Improving flavor of summer Keemun black tea by solid-state fermentation using Cordyceps militaris revealed by LC/MS-based metabolomics and GC/MS analysis.

Cordyceps militaris (C. militaris) has been approved and widely used in healthy food. The present study aimed to improve the flavor of summer Keemun black tea (KBT) using C. militaris solid-state fermentation. Combined with sensory evaluation, the volatile and non-volatile components of solid-state fermentation of KBT (SSF-KBT) and KBT were analyzed. The results showed that after the solid-state fermentation, the contents of total polyphenol, total flavonoid, and total free amino acids were significantly reduced. Further non-targeted metabolomics analysis revealed that the contents of non-galloylated catechins and d-mannitol increased, while the galloylated catechins and flavonoid glycosides decreased as did the bitterness and astringency of KBT. Dihydro-ß-ionone and ß-ionone (OAV = 59321.97 and 8154.17) were the aroma-active compounds imparting woody and floral odors in SSF-KBT, respectively. Current study provides a new avenue to develop summer-autumn KBT.

Two new catechins from Zijuan green tea enhance the fitness and lifespan of Caenorhabditis elegans via insulin-like signaling pathways.

Green tea polyphenols show positive effects on human health and longevity. However, knowledge of the antiaging properties of green tea is limited to the major catechin epigallocatechin gallate (EGCG). The search for new ingredients in tea with strong antiaging activity deserves further study. Here we isolated and identified two new catechins from Zijuan green tea, named zijuanin E (1) and zijuanin F (2). Their structures were identified by extensive high-resolution mass spectroscopy (HR-MS), nuclear magnetic resonance (NMR), ultraviolet-vis (UV), infrared (IR) and circular dichroism (CD) spectroscopic analyses, and their 13C NMR and CD data were calculated. We used the nematode Caenorhabditis elegans (C. elegans) to analyze the health benefits and longevity effects of 1 and 2. Compounds 1 and 2 (100 µM) remarkably prolonged the lifespan of C. elegans by 67.2% and 56.0%, respectively, delaying the age-related decline of phenotypes, enhancing stress resistance, and reducing ROS and lipid accumulation. Furthermore, 1 and 2 did not affect the lifespan of daf-16, daf-2, sir-2.1, and skn-1 mutant worms, suggesting that they might work via the insulin/IGF and SKN-1/Nrf2 signaling pathways. Meanwhile, 1 and 2 also exhibited strong antioxidant activity in vitro. Surface plasmon resonance (SPR) evidence suggests that zijuanins E and F have strong human serum albumin (HSA) binding ability. Together, zijuanins E and F represent a new valuable class of tea components that promote healthspan and could be developed as potential dietary therapies against aging.

Discovery and Targeted Isolation of Phenylpropanoid-Substituted Ester-Catechins Using UPLC-Q/TOF-HRMS/MS-Based Molecular Networks: Implication of the Reaction Mechanism among Polyphenols during Green Tea Processing.

Tea is an important beverage source of dietary polyphenols and well known for containing phenolic structure diversity. A series of phenylpropanoid-substituted catechins, flavonols, flavan-3-hexoside, and proanthocyanidin are present in different herbs with various biological activities, inspiring our exploration of phenylpropanoid-substituted ester type of catechins (PSECs) due to the enrichment of galloylated catechins in tea. In this study, we used a guiding-screening-location-isolation integrated route including creating a hypothesized PSEC dataset, MS/MS data acquiring, construction of molecular networks, and traditional column chromatography and preliminarily identified 14 PSECs by MS/MS spectrum. Two of these PSECs were further purified and elucidated by NMR and CD spectra. Further MS detection in tea products and fresh leaves suggests that the production of the two new compounds was enhanced during tea processing. The synthesis mechanism was proposed to obtain these types of components for further investigation on their roles in human health protection. This study provides an example for the exploration of new functional ingredients from food sources guided by MS/MS data-based networking, and also new insights into the reaction mechanism to form new catechin conjugates among polyphenols in green tea.

Two Pairs of Isomerically New Phenylpropanoidated Epicatechin Gallates with Neuroprotective Effects on H2O2-Injured SH-SY5Y Cells from Zijuan Green Tea and Their Changes in Fresh Tea Leaves Collected from Different Months and Final Product.

Zijuan tea ( Camellia sinensis var. assamica), an anthocyanin-rich cultivar with purple leaves, is a valuable material for manufacturing tea with unique color and flavor. In this paper, four new phenylpropanoid substituted epicatechin gallates (pECGs), Zijuanins A-D (1-4), were isolated from Zijuan green tea by different column chromatography. Their structures were identified by extensive high resolution mass spectroscopy (HR-MS), nuclear magnetic resonance (NMR), and experimental and calculated circular dichroism (CD) spectroscopic analyses. Detection of the changes in fresh tea leaves collected from April to September and the final processed product by high performance liquid chromatography (HPLC)-HRMS suggested that production of compounds 1 and 2 may be enhanced by the processing procedure of Zijuan green tea. Additionally, 1-4 were proposed to be synthesized through interaction between the abundant secondary metabolite ECG and phenolic acids from tea leaves by two key steps of phenol-dienone tautomerism. 1 and 2 showed impressive activity in protecting SH-SY5Y cells against H2O2-induced damage at the concentration of 1.0 µM.

Novel acetylcholinesterase inhibitors from Zijuan tea and biosynthetic pathway of caffeoylated catechin in tea plant.

Zijuan tea is a special cultivar of Yunnan broad-leaf tea (Camellia sinensis var. assamica) with purple buds, leaves, and stems. Phytochemical study on this tea led to the discovery of three hydroxycinnamoylated catechins (HCCs) (1-3), seven other catechins (4-10), three proanthocyanidins (11-13), five flavones and flavone glycosides (14-18), two alkaloids (19, 20), one steroid (21), and one phenylpropanoid glycoside (22). The isolation and structural elucidation of the caffeoylated catechin (1) by means of spectroscopic techniques were described. We also provide the first evidence that 1 is synthesized via a two-step pathway in tea plant. The three HCCs (1-3) were investigated on their bioactivity through molecular modeling simulation and biochemical experiments. Our results show that they bind acetylcholinesterase (AChE) tightly and have strong AChE inhibitory activity with IC50 value at 2.49, 11.41, 62.26µM, respectively.

Investigation on biochemical compositional changes during the microbial fermentation process of Fu brick tea by LC-MS based metabolomics.

Fu brick tea (FBT) is a unique post-fermented tea product which is fermented with fungi during the manufacturing process. In this study, we investigated the biochemical compositional changes occurring during the microbial fermentation process (MFP) of FBT based on non-targeted LC-MS, which was a comprehensive and unbiased methodology. Our data analysis took a two-phase approach: (1) comparison of FBT with other tea products using PCA analysis to exhibit the characteristic effect of MFP on the formation of Fu brick tea and (2) comparison of tea samples throughout the MFP of FBT to elucidate the possible key metabolic pathways produced by the fungi. Non-targeted LC-MS analysis clearly distinguished FBT with other tea samples and highlighted some interesting metabolic pathways during the MFP including B ring fission catechin. Our study demonstrated that those fungi had a significant influence on the biochemical profiles in the FBT and consequently contributed to its unique quality.

Comparison of cytotoxic extracts from fruiting bodies, infected insects and cultured mycelia of Cordyceps formosana.

A resazurin method was employed to test and compare cytotoxicity of extracts from fruiting bodies, insects and cultured mycelia of Cordyceps formosana against Chinese hamster ovary (CHO) cells. Results showed that the cultured mycelia had much stronger cytotoxicity than that of the fruiting bodies and infected insects. This suggests that using cultured mycelia to substitute a natural Cordyceps may result in poisoning. A combined method of HPLC-PAD-HRMS and cytotoxic analysis revealed that the most toxic compound (Compound 1) was found mainly in the cultured mycelia and also a small amount in the infected insect body of the Cordyceps, but not in the fruiting body. The second toxic compound (Compound 2) was found in all structures of Cordyceps and in cultured mycelia. Different contents of the toxic compounds resulted in the different cytotoxicity of the extracts. Compound 1 and Compound 2 were prepared with preparative HPLC as yellow and orange powders, respectively. Cytotoxic tests showed that the median lethal dose (LD50) against CHO cells of Compound 1 was 18.3 ± 0.2 and 103.7 ± 5.9 µg/mL for Compound 2. Compound 1 and Compound 2 were identified as rugulosin and skyrin by HRMS, UV and NMR data. The two compounds were never previously isolated from the genera Cordyceps and Hirsutella and their cytotoxicity against CHO cells was also reported for the first time.

EGCG inhibit chemical reactivity of iron through forming an Ngal-EGCG-iron complex.

Accumulated evidence indicates that the interconversion of iron between ferric (Fe(3+)) and ferrous (Fe(2+)) can be realized through interaction with reactive oxygen species in the Fenton and Haber-Weiss reactions and thereby physiologically effects redox cycling. The imbalance of iron and ROS may eventually cause tissue damage such as renal proximal tubule injury and necrosis. Many approaches were exploited to ameliorate the oxidative stress caused by the imbalance. (-)-Epigallocatechin-3-gallate, the most active and most abundant catechin in tea, was found to be involved in the protection of a spectrum of renal injuries caused by oxidative stress. Most of studies suggested that EGCG works as an antioxidant. In this paper, Multivariate analysis of the LC-MS data of tea extracts and binding assays showed that the tea polyphenol EGCG can form stable complex with iron through the protein Ngal, a biomarker of acute kidney injury. UV-Vis and Luminescence spectrum methods showed that Ngal can inhibit the chemical reactivity of iron and EGCG through forming an Ngal-EGCG-iron complex. In thinking of the interaction of iron and ROS, we proposed that EGCG may work as both antioxidant and Ngal binding siderphore in protection of kidney from injuries.

New limonoids and a dihydrobenzofuran norlignan from the roots of Toona sinensis.

Two new limonoids, toonins A (1) and B (2), and one new dihydrobenzofuran norlignan, toonin C (3), were isolated from the roots of Toona sinensis together with the ten known compounds 4-methoxy-6-(2',4'-dihydroxy-6'-methylphenyl)-pyran-2-one (4), bourjotinolone A (5), proceranone (6), matairesinol (7), 4-hydroxy-3-methoxybenzene-ethanol (8), syringic acid (9), isoscopoletin (10), lyoniresinol (11), aloeemodin (12), and ß-sitosterol (13). Their structures were elucidated on the basis of one- and two-dimensional spectroscopic analysis. Isolation of compounds 4, 6-13 from this plant is reported here for the first time.

Activity-guided isolation and identification of radical scavenging components in Gao-Cha tea.

Gao-Cha is a traditional Chinese health tea made from Acer ginnala. We performed a components and radical scavenging activity analysis to identify any medicinal components in this tea. High performance thin layer chromatography (HPTLC)-1,1-Diphenyl-2-picryhydrazyl (HPTLC-DPPH) assay showed that the methanolic extract contained strong radical scavengers. Quantitative analysis revealed that the IC(50) of the extract against 1 mM DPPH was 52.7 ± 0.6 µg/mL. Bioactive-guided isolations led to procurement of 3 radical scavengers with IC(50)s of 17.5 ± 2.1, 29.3 ± 2.5, and 21.6 ± 1.7 µg/mL, respectively. Analysis of the high resolution-electric spray ionization-mass spectrometer and (1)H, (13)C, distortionless enhancement by polarization transfer at 135°, heteronuclear quantum coherence, correlating spectroscopy coupling, and heteronuclear multiple bond coherence (HMBC) data revealed that the compounds were methyl 3, 4, 5-trihydroxybenzoate (1), quercetin-3-O-α-rhamnopyranoside (2), and 2,6-bis (3,4,5-trihydroxybenzoyl)-aceritol (3). Bioactive combined components analysis revealed that, apart from compounds 1, 2, and 3, the tea possibly contained radical scavengers: ginnalin A (4) and B (5), 2″-O-Galloylquercitrin (6) and 3″-O-Galloyl-quercitrin (7). Compounds 2, 6, and 7 were isolated from Acer ginnala for the first time. The positions of the 2 galloyl moieties in compound 3 were unambiguously established by the HMBC spectrum for the first time.