Investigation of Differentially Expressed Proteins Induced by Alteration of Natural Se Uptake with Ultrahigh-Performance Liquid Chromatography Quadrupole Orbitrap Uncovers the Potential Nutritional Value in Se-Enriched Green Tea

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.

Impacts of selenium enrichment on nutritive value and obesity prevention of Cordyceps militaris: A nutritional, secondary metabolite, and network pharmacological analysis

This study aimed to compare the nutritive value and obesity prevention of ordinary Cordyceps militaris (CM) and selenium-enriched CM (SeCM). The results indicated that Se enrichment significantly increased the total carbohydrate and soluble dietary fiber content, while the protein and insoluble dietary fiber content decreased. Although the fat content was not affected, the medium and long-chain fatty acids content significantly changed. Moreover, Se enrichment significantly elevated the secondary metabolites belonging to terpenoids and alkaloids, which are linked with the enhanced biosynthesis of secondary metabolites. Both CM and SeCM reduced body weight, adipose accumulation, impaired glucose tolerance, and lipid levels in high-fat diet (HFD)-fed mice, and there was no significant difference between them. Network pharmacological analysis revealed that dietary CM and SeCM prevented HFD-induced obesity and associated metabolic diseases with multi-ingredients acting on multi-targets. Overall, Se enrichment improved the nutritive value of CM without altering its role in preventing obesity.

Proteome reveals the mechanism of selenium-sulfur interaction in regulating isothiocyanate biosynthesis and the physiological metabolism of broccoli sprouts

Broccoli sprouts have a strong ability to accumulate isothiocyanate and selenium. In this study, the isothiocyanate content increased significantly as a result of ZnSO₄ stress. Particularly, based on the isothiocyanate content is not affected, the combined ZnSO₄ and Na₂SeO₃ treatment alleviated the inhibition of ZnSO₄ and induced selenium content. Gene transcription and protein expression analyses revealed the changes in isothiocyanate and selenium metabolite levels in broccoli sprouts. ZnSO₄ combined with Na₂SeO₃ was proven to activate a series of isothiocyanate metabolite genes (UGT74B1, OX1, and ST5b) and selenium metabolite genes (BoSultr1;1, BoCOQ5-2, and BoHMT1). The relative abundance of the total 317 and 203 proteins, respectively, in 4-day-old broccoli sprouts varied, and the metabolic and biosynthetic pathways for secondary metabolites were significantly enriched in ZnSO₄/control and ZnSO₄ combined Na₂SeO₃/ZnSO₄ comparisons. The findings demonstrated how ZnSO₄ combined with Na₂SeO₃ treatment reduced stress inhibition and the accumulation of encouraged selenium and isothiocyanates during the growth of broccoli sprouts.

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.

Integrative Transcriptome and Proteome Analysis Reveals the Absorption and Metabolism of Selenium in Tea Plants [Camellia sinensis (L.) O. Kuntze]

Certain tea plants (Camellia sinensis) have the ability to accumulate selenium. In plants, the predominant forms of bioavailable Se are selenite (SeO3 2-) and selenate (SeO4 2-). We applied transcriptomics and proteomics to hydroponically grown plants treated with selenite or selenate for 48 h in the attempt to elucidate the selenium absorption and assimilation mechanisms in tea. A total of 1,844 differentially expressed genes (DEGs) and 691 differentially expressed proteins (DEPs) were obtained by comparing the Na2SeO3 and Na2SeO4 treatments against the control. A GO analysis showed that the genes related to amino acid and protein metabolism and redox reaction were strongly upregulated in the plants under the Na2SeO3 treatment. A KEGG pathway analysis revealed that numerous genes involved in amino acid and glutathione metabolism were upregulated, genes and proteins associated with glutathione metabolism and ubiquinone and terpenoid-quinone biosynthesis were highly expressed. Genes participating in DNA and RNA metabolism were identified and proteins related to glutathione metabolism were detected in tea plants supplemented with Na2SeO4. ABC, nitrate and sugar transporter genes were differentially expressed in response to selenite and selenate. Phosphate transporter (PHT3;1a, PHT1;3b, and PHT1;8) and aquaporin (NIP2;1) genes were upregulated in the presence of selenite. Sulfate transporter (SULTR1;1 and SULTR2;1) expression increased in response to selenate exposure. The results of the present study have clarified Se absorption and metabolism in tea plants, and play an important theoretical reference significance for the breeding and cultivation of selenium-enriched tea varieties.