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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.

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.

Chlorogenic acids (CQAs), the esters of caffeic and quinic acid, are biologically important phenolic compounds present in many plant species. Nowadays the knowledge about their pro-health properties including anti-cancer activity is great. Yet the supposition that they may be helpful in fighting obesity and modify glucose-6-phosphatase involved in glucose metabolism has led to some revival of research on CQAs properties and their natural occurrence. Considering the growing interest in natural products rich in CQAs, it is not surprising that more efficient extraction methods, leading to obtained extracts with increased CQAs content, are currently being sought. It is worth mentioning here that this task is not very easy since these compounds readily degrade/transform to others. 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 marker in the quality control of various natural products. Yet due to their structural similarity and instability, and the fact that the number of commercially available standards of CQAs is limited to just a few, the correct analysis of these compounds in plants is another challenge that should be faced. The aim of this review is to summarize the recent advances in the chemical analysis of chlorogenic acids, including their natural sources, properties, and methods that have been developed to improve CQAs extraction and analysis, with special attention paid to 5-CQA as the compound of the CQAs family with many beneficial effects on human health.

Biological properties of menaquinone-7, one of the vitamin K2 vitamers (K2MK-7), both those proven and those that remain to be investigated, arouse extensive interest that goes beyond the strictly scientific framework. The most important of them is the prevention of age-related diseases, considering that we live in the times identified as the era of aging societies and many people are exposed to the vitamin K2MK-7 deficiency. Therefore, an effective analytical protocol that can be adopted as a diagnostic and preventive analytics tool is needed. Herein, a simple sample preparation method followed by the liquid chromatography-tandem mass spectrometry-based method (LC-MS/MS), was used for the selective and sensitive determination of K2MK-7 in serum samples. Under the optimized conditions, using 500 µL of serum and the same amount of n-hexane, the reproducibility and the accuracy were obtained in the ranges of 89–97% and 86–110%, respectively, and the limit of detection value was 0.01 ng/mL. This method was used for the routine analysis. Statistical interpretation of the data from 518 samples obtained during 2 years of practice allowed for obtaining information on the content and distribution of K2MK-7 in the Polish population, broken down by the sex and age groups.

Due to its health-promoting properties, resveratrol is one of the most desirable compounds in many industries. Hence, this work focused on finding the conditions of its extraction from Japanese knotweed which could be used on an industrial scale to obtain extracts with the best antioxidant properties. The contribution of polyphenolics to the activity of the obtained isolates was also assessed in this study. Ultrasound-assisted solvent extraction was used to prepare extracts in various solvents under conditions differing in extraction time, temperature, and ultrasound frequency. The extracts were tested for their ability to neutralize radicals and reduce metal ions. It was shown that although the best extractant was the same water–alcohol mixture, the optimal conditions for the extraction of resveratrol and polyphenols were different: 10 min, 50 °C and 80 kHz for resveratrol (for which the highest contents of resveratrol equals 0.91 mg/g was obtained) and 20 min, 25 °C and 37 kHz for polyphenolics (for which the total phenolic content equals 31.28 mg of gallic acid/g was determined) Under the latter conditions, one of the best antioxidant activities was also obtained. The results confirm that Japanese knotweed, despite its bad reputation in Europe as a very invasive species, can be used as a source of sought-after resveratrol and polyphenols.

Currently, there is a significant demand for natural biologically active compounds. Emphasis is placed on improving the quality and safety of processed natural products, which is understandable in light of the frequently observed instability of natural compounds and their degradation, among others, to compounds of unknown biological activity. In this paper, the influence of typical conditions of currently used assisted extraction techniques on the stability of 5-O-caffeoylquinic acid and 1,3-di-O-caffeoylquinic acid during their simulated and real extraction from plants was investigated. In the experiments, extraction assisted by microwave radiation, ultrasound and pressure in procedures known as MASE, UASE and PLE techniques, respectively, was used. By comparing the amounts of native plant components, i.e., compounds present in the extract obtained, as shown, by the non-destructive SSDM technique with the amounts of these compounds estimated in extracts obtained by the above-mentioned techniques, it was proven that their content is variable. These differences are a consequence of two opposing processes, i.e., the success of the isolation process (its efficiency) and the degree of degradation/transformation of the main components. The results of the studies presented here can reduce the share of the second of the above, and consequently contribute to more effective obtaining of phenolic compounds from plants.

Vitamin K, as a natural protector of our blood, bones, kidneys, and brain, is essential for human health. It is also considered an effective anti-aging agent with comprehensive biological effects, including antifungal, antibacterial, anti-inflammatory, analgesic, and even antioxidant properties. Of these, the least is known about the antioxidant properties of natural vitamin K. To fill this gap, this study compared the antioxidant properties of extracts obtained from commonly consumed green plants with different vitamin K contents with the activity of vitamin K standard solutions at concentrations corresponding to the vitamin K contents in the extracts. Various measurement methods were used in the research (i.e., DPPH, FRAP, CUPRAC, and the β-carotene bleaching test). Among the tested methods, the β-carotene bleaching test is the most sensitive in the assessment of this unusual compound. In light of the data presented, the antioxidant response of vitamin K alone is dose-dependent. However, in extracts, the activity of this compound is modulated by other constituents present in them. As a result, the activity does not always correlate with vitamin K content. The presented data supplement the knowledge about the antioxidant properties with the contribution resulting from the presence of vitamin K in green plant 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.

The health-promoting properties of vitamin K stimulate the growing interest in this compound, which translates into the development of new analytical methodologies for its determination. New, more efficient methods of its isolation are sought, paying increasingly more attention to the methods within currently available extraction techniques that, owing to the optimization of the process, not only increase the extraction efficiency but are also economical and environmentally friendly. This article proposes a procedure for the extraction and analysis of one of the vitamin K vitamers, i.e., vitamin K1, using PLE and LC-MS/MS. It has been shown that the PLE technique can be optimized with a mathematical model—accelerating and reducing the costs of the extraction process—which, together with process automation, bodes well for industrial applications. The optimized process was used to extract vitamin K1 from various vegetables, showing very different contents of the test compound ranging from 1.22 to 114.30 µg/g dry weight for avocado and spinach, respectively. In addition, by showing the effect of water within the material subjected to extraction on the variable yield of vitamin K1, attention was drawn to the need to standardize the analytical methods used in assessing the quality of food products.

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.