Data-Driven Deciphering of Latent Lesions in Heterogeneous Tissue Using Function-Directed t-SNE of Mass Spectrometry Imaging Data.

Mass spectrometry imaging (MSI), which quantifies the underlying chemistry with molecular spatial information in tissue, represents an emerging tool for the functional exploration of pathological progression. Unsupervised machine learning of MSI datasets usually gives an overall interpretation of the metabolic features derived from the abundant ions. However, the features related to the latent lesions are always concealed by the abundant ion features, which hinders precise delineation of the lesions. Herein, we report a data-driven MSI data segmentation approach for recognizing the hidden lesions in the heterogeneous tissue without prior knowledge, which utilizes one-step prediction for feature selection to generate function-specific segmentation maps of the tissue. The performance and robustness of this approach are demonstrated on the MSI datasets of the ischemic rat brain tissues and the human glioma tissue, both possessing different structural complexity and metabolic heterogeneity. Application of the approach to the MSI datasets of the ischemic rat brain tissues reveals the location of the ischemic penumbra, a hidden zone between the ischemic core and the healthy tissue, and instantly discovers the metabolic signatures related to the penumbra. In view of the precise demarcation of latent lesions and the screening of lesion-specific metabolic signatures in tissues, this approach has great potential for in-depth exploration of the metabolic organization of complex tissue.

Is Low-field NMR a Complementary Tool to GC-MS in Quality Control of Essential Oils? A Case Study: Patchouli Essential Oil.

High-field NMR is an expensive and important quality control technique. In recent years, cheaper and simpler low-field NMR has become available as a new quality control technique. In this study, 60 MHz 1H-NMR was compared with GC-MS and refractometry for the detection of adulteration of essential oils, taking patchouli essential oil as a test case. Patchouli essential oil is frequently adulterated, even today. In total, 75 genuine patchouli essential oils, 10 commercial patchouli essential oils, 10 other essential oils, 17 adulterants, and 1 patchouli essential oil, spiked at 20% with those adulterants, were measured. Visual inspection of the NMR spectra allowed for easy detection of 14 adulterants, while gurjun and copaiba balsams proved difficult and one adulterant could not be detected. NMR spectra of 10 random essential oils differed not only strongly from patchouli essential oil but also from one another, suggesting that fingerprinting by low-field NMR is not limited to patchouli essential oil. Automated chemometric evaluation of NMR spectra was possible by similarity analysis (Mahalanobis distance) based on the integration from 0.1 - 8.1 ppm in 0.01 ppm increments. Good quality patchouli essential oils were recognised as well as 15 of 17 deliberate adulterations. Visual qualitative inspection by GC-MS allowed for the detection of all volatile adulterants. Nonvolatile adulterants, and all but one volatile adulterant, could be detected by semiquantitation. Different chemometric approaches showed satisfactory results. Similarity analyses were difficult with nonvolatile adulterants. Refractive index measurements could detect only 8 of 17 adulterants. Due to advantages such as simplicity, rapidity, reproducibility, and ability to detect nonvolatile adulterants, 60 MHz 1H-NMR is complimentary to GC-MS for quality control of essential oils.

Combination of quantitative analysis and chemometric analysis for the quality evaluation of three different frankincenses by ultra high performance liquid chromatography and quadrupole time of flight mass spectrometry.

Frankincense has gained increasing attention in the pharmaceutical industry because of its pharmacologically active components such as boswellic acids. However, the identity and overall quality evaluation of three different frankincense species in different Pharmacopeias and the literature have less been reported. In this paper, quantitative analysis and chemometric evaluation were established and applied for the quality control of frankincense. Meanwhile, quantitative and chemometric analysis could be conducted under the same analytical conditions. In total 55 samples from four habitats (three species) of frankincense were collected and six boswellic acids were chosen for quantitative analysis. Chemometric analyses such as similarity analysis, hierarchical cluster analysis, and principal component analysis were used to identify frankincense of three species to reveal the correlation between its components and species. In addition, 12 chromatographic peaks have been tentatively identified explored by reference substances and quadrupole time-of-flight mass spectrometry. The results indicated that the total boswellic acid profiles of three species of frankincense are similar and their fingerprints can be used to differentiate between them.

Qualitative determination of volatile substances in different flavored cigarette paper by using headspace-gas chromatography-ion mobility spectrometry (HS-GC-IMS) combined with chemometrics.

In order to investigate the difference of volatile substances among flavored cigarette paper, which are supplied by several manufacturers with different batches, the stability of the complex system of scented cigarette paper was analyzed and evaluated. In this study, Headspace-gas chromatography-ion mobility spectrometry (HS-GC-IMS) was used to detect the aroma compounds of 23 flavored cigarette paper samples. Based on fingerprint analysis, the differences and changes of aroma compounds of different samples were studied in the form of data visualization. Principal component analysis, partial least squares regression analysis, cluster heatmap analysis and artificial neural network analysis were used to evaluate the stability of different cigarette paper. The results show that: A total of 29 volatile substances were identified from different scented cigarette paper. Fingerprint analysis revealed that the volatile substances of different cigarette paper samples were roughly the same, but not the content. The results of chemometrics analysis showed that there were significant differences in the characteristic aroma compounds of cigarette paper from different manufacturers. HS-GC-IMS technology combined with chemometrics method could be applied to determine the difference of volatile substances among different flavored cigarette paper, which theoretically and technically supported the quality stability maintenance and identification of flavored cigarette paper processed in different places.

Fingerprint analysis of phenolic acid extract of Salvia miltiorrhiza by digital reference standard analyzer with one or two reference standards.

BACKGROUND: Fingerprint analysis and simultaneous multi-components determination are crucial for the holistic quality control of traditional Chinese medicines (TCMs). Yet, reference standards (RS) are often commercially unavailable and with other shortages, which severely impede the application of these technologies. METHODS: A digital reference standard (DRS) strategy and the corresponding software called DRS analyzer, which supports chromatographic algorithms, spectrum algorithms, and the combination of these algorithms, was developed. The extensive function also enabled the DRS analyzer to recommend the chromatographic column based on big data. RESULTS: Various quality control methods of fingerprints of 11 compounds in polyphenolic acid extract of Salvia miltiorrhiza (S. miltiorrhiza) were developed based on DRS analyzer, involving relative retention time (RRT) method, linear calibration using two reference substances (LCTRS) technique, RRT combined with Photon Diode Array (PDA) method, LCTRS combined with PDA method. Additionally, the column database of samples was established. Finally, our data demonstrated that the DRS analyzer could accurately identify 11 compounds of the samples, using only one or two physical RSs. CONCLUSIONS: The DRS strategy is an automated, intelligent, objective, accurate, eco-friendly, universal, sharing, and promising method for overall quality control of TCMs that requires the usage of fewer RSs.

Application of Chemometric Algorithms in the High-Performance Thin-Layer Chromatography Fingerprint of Traditional Chinese Medicines.

Background: The use of HPTLC fingerprinting for the analysis of traditional Chinese medicines (TCMs) usually involves several image-processing steps. However, these image-processing steps are time consuming. Objective: We describe a new approach that applies artificial neural networks (ANN) directly to raw high-performance thin-layer chromatography HPTLC images. Methods: This approach combines image processing and chemometric modeling and was used to classify TCMs [dried tangerine eel (Chen Pi), green tangerine peel (Qing Pi), immature bitter orange fruit, and bitter orange fruit (Zhi Qiao)]. Images of the plates were processed with Chempattern and chemometric analysis including PCA, PLS-DA, and kNN were carried out all by ChemPattern. Results: The ANN model has an accuracy of 100.00% in all training, validation, and test sets, indicating excellent predictive performance and good generalization ability. The k-nearest neighbors (kNN) and partial least-square discriminant analysis (PLS-DA) models have accuracies of 90.91 and 72.73%, respectively, with the independent test set. The kNN model is also accurate, simple, and can be easily interpreted. Conclusions: HPTLC fingerprinting, combined with advanced image processing and proper chemometric algorithms, is a simple, efficient, and accurate method for the analysis of TCMs. Highlights: HPTLC fingerprints of four TCM crude drugs derived from Citrus spp. were compared by using image analysis algorithms. A new approach that applied ANN directly to raw HPTLC fingerprint images was described. Three image analysis algorithms based on kNN, PLS-DA and ANN are compared in the paper. The ANN model shows excellent predictive performance with high accuracy in test sets.

MassImager: A software for interactive and in-depth analysis of mass spectrometry imaging data.

Mass spectrometry imaging (MSI) has become a powerful tool to probe molecule events in biological tissue. However, it is a widely held viewpoint that one of the biggest challenges is an easy-to-use data processing software for discovering the underlying biological information from complicated and huge MSI dataset. Here, a user-friendly and full-featured MSI software including three subsystems, Solution, Visualization and Intelligence, named MassImager, is developed focusing on interactive visualization, in-situ biomarker discovery and artificial intelligent pathological diagnosis. Simplified data preprocessing and high-throughput MSI data exchange, serialization jointly guarantee the quick reconstruction of ion image and rapid analysis of dozens of gigabytes datasets. It also offers diverse self-defined operations for visual processing, including multiple ion visualization, multiple channel superposition, image normalization, visual resolution enhancement and image filter. Regions-of-interest analysis can be performed precisely through the interactive visualization between the ion images and mass spectra, also the overlaid optical image guide, to directly find out the region-specific biomarkers. Moreover, automatic pattern recognition can be achieved immediately upon the supervised or unsupervised multivariate statistical modeling. Clear discrimination between cancer tissue and adjacent tissue within a MSI dataset can be seen in the generated pattern image, which shows great potential in visually in-situ biomarker discovery and artificial intelligent pathological diagnosis of cancer. All the features are integrated together in MassImager to provide a deep MSI processing solution at the in-situ metabolomics level for biomarker discovery and future clinical pathological diagnosis.

[HPLC fingerprinting of radix paeoniae alba].

To establish a sensitive and specific HPLC method for quality control of Radix Paeoniae Alba, HPLC method was applied for quality assessment of Radix Paeoniae Alba. HPLC analysis was performed on a Symmetry C18 column (250 mm x 4. 6 mm ID, 5 microm, Waters, USA). The mobile phase consisted of acetonitrile (solvent A) and water containing 0.1% (v/v) phosphoric acid (solvent B) at a constant flow rate of 0.8 mL x min(-1). An increasing linear gradient (v/v) of solvent A was used (t/min, % A): (0,10), (5,10), (25,15), (45, 22), (46, 65), (50, 80) and (60, 80). The column temperature was set at 25 degrees C. The chromatograms were monitored at 230 nm and the on-line UV spectra were recorded in the range of 190 - 400 nm. The HPLC chromatographic fingerprinting of Radix Paeoniae Alba, showing 11 characteristic peaks, was established from 28 lots of Radix Paeoniae Alba. The areas of main chromatographic peaks were found to complied with the following rule: paeoniflorin > 1, 2, 3, 4, 6-penta-O-galloyl-glucos > albiflorin > methyl gallate > other compounds. The chromatographic fingerprinting of Radix Paeoniae Alba with high specificity can be used to control its quality and assure lot-to-lot consistency.

[Processing method and HPLC fingerprint of charred radix Scutellariae].

OBJECTIVE: To investigate the process and HPLC fingerprint of Charred Radix Scutellariae, and lay a foundation of Charred Radix Scutellariae quanlity control mode. METHOD: Select HPLC-UV fingerprint. Chromatogram condition: Hypersil C18 column (5.0 mm x 200 mm, 5 microm), mixtures of methanol, 0.4% phosphoric acid and acetonitrile as mobile phase in a gradient mode. Flow rate: 1.0 mL x min; Detection wavelength was set at 277 nm. RESULT: There were no evident differences among Charred Radix Scutellariae that were normatively manufactured and processed. CONCLUSION: This test proves the process is feasible, this method recurs well and can be used to provide scieitific basis for the normative process and quanlity control mode of Charred Radix Scutellariae.

[Study of HPLC-DAD fingerprint on complex traditional Chinese medicine proprietary preparation-Baoji pills].

OBJECTIVE: Based on 'Back-tracking' method, identification and quality evaluation of complex traditional Chinese medicine (TCM) preparation of Baoji pills (BJP) were carried out by HPLC fingerprint analysis. METHOD: HPLC-DAD fingerprint of BJP was conducted with Zorbax SB-C18 column and non-linear elution with the mobile phase consisted of acetonitrile-0.5% glacial acetic acid at column temperature 30 degrees C and detective wavelengths of 250 nm and 283 nm. From the established chromatographic pattern of BJP, track backward to the corresponding crude herbal drugs in the formula, attribution ofmost peaks in the BJP fingerprint can be disclosed. RESULT: The BJP HPLC fingerprint consisted of 44 peaks among which 35 peaks were assigned by parallel comparison with the fingerprint of the 10 corresponding crude drugs in the formula such as pueraria, pummelo peel, and magnolia bark, etc. and 22 peaks we reidentified by comparison with the chemical reference substances. CONCLUSION: The established HPLC fingerprint represents the whole character of BJP, which enhanced the specialty for control and assessment of the product quality. It exemplified much more effective for quality control than selecting any marker for qualitative or quantitative testing target. And the Back-tracking' experimental method extended the study mentality for complex formula TCM products chromatographic fingerprinting analysis.

A simple method for HPLC retention time prediction: linear calibration using two reference substances.

BACKGROUND: Analysis of related substances in pharmaceutical chemicals and multi-components in traditional Chinese medicines needs bulk of reference substances to identify the chromatographic peaks accurately. But the reference substances are costly. Thus, the relative retention (RR) method has been widely adopted in pharmacopoeias and literatures for characterizing HPLC behaviors of those reference substances unavailable. The problem is it is difficult to reproduce the RR on different columns due to the error between measured retention time (tR) and predicted tR in some cases. Therefore, it is useful to develop an alternative and simple method for prediction of tR accurately. METHODS: In the present study, based on the thermodynamic theory of HPLC, a method named linear calibration using two reference substances (LCTRS) was proposed. The method includes three steps, procedure of two points prediction, procedure of validation by multiple points regression and sequential matching. The tR of compounds on a HPLC column can be calculated by standard retention time and linear relationship. RESULTS: The method was validated in two medicines on 30 columns. CONCLUSION: It was demonstrated that, LCTRS method is simple, but more accurate and more robust on different HPLC columns than RR method. Hence quality standards using LCTRS method are easy to reproduce in different laboratories with lower cost of reference substances.

Chromatographic fingerprint analysis--a rational approach for quality assessment of traditional Chinese herbal medicine.

Traditional Chinese Herbal Medicine (TCHM) contain multiple botanicals, each of which contains many compounds that may be relevant to the medicine's putative activity. Therefore, analytical techniques that look at a suite of compounds, including their respective ratios, provide a more rational approach to the authentication and quality assessment of TCHM. In this paper we present several examples of applying chromatographic fingerprint analysis for determining the identity, stability, and consistency of TCHM as well as the identification of adulterants as follows: (1) species authentication of various species of ginseng (Panax ginseng, Panax quinquefolium, Panax noto-ginseng) and stability of ginseng preparations using high performance thin-layer chromatography (HPTLC) fingerprint analysis; (2) batch-to-batch consistency of extracts of Total Glycosides of Peony (TGP), to be used as a raw material and in finished products (TGP powdered extract products), using high performance liquid chromatography (HPLC) fingerprint analysis with a pattern recognition software interface (CASE); (3) documenting the representative HPLC fingerprints of Immature Fruits of Terminalia chebula (IFTC) through the assessment of raw material, in-process assay of the extracts, and the analysis of the finished product (tablets); (4) HPLC fingerprint study demonstrating the consistent quality of total flavonoids of commercial extracts of ginkgo (Ginkgo biloba) leaves (EGb) along with detection of adulterations. The experimental conditions as well as general comments on the application of chromatographic fingerprint analysis are discussed.

High-performance thin-layer chromatographic fingerprints of isoflavonoids for distinguishing between Radix Puerariae Lobate and Radix Puerariae Thomsonii.

The roots of Pueraria lobata (Wild.) Ohwi and Pueraria thomsonii Benth have been officially recorded in all editions of Chinese Pharmacopoeia under the same monograph 'Gegen' (Radix Puerariae, RP). However, in its 2005 edition, the two species were separated into both individual monographs, namely 'Gegen' (Radix Puerariae Lobatae, RPL) and 'Fenge' (Radix Puerariae Thomsonii, RPT), respectively, due to their obvious content discrepancy of puerarin, the major active constituent. In present paper, the fingerprint of high-performance thin-layer chromatography (HPTLC) combining digital scanning profiling was developed to identify and distinguish the both species in detail. The unique properties of the HPTLC fingerprints were validated by analyzing ten batches of Pueraria lobata and P. thomsonii samples, respectively. The common pattern of the HPTLC images of the roots of Pueraria spp. and the respective different ratios of the chemical distribution can directly discern the two species. The corresponding digital scanning profiles provided an easy way for quantifiable comparison among the samples. Obvious difference in ingredient content and HPTLC patterns of the two species questioned their bio-equivalence and explained that recording both species separately in the current edition of Chinese Pharmacopoeia (2005 edition) is reasonable due to not only the content of major constituent, puerarin, but also the peak-to-peak distribution in the fingerprint and integration value of the total components. Furthermore, the HPTLC fingerprint is also suitable for rapid and simple authentication and comparison of the subtle difference among samples with identical plant resource but different geographic locations.

Evaluation of traditional Chinese herbal medicine: Chaihu (Bupleuri Radix) by both high-performance liquid chromatographic and high-performance thin-layer chromatographic fingerprint and chemometric analysis.

Chaihu (Bupleuri Radix), roots of Bupleurum chinense and B. scorzonerifolium, is an authentic Chinese Materia Medica in the Chinese Pharmacopoeia. Some other species such as the roots of B. falcatum, B.bicaule and B. marginatum var. stenophyllum similar to Chaihu can also be occasionally found in local raw herb markets. The quality of 33 lots of authenticated Chaihu samples vs. 31 lots of commercial samples was evaluated by both high-performance liquid chromatography-evaporative light scattering detector (HPLC-ELSD) and high-performance thin-layer chromatography (HPTLC) analyses of its principal bioactive components (saikosaponins). The pre-treated data acquired from both HPLC fingerprints and HPTLC fluorescent images were processed by chemometrics for similarity and pattern recognition, including Artificial Neural Networks (ANNs), k-nearest neighbor (k-NN) and an expert's panel. It was apparent that k-NN classifier exhibited good performance with sufficient flexibility for processing HPTLC fingerprint images which were otherwise not easily dealt with by other algorithms due to the shift of R(f) values and varying hue/saturation of the band colours between different TLC plates. These two chromatographic fingerprint methods can be considered complementary measure of quality control. The roots of Chaihu from different species of the genus Bupleurum could readily be distinguished from each other so that commercial samples can easily be classified. Chaihu collected from several major herbal distribution centers was found to belong to B. chinense with great variation in the content of its major saikosaponins.

Species differentiation and quality assessment of Radix Paeoniae Rubra (Chi-shao) by means of high-performance liquid chromatographic fingerprint.

There are two species under the monograph of Radix Paeoniae Rubrae ("Chi-shao" in Chinese) in Chinese Pharmacopoeia 2005 edition-Paeonia lactiflora Pallas and Paeonia veitchii Lynch. Due to different species and growing conditions, there are significant chemical differences between the two species, which may result in the improper clinical usage under the same name. Chemical pattern expressed by high performance liquid chromatographic (HPLC) fingerprint analysis can play an important role in species differentiation and quality control of Radix Paeoniae Rubra. In the present work, HPLC fingerprints of two kinds of Radix Paeoniae Rubra have been established and analysed with chemometric methods including similarity evaluation and principal component analysis. Both of the fingerprint common patterns of the two species comprise 13 characteristic peaks, nine of which were common peaks of the two species. However, significant differences between the roots of P. veitchii and P. lactiflora exist not only in the content of certain constituents, especially phenolic acids but also in peak-to-peak ratios expressed by the fingerprint patterns. According to the recent pharmacological studies on polyphenolic constituents, root originating from P. veitchii may possess better efficacy and quality than that from P. lactiflora. Our research reveals that further pharmacological investigation is very necessary to determine whether the two species should be embodied under the same monograph in Chinese Pharmacopoeia.