Chlorogenic acids – their properties, occurrence and analysis

Chlorogenic acids (CQAs), the esters of caffeic acid and quinic acid, are biologically important phenolic compounds present in many plant species. Nowadays much is known from their pro-health properties, including anti-cancer activity. Yet, the supposition that they may be helpful in fighting obesity and modify glucose-6-phosphatase involved in glucose metabolism have led to a revival of research on CQAs properties and their natural occurrence. Much attention is also paid to the proper analysis of CQAs content in plants and plant products due to the fact that the main CQAs representative in nature i.e. 5-O-caffeoylquinic acid (5-CQA) is commonly employed as a quality marker in the control of various natural products.The common procedures used so far for CQAs determination in plants involve conventional long lasting solvent extraction realized at higher temperatures prior to chromatographic analysis. The drawbacks associated to the conventional extraction techniques have led to the search for new alternative extraction processes that additionally could improve extracts quality. The latter is particularly important as regards CQAs applications, and the fact that these compounds easily transform/degrade to others. According to reports, the conventional heating of 5-CQA in the presence of water causes its isomerization and transformation. The reports prove that 5-CQA not only isomerizes to 3- and 4-O-caffeoylquinic acid, but also undergoes other transformations such as esterification and reactions with water. Hence, in the attempt to improve the process of chlorogenic acids extraction and to make it more effective and environmentally friendly, innovative so-called "enhanced" techniques of extraction have been recently developed and applied. To guarantee the proper analysis of compounds with very similar properties forming the chlorogenic acids family and their numerous transformation/degradation products, hyphenated techniques, in particular LC-MS, are currently being used

Analysis of serum homocysteine in the laboratory practice - comparison of the direct chemiluminescence immunoassay and high performance liquid chromatography coupled with fluorescent detection

Introduction: Effective diagnosis of cardiovascular diseases requires the right tools to be used enabling selective and sensitive analysis of their biomarkers. One of them is homocysteine (Hcy), nowadays determined by immunoassays and chromatographic methods. This study aims to compare the results obtained by direct chemiluminescence immunoassay (CLIA) and high performance liquid chromatography with fluorescent detection (HPLC-FD) using commercial kits. Materials and methods: Homocysteine concentration was determined in serum samples obtained from 101 individuals, using Atellica IM HCY (Siemens Healthineers, Erlangen, Germany) and HCY in plasma/serum – HPLC-FD (Chromsystems Instruments & Chemicals GmbH, Gräfelfing, Germany) tests validated for routine analysis. The latter was applied as a reference method. The comparability and agreement between the tested methods were evaluated using the Passing-Bablok (PB) regression analysis and the Bland-Altman (BA) method of the differences analysis. Results: Studies showed that CLIA gives higher Hcy concentrations (15.7 ± 4.14 μmol/L). Passing-Bablok regression analysis of the results obtained with CLIA (y) compared with HPLC-FD (x) yielded an intercept of 0.22 (95%CI: - 2.16 to 2.46) and slope of 1.58 (95%CI: 1.33 to 1.87). Bland-Altman analysis demonstrated a systematic positive bias for CLIA of 5.85 ± 2.77 μmol/L. Conclusions: Methods disagreement precludes their interchangeability. Lower Hcy values by HPLC-FD result from its greater selectivity. High performance liquid chromatography with fluorescent detection should be considered as preferential method for analysing Hcy in blood serum as well as the recommended reference method for routine clinical analysis. This fact, however, imposes the need to establish new reference ranges

The development of new methodology for determination of vincristine (VCR) in human serum using LC-MS/MS-based method for medical diagnostics

In this article, we have presented the development and validation of a rapid and sensitive reversed-phase liquid chromatography with tandem mass spectrometry (LC-MS/MS) method for the determination of vincristine (VCR) in patient serum samples. Chromatographic separation was achieved on a Kinetex(®) (Singapore) column using a mobile phase consisting of 25 mM acetic acid and 0.3% formic acid (A) and methanol (B) in a gradient elution mode at a flow rate of 0.3 mL/min. The VCR and internal standard (vinblastine) were monitored using the multiple reaction monitoring mode under positive electrospray ionization. The lower limit of quantification (LLOQ) was 0.67 ng/mL, and the upper limit of quantification (ULOQ) was 250 ng/mL for VCR. The calculated values of LOD and LOQ for VCR were 0.075 and 0.228 ng/mL, respectively. The calibration curve was linear over the VCR concentration range of 1.0–250 ng/mL in serum. The intra- and inter-day precision and precision were within the generally accepted criteria for the bioanalytical method (<15%). The method was successfully applied to the analysis of serum samples in clinical practice

Combination of Sea Sand Disruption Method and Ion-Pair Solid-Phase Extraction for Effective Isolation and Purification of Chlorogenic Acid from Plants Prior to the HPLC Determination

Chlorogenic acid (CQA) is one of phenolics commonly found in higher plants, possessing numerous health-promoting effects on humans. Unfortunately, it is easily degraded/transformed into other substances during extraction. Therefore, its reliable analysis requires a special approach that does not involve high temperatures. This paper presents a very simple method of CQA isolation using the sea sand disruption method with subsequent purification of the extract using the ion-pair solid-phase extraction process, followed by HPLC–DAD detection. It was found that control of the ion pairing reagent concentration and sample pH is crucial to improve purification, and that the best results, with recovery exceeding 98%, were obtained for 0.05 M tetrabutylammonium bisulfate at pH 7 when the ion pairs were formed directly in the extract and eluted from the C18 sorbent using an acidified methanol–water mixture. The practical potential of the developed procedure was verified by using it for CQA isolation from different plants. The approach represents one of the contemporary analytical trends and current advances in the solid phase extraction, in which several sorption extraction techniques are combined to ensure high-quality analytical results

Comparison of the Antioxidant Properties of Extracts Obtained from Walnut Husks as well as the Influence of Juglone on Their Evaluation

Concern for the future of the next generation leads to the search for alternative solutions for the proper management of materials considered as useless waste. This study fits into this research trend. Its aim is to demonstrate the potential of walnut husks as a source of compounds with antioxidant properties that can be used in non-food industries. Pressurized liquid extraction, i.e., one of the modern green extraction techniques used on an industrial scale, as well as conventional extraction in Soxhlet and maceration were applied to prepare the extracts. In order to assess in depth their antioxidant activity in relation to the content of characteristic components, various activity assessment methods were used in this research. The results proved that the husk components have such antioxidant properties that they can be of interest to the cosmetics and pharmaceutical industries regarding the management of this waste. The results confirmed the usefulness of assisted extraction in increasing the ecological and economic values of the proposed waste disposal. Moreover, they showed that juglonehas very weak antioxidant properties, and the antioxidant effect of the mixture containing husk extract and juglone solution is mainly additive

Antioxidant Properties of Selected Flavonoids in Binary Mixtures—Considerations on Myricetin, Kaempferol and Quercetin

Flavonoids, secondary plant metabolites with many health-promoting properties, including antioxidant, are a valuable component of food products, especially functional foods. In the latter, plant extracts are commonly used, the properties of which are attributed to the characteristic main ingredients. However, in a mixture the antioxidant properties of the individual ingredients do not always show an additive effect. This paper presents and discusses the antioxidant properties of naturally occurring flavonoid aglycones and their binary mixtures. In the experiments, model systems were used that differed in the volume of the alcoholic antioxidant solution in the measuring system and its concentration in the range in which it occurs in nature. Antioxidant properties were determined by ABTS and DPPH methods. The presented data proved that the dominant resultant effect in the mixtures is antioxidant antagonism. The magnitude of the observed antagonism depends on the mutual relations of individual components, their concentrations and the method used to assess antioxidant properties. It was shown that the observed non-additive antioxidant effect of the mixture results from the formation of intramolecular hydrogen bonds between phenolic groups of the antioxidant molecule. The presented results may be useful in the context of proper design of functional foods

A Concise Profile of Gallic Acid—From Its Natural Sources through Biological Properties and Chemical Methods of Determination

Nature is a valuable source of anti-oxidants that have a health-promoting effect by inhibiting various undesirable changes leading to cell degradation and, consequently, potential disease ailments. One of them is gallic acid which has been used as a healing agent since ancient times. Currently, due to various beneficial properties, this compound is considered to be one of the main phenolic acids of great importance in numerous industries. It is commonly used as a substance protecting against the harmful effects of UV radiation, an astringent in cosmetic preparations, and a preservative in food products. Therefore, gallic acid is now deemed essential for both human health and industry. Increasingly better methods of its isolation and analysis are being developed, and new solutions are being sought to increase its production. This review, presenting a concise characterization of gallic acid, updates the knowledge about its various biological activities and methods used for its isolation and determination, including chromatographic and non-chromatographic methods

Anthracene derivatives in some species of Rumex L. genus

Eight anthracene derivatives (chrysophanol, physcion, emodin, aloe-emodin, rhein, barbaloin, sennoside A and sennoside B) were signified in six species of Rumex L. genus: R. acetosa L., R. acetosella L., R. confertus Willd., R. crispus L., R. hydrolapathum Huds. and R. obtusifolius L. For the investigations methanolic extracts were prepared from the roots, leaves and fruits of these species. Reverse Phase High Performance Liquid Chromatography was applied for separation, identification and quantitative determination of anthracene derivatives. The identity of these compounds was further confirmed with UV-VIS. Received data were compared. The roots are the best organs for the accumulation of anthraquinones. The total amount of the detected compounds was the largest in the roots of R. confertus (163.42 mg/g), smaller in roots R. crispus (25.22 mg/g) and the smallest in roots of R. hydrolapathum (1.02 mg/g)