Determining the true content of quercetin and its derivatives in plants employing SSDM and LC–MS analysis

Synthesis of some polyphenolics from contents of onion skin and discovery of the promoter effect on barley germination

Facile synthesis and characterisation of three natural compounds and their two synthetic analogues based on onion skin content were performed. Both OSE and 2,4,6-trihydroxyphenylglyoxylic acid was induced effect on cell proliferation during barley germination with a difference of approximately %4 compared to the control group.

Quercetin as one of the most abundant represented biological valuable plant components with remarkable chemoprotective effects - A review

As a consequence of environmental quality changes as well as changes in our population's lifestyle, there is rapidly increasing variability and many so-called lifestyle disorders, allergies, and food intolerances (also known as non-allergic food hypersensitivity). Unhealthy eating practices, an inappropriate food composition with an excessive energy intake, a high intake of saturated fats, simple sugars, and salt, as well as an inadequate intake of fibre, vitamins, and substances with preventive effects (such as antioxidants), are some of the factors causing this detrimental phenomenon. Enhanced consumption of plant foods rich in valuable secondary metabolites such as phenolic acids and flavonoids with the benefit on human health, food research focused on these components, and production of foods with declared higher content of biologically active and prophylactic substances are some ways how to change and improve this situation. A unique class of hydroxylated phenolic compounds with an aromatic ring structure are called flavonoids. One unique subclass of flavonoids is quercetin. This phytochemical naturally takes place in fruits, vegetables, herbs, and other plants. Quercetin and its several derivates are considered to be promising substances with significant antidiabetic, antibacterial, anti-inflammatory, and antioxidant effects, which could also act preventively against cardiovascular disease, cancer, or Alzheimer's disease.

Analytical Methods for the Determination of Quercetin and Quercetin Glycosides in Pharmaceuticals and Biological Samples

Flavonoids are plant-derived compounds that have several health benefits, including antioxidative, anti-inflammatory, anti-mutagenic, and anti-carcinogenic effects. Quercetin is a flavonoid that is widely present in various fruits, vegetables, and drinks. Accurate determination of quercetin in different samples is of great importance for its potential health benefits. This review, is an overview of sample preparation and determination methods for quercetin in diverse matrices. Previous research on sample preparation and determination methods for quercetin are summarized, highlighting the advantages and disadvantages of each method and providing insights into recent developments in quercetin sample treatment. Various analytical techniques are discussed including spectroscopic, chromatographic, electrophoretic, and electrochemical methods for the determination of quercetin and its derivatives in different samples. UV-Vis (Ultraviolet-visible) spectrophotometry is simple and inexpensive but lacks selectivity. Chromatographic techniques (HPLC, GC) offer selectivity and sensitivity, while electrophoretic and electrochemical methods provide high resolution and low detection limits, respectively. The aim of this review is to comprehensively explore the determination methods for quercetin and quercetin glycosides in diverse matrices, with emphasis on pharmaceutical and biological samples. The review also provides a theoretical basis for method development and application for the analysis of quercetin and quercetin glycosides in real samples.

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.

Quercetin: A Functional Food-Flavonoid Incredibly Attenuates Emerging and Re-Emerging Viral Infections through Immunomodulatory Actions

Many of the medicinally active molecules in the flavonoid class of phytochemicals are being researched for their potential antiviral activity against various DNA and RNA viruses. Quercetin is a flavonoid that can be found in a variety of foods, including fruits and vegetables. It has been reported to be effective against a variety of viruses. This review, therefore, deciphered the mechanistic of how Quercetin works against some of the deadliest viruses, such as influenza A, Hepatitis C, Dengue type 2 and Ebola virus, which cause frequent outbreaks worldwide and result in significant morbidity and mortality in humans through epidemics or pandemics. All those have an alarming impact on both human health and the global and national economies. The review extended computing the Quercetin-contained natural recourse and its modes of action in different experimental approaches leading to antiviral actions. The gap in effective treatment emphasizes the necessity of a search for new effective antiviral compounds. Quercetin shows potential antiviral activity and inhibits it by targeting viral infections at multiple stages. The suppression of viral neuraminidase, proteases and DNA/RNA polymerases and the alteration of many viral proteins as well as their immunomodulation are the main molecular mechanisms of Quercetin's antiviral activities. Nonetheless, the huge potential of Quercetin and its extensive use is inadequately approached as a therapeutic for emerging and re-emerging viral infections. Therefore, this review enumerated the food-functioned Quercetin source, the modes of action of Quercetin for antiviral effects and made insights on the mechanism-based antiviral action of Quercetin.

Multidirectional Characterization of Phytochemical Profile and Health-Promoting Effects of Ziziphora bungeana Juz. Extracts

Ziziphora species (Lamiaceae) have been used in traditional medicine as sedatives, antiseptics, carminatives, or expectorants. Despite their common applications in phytotherapy, there is still lack of evidence about the composition of their extracts and its impact on biological properties of the plants. The aim of this study was to evaluate the content of Ziziphora bungeana, a less studied species growing in Kazakhstan, using HPLC-ESI-QTOF-MS/MS instrumentation and to determine its antimicrobial, antioxidant, and cytotoxic activity together with inhibitory properties against tyrosinase and toxicity in erythrocyte lysis assay. Extracts from Z. bungeana were found to be sources of flavonoids, phenolic acids, organic acids, and terpenes that determined their antiradical activity. The minimum inhibitory concentrations of extracts were lower for Gram-positive bacteria (1.25-10 mg/mL) than for Gram-negative bacteria and fungi (5-20 mg/mL). The EC₅₀ value calculated for antiradical activity ranged between 15.00 ± 1.06 µg/mL and 13.21 ± 3.24 µg/mL for ABTS and DPPH assays, respectively. Z. bungeana extracts were found to decrease the activity of tyrosinase by 50% (at 200 µg/mL) similarly to kojic acid and were slightly cytotoxic for human melanoma A375 cell line (at 200 µg/mL) with no effect on HaCaT keratinocytes. In the end, Z. bungeana did not reveal toxic effects in hemolytic assay as compared to the positive control Triton X-100. The performed tests show potential application of the plant in the treatment of infectious diseases, disorders caused by free radicals, and skin problems.

Correlation Study of Biological Activity with Quercetin and Phenolics Content in Onion Extracts

In this study it was shown that the fungistatic and antioxidant activities of onion extracts are related to the type of liquid used as the extractant and the technique of its preparation. A change in the antioxidant properties of white and red onion extracts was demonstrated with the change of the temperature of the pressurized hot water extraction process, which can be easily related to the changes accompanying the process of thermal processing of vegetables and fruits during cooking. Owing to the experimental and mathematical approaches concerning both the main and characteristic components of onions, i.e., quercetin and phenols, respectively, with the biological activity of the extracts, it was possible to demonstrate the significant share of these compounds in the antifungal and antioxidant properties of the extracts. Considering that the research was carried out, inter alia, on onion husks, demonstrating a very high potential of biological properties of this waste material from agricultural production, the research results presented in the paper should encourage the popularization of the use of this so far underestimated raw material for the production of various functional materials.

New Insights into Vitamin K-From Its Natural Sources through Biological Properties and Chemical Methods of Quantitative Determination

Vitamin K is one of the many health-promoting substances whose impact on the human body has been underestimated until recently. However, recently published research results have changed this situation, prompting some researchers to consider it a new panacea for diseases of old age. The result is a significant increase in interest in the accurate analysis of vitamin K in various types of samples, ranging from food, through dietary supplements, to biological matrices and clinical trials, both observational and interventional. This review summarizes the current state of knowledge about the proven and speculated biological activity of vitamin K and its importance for the world's aging societies, including the methods used for its isolation and analysis in various matrices types. Of all the analytical methods, the currently preferred methods of choice for the direct analysis of vitamin K are chromatographic methods, in particular liquid chromatography-tandem mass spectrometry. This technique, despite its sensitivity and selectivity, requires an appropriate stage of sample preparation. As there is still room for improvement in the efficiency of these methods, especially at the sample preparation stage, this review shows the directions that need to be taken to make these methods faster, more efficient and more environmentally friendly.

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.

A Central Composite Design in increasing the quercetin content in the aqueous onion waste isolates with antifungal and antioxidant properties

In this study, to increase the content of quercetin in the isolates obtained from the white and red onion scales, in accordance with the zero waste philosophy, using water as an environmentally and healthy friendly extractant, a mathematical model was constructed, based on the Central Composite Design. The suitability of the model for the accurate and quick study of complex relationships was demonstrated by obtaining a statistically insignificant difference in the yield predicted by the model and that determined experimentally under optimal extraction conditions, i.e., 44.14 mg/g (33.57 mg/g) and 45.54 mg/g (33.31 mg/g) for white (red) onion scales, respectively. To present the obtained isolates applicability, their biological activity was assessed in terms of antioxidant activity and antifungal activity against various fungi, showing properties that are sufficient to encourage the use of this material, previously treated as worthless waste, for the production of various functional ingredients, including functional food additives. Moreover, they can be also used to produce safe and effective protectants meeting the GRAS criteria.

Solubility and Thermal Degradation of Quercetin in CO2-Expanded Liquids

The solubility of quercetin and its thermal degradation was studied in CO₂-expanded ethanol and ethyl lactate. An equipment setup was constructed that enabled the separation of the products of degradation while quantifying the solubility of quercetin. Three different conditions of temperature were analyzed (308, 323, and 343 K) at 10 MPa. Higher solubility and thermal degradation of quercetin were observed for CO₂-expanded ethyl lactate in comparison with CO₂-expanded ethanol. At the same time, as the amount of CO₂ was increased in the CO₂-expanded liquids mixtures, the thermal degradation of quercetin decreased for almost all the conditions of temperature considered in this work. The importance of considering thermal degradation while performing solubility measurements of compounds that are thermally unstable such as quercetin was highlighted.

Umbelliferone instability during an analysis involving its extraction process

ABSTRACT

Umbelliferone (7-hydroxycoumarin) is one of the most popular compounds of the coumarins family. This compound receives the attention of scientists due to its diverse bioactivities in a number of applications in various therapeutic fields. An interesting aspect of umbelliferone is its structural lability. The enzymatic degradation process of umbelliferone to its hydroxylated (esculetin), glucosylated (skimmin), and methylated (herniarin) derivatives is already known from the literature. In this paper, we describe the possibility of umbelliferone transformation to other derivatives. We found that eight compounds were formed from umbelliferone during its simulated extraction under reflux performed in different conditions (different heating times and solvents used). Six of them (4,7-dihydroxy-3,4-dihydro-2H-chromen-2-one, 3,7-dihydroxy-3,4-dihydro-2H-chromen-2-one, methyl (2E)-3-(2,4-dihydroxyphenyl)prop-2-enoate, ethyl (2E)-3-(2,4-dihydroxyphenyl)prop-2-enoate, (2E)-3-[2-(acetyloxy)-4-hydroxyphenyl]prop-2-enoic acid, (2E)-3-(2-amino-4-hydroxyphenyl)prop-2-enoic acid) have not been reported yet. Some of these compounds were also identified in extracts of plant materials containing umbelliferone-chamomile flower and cinnamon bark. Compound separation was carried out using the HPLC apparatus. All compounds were identified based on their MS fragmentation paths. The presented results are useful for food producers and consumers, as umbelliferone transformation products can be formed during food product storage, their preparation or processing.

GRAPHICAL ABSTRACT