Discovery of Se-containing flavone in Se-enriched green tea and the potential application value in the immune regulation

A new consecutive high-performance counter-current chromatography approach based on co-current and overlap mode for isolating active compounds from olive leaves

Conventional consecutive separation methods based on overlapping injection modes produce interactions between samples as the separation time increases. This will lead to a reduction in the purity of the target due to the gradual saturation of the stationary phase distribution. To enhance the purity of the sample preparation and separation efficiency, we devised a consecutive separation method under high-performance counter-current chromatography (HPCCC) utilizing co-current elution and overlapping injection. The method was used for the separation and preparation of olive leaves for their main bioactive polyphenolic constituents. Six HPCCC separations were conducted in reversed-phase mode using a two-phase solvent system consisting of petroleum ether/ethyl acetate/water (1:40:40, v/v). Finally, 302.7 mg of luteolin-4'-O-β-D-glucoside and oleuropein were isolated from 720 mg of crude sample with purities of 93.3% and 96.2%, respectively. The optimization strategy outlined in this study can be used to enhance the extraction of bioactive components from olive leaves.

Biological potential and mechanisms of Tea's bioactive compounds: An Updated review

BACKGROUND

Tea (Camellia sinensis) has a rich history and is widely consumed across many countries, and is categorized into green tea, white tea, oolong tea, yellow tea, black tea, and dark tea based on the level of fermentation. Based on a review of previous literature, the commonly recognized bioactive substances in tea include tea polyphenols, amino acids, polysaccharides, alkaloids, terpenoids, macro minerals, trace elements, and vitamins, which have been known to have various potential health benefits, such as anticancer, antioxidant, anti-inflammatory, anti-diabetes, and anti-obesity properties, cardiovascular protection, immune regulation, and control of the intestinal microbiota. Most studies have only pointed out the characteristics of tea's bioactivities, so a comprehensive summary of the pharmacological characteristics and mechanisms of tea's bioactivities and their use risks are vital.

AIM OF REVIEW

This paper aims to summarize tea's bioactive substances of tea and their pharmacological characteristics and mechanisms, providing a scientific basis for the application of bioactive substances in tea and outlining future research directions for the study of bioactive substances in tea.

KEY SCIENTIFIC CONCEPTS OF REVIEW

This review summarizes the main biologically active substances, pharmacological effects, and mechanisms and discusses the potential risks. It may help researchers grasp more comprehensive progress in the study of tea bioactive substances to further promote the application of tea as a natural bioactive substance in the medical field.

Effects of Foliar Dressing with Chemical Nano-Selenum and Na2SeO3 on the Antioxidant System and Accumulation of Se and Bioactive Components in Cyclocarya paliurus (Sweet Tea Tree)

Selenium (Se)-rich Cyclocarya paliurus is popular for its bioactive components, and exogenous Se fortification is the most effective means of enrichment. However, the effects of exogenous Se fortification on the nutritional quality of C. paliurus are not well known. To investigate the nutrient contents and antioxidant properties of C. paliurus following Se treatment, we used a foliar spray to apply Se in two forms-chemical nano-Se (Che-SeNPs) and sodium selenite (Na2SeO3). Sampling began 10 days after spraying and was conducted every 5 days until day 30. The Se, secondary metabolite, malondialdehyde contents, antioxidant enzyme activity, Se speciation, and Se-metabolism-related gene expression patterns were analyzed in the collected samples. Exogenous Se enhancement effectively increased the Se content of leaves, reaching a maximum on days 10 and 15 of sampling, while the contents of flavonoids, triterpenes, and polyphenols increased significantly during the same period. In addition, the application of Se significantly enhanced total antioxidant activity, especially the activity of the antioxidant enzyme peroxidase. Furthermore, a positive correlation between the alleviation of lipid peroxidation and Se content was observed, while methylselenocysteine formation was an effective means of alleviating Se stress. Finally, Na2SeO3 exhibited better absorption and conversion efficiency than Che-SeNPs in C. paliurus.

Selenium-Mediated (-)-Epigallocatechin-3-Gallate Dynamics via Flavanone-3-Hydroxylase Regulation of Flavonoid Biosynthesis in Fu Tea (Camellia sinensis (L.) O. Kuntze)

Tea (Camellia sinensis (L.) O. Kuntze) is a highly selenium enrichment capacity plant; high selenium concentration contributes to the occurrence of oxidative stress and protein misfolding in tea plants, whereas flavonoids can chelate heavy metals to protect plants from oxidative stress caused by metal exposure. Nevertheless, the role of catechins in flavonoid synthesis and nutrient metabolism under selenium stress remains unidentified. Combining Word2vec and HNSW utilizing UHPLC-Q-Orbitrap HRMS-MS/MS to implement rapid matching annotation of the structural information on metabolites in Fu tea, we found that selenium-mediated changes in catechins in Fu tea were mainly associated with flavonoid biosynthesis pathways. The results demonstrated that selenium treatment increased benign selenol analogues (glutathioselenol) in tea and identified the novel selenopeptide PRSeMW (m/z 636.22571, Pro-Arg-SeMet-Trp) in selenium-enriched Fu tea samples to enhance the health benefits of tea. The selenium levels were negatively correlated with N5-ethyl-l-glutamine (11.63 to 4.26 mg kg-1) and (-)-epigallocatechin (13.26 to 11.19 mg kg-1), increasing the accumulation of tea polyphenols ((-)-catechin gallate, (-)-epigallocatechin 3-gallate, and (+)-gallocatechin), and decreasing the level of caffeine. These discoveries provide new insights into the mechanism of tea polyphenol-mediated transformation of selenium in Fu tea and theoretical support for the quality assessment of selenium-enriched tea.

Selenosugar, selenopolysaccharide, and putative selenoflavonoid in plants

Selenium (Se) is a naturally occurring essential micronutrient that is required for human health. Selenium supports cellular antioxidant defense and possesses bioeffects such as anti-inflammation, anti-cancer, anti-diabetic, and cardiovascular and liver protective effects arising from Se-enhanced cellular antioxidant activity. Past studies on Se have focused on elucidating Se speciation in foods, biofortification strategies to produce Se-enriched foods to address Se deficiency in the population, and the biochemical activities of Se in health. The bioavailability and toxicity of Se are closely correlated to its chemical forms and may exhibit varying effects on body physiology. Selenium exists in inorganic and organic forms, in which inorganic Se such as sodium selenite and sodium selenate is more widely available. However, it is a challenge for safe and effective supplementation considering inorganic Se low bioavailability and high cytotoxicity. Organic Se, by contrast, exhibits higher bioavailability and lower toxicity and has a more diverse composition and structure. Organic Se exists as selenoamino acids and selenoproteins, but recent research has provided evidence that it also exists as selenosugars, selenopolysaccharides, and possibly as selenoflavonoids. Different food categories contain various Se compounds, and their Se profiles vary significantly. Therefore, it is necessary to delineate Se speciation in foods to understand their impact on health. This comprehensive review documents our knowledge of the recent uncovering of the existence of selenosugars and selenopolysaccharides and the putative evidence for selenoflavonoids. The bioavailability and bioactivities of these food-derived organic Se compounds are highlighted, in addition to their composition, structural features, and structure-activity relationships.

Sustainable chromatographic purification of milbemectin: Application of high-speed countercurrent chromatography coupled with off-line atmospheric pressure solid analysis probe-high resolution mass spectrometry

Isolation of valuable chemicals is an important process in reagent manufacturing for the pharmaceutical and food science industries. This process is traditionally time-consuming, expensive, and consumes vast amounts of organic solvents. Considering green chemistry and sustainability concerns, we sought to develop a sustainable chromatographic purification methodology for obtaining antibiotics by focusing on the reduction of organic solvent waste generation. Milbemectin (mixture of milbemycin A3 and milbemycin A4) was successfully purified using high-speed countercurrent chromatography (HSCCC) and pure fractions (>98% purity, HPLC) could be identified using the organic solvent fee atmospheric pressure solid analysis probe mass spectrometry (ASAP-MS). The organic solvents required for HSCCC could be redistilled and recycled for continued HSCCC purification, thus reducing the consumption of organic solvent (n-hexane/ethyl acetate) by 80+%. Optimization of the two-phase solvent system (n-hexane/ethyl acetate/methanol/water, 9/1/7/3, v/v/v/v) for HSCCC was assisted computationally, thereby reducing solvent waste from an experimental determination. Our proposal application of HSCCC and offline ASAP-MS provides proof of concept for a sustainable, preparative scale, chromatographic purification methodology for obtaining antibiotics in high purity.

Insights into the key quality components in Se-Enriched green tea and their relationship with Selenium

Selenium-enriched green tea (Se-GT) is of increasing interest because of its health benefits, but its quality components obtained limited research. In this study, Enshi Se-enriched green tea (ESST, high-Se green tea), Pingli Se-enriched green tea (PLST, low-Se green tea), and Ziyang green tea (ZYGT, common green tea) were subjected to sensory evaluation, chemical analysis, and aroma profiling. Chemical profiles in Se-GT were consistent with the taste attributes of the sensory analysis. 9 volatiles were identified as key odorants of Se-GT based on multivariate analysis. Correlations between Se and quality components were further assessed and highly Se-related compounds contents in these three tea samples were compared. The results showed that most amino acids and non-gallated catechins were highly negatively correlated with Se, while gallated catechins exhibited strong positive correlation with Se. And there were strong and significant associations between the key aroma compounds and Se. Moreover, 11 differential markers were found between Se-GTs and common green tea, including catechin, serine, glycine, threonine, l-theanine, alanine, valine, isoleucine, leucine, histidine, and lysine. These findings provide great potential for quality evaluation of Se-GT.

Research Progress on the Effects of Selenium on the Growth and Quality of Tea Plants

Selenium (Se) is an essential trace element for humans and animals, and it plays an important role in immune regulation and disease prevention. Tea is one of the top three beverages in the world, and it contains active ingredients such as polyphenols, theanine, flavonoids, and volatile substances, which have important health benefits. The tea tree has suitable Se aggregation ability, which can absorb inorganic Se and transform it into safe and effective organic Se through absorption by the human body, thereby improving human immunity and preventing the occurrence of many diseases. Recent studies have proven that 50~100.0 mg/L exogenous Se can promote photosynthesis and absorption of mineral elements in tea trees and increase their biomass. The content of total Se and organic selenides in tea leaves significantly increases and promotes the accumulation of polyphenols, theanine, flavonoids, and volatile secondary metabolites, thereby improving the nutritional quality of tea leaves. This paper summarizes previous research on the effects of exogenous Se treatment on the growth and quality of tea trees to provide a theoretical basis and technical support for the germplasm selection and exploitation of Se-rich tea.