Sensory-directed isolation and identification of an intense salicin-like bitter compound in infected teas with bird's eye spot disease.

Teas infected with bird's eye spot disease generally exhibited a lingering and long-lasting, salicin-like bitter taste, which was unpalatable to consumers. Sensory-directed isolation processes have been performed in this study to investigate the salicin-like bitter compounds in infected teas. Results showed that infected teas were extracted using a 70% methanol aqueous solution to produce methanol extract, which was then further separated by sequential solvent extraction (SSE) to obtain dichloromethane extract, which contained the salicin-like bitter compounds. The dichloromethane extract was then isolated by flash chromatography to produce two salicin-like bitter fractions, eluted using 60% and 65% methanol aqueous solution. Finally, these two salicin-like bitter fractions were analyzed by RP-HPLC using 60-68% and 70-75% methanol aqueous solution, respectively, affording the location of the salicin-like bitter compounds in RP-HPLC chromatograms. Moreover, a new ursane-type triterpenoid, camellisin A methyl ester, was identified from infected teas. This study has provided preliminary isolation methods of salicin-like bitter compounds from the infected teas, which were essential to designing targeted debittering strategies for infected teas and improving the quality of the finished tea and the effective utilization of fresh tea leaves.

Metabolites and metagenomic analysis reveals the quality of Pu-erh "tea head".

Tea head, a derivative product of Pu-erh tea, are tight tea lumps formed during pile-fermentation. The aim of this study was to reveal the differences of quality-related metabolites and microbial communities between ripened Pu-erh tea (PE-21) and tea heads (CT-21). Compared with PE-21, CT-21 showed a more mellow and smooth taste with slight bitterness and astringency, and can withstand multiple infusions. Metabolites analysis indicated CT-21 had more abundant water-soluble substances (47.39%) and showed significant differences with PE-21 in the main compositions of amino acids, catechins and saccharides which contributed to the viscosity of tea liquor, mellow taste and the tight tea lumps formation. Microbial communities and COG annotation analysis revealed CT-21 had lower abundance of Bacteria (84.05%), and higher abundance of Eukaryota (15.10%), carbohydrate transport and metabolism (8.28%) and glycoside hydrolases (37.36%) compared with PE-21. The different microbial communities may cause metabolites changes, forming distinct flavor of Pu-erh.

Characterization of triterpenoids as possible bitter-tasting compounds in teas infected with bird's eye spot disease.

Tea infected with bird's eye spot disease generally imparts a long-lasting bitter taste, which is unacceptable to most consumers. This study has comprehensively evaluated the taste profiles of infected and healthy teas and investigated their known bitter compounds previously reported in tea. Quantification analyses and calculation of dose-over-threshold (DoT) factors revealed that no obvious difference was visualized in catechins, caffeine, bitter amino acids, and flavonols and their glycosides between infected and healthy tea samples, which was also verified by principal component analysis (PCA) and hierarchical cluster analysis (HCA). Therefore, these known bitter compounds have been ruled out as critical contributors to the long-lasting bitterness of infected teas. Furthermore, Gel permeation chromatography, sensory analysis, and UPLC-Q-TOF-MS were employed and identified 13 substances from the target bitter fractions, including caffeine, ten triterpenoids, and two oxylipins. The higher triterpenoid levels were supposed to be the reason causing the long-lasting bitterness. This study has provided a research direction for the molecular basis of the long-lasting bitterness of infected tea leaves with bird's eye spot disease.

Characteristics of Leaf Spot Disease Caused by Didymella Species and the Influence of Infection on Tea Quality.

Leaf spots are the most damaging and common foliar diseases of tea and are caused by several species of fungi. During 2018 to 2020, leaf spot diseases showing different symptoms (large and small spots) were observed in commercial tea plantations in Guizhou and Sichuan provinces of China. The pathogen causing the two different sized leaf spots was identified as the same species (Didymella segeticola) based on morphological characteristics, pathogenicity, and multilocus phylogenetic analysis using the combined ITS, TUB, LSU, and RPB2 gene regions. Microbial diversity analysis of lesion tissues from small spots on naturally infected tea leaves further confirmed Didymella to be present as the main pathogen. Results of sensory evaluation and quality-related metabolite analysis of tea shoots infected with the small leaf spot symptom indicated that D. segeticola negatively affected the quality and flavor of tea by changing the composition and content of caffeine, catechins, and amino acids. In addition, the significantly reduced amino acid derivatives in tea are confirmed to be positively associated with the enhanced bitter taste. The results improve our understanding of the pathogenicity of Didymella species and the influence of Didymella on the host plant, Camellia sinensis.

Non-volatile metabolites profiling analysis reveals the tea flavor of "Zijuan" in different tea plantations.

Characteristic metabolites including tea polyphenols, amino acids, catechins, caffeine, sugars and anthocyanins were fully analyzed by high performance liquid chromatography (HPLC), gas chromatography tandem mass spectrometry (GC-MS) and ultra-high performance liquid chromatography (UHPLC)-ESI-tandem mass spectrometry (MS/MS), and showed significant differences among Zijuan tea from different plantations in Yunnan province (YN-ZJ), Qijiang (QJ-ZJ) and Ersheng (ES-ZJ) district, China, indicating that Zijuan is significantly influenced by growth conditions. Monosaccharides were the most abundant soluble sugars in YN-ZJ and ES-ZJ, while disaccharides was abundant in QJ-ZJ. d-galactose, d-mannose, d-sorbitol, inositol, d-glucose, d-galacturonic acid and raffinose involved in galactose metabolism were significantly changed (P < 0.05). Delphinidin, cyanidin, pelargonidin and their glycoside derivatives were the major anthocyanins, and showed significant differences among Zijuan samples. Flavonoids and procyanidins abundant in Zijuan provided more substrates for anthocyanins accumulation. This study presented comprehensive chemical profiling and characterized metabolites of Zijuan in different tea plantations.

A New Colletotrichum Species Associated with Brown Blight Disease on Camellia sinensis.

Brown blight, as the most damaging and common foliar disease of the tea plant (Camellia sinensis) in China, has been recently reported to be caused by different species of the genus Colletotrichum. During the years 2016 to 2017, tea plants in commercial tea cultivation areas of Chongqing City that reported significant incidences of brown blight disease were investigated and then analyzed using both morphological characteristics and multilocus phylogenetic analysis. The results showed that at least five species of Colletotrichum were identified, including four well-known species (Colletotrichum gloeosporioides, C. camelliae, C. fioriniae, and C. karstii) and one novel species (C. chongqingense), indicating that there is remarkable species diversity in Colletotrichum spp. present as pathogens. Results of pathogenicity analyses confirmed that C. chongqingense was the causal agent of brown blight and different isolates differed in virulence. C. chongqingense, as a novel pathogen, has never been reported as being associated with brown blight disease in tea plants or anthracnose in other host plants anywhere in the world. Knowledge of the Colletotrichum populations will facilitate further studies addressing the relationships between Colletotrichum spp. and their host plant Camellia sinensis.

Metabolism of Gallic Acid and Its Distributions in Tea (Camellia sinensis) Plants at the Tissue and Subcellular Levels.

In tea (Camellia sinensis) plants, polyphenols are the representative metabolites and play important roles during their growth. Among tea polyphenols, catechins are extensively studied, while very little attention has been paid to other polyphenols such as gallic acid (GA) that occur in tea leaves with relatively high content. In this study, GA was able to be transformed into methyl gallate (MG), suggesting that GA is not only a precursor of catechins, but also can be transformed into other metabolites in tea plants. GA content in tea leaves was higher than MG content-regardless of the cultivar, plucking month or leaf position. These two metabolites occurred with higher amounts in tender leaves. Using nonaqueous fractionation techniques, it was found that GA and MG were abundantly accumulated in peroxisome. In addition, GA and MG were found to have strong antifungal activity against two main tea plant diseases, Colletotrichum camelliae and Pseudopestalotiopsis camelliae-sinensis. The information will advance our understanding on formation and biologic functions of polyphenols in tea plants and also provide a good reference for studying in vivo occurrence of specialized metabolites in economic plants.

Leukocytapheresis Therapy for Rheumatoid Arthritis: Results Compared with Control Trial.

CONTEXT: Rheumatoid arthritis (RA) is a chronic multisystem autoimmune disease, mainly characterized by synovitis and with symmetrical joint involvement. LCAP therapy for RA patients has been shown to be safe and efficacious in some developed countries for over a decade. OBJECTIVE: The study intended to evaluate the efficacy and safety of leukocytopheresis (LCAP) for treatment of rheumatoid arthritis (RA) and to study the influence of treatment on the levels of various serum cytokines. DESIGN: The study was a nonblinded, nonrandomized, controlled trial. SETTING: The study took place in the Department of Rheumatology and Immunology at Beijing Hospital at the National Center of Gerontology in Beijing, China. PARTICIPANTS: Participants were 51 patients with RA at the hospital with a 28-joint disease activity score (DAS28) exceeding the 3.20 needed to fulfill the classification criteria of the American College of Rheumatology (ACR). INTERVENTION: Participants were divided into 2 groups. One group (intervention group) received LCAP therapy (n = 20), while the control group (n = 31) received disease-modifying antirheumatic drugs (DMARDs). Patients receiving the LCAP therapy were treated using a Cellsorba column every 5 days for a total of 5 treatments. OUTCOME MEASURES: Clinical assessment of participants' symptoms included: (1) a tender-joint count, (2) a swollen-joint count, (3) erythrocyte sedimentation rates (ESR), (4) C-reactive protein levels (CRP), (5) a visual analog scale (VAS) for pain, (6) the DAS28 C-reactive protein (DAS28-CRP) scores, and the Health Assessment Questionnaire Disability Index (HAQ-DI). The study also evaluated participants' scores for the American College of Rheumatology (ACR) Core Data Set. Serum collected before and after therapy from both groups was analyzed for the levels of bradykinin, serotonin, heat shock protein 70, human CXC-chemokine ligand 16 (CXCL16), prostaglandin E2, and macrophage inflammation protein 1α. RESULTS: At week 4 for participants receiving the LCAP therapy, ACR20, ACR50, and ACR70 were observed in 55%, 30%, and 20% of patients, respectively, compared to 19.4%, 3.2%, and 0% for patients in the control group (P < .05). Also, at week 24 of LCAP therapy, ACR20, ACR50, and ACR70 were observed in 70%, 50%, and 30% of patients, respectively, which was significantly higher than the 25.8%, 12.9%, and 3.2% of patients in the control group (P < .05). The serum levels of CXCL16 and serotonin were significantly reduced in the LCAP group compared with control group. CONCLUSIONS: This study indicated that LCAP therapy can significantly decrease RA disease activity and is a safe and effective alternative therapy. LCAP therapy significantly reduced serum CXCL16 and serotonin levels, offering a putative mechanism by which it improves the articular symptoms of RA.

Pestalotiopsis-Like Species Causing Gray Blight Disease on Camellia sinensis in China.

Gray blight of tea, caused by several Pestalotiopsis-like species, is one of the most destructive foliar diseases in tea cultivation yet the characteristics of these pathogens have not been confirmed until now. With morphological and multigene phylogenetic analyses, we have identified the gray blight fungi as Pseudopestalotiopsis camelliae-sinensis, Neopestalotiopsis clavispora, and Pestalotiopsis camelliae. Phylogenetic analyses derived from the combined internal transcribed spacer, ß-tubulin, and translation elongation factor 1-α gene regions successfully resolved most of the Pestalotiopsis-like species used in this study with high bootstrap supports and revealed three major clusters representing these three species. Differences in colony appearance and conidia morphology (shape, size, septation, color and length of median cells, and length and number of apical and basal appendages) were consistent with the phylogenetic grouping. Pathogenicity tests validated that all three species isolated from tea leaves were causal agents of gray blight disease on tea plant (Camellia sinensis). This is the first description of the characteristics of the three species Pseudopestalotiopsis camelliae-sinensis, N. clavispora, and Pestalotiopsis camelliae as causal agents of tea gray blight disease in China.