detection was performed at 300 and 330nm. The developed method complied with all required validation parameters, and showed to be linear, precise, accurate, selective and robust for all caffeic acid derivatives. Using the validated method, the levels of caftaric acid (0.110-0.507%w/w), chicoric acid (0.040-0.179%w/w) and chlorogenic acid (0.013-0.084%w/w) were determined in five commercial dried extracts of E. purpurea, with significant variation in the contents between different samples, indicating the need of standardization and control of individual caffeic acid derivatives in commercial extracts.

Solvothermal sol–gel synthesis of TiO2-cellulose nanocrystalline composites

Due to its unique supramolecular structure, cellulose is widely used as a template agent, ensuring an easy structuring of anatase TiO2 particles with subsequent release after the organics burning. This work is devoted to the synthesis of microcrystalline cellulose-TiO2 (MCC-TiO2) composite photocatalyst by preserving the intermediate organic–inorganic structures. A series of the MCC-TiO2 materials were prepared via solvothermal sol–gel method in n-decane and caproic acid solvents and characterized by X-ray diffraction, transmission electron microscopy, IR spectroscopy, 1H NMR and TG/DSC methods. The photocatalytic activity of the prepared materials was evaluated by the decomposition of formic acid in aqueous solutions. The composites failed to be formed in n-decane, while in caproic acid, acting as solvent and reagent, anatase TiO2 nanoparticles were formed onto the crystalline domains of cellulose, tightly fixed due to covalent Ti–O–C bonds. The materials formed in caproic acid showed a higher photocatalytic activity, explained by a complementarity of the organic and inorganic components. The specific activity (normalized on TiO2 mass) of best synthetized composite materials was almost twice higher than that of Aeroxide P25 TiO2 reference photocatalyst.

Розробка та валідація ВЕРХ-МС методики визначення мемантину гідрохлориду для вивчення профілів розчинення

A method for quantitative determination of memantine hydrochloride by HPLC with mass spectrometric detection (HPLC-MS), suitable for the study of dissolution profiles of tablets "Mematon IС" was developed. Chromatographic determination was performed using a mobile phase of methanol - 0.1% (v/v) aqueous solution of formic acid (55:45) on a column of Zorbax Eclipse Plus C18 size 10 cm Ч 4.6 mm (3.5 μm) at a flow rate of 1 ml/min. The linearity interval in the appropriate dissolution media is 35 - 150 % of the normalized content of memantine hydrochloride in the tablet. The method is validated on the parameters of specificity, accuracy, correctness, linearity in the studied range of concentrations, robustness. The stability of the tested solutions and reference solutions in the case of their storage at room temperature for 24 hours was confirmed. It is established that in the case of the study of solutions prepared in a dissolution medium of 0.1 M hydrochloric acid solution pH 1.2, there is a need to preneutralize hydrochloric acid before analysis, because it, as stronger than formic acid, almost completely ionizes all dissolved molecules, which leads to a significant deviation of the linear dependence of the analytical signal on the concentration of the analyte. Neutralization is performed with 0.1 M sodium hydroxide solution, which is added to the sample of the test solution. The release of more than 85 % of memantine hydrochloride in 15 min in all dissolution media indicates the similarity of the dissolution profiles and does not require the calculation of the similarity factor f2.

The rapid profiling and simultaneous determination of 12 major alkaloids in Nauclea officinalis by UPLC-Q-TOF-MS and HPLC-ESI-MS/MS.

For the first time, we determined the phytochemical profile of alkaloids from N. officinalis using ultraperformance liquid chromatography-quadrupole-time-of-flight-tandem mass spectrometry (UPLC-Q-TOF-MS/MS). A rapid, specific, and sensitive high-performance liquid chromatography-tandem mass spectrometry method was subsequently developed and fully validated for the simultaneous determination of 12 major alkaloid constituents in N. officinalis: pumiloside; naucleoxoside A; naucleoxoside B; nauclefine; angustidine; angustoline; (3S,19S)-3,14-dihydroangustoline ([α]20D: (-)191°); (3S,19R)-3,14-dihydroangustoline ([α]20D: (-)294.7°); strictosamide; angustine; vincosamide; and 3,14-dihydroangustine. The analytes were detected with an electrospray ionization (ESI) source and multiple reaction monitoring (MRM) using positive scanning mode. Three pairs of epimers (naucleoxoside A and naucleoxoside B; (3S,19S)-3,14-dihydroangustoline ([α]20D: (-)191°) and (3S,19R)-3,14-dihydroangustoline ([α]20D: (-)294.7°); and strictosamide and vincosamide) were successfully separated using an ACQUITY UPLC® BEH C18 column (2.1 mm × 100 mm, 1.7 μm) at 30 °C, with a gradient mobile phase consisting of 0.1% formic acid aqueous solution (A) and acetonitrile (B), a flow rate of 0.2 mL min-1, and a total run time of 30 min. All calibration curves exhibited excellent linear regression (r > 0.999) within the test range. The precision, repeatability, and stability of the method toward the 12 alkaloid compounds were less than 2.0% in terms of the relative standard deviation (RSD) values. The mean recoveries for all compounds were between 98.7% and 101.1%, with RSD values ranging from 0.55% to 1.7% for N. officinalis samples.

Neochlorogenic acid: an anti-HIV active compound identified by screening of Cortex Mori [Morus Alba L. (Moraceae)

Context Chinese herbs such as Cortex Mori [Morus alba L. (Moraceae)] may inhibit human immunodeficiency virus (HIV), but active compounds are unknown. Objective Screening of Cortex Mori and other herbs for anti-HIV active compounds. Materials and methods HIV-1 virus (multiplicity of infection: 20), and herbs (dissolved in dimethyl sulfoxide, working concentrations: 10, 1, and 0.1 mg/mL) such as Cortex Mori, etc., were added to 786-O cells (105 cell/well). Zidovudine was used as a positive control. Cell survival and viral inhibition rates were measured. The herb that was the closest inactivity to zidovudine was screened. Mass spectrometry identified the active compounds in herbs (mobile phase: 0.05% formic acid aqueous solution and acetonitrile, gradient elution, detection wavelength: 210 nm). The effect of the compounds on reverse transcriptase (RT) products were evaluated by real-time PCR. Gene enrichment was used to analyse underlying mechanisms. Results With a dose of 1 mg/mL of Cortex Mori, the cell survival rate (57.94%) and viral inhibition rate (74.95%) were closest to the effect of zidovudine (87.87%, 79.81%, respectively). Neochlorogenic acid, one of the active ingredients, was identified by mass spectrometry in Cortex Mori. PCR discovery total RT products of neochlorogenic acid group (mean relative gene expression: 6.01) significantly inhibited (control: 35.42, p < 0.0001). Enrichment analysis showed that neochlorogenic acid may act on haemopoietic cell kinase, epidermal growth factor receptor, sarcoma, etc., thus inhibiting HIV-1 infection. Conclusions For people of low socioeconomic status affected by HIV, Chinese medicine (such as Cortex Mori) has many advantages: it is inexpensive and does not easily produce resistance. Drugs based on active ingredients may be developed and could have important value.