Monitoring batch-to-batch reproducibility using direct analysis in real time mass spectrometry and multivariate analysis: A case study on precipitation

Development of quality control parameters for two Bhutanese medicinal plants (Aster flaccidus Bunge and Aster diplostephioides (DC.) Benth. ex C.B.Clarke) using traditional and modern pharmacognostical platforms

Bhutan's scholarly traditional medical system is called Bhutanese Sowa Rigpa medicine (BSM). It was integrated with the modern healthcare system in 1967. Over 200 medicinal plants are used to produce more than 100 poly-ingredient medicinal formulations. Although BSM is supported by well-documented principles, pharmacopoeias, diagnostic procedures, treatment regimens, and traditional quality assurance systems, modern quality control parameters have become essential to distinguish closely related species and prevent contamination from exogenous impurities. This study aims to establish reliable analytical methods and quality control parameters for Aster flaccidus Bunge and Aster diplostephioides (DC.) Benth. ex C.B. Clarke used as ingredients in the BMS poly-ingredient medicinal formulations. Furthermore, their reported phytochemicals and biological activities are also discussed in this study. Standard pharmacognostic techniques, including macroscopical and microscopical examinations of crude drugs, were employed to establish the quality control parameters for two Aster species. The physicochemical limits were determined as per the World Health Organization (WHO)-recommended guidelines and methods described in the Thai herbal pharmacopoeia. A high-performance thin-layer liquid chromatography (HPTLC) was used to develop a comparative chromatogram/phytochemical fingerprint for the crude extracts obtained from two Aster species. A literature review was conducted to record their isolated phytochemicals and biological activities. Two Aster species possess macro- and microscopic features such as colour, appearance, and shape. Physicochemical analysis of crude drugs from two Aster species including HPTLC fingerprinting of their methanol crude extracts also yielded adequate data to differentiate and confirm two Aster species before adding them to the BSM poly-ingredient medicinal formulations. From the literature review, only A. flaccidus was found to be studied for its phytochemical constituents, whereby 11 pure compounds were isolated from aerial parts and roots. The current study revealed distinct species-specific distinguishing features, including ecological adaptation, micromorphology, anatomy, physicochemical values, HPTLC chromatograms. These parameters can be used to authenticate the species identity and prevent adulterations, thereby improving the quality and safety of BSM formulations.

Characterization of effective phytochemicals in traditional Chinese medicine by mass spectrometry

Traditional Chinese medicines (TCMs) have been widely used in clinical and healthcare applications around the world. The characterization of the phytochemical components in TCMs is very important for studying the therapeutic mechanism of TCMs. In the analysis process, sample preparation and instrument analysis are key steps to improve analysis performance and accuracy. In recent years, chromatography combined with mass spectrometry (MS) has been widely used for the separation and detection of trace components in complex TCM samples. This article reviews various sample preparation techniques and chromatography-MS techniques, including the application of gas chromatography-MS and liquid chromatography-MS and other MS techniques in the characterization of phytochemicals in TCM materials and Chinese medicine products. This article also describes a new ambient ionization MS method for rapid and high-throughput analysis of TCM components.

HPLC fingerprinting-based multivariate analysis of chemical components in Tetrastigma Hemsleyanum Diels et Gilg: Correlation to their antioxidant and neuraminidase inhibition activities

Tetrastigma Hemsleyanum Diels & Gilg (TDG) has attracted growing attention in China; however, there were few studies on its bioactive components. Herein, the characteristic chemical components and dual antioxidant and neuraminidase inhibitory activities of fifteen batches of TDG from different places of origin and their relevance were investigated. The HPLC fingerprint was first established and the marker components were identified by using UPLC-Q-TOF-MS/MS. Catechin-5-O-β-d-glucopyranoside, tartaric acid, (1R, 2R, 4S)-2-hydroxy-1, 8-cineole-β-d-glucopyranoside, and phlorizin were identified for the first time. The result of multivariate statistical analysis indicated that multiple components have a significant contribution to the classification of TDG, such as chlorogenic acid, saccharumoside C/D, robinin, procyanidin B₂, rutin, isoquercitrin, etc. Then, the antioxidant and neuraminidase inhibitory activities of fifteen batches of TDG were measured. The result of grey relationship analysis showed that the contents of rutin, isoquercitrin, kaempferol-3-rutinoside, and astragalin were positively correlated with these two activities with correlation coefficients more than 0.8. The quantitative analysis of these four bioactive compounds was performed by using HPLC-DAD. The recovery rate of the method varied from 98.02% to 100.21%, the RSD values of precision, stability and repeatability were between 1.32-3.15 %, and the R value of the linear equation was above 0.9990. To sum up, this study is valuable in the quality control of TDG.

Improving selective channel occlusion of complex hydrocarbons and fatty acid methyl esters in urea crystals by using an expendable 3D-printed microfluidic device for sample preparation in untargeted petroleomics

In this study, we describe a proof-of-concept investigation of the potential and limitations of employing channel occlusion for sample preparation in untargeted analysis in petroleomics. A middle petroleum distillate composed of fatty acid methyl esters (FAME) and a complex mixture of linear, branched, and cyclic hydrocarbons were selected as the model samples for this investigation. A microfluidic device was engineered to overcome the limitations of channel occlusion, resulting in a quick and robust method for sample preparation. The 3D-printed device using fused deposition modelling (FDM) allowed the combination of a 13-h multi-step sample handling protocol into a 2-min single-step procedure, which is also automation-friendly. Such developments were also evaluated using the analytical eco-scale to guide the development of a green analytical method. The relative standard deviation decreased 2-fold with method miniaturization. The efficiency of n-alkane removal was extended from tridecane (n-C₁₃) to heptadecane (n-C₁₇), compared to original method (n-C₁₆ to n-C₁₇). The analytical performance of the method was investigated for untargeted analysis. The tool used to probe the intra- and inter-class variance was multi-way principal component analysis (MPCA). MPCA modelling revealed that both methods generated equivalent chemical information, highlighting the benefits of reliable and reproducible sample preparation methods, especially for untargeted analysis. Such awareness is critical to avoid the generation of misleading results in fields that heavily rely on untargeted analysis and fingerprinting, such as petroleomics.

Recent advances of novel technologies for quality consistency assessment of natural herbal medicines and preparations

Quality consistency is one of the basic attributes of medicines, but it is also a difficult problem that natural medicines and their preparations must face. The complex chemical composition and comprehensive pharmacological action of natural medicines make it difficult to simply apply the commonly used evaluation methods in chemical drugs. It is thus urgent to explore the novel evaluation methods suitable for the characteristics of natural medicines. With the rapid development of analytical techniques and the deepening understanding of the quality of natural herbs, increasing numbers of researchers have proposed many new ideas and technologies. This review mainly focuses on the basic principles, technical characteristics and application examples of the chemical evaluation, biological evaluation methods and their combination in quality consistency evaluation of natural herbs. On the bases of chemical evaluation and clinical efficacy, new methods reflecting their pharmacodynamic mechanism and safety characteristics will be developed, and gradually towards accurate quality control, to achieve the goal of quality consistency. We hope that this manuscript can provide new ideas and technical references for the quality consistency of natural drugs and their preparations, thus better guarantee their clinical efficacy and safety, and better promote industrial development.

Prediction Model of Aryl Hydrocarbon Receptor Activation by a Novel QSAR Approach, DeepSnap-Deep Learning

The aryl hydrocarbon receptor (AhR) is a ligand-dependent transcription factor that senses environmental exogenous and endogenous ligands or xenobiotic chemicals. In particular, exposure of the liver to environmental metabolism-disrupting chemicals contributes to the development and propagation of steatosis and hepatotoxicity. However, the mechanisms for AhR-induced hepatotoxicity and tumor propagation in the liver remain to be revealed, due to the wide variety of AhR ligands. Recently, quantitative structure–activity relationship (QSAR) analysis using deep neural network (DNN) has shown superior performance for the prediction of chemical compounds. Therefore, this study proposes a novel QSAR analysis using deep learning (DL), called the DeepSnap–DL method, to construct prediction models of chemical activation of AhR. Compared with conventional machine learning (ML) techniques, such as the random forest, XGBoost, LightGBM, and CatBoost, the proposed method achieves high-performance prediction of AhR activation. Thus, the DeepSnap–DL method may be considered a useful tool for achieving high-throughput in silico evaluation of AhR-induced hepatotoxicity.

Evaluation of a multiple and global analytical indicator of batch consistency: traditional Chinese medicine injection as a case study

This paper evaluates a multiple and global analytical indicator of batch consistency in traditional Chinese medicine injections (TCMIs) via a chemometrics tool, which is more comprehensive to appraise quality consistency of different batches of injections than the traditional method of fingerprint similarity. A commonly used TCMI, Salviae miltiorrhizae and ligustrazine hydrochloride injection (SLI), was employed as a model. With the aid of a chemometrics tool (principal component analysis, PCA), evaluation of multiple and global analytical indicators of batch consistency, which included saccharides, phenolic acids and inorganic salts (18 indicators in total), was carried out to appraise the quality consistency of 13 batches of injection provided by the Guizhou Baite Pharmaceutical Co., Ltd. (Guizhou, China). Compared with the traditional HPLC-UV fingerprint similarity evaluation, the method proposed in the paper can more comprehensively and correctly reflect the quality consistency of different batches of injections. In this paper, the multi-index evaluation result showed poor batch consistency, which was more consistent with the determination results, while the fingerprint similarity evaluation results still showed good batch consistency. The HPLC-UV fingerprint reflects only substances with UV absorption, but it is not able to reflect substances without UV absorption or weak UV absorption, which leads to inappropriate conclusions. Therefore, quality consistency of injections can be effectively appraised by evaluation of multiple and global analytical indicators, instead of HPLC-UV fingerprint only. For visualizing the batch consistency of the multiple and global analytical indicators, a heat map was used to represent the fluctuation. Furthermore, critical indicator identification was also applied to select several indicators that should be paid more attention during the process of quality control of injection. And the analysis result showed that Na+, fructose (Fru), glucose (Glc), manninotriose (Man), danshensu (DSS) and salvianolic acid B (SAB) are the indicators that should be given more attention when controlling the quality of injections, also called critical quality control indicators. The proposed method provides a reference for the quality control of TCMIs and has broad application potential.

On-line monitoring the extract process of Fu-fang Shuanghua oral solution using near infrared spectroscopy and different PLS algorithms

An on-line near infrared (NIR) spectroscopy monitoring method with an appropriate multivariate calibration method was developed for the extraction process of Fu-fang Shuanghua oral solution (FSOS). On-line NIR spectra were collected through two fiber optic probes, which were designed to transmit NIR radiation by a 2mm flange. Partial least squares (PLS), interval PLS (iPLS) and synergy interval PLS (siPLS) algorithms were used comparatively for building the calibration regression models. During the extraction process, the feasibility of NIR spectroscopy was employed to determine the concentrations of chlorogenic acid (CA) content, total phenolic acids contents (TPC), total flavonoids contents (TFC) and soluble solid contents (SSC). High performance liquid chromatography (HPLC), ultraviolet spectrophotometric method (UV) and loss on drying methods were employed as reference methods. Experiment results showed that the performance of siPLS model is the best compared with PLS and iPLS. The calibration models for AC, TPC, TFC and SSC had high values of determination coefficients of (R(2)) (0.9948, 0.9992, 0.9950 and 0.9832) and low root mean square error of cross validation (RMSECV) (0.0113, 0.0341, 0.1787 and 1.2158), which indicate a good correlation between reference values and NIR predicted values. The overall results show that the on line detection method could be feasible in real application and would be of great value for monitoring the mixed decoction process of FSOS and other Chinese patent medicines.

An improved method for the determination of 5-hydroxymethylfurfural in Shenfu injection by direct analysis in real time-quadrupole time-of-flight mass spectrometry

The emergence of direct analysis in real time (DART) ion source provides the great possibility for rapid analysis of hazardous substance in drugs. DART mass spectrometry (DART-MS) enabled the conducting of a fast and non-contact analysis of various samples, including solid or liquid ones, without complex sample preparation or chromatographic separation. In this study, a modified DART-quadrupole time-of-flight mass spectrometry (DART-QTOF-MS) method was developed for identification and determination of 5-hydroxymethylfurfural (5-HMF) in Shenfu (SF) injection. The quantitative transfer of sample solution was introduced to the glass tips of DIP-it sampler at a fixed volume, which significantly increases the repeatability and accuracy of analytical results. The protonated ion of dibutyl phthalate in the atmosphere was used as the reference mass for TOF-MS recalibration during the data acquisition for constant high accuracy mass measurements. Finally, the developed DART-MS method was used to determine 5-HMF in seven batches of SF injection, and the contents of 5-HMF were not higher than 100 µg/mL. The results obtained were further confirmed by an ultra-high performance liquid chromatography combined with triple quadrupole mass spectrometer (UHPLC-QQQ-MS). The overall results demonstrated that the DART-QTOF-MS method could be applied as an alternative technique for rapid monitoring 5-HMF in herbal medicine injection. Copyright © 2015 John Wiley & Sons, Ltd.

On-line coupling of macroporous resin column chromatography with direct analysis in real time mass spectrometry utilizing a surface flowing mode sample holder

A surface flowing mode sample holder was designed as an alternative sampling strategy for direct analysis in real time mass spectrometry (DART-MS). With the sample holder, the on-line coupling of macroporous resin column chromatography with DART-MS was explored and the new system was employed to monitor the column chromatography elution process of Panax notoginseng. The effluent from macroporous resin column was first diluted and mixed with a derivatization reagent on-line, and the mixture was then directly transferred into the ionization region of DART-MS by the sample holder. Notoginsenosides were methylated and ionized in a metastable helium gas stream, and was introduced into MS for detection. The on-line system showed reasonable repeatability with a relative standard deviation of 12.3% for the peak area. Three notoginsenosides, i.e. notoginsenoside R1, ginsenoside Rb1 and ginsenoside Rg1, were simultaneously determined during the eluting process. The alteration of the chemical composition in the effluent was accurately identified in 9 min, agreeing well with the off-line analysis. The presented technique is more convenient compared to the traditional UPLC method. These results suggest that the surface flowing mode DART-MS has a good potential for the on-line process monitoring in the pharmaceutical industry.