Pu-erh Tea Protects the Nervous System by Inhibiting the Expression of Metabotropic Glutamate Receptor 5

Bioactive components and mechanisms of Pu-erh tea in improving levodopa metabolism in rats through COMT inhibition

Catechol-O-methyltransferase (COMT) plays a central role in the metabolic inactivation of endogenous neurotransmitters and xenobiotic drugs and hormones having catecholic structures. Its inhibitors are used in clinical practice to treat Parkinson's disease. In this study, a fluorescence-based visualization inhibitor screening method was developed to assess the inhibition activity on COMT both in vitro and in living cells. Following the screening of 94 natural products, Pu-erh tea extract exhibited the most potent inhibitory effect on COMT with an IC50 value of 0.34 μg mL-1. In vivo experiments revealed that Pu-erh tea extract substantially hindered COMT-mediated levodopa metabolism in rats, resulting in a significant increase in levodopa levels and a notable decrease in 3-O-methyldopa in plasma. Subsequently, the chemical components of Pu-erh tea were analyzed using UHPLC-Q-Exactive Orbitrap HRMS, identifying 24 major components. Among them, epigallocatechin gallate, gallocatechin gallate, epicatechin gallate, and catechin gallate exhibited potent inhibition of COMT activity with IC50 values from 93.7 nM to 125.8 nM and were the main bioactive constituents in Pu-erh tea responsible for its COMT inhibition effect. Inhibition kinetics analyses and docking simulations revealed that these compounds competitively inhibit COMT-mediated O-methylation at the catechol site. Overall, this study not only explained how Pu-erh tea catechins inhibit COMT, suggesting Pu-erh tea as a potential dietary intervention for Parkinson's disease, but also introduced a new strategy for discovering COMT inhibitors more effectively.

Metabotropic glutamate receptors (mGluRs) in epileptogenesis: an update on abnormal mGluRs signaling and its therapeutic implications

Epilepsy is a neurological disorder characterized by high morbidity, high recurrence, and drug resistance. Enhanced signaling through the excitatory neurotransmitter glutamate is intricately associated with epilepsy. Metabotropic glutamate receptors (mGluRs) are G protein-coupled receptors activated by glutamate and are key regulators of neuronal and synaptic plasticity. Dysregulated mGluR signaling has been associated with various neurological disorders, and numerous studies have shown a close relationship between mGluRs expression/activity and the development of epilepsy. In this review, we first introduce the three groups of mGluRs and their associated signaling pathways. Then, we detail how these receptors influence epilepsy by describing the signaling cascades triggered by their activation and their neuroprotective or detrimental roles in epileptogenesis. In addition, strategies for pharmacological manipulation of these receptors during the treatment of epilepsy in experimental studies is also summarized. We hope that this review will provide a foundation for future studies on the development of mGluR-targeted antiepileptic drugs.

Biological Potential and Mechanisms of Tea's Bioactive Compounds in Tea: 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 The aim of this paper is to summarize the 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 to 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.

Simultaneous Determination of Pesticide Residues and Mycotoxins in Storage Pu-erh Tea Using Ultra-High-Performance Liquid Chromatography Coupled with Tandem Mass Spectrometry

Mycotoxins and pesticides are the most concerning chemical contaminants that can affect the quality of Pu-erh tea during its production and storage. This study presents a method that can simultaneously determine 31 pesticide residues and six mycotoxins in Pu-erh tea within 11 min using ultra-high-performance liquid chromatography coupled with tandem mass spectrometry (UPLC-MS/MS) after QuEChERS extraction. The lower limit of quantification (LOQ) for all analytes ranged between 0.06 and 50 ppb. Recoveries for each pesticide and mycotoxin ranged between 62.0 and 130.3%, with intra- and inter-day precisions lower than 15%. Good linear relationships were obtained, with correlation coefficients of r2 > 0.991 for all analytes. The established method was applied to 31 Pu-erh tea samples, including raw and ripened Pu-erh tea with different storage times. As a result, pesticide residues were not detected in any of the collected samples, and the mycotoxins detected in the samples were well below the official maximum residue limits (MRLs). Notably, the levels of aflatoxin B1 (AFB1), aflatoxin G1 (AFG1) and aflatoxin G2 (AFG2) were lower than 1 ppb in the samples stored for more than 30 years.

Pathophysiological mechanism and natural preventive and therapeutic strategies of Alzheimer's disease

Alzheimer's disease (AD) is characterized by the presence of two types of protein deposits in the brain, amyloid plaques and neurofibrillary tangles. The first one are dense deposits of beta amyloid protein, the second one are dense deposits of the protein tau. These proteins are present in all of our brains, but in AD they act unusually, leading to neuronal degeneration. This review will provide an overview of the AD, including the role of amyloid beta and tau, and mechanisms that lead to the formation of plaques and tangles. The review will also cover the existing researches that have focused on the inhibition of amyloid beta formation, cholinesterase, tau hyperphosphorylation, the pathogenic mechanisms of apoE4, and GSK-3 as a solution that could be used to slow or prevent the disease.

Tea intake or consumption and the risk of dementia: a meta-analysis of prospective cohort studies

Purpose

Dementia affects as many as 130 million people, which presents a significant and growing medical burden globally. This meta-analysis aims to assess whether tea intake, tea consumption can reduce the risk of dementia, Alzheimer's disease (AD) and Vascular dementia (VD).

Patients and methods

Cochrane Library, PubMed and Embase were searched for cohort studies from inception to November 1, 2022. The Newcastle Ottawa Quality Assessment Scale (NOS) was applied to evaluate the risk of bias of the included studies. We extracted the data as the relative risks (RRs) for the outcome of the interest, and conducted the meta-analysis utilizing the random effect model due to the certain heterogeneity. Sensitivity analysis were performed by moving one study at a time, Subgroup-analysis was carried out according to different ages and dementia types. And the funnel plots based on Egger's and Begger's regression tests were used to evaluate publication bias. All statistical analyses were performed using Stata statistical software version 14.0 and R studio version 4.2.0.

Results

Seven prospective cohort studies covering 410,951 individuals, which were published from 2009 and 2022 were included in this meta-analysis. The methodological quality of these studies was relatively with five out of seven being of high quality and the remaining being of moderate. The pooling analysis shows that the relationship between tea intake or consumption is associated with a reduced risk of all-cause dementia (RR = 0.71, 95% CI [0.57-0.88], I² = 79.0%, p < 0.01). Further, the subgroup-analysis revealed that tea intake or consumption is associated with a reduced risk of AD (RR = 0.88, 95% CI [0.79-0.99], I² = 52.6%, p = 0.024) and VD (RR = 0.75, 95% CI [0.66-0.85], I = 0.00%, p < 0.001). Lastly, tea intake or consumption could reduce the risk of all-cause dementia to a greater degree among populations with less physical activity, older age, APOE carriers, and smokers.

Conclusion

Our meta-analysis demonstrated that tea (green tea or black tea) intake or consumption is associated with a significant reduction in the risk of dementia, AD or VD. These findings provide evidence that tea intake or consumption should be recognized as an independent protective factor against the onset of dementia, AD or VD.

Antioxidative polyphenols attenuate pyocyanin-induced ROS production in neuronal HT22 cell lines

Pyocyanin, a secreted virulence factor, plays an essential role during Pseudomonas aeruginosa infection. Infection of the central nervous system by this bacterium results in high mortality, but the studies on its mechanism are still rather limited. In this study, we first evaluate the neuronal damage caused by pyocyanin exposure in neuronal HT22 cells. Pyocyanin leads to mitochondrial syndrome and antioxidant defense disruption, therefore increasing intercellular reactive oxygen species (ROS) production. Several typical superior antioxidant polyphenols effectively protect against pyocyanin-induced neuronal cell damage. These findings suggest the neuronal protective activity more or less relies on the structure, rather than the residues. Pre-incubation of catechin activates the essential pathway, indicating inverse correlation of ERK and AMPK phosphorylation participates in this process. These data outline a novel strategy to eliminate intracellular generated ROS. The investigated candidates could be potentially used as therapeutic agents against various ROS-related neurological diseases.

Flavor perception and health benefits of tea

As one of the most consumed non-alcoholic beverages in the world, tea is acclaimed for its pleasant flavor and various health benefits. Different types of tea present a distinctive flavor and bioactivity due to the changes in the composition and proportion of respective compounds. This article aimed to provide a more comprehensive understanding of tea flavor (including aroma and taste) and the character of tea in preventing and alleviating diseases. The recent advanced modern analytical techniques for revealing flavor components in tea, including enrichment, identification, quantitation, statistics, and sensory evaluation methodologies, were summarized in the following content. Besides, the role of tea in anti-cancer, preventing cardiovascular disease and metabolic syndrome, anti-aging and neuroprotection, and regulating gut microbiota was also listed in this article. Moreover, questions and outlooks were mentioned to objectify tea products' flavor quality and health benefits on a molecular level and significantly promote our understanding of the comprehensive value of tea as a satisfactory health beverage in the future.

The medicinal value of tea drinking in the management of COVID-19

Corona Virus Disease 2019 (COVID-19) is presently the largest international public health event, individuals infected by the virus not only have symptoms such as fever, dry cough, and lung infection at the time of onset, but also possibly have sequelae in the cardiovascular system, respiratory system, nervous system, mental health and other aspects. However, numerous studies have depicted that the active ingredients in tea show good antiviral effects and can treat various diseases by regulating multiple pathways, and the therapeutic effects are associated with the categories of chemical components in tea. In this review, the differences in the content of key active ingredients in different types of tea are summarized. In addition, we also highlighted their effects on COVID-19 and connected sequelae, further demonstrating the possibility of developing a formulation for the prevention and treatment of COVID-19 and its sequelae through tea extracts. We have a tendency to suggest forestalling and treating COVID-19 and its sequelae through scientific tea drinking.

Can habitual tea drinking be an effective approach against age-related neurodegenerative cognitive disorders: A systematic review and meta-analysis of epidemiological evidence

Our present knowledge about the efficacy of tea consumption in improving age-related cognitive disorders is incomplete since previous epidemiological studies provide inconsistent evidence. This unified systematic review and meta-analysis based on updated epidemiological cohort studies and randomized controlled trials (RCTs) evidence aimed to overcome the limitations of previous reviews by examining the efficacy of distinct types of tea consumption. PubMed, Embase, and MEDLINE were searched up to May 20, 2022, and 23 cohorts and 12 cross-sectional studies were included. Random-effects meta-analyses were conducted to obtain pooled RRs or mean differences with 95% CIs. The pooled RRs of the highest versus lowest tea consumption categories were 0.81 (95% CIs: 0.75-0.88) and 0.69 (95% CIs: 0.61-0.77), respectively. The pooled mean difference of four included RCTs revealed a beneficial effect of tea on cognitive dysfunction (MMSE ES: 1.03; 95% CI, 0.14-1.92). Subgroup analyses further demonstrated that green and black tea intake was associated with a lower risk of cognitive disorders in eastern countries, especially in women. The evidence quality was generally low to moderate. The present review provides insight into whether habitual tea consumption can be an effective approach against age-related neurodegenerative cognitive disorders and summarizes potential mechanisms based on currently published literature.

Investigation and dynamic profiling of oligopeptides, free amino acids and derivatives during Pu-erh tea fermentation by ultra-high performance liquid chromatography tandem mass spectrometry

Microbial fermentation is the critical step of Pu-erh tea manufacture, which will induce dramatic changes in the chemical composition and content of tea. In this research, we applied multi-methods based on UHPLC-Q-TOF/MS to profile the dynamic changes of oligopeptides, free amino acids, and derivatives (OPADs) during Pu-erh fermentation and predicted the potential bioactivities in silico. A total of 60 oligopeptides, 18 free amino acids, and 42 amino acid derivatives were identified, and the contents of most of them decreased after fermentation. But several N-acetyl amino acids increased 7-36 times after fermentation, and they might be the potential inhibitors of neurokinin-1 receptor. Moreover, the results of metamicrobiology showed Aspergillus niger and Aspergillus luchuensis were more prominent to metabolize protein, oligopeptides, and amino acids. Overall, these findings provide valuable insights about dynamic variations of OPADs during Pu-erh tea fermentation and are beneficial for guiding practical fermentation and quality control of Pu-erh tea.

Caffeinated drinks, fruit juices, and epilepsy: A systematic review

The aim of this systematic review was to provide the required information regarding different aspects of the relationship between epilepsy/antiseizure medications and non-alcoholic drinks. The recommendations of the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) statement were followed. MEDLINE and Scopus from the inception until 7 August 2021 were systematically searched. These key words were used: "epilepsy" OR "seizure" OR "antiepileptic" OR "antiseizure" OR "anticonvulsant" AND "coffee" OR "tea" OR "soda" OR "juice" OR "drink" OR "cola" OR "diet" (35 key word combinations). The primary search yielded 21 458 publications (PubMed, n = 4778; Scopus, n = 16 680). Only 50 studies met all the inclusion criteria and were included in the current systematic review. In total, 17 articles investigated various non-alcoholic drinks in human studies, 11 studies were case reports/series, and 22 articles were animal/in vitro studies. None of the studies provided a class 1 of evidence. There is limited evidence suggesting that certain drinks (eg, caffeinated energy drinks) might trigger seizures. Patients with epilepsy should avoid excessive consumption of certain fruit juices (eg, grapefruit, lime, pomegranate, kinnow, and star fruit) and caffeinated drinks. However, daily coffee and tea intake can be part of a healthy balanced diet, and their consumption does not need to be stopped in patients with epilepsy. Coffee/tea consumption is not harmful if consumed at levels of 200 mg (caffeine) in one sitting (about 2½ cups of coffee) or 400 mg daily (about five cups of coffee).

A Novel Role of A2AR in the Maintenance of Intestinal Barrier Function of Enteric Glia from Hypoxia-Induced Injury by Combining with mGluR5

During acute intestinal ischemia reperfusion (IR) injury, the intestinal epithelial barrier (IEB) function is often disrupted. Enteric glial cells (EGCs) play an important role in maintaining the integrity of IEB functions. However, how EGCs regulate IEB function under IR stimulation is unknown. The present study reveals that the adenosine A_2A receptor (A_2AR) is important for mediating the barrier-modulating roles of EGCs. A_2AR knockout (KO) experiments revealed more serious intestinal injury in A_2AR KO mice than in WT mice after IR stimulation. Moreover, A_2AR expression was significantly increased in WT mice when challenged by IR. To further investigate the role of A_2AR in IEB, we established an in vitro EGC-Caco-2 co-culture system. Hypoxia stimulation was used to mimic the process of in vivo IR. Treating EGCs with the CGS21680 A_2AR agonist attenuated hypoxia-induced intestinal epithelium damage through up-regulating ZO-1 and occludin expression in cocultured Caco-2 monolayers. Furthermore, we showed that A_2AR and metabotropic glutamate receptor 5 (mGluR5) combine to activate the PKCα-dependent pathway in conditions of hypoxia. This study shows, for the first time, that hypoxia induces A_2AR-mGluR5 interaction in EGCs to protect IEB function via the PKCα pathway.

Pu-erh tea ameliorates obesity and modulates gut microbiota in high fat diet fed mice

Obesity is regarded to be associated with fat accumulation, chronic inflammation, and gut microbiota dysbiosis. Raw and ripened pu-erh tea extract (PETe) have the effect of reducing body weight gain and fat accumulation, which are associated with gut microbiota. However, little is known about the difference of raw and ripened PETe on the regulation of gut microbiota. Here, our results suggested that supplementation of raw and ripened PETe displayed similar anti-obesogenic effect in high fat diet (HFD)-induced obesity mice, by attenuating the body weight gain, fat accumulation, oxidative injury, and low-grade inflammation, improving the glucose tolerance, alleviating the metabolic endotoxemia, and regulating the mRNA and protein expression levels of the lipid metabolism-related genes. 16S rRNA sequencing of fecal samples indicated that raw and ripened PETe intervention displayed different regulatory effect on the HFD-induced gut microbiota dysbiosis at different taxonomic levels. The microbial diversity, the relative abundance of Firmicutes and Bacteroidetes as well as F/B ratio were reversed more closer to normal by ripened PETe. Phylotypes of Bacteroidaceae, Ruminococcaceae, Lachnospiraceae, Muribaculaceae, and Rikenellaceae which are negatively correlated with obesity were enhanced notably by the intervention of ripened PETe, while Erysipelotrichaceae and Lactobacillaceae which have positive correlation with obesity were decreased dramatically. In addition, the treatment of ripened PETe had better effect on the increase of benefical Bacteroides, Alistipes, and Akkemansia and decrease of obesity associated Faecalibaculum and Erysipelatoclostridium (p < 0.05). These findings suggested that pu-erh tea especially ripened pu-erh tea could serve as a great candidate for alleviation of obesity in association with the modulation of gut microbiota.

Novel pentacyclic triterpenes exhibiting strong neuroprotective activity in SH-SY5Y cells in salsolinol- and glutamate-induced neurodegeneration models

Novel triterpene derivatives were prepared and evaluated in salsolinol (SAL)- and glutamate (Glu)-induced models of neurodegeneration in neuron-like SH-SY5Y cells. Among the tested compounds, betulin triazole 4 bearing a tetraacetyl-β-d-glucose substituent showed a highly potent neuroprotective effect. Further studies revealed that removal of tetraacetyl-β-d-glucose part (free triazole derivative 10) resulted in strong neuroprotection in the SAL model at 1 μM, but this derivative suffered from cytotoxicity at higher concentrations. Both compounds modulated oxidative stress and caspase-3,7 activity, but 10 showed a superior effect comparable to the Ac-DEVD-CHO inhibitor. Interestingly, while both 4 and 10 outperformed the positive controls in blocking mitochondrial permeability transition pore opening, only 4 demonstrated potent restoration of the mitochondrial membrane potential (MMP) in the model. Derivatives 4 and 10 also showed neuroprotection in the Glu model, with 10 exhibiting the strongest oxidative stress reducing effect among the tested compounds, while the neuroprotective activity of 4 was probably due recovery of the MMP.

Cytokinin Plant Hormones Have Neuroprotective Activity in In Vitro Models of Parkinson's Disease

Cytokinins are adenine-based phytohormones that regulate key processes in plants, such as cell division and differentiation, root and shoot growth, apical dominance, branching, and seed germination. In preliminary studies, they have also shown protective activities against human neurodegenerative diseases. To extend knowledge of the protection (protective activity) they offer, we investigated activities of natural cytokinins against salsolinol (SAL)-induced toxicity (a Parkinson's disease model) and glutamate (Glu)-induced death of neuron-like dopaminergic SH-SY5Y cells. We found that kinetin-3-glucoside, cis-zeatin riboside, and N6-isopentenyladenosine were active in the SAL-induced PD model. In addition, trans-, cis-zeatin, and kinetin along with the iron chelator deferoxamine (DFO) and the necroptosis inhibitor necrostatin 1 (NEC-1) significantly reduced cell death rates in the Glu-induced model. Lactate dehydrogenase assays revealed that the cytokinins provided lower neuroprotective activity than DFO and NEC-1. Moreover, they reduced apoptotic caspase-3/7 activities less strongly than DFO. However, the cytokinins had very similar effects to DFO and NEC-1 on superoxide radical production. Overall, they showed protective activity in the SAL-induced model of parkinsonian neuronal cell death and Glu-induced model of oxidative damage mainly by reduction of oxidative stress.

The synthesis and cholinesterase inhibitory activities of solasodine analogues with seven-membered F ring

Solasodine analogues containing a seven-membered F ring with a nitrogen atom placed at position 22a were prepared from diosgenin or tigogenin in a four-step synthesis comprising of the simultaneous opening of the F-ring and introduction of cyanide in position 22α, activation of the 26-hydroxyl group as mesylate, nitrile reduction, and N-cyclization. Solasodine, six obtained 22a(N)-homo analogues, as well as four 26a-homosolasodine derivatives and their open-chain precursors (13 in total) were tested as potential inhibitors of acetyl- and butyryl-cholinesterases and showed activity at micromolar concentrations. The structure-activity relationship study revealed that activities against studied esterases are affected by the structure of E/F rings and the substitution pattern of ring A. The most potent compound 8 acted as non-competitive inhibitors and exerted IC₅₀ = 8.51 μM and 7.05 μM for eeAChE and eqBChE, respectively. Molecular docking studies revealed the hydrogen bond interaction of 8 with S293 of AChE; further rings are stabilized via hydrophobic interaction (ring A) or interaction with Y341 and W286 (rings B and C). Biological experiments showed no neurotoxicity of differentiated SH-SY5Y cells. More importantly, results from neuroprotective assay based on glutamate-induced cytotoxicity revealed that most derivatives had the ability to increase the viability of differentiated SH-SY5Y cells in comparison to galantamine and lipoic acid assayed as standards. The newly synthesized solasodine analogues are able to inhibit and to bind cholinesterases in noncompetitive mode of inhibition and exhibited neuroprotection potential of differentiated neuroblastoma cells after Glu-induced toxicity.

Integrated proteomics and metabolomics analysis of tea leaves fermented by Aspergillus niger, Aspergillus tamarii and Aspergillus fumigatus

Post-fermented Pu-erh tea (PFPT) is a microbially-fermented tea with distinct sensory qualities and multiple health benefits. Aspergillus are the dominant fungi in the fermentation and the main contributors to the characteristics of PFPT, so their underlying functions warrant detailed study. Here, tea leaves were fermented by Aspergillus niger, Aspergillus tamarii and Aspergillus fumigatus, and resulting samples (designated as Asn, Ast and Asf, respectively) were analyzed by proteomic and metabolomic methods. Changes to the composition of flavonoids, glycerophospholipids, organo-oxygen compounds and fatty acids resulting from Aspergillus fermentation were observed. Carbohydrate-active enzymes, e.g., endoglucanases and cellulases, for degradation of cellulose, starch, lignin, pectin, xylan and xyloglucan were identified. Glycoside hydrolase, glycosyltransferases, tannase, laccases, vanillyl-alcohol oxidases and benzoquinone reductase were identified and hypothesized to catalyze hydrolysis, oxidation, polymerization and degradation of phenolic compounds. Together, functions of Aspergillius were demonstrated as production of enzymes to change concentrations and compositions of metabolites in tea leaves.

The Impact of Dietary Supplementation of Whole Foods and Polyphenols on Atherosclerosis

The purpose of this review is to highlight current research on the benefits of supplementation with foods with a diverse polyphenol composition, including fruits, vegetables, nuts, grains, oils, spices, and teas in blunting atherosclerosis. We searched PubMed for publications utilizing whole food or polyphenols prepared from whole foods in Apolipoprotein E (ApoE) or Low-Density Lipoprotein Receptor (LDLR) knockout mice, and identified 73 studies in which plaque was measured. The majority of the studies reported a reduction in plaque. Nine interventions showed no effect, while three using Agaricus blazei mushroom, HYJA-ri-4 rice variety, and safrole-2', 3'-oxide (SFO) increased plaque. The mechanisms by which atherosclerosis was reduced include improved lipid profile, antioxidant status, and cholesterol clearance, and reduced inflammation. Importantly, not all dietary interventions that reduce plaque showed an improvement in lipid profile. Additionally, we found that, out of 73 studies, only 9 used female mice and only 6 compared both sexes. Only one study compared the two models (LDLR vs. ApoE), showing that the treatment worked in one but not the other. Not all supplementations work in both male and female animals, suggesting that increasing the variety of foods with different polyphenol compositions may be more effective in mitigating atherosclerosis.

Natural compounds attenuate heavy metal-induced PC12 cell damage

Objectives

To investigate the neuroprotective effects of six natural compounds (caffeine, gallic acid, resveratrol, epigallocatechin gallate [EGCG], L-ascorbic acid and alpha tocopherol [Vitamin E] on heavy metal-induced cell damage in rat PC12 cells.

Methods

In this in vitro experiment, rat PC12 cells were exposed to four heavy metals (CdCl₂, HgCl₂, CoCl₂ and PbCl₂) at different concentrations and cell apoptosis, necrosis and oxidative stress were assessed with and without the addition of the six natural compounds.

Results

The metals decreased cell viability but the natural compounds attenuated their effects on apoptosis, necrosis and reactive oxygen species (ROS) levels. Mitochondrial protein changes were involved in the regulation.

Conclusion

Overall, the natural compounds did provide protection against the metal-induced PC12 cell damage. These data suggest that natural compounds may have therapeutic potential against metal-induced neurodegenerative disease.

Comparison of Potent Odorants in Raw and Ripened Pu-Erh Tea Infusions Based on Odor Activity Value Calculation and Multivariate Analysis: Understanding the Role of Pile Fermentation

Infusions prepared from raw pu-erh tea (RAPT) and ripened pu-erh tea (RIPT) showed remarkable aroma differences. Predominant odorants in RAPT and RIPT infusions were identified and compared by the combined use of gas chromatography-olfactometry, aroma extract dilution analysis, odor activity values (OAVs), and multivariate analysis. A total of 35 and 19 odorants (OAV > 1) were detected in RIPT and RAPT, respectively. Odorants in RAPT and RIPT are significantly different in both odor properties and aroma compound intensities. Overall, RAPT contained a complex variety of chemical classes with diverse odors and moderate odor intensities, while RIPT is dominated by structurally and organoleptically similar compounds with high potency. Specifically, stale and musty smelling methoxybenzenes contributed the most to RIPT, while floral-, sweet-, and woody-smelling terpene alcohols, terpene ketones, and phenolic compounds were the predominant odorants in RAPT. Orthogonal partial least squares discriminant analysis revealed that linalool, α-ionone, 1,2,4-trimethoxybenzene, 1,2,3-trimethoxy-5-methylbenzene, 1,2,3,4-tetramethoxybenzene, and 1,2,3-trimethoxybenzene underwent remarkable changes during pile fermentation and could be used as potential odor-active markers for RIPT and RAPT discrimination. The comprehensive aroma characterization of pu-erh tea and determination of the effect of pile fermentation on odorant alteration herein will provide guidance for pu-erh tea flavor quality control and evaluation.

MAPK Pathway Inhibitors Attenuated Hydrogen Peroxide Induced Damage in Neural Cells

Background

Oxidative stress due to reactive oxygen species plays a central role in pathophysiology of neurodegenerative diseases. Inhibition of mitogen-activated protein kinase (MAPK) cascades attenuates the oxidative induced cell stress and behaves as potential neuroprotection agent.

Materials and Methods

In this study, we evaluate hydrogen peroxide induced neural cell stress and determine how different MAPK inhibitors restore the cell damage.

Results

The results indicated that oxidative stress induced by neural cell damage commonly exists, and MAPK inhibitors partially and selectively attenuated the cell damage by reducing ROS production and cell apoptosis. The cultured neurons are more susceptible to hydrogen peroxide than subculture cells.

Conclusion

We conclude that the essential role of different MAPK inhibitors is to attenuate the hydrogen peroxide induced neuronal cell damage. Those data broaden the implication between individual neural cells and different MAPK inhibitors and give clues for oxidative stress induced neural diseases.

Ripe and Raw Pu-Erh Tea: LC-MS Profiling, Antioxidant Capacity and Enzyme Inhibition Activities of Aqueous and Hydro-Alcoholic Extracts

Herein, we reported a detailed profiling of soluble components of two fermented varieties of Chinese green tea, namely raw and ripe pu-erh. The identification and quantification of the main components was carried out by means of mass spectrometry and UV spectroscopy, after chromatographic separation. The antioxidant capacity towards different radical species, the anti-microbial and the enzyme inhibition activities of the extracts were then correlated to their main constituents. Despite a superimposable qualitative composition, a similar caffeine content, and similar enzyme inhibition and antimicrobial activities, raw pu-erh tea extract had a better antioxidant capacity owing to its higher polyphenol content. However, the activity of raw pu-erh tea seems not to justify its higher production costs and ripe variety appears to be a valid and low-cost alternative for the preparation of products with antioxidant or antimicrobial properties.

Attenuated glutamate induced ROS production by antioxidative compounds in neural cell lines

Glutamate is an excitatory neurotransmitter involved in neural function. Excess accumulation of intercellular glutamate leads to increasing concentration of reactive oxygen species (ROS) and reactive nitrogen species (RNS) in neuronal cells. In this study, we investigated the antioxidant activity of several typical superior compounds among four neuronal cells, and determined the scavenging activity of free radicals. The in vivo assay was also carried out to compare the protective effect of glutamate-induced cell damage. Hierarchical clustering analysis was used to identify the common properties. Glutamate induced neurotoxicity and ROS production, suggesting glutamate cytotoxicity was related to oxidative stress and widely exists in different cell lines. Those screening compounds exhibited strong antioxidant ability, but low cytotoxicity to neuronal cells, acting as agents against neurodegenerative diseases. Finally, a hierarchical clustering analysis assay indicated that hyperoside and rutin hydrate are the most effective compounds for attenuating intercellular ROS levels. The results suggested the activity more or less relies on structure, rather than residues. These data generate new supporting ideas to remove intracellular ROS and the identified compounds serve as potential therapeutic agents in multiple neurological diseases.

Glutamate is an excitatory neurotransmitter involved in neural function.

Epigallocatechin Gallate Is the Most Effective Catechin Against Antioxidant Stress via Hydrogen Peroxide and Radical Scavenging Activity

Background

Hydrogen peroxide-induced neuronal oxidative stress is a serious threat to the nervous system. Catechins and related compounds are effective radical scavengers that protect against nerve cell damage.

Material/Methods

Here, we investigated the antioxidant property of various catechins in protecting against hydrogen peroxide, as well as their radical-scavenging activity.

Result

We found that catechins treatment effectively protected HT22 cells against H₂O₂-induced cell viability by decreasing and attenuating reactive oxidative species production in different proportions. In addition, all tested catechins performed radical scavenging activity, and partially removed the free radicals. Among all investigated catechins, epigallocatechin gallate was the most effective against ROS production and had the strongest radical-scavenging activity. These results suggest that beneficial effects were strongly related with structure of catechins, mainly because of the hydroxyl and galloyl groups.

Conclusions

In conclusion, epigallocatechin gallate is the most effective antioxidant polyphenol against hydrogen peroxide and radical-scavenging activity.

Pu-erh Tea Extract Ameliorates Ovariectomy-Induced Osteoporosis in Rats and Suppresses Osteoclastogenesis In Vitro

Background and Objective: Tea drinking is associated with positive effects on bone health and may protect against osteoporosis, especially in elderly women. Pu-erh tea has many beneficial effects on human health; however, whether Pu-erh tea has anti-osteoporotic potential remains unclear. Thus, we investigated the effects of Pu-erh tea extract (PTE) on ovariectomy-induced osteoporosis in rats and on osteoclastogenesis in vitro.

Methods: Female Wistar rats were divided into six groups: the sham, model, and Xian-Ling-Gu-Bao capsule (XLGB) groups, and the low-, medium-, and high-dose PTE groups. Ovariectomized (OVX) rats were used as an animal model of osteoporosis. The animals were intragastrically administered distilled water, XLGB, or different concentrations of PTE for 13 weeks. Body weight, blood biochemical indicators, relative organ coefficients, femoral bone mineral density (BMD), bone biomechanical properties, and bone microarchitecture were examined and analyzed. Additionally, the in vitro effects of PTE on osteoclastic activities were investigated using the RAW 264.7 cell line as an osteoclast differentiation model. The effects of PTE on osteoclast differentiation and the expression of osteoclast-specific genes and proteins were determined.

Results: PTE reduced OVX-induced body weight gain after 6 weeks of treatment, and the high-dose exerted a significant effect. High-dose PTE significantly ameliorated OVX-induced estradiol (E₂) deficiency. PTE treatment maintained calcium and phosphorus homeostasis and improved other blood biochemical parameters to various degrees. In addition, PTE treatment improved organ coefficients of the femur, uterus, and vagina and improved femoral BMD and bone biomechanical properties. PTE treatment strikingly ameliorated bone microarchitecture. Moreover, in the in vitro studies, osteoclast differentiation using the differentiation cell model was significantly inhibited by PTE without cytotoxic effects. Additionally, PTE efficaciously suppressed the expression of key osteoclast-specific genes and proteins.

Conclusion: PTE can ameliorate ovariectomy-induced osteoporosis in rats and suppress osteoclastogenesis in vitro.