Mechanisms and quality variations of non-volatile and volatile metabolites in black tea from various ages of tea trees: Insights from metabolomics analysis.

The sensory quality of black tea (BT) influenced by various factors, among which tree age is particularly significant. People prefer BT produced by fresh leaves from old tea trees, yet the correlation between tree age and tea quality has not been thoroughly investigated. In this study, we analyzed the quality of BT from young trees (H-JYH) and old trees (H-OJYH) using e-tongue technology and sensory evaluation. Our findings revealed that H-OJYH had stronger sweetness and sourness, richer flavor, and diminished bitter-astringency compared to H-JYH. 1231 non-volatile metabolites and 504 volatile metabolites were discovered by ultra-performance liquid chromatography (UPLC) and gas chromatography-mass spectrometry (GC-MS). L-tartaric acid and trans-citridic acid were found to contribute to increase acidity, and 7,8-dihydroxy-6-methoxycoumarin and d-fructose 6-phosphate were associated with enhanced sweetness in H-OJYH. Additionally, lower levels of octyl gallate and vanillic acid in H-OJYH contributed to the diminished bitter-astringency. ß-ionone, 2-phenylethanol and phenylacetaldehyde merged as characteristic compounds of older tree BT with stronger floral and sweet aroma. Our study serves as a guideline to explore the relationship between tree age and tea quality.

Study on flavor quality formation in green and yellow tea processing by means of UPLC-MS approach.

Yellow tea (YT) has an additional process of yellowing before or after rolling than green tea (GT), making YT sweeter. We analyzed the variations of composition and taste throughout the withering, fixing and rolling steps using UPLC-MS/MS and sensory evaluation, and investigated the influence of various yellowing times on flavor profile of YT. 532 non-volatile metabolites were identified. Withering and fixing were the important processes to form the taste quality of GT. Withering, fixing and yellowing were important processes to form flavor profile of YT. Withering mainly regulated bitterness and astringency, and fixing mainly regulated bitterness, astringency and sweetness of YT and GT. Yellowing mainly regulated sweetness of YT. Trans-4-hydroxy-L-proline and glutathione reduced form as the key characteristic components of YT, increased significantly during yellowing mainly through Arginine and proline metabolism and ABC transporters. The paper offers a systematic insight into intrinsic mechanisms of flavor formation in YT and GT.

Analysis of aroma quality changes of large-leaf black tea in different storage years based on HS-SPME and GC-MS.

The reasons for the change in volatile metabolites and aroma of black tea during storage remain unclear. Therefore, we used HS-SPME and GC-MS methods to analyze the aroma compounds of new tea (2021) versus aged tea groups (2015, 2017, and 2019). A total of 109 volatile components were identified. During storage, 36 metabolites mainly with floral and fruity aromas decreased significantly, while 18 volatile components with spicy, sour, and woody aromas increased significantly. Linalool and beta-ionone mainly contributed to sweet and floral aromas of freshly-processed and aged black tea, respectively. Isovaleric acid and hexanoic acid mainly caused sour odor of aged black tea. The monoterpene biosynthesis and secondary metabolic biosynthesis pathways might be key metabolic pathways leading to changes in the relative content of metabolites during storage of black tea. Our study provides theoretical support for fully understanding the changes in the aroma quality of black tea during storage.

The formation mechanism of aroma quality of green and yellow teas based on GC-MS/MS metabolomics.

Aroma is a crucial determinant of tea quality. While some studies have examined the aroma of yellow tea, there are no reports of the difference and formation mechanism of aroma quality between yellow and green teas from the same tea tree variety. This study employed gas chromatography-mass spectrometry to investigate the difference and formation mechanism of the aroma of yellow and green tea at the omics level, based on sensory evaluation. The sensory evaluation revealed that green tea has a distinct faint scent and bean aroma, while yellow tea, which was yellowed for 48 h, has a noticeable corn aroma and sweet fragrance. A total of 79 volatile metabolites were detected in the processing of yellow and green tea, covering 11 subclasses and 27 were differential volatile metabolites. Benzoic acid, 2-(methylamino-), methyl ester, terpinen-4-ol ethanone, 1-(1H-pyrrol-2-yl-), 3-penten-2-one, 4-methyl- and benzaldehyde were characteristic components of the difference in aroma quality between green and yellow teas. Eleven volatile metabolites significantly contributed to the aroma quality of green and yellow teas, especially acetic acid, 2-phenylethyl ester, with rose and fruity aromas. KEGG enrichment analysis showed that the arginine and proline metabolism might be the key mechanism of aroma formation during green and yellow teas' processing. These finding provide a theoretical basis way for the aroma formation of green and yellow teas.

Metabolomics reveals the effects of different storage times on the acidity quality and metabolites of large-leaf black tea.

Most aged tea has superior sensory qualities and good health benefits. The content of organic acids determines of the quality and biological effects of aged tea, but there are no reports of the effect of storage on the composition and relative proportion of acidic compounds in black tea. This study analyzed and compared the sourness and metabolite profile of black tea produced in 2015, 2017, 2019 and 2021 using pH determination and UPLC-MS/MS. In total, 28 acidic substances were detected, with 17 organic acids predominating. The pH of black tea decreased significantly during storage from pH 4.64 to pH 4.25 with significantly increased in l-ascorbic acid, salicylic acid, benzoic acid and 4-hydroxybenzoic acid. The metabolic pathways ascorbate biosynthesis, salicylate degradation, toluene degradation, etc. were mainly enriched. These findings provide a theoretical basis to regulate the acidity of aged black tea.

A new mutation c.685G>A:p.E229K in the KCNJ11 gene: A case report of maturity-onset diabetes of the young13.

INTRODUCTION: Maturity-onset diabetes of the young (MODY) is an autosomal dominant monogenic diabetes. We report a pair of father and son diagnosed as MODY13 with a new mutation c.685G>A:p.E229K in the inwardly rectifying subfamily J, member 11 (KCNJ11) gene. CASE PRESENTATION: A pair of father and son was examined after admission to the hospital and a whole exome test performed. Whole exome test showed that there was a mutation c.685G>A:p.E229K in the KCNJ11 gene encoding a potassium channel, KCNJ11. CONCLUSIONS: The diagnosis of MODY13 requires genetic testing. After confirmation, medication and diet need to be adjusted to control blood glucose. The treatment plan was adjusted. After glimepiride was administered, symptoms of diabetes were effectively improved. According to our knowledge, this is the first reported mutation of c.685G>A:p.E229K in the KCNJ11 gene.

A Combination of circRNAs as a Diagnostic Tool for Discrimination of Papillary Thyroid Cancer.

BACKGROUND AND AIM: Circular RNAs (circRNAs) have been highlighted to exert essential biological functions in papillary thyroid cancer (PTC). The purpose of this study was explore diagnostic utility of circRNAs in PTC patients. PATIENTS AND METHODS: The distinctive expression profile of serum circRNAs was determined by individual quantitative real-time PCR (qRT-PCR) in two independent cohorts of 113 PTC patients, 80 thyroid nodules, and 111 healthy controls (HCs). A combination of circRNAs (circRNA-based combination index) was constructed by logistic regression. RESULTS: Individual qRT-PCR identification showed that two circRNAs (circRAPGEF5 and hsa_circ_0058124) were significantly up-regulated in PTC patients compared with HCs and thyroid nodules. Receiver-operating characteristic (ROC) curve analysis suggested that a combination of circRNAs was superior to individual circRNA in distinguishing PTC patients from HCs and thyroid nodules with area under ROC curve of more than 0.80. Furthermore, the combination of circRNAs increased significantly after systematic treatment, suggesting that it could monitor PTC dynamics. Additionally, the combination of circRNAs was independently correlated with PTC presence. CONCLUSION: The combination of these altered circRNAs was correlated with PTC and may serve as a novel diagnostic approach.

Increased serum/plasma fibroblast growth factor 21 in type 2 diabetes mellitus: a systematic review and meta-analysis.

OBJECTIVES: Fibroblast growth factor-21 (FGF-21) plays an important role in glucose and lipid metabolism. This study aims to systemically review the evidence regarding the relationship between the FGF-21 levels and type 2 diabetes mellitus (T2DM), as well as the related influential factors. METHODS: Research related to plasma/serum FGF-21 levels in patients with T2DM and healthy controls were searched in PubMed, EMBASE and The Cochrane Library databases (up to 31 March 2017). Pooled standard mean difference (SMD) with 95% CI was calculated by fixed-effect or random-effect model analysis. Heterogeneity test was performed by the Q-statistic and quantified using I 2, and publication bias was evaluated using a funnel plot and Egger's linear regression test. RESULTS: In total, 317 articles were obtained after searching databases, and 11 studies with 866 patients with T2DM and 629 controls were finally included. Meta-analysis revealed that, compared with the control group, the T2DM group had a significantly higher plasma/serum FGF-21 level (p < 0.001), with the SMD of 1.34% and 95% CI (0.70 to 1.98). Meta-regression analysis and subgroup analyses suggested that body mass index (BMI), triglycerides (TG) and total cholesterol (TC) were likely related to the observed FGF-21 differences between two groups. CONCLUSIONS: Overall, our study suggests that patients with T2DM have significantly higher plasma/serum FGF-21 levels, and the FGF-21 levels were influenced by BMI, TC and TG.

Silibinin ameliorates diabetic nephropathy via improving diabetic condition in the mice.

Diabetic nephropathy (DN) is a major cause of end-stage renal disease and one of the most severe diabetic complications. However, there is lack of effective treatments for DN and the underlying mechanisms of the renal injury remain unclear. In current study, we evaluated the effects of silibinin on DN and further explored the underlying mechanisms. We administrated silibinin to db/db mice for 10 weeks. Then we monitored the diabetic metabolic parameters, kidney function, oxidative stress and AKT signaling pathway in db/db mice. Administration of silibinin to db/db mice improved diabetic condition, as evidenced by the decrease of body weight, HbAc1level and serum insulin level in db/db mice. Silibinin prevented kidney injury and attenuated oxidative stress in db/db mice. Silibinin activated AKT signaling pathway and decreased the levels of p-GSK-3ß, Bax and cleaved caspase-3. Silibinin ameliorates diabetic nephropathy by activating the AKT signaling pathway.