A review of Quantitative Structure (Chromatographic) Retention Relationships is presented. A study of predictive chemical structure descriptors is also discussed.
Chamomile has been used as an herbal medication since ancient times and is still popular because it contains various bioactive phytochemicals that could provide therapeutic effects. In this study, a ...simple and reliable HPLC method was developed to evaluate the quality consistency of nineteen chamomile samples through establishing a chromatographic fingerprint, quantification of phenolic compounds and determination of antioxidant activity. For fingerprint analysis, 12 peaks were selected as the common peaks to evaluate the similarities of commercial samples of chamomile obtained from different manufacturers. A similarity analysis was performed to assess the similarity/dissimilarity of chamomile samples where values varied from 0.868 to 0.990 what indicating that samples from different manufacturers were consistent. Additionally, simultaneous quantification of five phenolic acids (gallic, caffeic, syringic, p-coumaric, ferulic) and four flavonoids (rutin, myricetin, quercetin and keampferol) was performed to interpret the quality consistency. In quantitative analysis, the nine individual phenolic compounds showed good regression (
> 0.9975). Inter- and intra-day precisions for all analyzed compounds expressed as relative standard deviation (CV) ranged from 0.05% to 3.12%. Since flavonoids and other polyphenols are commonly recognized as natural antioxidants, the antioxidant activity of chamomile samples was evaluated using 1,1-diphenyl-2-picrylhydrazyl (DPPH) radical scavenging activity and ferric reducing/antioxidant power (FRAP) assay. Correlation analysis was used to assess the relationship between antioxidant activity and phenolic composition, and multivariate analysis (PCA and HCA) were applied to distinguish chamomile samples. Results shown in the study indicate high similarity of chamomile samples among them, widely spread in the market and commonly used by people as infusions or teas, as well as that there were no statistically significant differences among them, which in turn is a proof of high quality of commercially available samples of chamomile. The study indicated that the combination of chromatographic fingerprint and quantitative analysis can be readily utilized as a quality consistency method for chamomile and related medicinal preparations. Moreover, the applied strategy seems to be the most promising for the assessment of the investigated plant material.
This study describes application of liquid chromatography coupled with triple quadrupole mass spectrometry (LC‐MS) for evaluation of vitamin C stability, the objective being prediction of the ...degradation products. Detection was performed with an UV detector (UV‐Vis) in sequence with a triple‐quad mass spectrometer in the multiple reaction mode. The negative ion mode of ESI and MS‐MRM transitions of m/z 175→115 (quantifier) and 175→89 (qualifier) for ascorbic acid was used. All the validation parameters were within the range of acceptance proposed by the Food and Drug Administration. The method was fully validated in terms of linearity, LOD, LOQ, accuracy, and interday precision. Validation experiments revealed good linearity with R2 = 0.999 within the established concentration range, and excellent repeatability (9.3%). The LOD of the method was 0.1524 ng/mL whereas the LOQ was 0.4679 ng/mL. LC‐MS methodology proves to be an improved, simple, and fast approach to determining the content of vitamin C and its degradation products with high sensitivity, selectivity, and resolving power within 6 minutes of analysis.
► A fast LC–MS/MS method for simultaneous analysis of 12 nucleosides was developed. ► 129 urine samples were analyzed after extraction with PBA Varian columns. ► The method was validated in terms of ...all general validation parameters. ► The advanced statistical analysis was applied to evaluate role of nucleosides as cancer biomarkers.
The aim of this work was a comprehensive analysis of metabolite profiles of nucleosides from biological samples obtained from patients with urogenital cancer disease as well as an interpretation of cancer-related patterns of the analyzed profiles. In our study we proposed a targeted approach that was focused on the simultaneous determination of twelve nucleosides from over a hundred urine samples. For analytes’ quantification high performance liquid chromatography technique hyphenated with tripple quadrupole mass spectrometer was applied. The developed method was validated in terms of linearity, precision, accuracy as well as in terms of limit of quantification and limit of detection. The obtained, normalized data set was analyzed using univariate statistical analysis. The achieved results revealed statistically significant (p<0.05) differences between levels of five nucleosides determined in urine samples from cancer patients and healthy volunteers, namely: 6-methyladenosine, inosine, N-2-methylguanosine, 3-methyluridine and N,N-dimethylguanosine. Basing on the putative markers we built the discrimination models using partial least squares discriminant analysis as well as K-nearest neighbor method. The sensitivity and specificity of the markers calculated from the obtained models were in the range of 61.9–88.89% and 27.78–50%, respectively. The proposed procedure can be considered as a holistic approach for metabolites’ analysis and includes clinical, analytical and bioinformatics sections.
In transcriptomics, micro RNAs (miRNAs) has gained much interest especially as potential disease indicators. However, apart from holding a great promise related to their clinical application, a lot ...of inconsistent results have been published. Our aim was to compare the miRNA expression levels in ovarian cancer and healthy subjects using the Bayesian multilevel model and to assess their potential usefulness in diagnosis. We have analyzed a case-control observational data on expression profiling of 49 preselected miRNA-based ovarian cancer indicators in 119 controls and 59 patients. A Bayesian multilevel model was used to characterize the effect of disease on miRNA levels controlling for differences in age and body weight. The difference between the miRNA level and health status of the patient on the scale of the data variability were discussed in the context of their potential usefulness in diagnosis. Additionally, the cross-validated area under the ROC curve (AUC) was used to assess the expected out-of-sample discrimination index of a different sets of miRNAs. The proposed model allowed us to describe the set of miRNA levels in patients and controls. Three highly correlated miRNAs: miR-101-3p, miR-142-5p, miR-148a-3p rank the highest with almost identical effect sizes that ranges from 0.45 to 1.0. For those miRNAs the credible interval for AUC ranged from 0.63 to 0.67 indicating their limited discrimination potential. A little benefit in adding information from other miRNAs was observed. There were several miRNAs in the dataset (miR-604, hsa-miR-221-5p) for which inferences were uncertain. For those miRNAs more experimental effort is needed to fully assess their effect in the context of new hits discovery and usefulness as disease indicators. The proposed multilevel Bayesian model can be used to characterize the panel of miRNA profile and to assess the difference in expression levels between healthy and cancer individuals.
This study aimed to evaluate the protective role of ground raspberry seeds (RBS) as a source of polyphenols and essential fatty acids on blood plasma enzymatic antioxidant status, lipid profile, and ...endothelium-intact vasodilation during physiological and pathological conditions. Young normotensive Wistar-Kyoto rats (WKYs) and spontaneously hypertensive rats (SHRs) at ten weeks of age were fed with either a control diet or were supplemented with added 7% RBS for six weeks (
= 6). The main component of RBS was dietary fiber (64%) and the main polyphenols were ellagitannins (1.2%) and flavan-3-ols (0.45%). Irrespective of the rat model, ground RBS decreased liver enzyme aspartate aminotransferase (0.9-fold) and hydrogen peroxide scavenging capacity (Catalase, 0.9-fold). In supplemented SHRs, preincubation with inducible nitric oxide synthase (iNOS) inhibitor 1400W, nonselective cyclooxygenase (COX) inhibitor indomethacin, selective COX-2 inhibitor NS-398, prostacyclin (PGI
) synthesis inhibitor tranylcypromine (TCP), thromboxane receptor (TP) antagonist SQ-29548, thromboxane synthesis inhibitor furegrelate, and 20-HETE synthesis inhibitor HET0016 induced the same relaxant response to acetylcholine as in the nonsupplemented control group. In supplemented WKYs, atherogenic index was decreased (0.8-fold), while iNOS and COX-2-derived PGI
increased acetylcholine-induced vasodilation. These effects of ground RBS may constitute a potential mechanism for preventing cardiovascular diseases.
Among the currently available commercial eye drops with cyclosporine A (Cs) there is a lack of long-acting dosage forms and products with a concentration of the drug substance higher than 0.1%, ...although Cs is widely used in ophthalmology. The aim of the research was to conduct the microscopic and biopharmaceutical evaluation of two formulations, an emulsion (EM) and a self-emulsifying oil (SEO), both with 0.5% of Cs, proposed for use in eye drops, and the comparison of both. SEO eye drops with Cs or any other drug substance are currently not available as marketed products, and the highest concentration of Cs in the ocular emulsion is only 0.1%. The microscopic evaluation of the emulsion and the SEO after emulsification with water was carried out using a high-resolution digital microscopy. The properties of both preparations were compared using the high dynamic range function or optical shadow effect mode. Images in the 3D composition mode were also recorded. The
study of the Cs formulations was performed on male albino rabbits. The eye tolerance of the preparations was assessed using the ocular irritation test, which is a modified Draize test.
carriers (without the drug substance) were also subjected to irritation testing. The concentration of Cs in the tissues (cornea and conjunctiva) and fluids (tear fluid and aqueous humor) of the rabbit eye was determined after multiple instillations of Cs-EM or Cs-SEO. The tested preparations were compared using the digital microscopy technique, which highlights the features of the formulations and eliminates the risk of unnoticeable properties that are difficult to observe in classical optical microscopy. Both tested Cs-loaded formulations are classified as practically non-irritating. There were also no significant differences when testing the
carriers. After a topical administration, Cs was widely distributed in all tissues (e.g., in cornea 1.3 ng/mg and 1.0 ng/mg) and fluids of the eye (e.g., in tear fluid 11.6 µg/mL and 4.3 µg/mL), after the administration of Cs-SEO and Cs-EM, respectively. The obtained results allow us to recognize both tested formulations, the emulsion and the self-emulsifying oil with 0.5% Cs content, as carriers safe for ophthalmic use and effective in delivering the drug substance to the structures of the eye.
The importance of lipophilicity for pharmacological and toxicological potency of xenobiotics has been recognized for a century. The reference lipophilicity scale is defined by the logarithm of ...partition coefficient, log P, determined in the loctanol- water partition system. The tediousness of determinations and limited interlaboratory reproducibility of log P, on one hand, and the observations of linear relationship between log P and chromatographic retention parameters, on the other hand, gave rise to the substitution of the former by the readily available chromatographic data. Since its introduction, the reversed-phase high - performance liquid chromatography (HPLC), which has been viewed in terms of partition of a solute between a polar, aqueous mobile phase and a nonpolar stationary phase appeared especially suitable for lipophilicity (hydrophobicity) determination. The method got wide acceptance and has officially been recommended by the OECD. Fundamental relationships between chromatographic parameters are reviewed from the point of view of convenient and reliable lipophilicity measurements. The advantages and disadvantages of the stationary phase materials, which are presently employed for the determination of lipophilicity as well as those of specific HPLC systems and procedures, are critically reported. The literature on the application of chromatographic and electrochromatographic methods for assessment of lipophilicity of xenobiotics is reviewed. A separate paragraph is devoted to interpretation of retention parameters from HPLC systems comprising biomacromolecules. Role of lipophilicity in drug-biomacromolecule interactions is discussed in terms of quantitative structure-retention relationships (QSRR). Finally, reports are analyzed on systemic information which can be extracted by multivariate methods of data processing, like principal component analysis (PCA), from sets of lipophilicity parameters determined in diverse HPLC systems.
Trigonelline is a pyridine alkaloid found in fenugreek seeds and coffee beans. Most of the previous studies are concerned with the quantification of trigonelline along with other constituents in ...coffee herbs or beverages. Only a few have focused on its determination in animal or human tissues by applying different modes of HPLC with UV or MS detection. The aim of the study was to develop and validate a fast and simple method for trigonelline determination in serum by the use of hydrophilic interaction liquid chromatography (HILIC) with ESI‐MS/MS detection. Separation of trigonelline was achieved on a Kinetex HILIC column operated at 35°C with acetonitrile–ammonium formate (10 mm, pH = 3) buffer mixture (55:45, v/v) as the mobile phase. The developed method was successfully applied to determine trigonelline concentration in mouse serum after intravenous administration of 10 mg/kg. The developed assay is sensitive (limit of detection = 1.5 ng/mL, limit of quantification = 5.0 ng/mL) and linear in a concentration range from 5.0 to 250.0 ng/mL. Sample preparation is limited to deproteinization, centrifugation and filtration. The application of the HILIC mode of chromatography with MS detection and selection of deuterated trigonelline as internal standard allowed a rapid and precise method of trigonelline quantification to be to developed.
Non-targeted metabolomics constitutes a part of the systems biology and aims at determining numerous metabolites in complex biological samples. Datasets obtained in the non-targeted metabolomics ...studies are high-dimensional due to sensitivity of mass spectrometry-based detection methods as well as complexity of biological matrices. Therefore, a proper selection of variables which contribute into group classification is a crucial step, especially in metabolomics studies which are focused on searching for disease biomarker candidates. In the present study, three different statistical approaches were tested using two metabolomics datasets (RH and PH study). The orthogonal projections to latent structures-discriminant analysis (OPLS-DA) without and with multiple testing correction as well as the least absolute shrinkage and selection operator (LASSO) with bootstrapping, were tested and compared. For the RH study, OPLS-DA model built without multiple testing correction selected 46 and 218 variables based on the VIP criteria using Pareto and UV scaling, respectively. For the PH study, 217 and 320 variables were selected based on the VIP criteria using Pareto and UV scaling, respectively. In the RH study, OPLS-DA model built after correcting for multiple testing, selected 4 and 19 variables as in terms of Pareto and UV scaling, respectively. For the PH study, 14 and 18 variables were selected based on the VIP criteria in terms of Pareto and UV scaling, respectively. In the RH and PH study, the LASSO selected 14 and 4 variables with reproducibility between 99.3 and 100%, respectively. In the light of PLS-based models, the larger the search space the higher the probability of developing models that fit the training data well with simultaneous poor predictive performance on the validation set. The LASSO offers potential improvements over standard linear regression due to the presence of the constrain, which promotes sparse solutions. This paper is the first one to date utilizing the LASSO penalized logistic regression in untargeted metabolomics studies.
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