Application of Fourier transform infrared spectroscopy and orthogonal projections to latent structures/partial least squares regression for estimation of procyanidins average degree of polymerisation

Raman-based PAT for VLP precipitation: systematic data diversification and preprocessing pipeline identification

Virus-like particles (VLPs) are a promising class of biopharmaceuticals for vaccines and targeted delivery. Starting from clarified lysate, VLPs are typically captured by selective precipitation. While VLP precipitation is induced by step-wise or continuous precipitant addition, current monitoring approaches do not support the direct product quantification, and analytical methods usually require various, time-consuming processing and sample preparation steps. Here, the application of Raman spectroscopy combined with chemometric methods may allow the simultaneous quantification of the precipitated VLPs and precipitant owing to its demonstrated advantages in analyzing crude, complex mixtures. In this study, we present a Raman spectroscopy-based Process Analytical Technology (PAT) tool developed on batch and fed-batch precipitation experiments of Hepatitis B core Antigen VLPs. We conducted small-scale precipitation experiments providing a diversified data set with varying precipitation dynamics and backgrounds induced by initial dilution or spiking of clarified Escherichia coli-derived lysates. For the Raman spectroscopy data, various preprocessing operations were systematically combined allowing the identification of a preprocessing pipeline, which proved to effectively eliminate initial lysate composition variations as well as most interferences attributed to precipitates and the precipitant present in solution. The calibrated partial least squares models seamlessly predicted the precipitant concentration with R 2 of 0.98 and 0.97 in batch and fed-batch experiments, respectively, and captured the observed precipitation trends with R 2 of 0.74 and 0.64. Although the resolution of fine differences between experiments was limited due to the observed non-linear relationship between spectral data and the VLP concentration, this study provides a foundation for employing Raman spectroscopy as a PAT sensor for monitoring VLP precipitation processes with the potential to extend its applicability to other phase-behavior dependent processes or molecules.

Fourier transform infrared spectroscopy in monitoring the wine production

The complexity of the wine matrix makes monitoring of the winemaking process from the grapes to the final product crucial for the wine industry. In this context, analytical methodologies that can combine good accuracy, robustness, high sample throughput, “green character”, and by preference real-time analysis, are on-demand to create high-quality vitivinicultural products. In the last years, Fourier-transform Infrared Spectroscopy (FTIR) combined with chemometric analysis has been evaluated in several studies as an effective analytical tool for the wine sector. Some applications of FTIR spectroscopy have been already accepted by the wine industry, mainly for the prediction of basic oenological parameters, using portable and non-portable instruments, but still many others are waiting to be thoroughly developed. This literature review aims to provide a critical synopsis of the most important studies assessing grape and wine quality and authenticity, and to identify possible gaps for further research, meeting the needs of the modern wine industry and the expectations of most demanding consumers. The FTIR studies were grouped according to the main sampling material used - 1) leaves, stems, and berries; 2) grape must and wine applications - along with a summary of the basic limitations and future perspectives of this analytical technique.

An integration strategy combined progressive multivariate statistics with anticoagulant activity evaluation for screening anticoagulant quality markers in Chinese patent medicine

ETHNOPHARMACOLOGICAL RELEVANCE

The cardiovascular and cerebrovascular diseases affect human health globally. Naoxintong capsules (NXTs), a famous Chinese Patent Medicine, has been especially applied to treat cerebral infarction and coronary heart disease in clinical practice. The anticoagulant activity of this prescription plays an important role in this course of treatment.

AIM OF THE STUDY

Thrombin and factor Xa (FXa) are two key targets considering the anticoagulant activity. The purpose of this investigation is to screen the quanlity markers as key thrombin and FXa inhibitors for the anticoagulant activity oriented quality control of Chinese patent medicine.

MATERIALS AND METHODS

Simple multi-polar solvent extraction processes using various proportions of solvents were conducted and their thrombin/FXa inhibitory activities were evaluated in vitro. Bivariate correlation analysis (BCA), grey correlation analysis (GCA), and orthogonal partial least squares discriminate analysis (OPLS-DA) were adopted for screening the potential active markers related to the anticoagulant activity. The chemical structures of these active compounds were identified by UHPLC-Q-TOF-MS/MS and their thrombin/FXa inhibitory activity was determined. The molecular docking technology was applied to explore the interaction between the compounds and targets. The contribution of these anticoagulant active ingredients in NXT was also investigated. Last but not the least, the contents of these markers in NXT were determined by liquid chromatography-electrospray ionization tandem triple quadrupole mass spectrometry (HPLC-ESI-MS/MS) method.

RESULTS

The results showed that the NXT extract exhibited great activity against thrombin and FXa, especially extracted by 75% methanol (v/v). Six marker compounds with potential anticoagulant activity were screened out. Therein, four of the active compounds owing thrombin inhibitory activity (paeoniflorin, lithospermic acid, salvianolic acid B, Z-ligustilide) and five of the active compounds owing FXa inhibitory activity (3,5-dicaffeoylquinic acid, rosmarinic acid, lithospermic acid, salvianolic acid B and Z-ligustilide). In addition, these active compounds accounted for a large proportion of thrombin/FXa inhibitory activity of NXTs. The binding energy also showed the strong interaction formed by close connection of the compounds to the residues of targets.

CONCLUSIONS

The proposed integrated stategy could be an efficient strategy to screen potential thrombin/FXa inhibitors for the bioactivity related quanlity control of Chinese patent medicine.

Synthesis and experimental/computational characterization of sorghum procyanidins-gelatin nanoparticles

In this research, sorghum procyanidins (PCs) and procyanidin B1 (PB1) were encapsulated in gelatin (Gel) to form nanoparticles as a strategy to maintain their stability and bioactivity and for possible applications as inhibitors of metalloproteinases (MMPs) of the gelatinase type. Encapsulation was carried out by adding either PCs or PB1 to an aqueous solution of A- or B-type Gel (GelA or GelB) at different concentrations and pH. Under this procedure, the nanoparticles PCs-GelA, PCs-GelB, PB1-GelA, and PB1-GelB were synthesized and subsequently characterized by experimental and computational methods. Scanning electron microscopy (SEM) and transmission electron microscopy (TEM) revealed that all types of nanoparticles had sizes in the range of 22-138 nm and tended to adopt an approximately spherical morphology with a smooth surface, and they were immersed in a Gel matrix. Spectral analysis indicated that the nanoparticles were synthesized by establishing hydrogen bonds and hydrophobic interactions betweenGel and the PCs or PB1. Study of simulated gastrointestinal digestion suggested that PCs were not released from the Gel nanoparticles, and they maintained their morphology (SEM analysis) and antioxidant activity determined by Trolox-equivalent antioxidant capacity (TEAC) assay. Computational characterization carried out through molecular docking studies of PB1 with Gel or (pro-)metalloproteinase-2 [(pro-)MMP-2], as a model representative of the PCs, showed very favorable binding energies (around -5.0 kcal/mol) provided by hydrogen bonds, van der Waals interactions, and desolvation. Additionally, it was found that PB1 could act as a selective inhibitor of (pro-)MMP-2.

UHPLC-qMS spectrum-effect relationships for Rhizoma Paridis extracts

Rhizoma Paridis (RP) with significant anti-tumor and haemostatic effects, has been used as the raw material of many Traditional Chinese preparations. However, its active ingredients are still unclear. The present study aimed to discover bioactive ingredients from RP based on spectrum-relationship and chemometric methods. Firstly, the saponins extract was prepared by phytochemical methods. Furthermore, UHPLC-QTOF-MS and UHPLC-qMS were incorporated to establish an efficient and sensitive method for obtaining the chemical profiles of RP. A total of 34 saponins were characterized in RP and 13 of them were assigned as common peaks in 25 batches of samples. After evaluation of the anti-tumor and haemostatic activities of samples, spectrum-effect relationships were investigated by the grey relational analysis (GRA), orthogonal projections to latent structures (OPLS) and back propagation artificial neural network (BP-ANN). These analyses showed that polyphyllin VII (P27), polyphyllin II (P30), dioscin (P31) and polyphyllin I (P33) play a role in the haemostatic effects of RP whereas polyphyllin VII (P27), dioscin (P31), polyphyllin I (P33), progenin III (P34) were assigned as candidate ingredients accounting for the anti-tumor activity of RP. The anti-tumor and haemostatic activities of these screened ingredients were subsequently verified in vitro. Collectively, the present study established the spectrum-effect relationship mode of RP and discovered the bioactive compounds of RP, which could be also used for exploration of bioactive compounds in herbal medicines, especially for trace compounds.

Red Wine Age Estimation by the Alteration of Its Color Parameters: Fourier Transform Infrared Spectroscopy as a Tool to Monitor Wine Maturation Time

Color, phenolic content, and chemical age values of red wines made from Cretan grape varieties (Kotsifali, Mandilari) were evaluated over nine months of maturation in different containers for two vintages. The wines differed greatly on their anthocyanin profiles. Mid-IR spectra were also recorded with the use of a Fourier Transform Infrared Spectrophotometer in ZnSe disk mode. Analysis of Variance was used to explore the parameter's dependency on time. Determination models were developed for the chemical age indexes using Partial Least Squares (PLS) (TQ Analyst software) considering the spectral region 1830-1500 cm-1. The correlation coefficients (r) for chemical age index i were 0.86 for Kotsifali (Root Mean Square Error of Calibration (RMSEC) = 0.067, Root Mean Square Error of Prediction (RMSEP) = 0,115, and Root Mean Square Error of Validation (RMSECV) = 0.164) and 0.90 for Mandilari (RMSEC = 0.050, RMSEP = 0.040, and RMSECV = 0.089). For chemical age index ii the correlation coefficients (r) were 0.86 and 0.97 for Kotsifali (RMSEC 0.044, RMSEP = 0.087, and RMSECV = 0.214) and Mandilari (RMSEC = 0.024, RMSEP = 0.033, and RMSECV = 0.078), respectively. The proposed method is simpler, less time consuming, and more economical and does not require chemical reagents.

Direct and simultaneous quantification of tannin mean degree of polymerization and percentage of galloylation in grape seeds using diffuse reflectance fourier transform-infrared spectroscopy

The direct and simultaneous quantitative determination of the mean degree of polymerization (mDP) and the degree of galloylation (%G) in grape seeds were quantified using diffuse reflectance infrared Fourier transform spectroscopy and partial least squares (PLS). The results were compared with those obtained using the conventional analysis employing phloroglucinolysis as pretreatment followed by high performance liquid chromatography-UV and mass spectrometry detection. Infrared spectra were recorded in solid state samples after freeze drying. The 2nd derivative of the 1832 to 1416 and 918 to 739 cm(-1) spectral regions for the quantification of mDP, the 2nd derivative of the 1813 to 607 cm(-1) spectral region for the degree of %G determination and PLS regression were used. The determination coefficients (R(2) ) of mDP and %G were 0.99 and 0.98, respectively. The corresponding values of the root-mean-square error of calibration were found 0.506 and 0.692, the root-mean-square error of cross validation 0.811 and 0.921, and the root-mean-square error of prediction 0.612 and 0.801. The proposed method in comparison with the conventional method is simpler, less time consuming, more economical, and requires reduced quantities of chemical reagents and fewer sample pretreatment steps. It could be a starting point for the design of more specific models according to the requirements of the wineries.

The role of visible and infrared spectroscopy combined with chemometrics to measure phenolic compounds in grape and wine samples

The content of phenolic compounds determines the state of phenolic ripening of red grapes, which is a key criterion in setting the harvest date to produce quality red wines. Wine phenolics are also important quality components that contribute to the color, taste, and mouth feel of wines. Spectroscopic techniques (e.g., near and mid infrared) offer the potential to simplify and reduce the analytical time for a range of grape and wine analytes. It is this characteristic, together with the ability to simultaneously measure several analytes in the same sample at the same time, which makes these techniques very attractive for use in both industry and research. The objective of this mini review is to present examples and to discuss different applications of visible (VIS), near infrared (NIR) and mid infrared (MIR) to assess and measure phenolic compounds in grape and wines.

Interaction of phenolic compounds with bovine serum albumin (BSA) and α-amylase and their relationship to astringency perception

The ability of grape seed extracts to bind to bovine serum albumin (BSA) and α-amylase was studied by fluorescence quenching of protein intrinsic fluorescence and nephelometry. The influence of grape seed ripeness on astringency was also evaluated. From the spectra obtained, the modified Sterm-Volmer (K(app)) and the bimolecular quenching constants were calculated. Results showed that grape seed extracts had good affinity for proteins. The association strength of tannin-protein interactions varied with changes in tannin structure associated with the degree of ripeness affecting the binding/quenching process. In all cases studied, higher values of K(app) were obtained in samples at harvest which have greater ability to bind to proteins than have samples at post-veraison time. Nephelometric assays show the same trend as do fluorescence quenching studies. A possible explanation for this is that, as seeds ripen, their tannins increase in molecular mass, which relates to an increase in hydrophobicity of the molecules, and this increases protein affinity. However, that is contrary to the reported decrease in astringency of grape seeds during maturity. This indicates that tannin-protein interactions are not the only explanation for the complex sensations of astringency of grape seeds.