Neuroprotective Effects of Theaflavins Against Oxidative Stress-Induced Apoptosis in PC12 Cells

Medicinal herbal remedies in neurodegenerative diseases: an update on antioxidant potential

It has been widely documented that medicinal herbal remedies are effective, have fewer side effects than conventional medicine, and have a synergistic effect on health collaborations in the fight against complicated diseases. Traditional treatments for neurological problems in ancient times sometimes involved the use of herbal remedies and conventional methods from East Asian countries including India, Japan, China, and Korea. We collected and reviewed studies on plant-derived neuroprotective drugs and tested them in neurotoxic models. Basic research, preclinical and clinical transgene research can benefit from in silico, in vitro, and in vivo investigations. Research, summaries of the extracts, fractions, and herbal ingredients were compiled from popular scientific databases, which were then examined according to origin and bioactivity. Given the complex and varied causes of neurodegeneration, it may be beneficial to focus on multiple mechanisms of action and a neuroprotection approach. This approach aims to prevent cell death and restore function to damaged neurons, offering promising strategies for preventing and treating neurodegenerative diseases. Neurodegenerative illnesses can potentially be treated with natural compounds that have been identified as neuroprotective agents. To gain deeper insights into the neuropharmacological mechanisms underlying the neuroprotective and therapeutic properties of naturally occurring antioxidant phytochemical compounds in diverse neurodegenerative diseases, this study aims to comprehensively review such compounds, focusing on their modulation of apoptotic markers such as caspase, Bax, Bcl-2, and proinflammatory markers. In addition, we delve into a range of efficacies of antioxidant phytochemical compounds as neuroprotective agents in animal models. They reduce the oxidative stress of the brain and have been shown to have anti-apoptotic effects. Many researches have demonstrated that plant extracts or bioactive compounds can fight neurodegenerative disorders. Herbal medications may offer neurodegenerative disease patients' new treatments. This may be a cheaper and more culturally appropriate alternative to standard drugs for millions of people with age-related NDDs.

In silico and in vivo discovery of antioxidant sea cucumber peptides with antineurodegenerative properties

Since oxidative stress is often associated with neurodegenerative diseases, antioxidants are likely to confer protection against neurodegeneration. Despite an increasing number of food-derived peptides being identified as antioxidants, their antineurodegenerative potentials remain largely unexplored. Here, a sea cucumber peptide preparation - the peptide-rich fraction of <3 kDa (UF<3K) obtained by ultrafiltration from Apostichopus japonicus protein hydrolyzate - was found to protect PC12 cells and Caenorhabditis elegans from neurodegeneration by reducing oxidative stress and apoptosis, demonstrating its in vitro and in vivo neuroprotective effects. As many food-originated peptides are cryptides (cryptic peptides - short amino acid sequences encrypted in parent proteins) released in quantities by protein hydrolysis, UF<3K was subjected to sequencing analysis. As expected, a large repertoire of peptides were identified in UF<3K, establishing a sea cucumber cryptome (1238 peptides in total). Then 134 peptides were randomly selected from the cryptome (>10%) and analyzed for their antioxidant activities using a number of in silico bioinformatic programs as well as in vivo experimental assays in C. elegans. From these results, a novel antioxidant peptide - HoloPep#362 (FETLMPLWGNK) - was shown to not only inhibit aggregation of neurodegeneration-associated polygluatmine proteins but also ameliorate behavioral deficits in proteotoxicity nematodes. Proteomic analysis revealed an increased expression of several lysosomal proteases by HoloPep#362, suggesting proteostasis maintenance as a mechanism for its antineurodegenerative action. These findings provide an insight into the health-promoting potential of sea cucumber peptides as neuroprotective nutraceuticals and also into the importance of training in silico peptide bioactivity prediction programs with in vivo experimental data.

Theaflavine inhibits hepatic stellate cell activation by modulating the PKA/LKB1/AMPK/GSK3β cascade and subsequently enhancing Nrf2 signaling

Activation of hepatic stellate cells (HSCs) constitutes a crucial etiological factor leading to liver fibrosis. Theaflavine (TF) is a characteristic bioactive compound in fermented tea. Here, we found that TF attenuated the activation of LX-2 HSCs induced by transforming growth factor-β1 (TGF-β1). TF potentiated nuclear factor erythroid 2-related Factor 2 (Nrf2) signaling. Knockdown of Nrf2 abrogated TF-mediated resistance to TGF-β1. Liver kinase B1 (LKB1), AMP-activated kinase (AMPK), and glycogen synthase kinase-3β (GSK3β) are upstream regulators of Nrf2. TF modulated the LKB1/AMPK/GSK3β axis. Inhibition of AMPK or knockdown of LKB1 crippled TF-mediated potentiation of Nrf2. Protein kinase A (PKA) catalyzes LKB1 phosphorylation. In LX-2 cells, TF increased the LKB1/PKA interaction without affecting their contents. Inhibition of PKA abolished TF-mediated potentiation of LKB1/Nrf2 and abrogated the inhibitory effects of TF on their activation. TF also enhanced direct binding between purified catalytic subunit α of PKA (PKA-Cα) and LKB1 proteins in vitro. Molecular docking indicated that TF showed binding activity with both LKB1 and PKA-Cα proteins. In mouse primary HSCs, TF elevated LKB1/PKA-Cα binding, boosted LKB1 phosphorylation, potentiated Nrf2 and suppressed their spontaneous activation. PKA inhibition or LKB1 knockdown eliminated TF-mediated induction of Nrf2 and suppression of HSC activation. Furthermore, TF considerably alleviated CCl4-induced mouse liver fibrosis. In mouse livers, TF increased the LKB1/PKA-Cα interaction, upregulated LKB1 phosphorylation and modulated its downstream AMPK/GSK3β/Nrf2 cascade. Our findings collectively indicated that TF suppresses HSC activation. Mechanistically, TF elevated the LKB1/PKA interaction in HSCs, which increased LKB1 phosphorylation and subsequently modulated the downstream AMPK/GSK3β/Nrf2 axis.

Theaflavin-3,3'-digallate ameliorates learning and memory impairments in mice with premature brain aging induced by D-galactose

Age-related neurodegenerative diseases accompanied by learning and memory deficits are growing in prevalence due to population aging. Cellular oxidative stress is a common pathomechanism in multiple age-related disorders, and various antioxidants have demonstrated therapeutic efficacy in patients or animal models. Many plants and plant extracts possess potent antioxidant activity, but the compounds responsible are frequently unknown. Identification and evaluation of these phytochemicals is necessary for optimal targeted therapy. A recent study identified theaflavin-3,3'-digallate (TFDG) as the most potent among a large series of phytochemical antioxidants. Here we examined if TFDG can mitigate learning and memory impairments in the D-galactose model of age-related neurodegeneration. Experimental mice were injected subcutaneously with D-galactose (120 mg/kg) for 56 days. In treatment groups, different doses of TFDG were administered daily by gavage starting on day 29 of D-galactose injection. Model mice exhibited poor learning and memory in the novel object recognition and Y-maze tests, reduced brain/body mass ratio, increased brain glutamate concentration and acetylcholinesterase activity, decreased brain acetylcholine concentration, and lower choline acetyltransferase, glutaminase, and glutamine synthetase activities. Activities of antioxidant enzymes glutathione peroxidase and superoxide dismutase were also reduced, while the concentration of malondialdehyde, a lipid peroxidation product, was elevated. Further, antioxidant genes Nrf2, Prx2, Gsh-px1, and Sod1 were downregulated in brain. Each one of these changes was dose-dependently reversed by TFDG. TFDG is an effective antioxidant response inducer and neuroprotectant that can restore normal neurotransmitter metabolism and ameliorate learning and memory dysfunction in the D-galactose model of age-related cognitive decline.

Myricetin improves apoptosis after ischemic stroke via inhibiting MAPK-ERK pathway

BACKGROUND

Neuronal apoptosis is the main cause for the disabilities and deaths of patients suffered with stroke. Neuroprotectants are clinically used to reduce neuronal apoptosis in ischemic stroke. However, the current neuroprotectants have multiple limitations. Myricetin is beneficial for multiple neurodegenerative diseases, but the role of myricetin as a neuroprotective agent in ischemic stroke is still not fully understood.

METHODS AND RESULTS

Middle cerebral artery occlusion, Terminal deoxynucleotidyl transferase dUTP nick-end labeling staining and Western blots were used to explore the anti-apoptotic effects of myricetin in vivo. Flow cytometry, Western blots and Ca²⁺ staining were used to study the neuroprotective effects of myricetin in vitro. In this study, we first demonstrated that myricetin reduced neuronal apoptosis after ischemia in vivo and in vitro. And, among the factors of apoptosis after ischemic stroke, excitotoxicity, oxidative stress and inflammation-induced apoptosis can be alleviated by myricetin. Moreover, we further demonstrated that myricetin was able to improve neuronal intrinsic apoptosis by inhibiting the phosphorylation of extracellular signal-regulated kinase in the oxygen and glucose deprivation in vitro.

CONCLUSIONS

Summarily, our results support myricetin as a novel neuroprotectant for the prevention or treatment of ischemic stroke via MAPK-ERK signaling pathway.

Theaflavins in Black Tea Mitigate Aging-Associated Cognitive Dysfunction via the Microbiota-Gut-Brain Axis

Aging-associated cognitive dysfunction has a great influence on the lifespan and healthspan of the elderly. Theaflavins (TFs), a mixture of ingredients formed from enzymatic oxidation of catechins during the manufacture of tea, have a positive contribution to the qualities and antiaging activities of black tea. However, the role of TFs in mitigating aging-induced cognitive dysfunction and the underlying mechanism remains largely unknown. Here, we find that TFs effectively improve behavioral impairment via the microbiota-gut-brain axis: TFs maintain gut homeostasis by improving antioxidant ability, strengthening the immune response, increasing the expression of tight junction proteins, restructuring the gut microbiota, and altering core microbiota metabolites, i.e., short-chain fatty acids and essential amino acids (SCFAs and AAs), and upregulating brain neurotrophic factors. Removing the gut microbiota with antibiotics partly abolishes the neuroprotective effects of TFs. Besides, correlation analysis indicates that the decrease in gut microbiota, such as Bacteroidetes and Lachnospiraceae, and the increase in microbiota metabolites' levels are positively correlated with behavioral improvements. Taken together, our findings reveal a potential role of TFs in mitigating aging-driven cognitive dysfunction via the microbiota-gut-brain axis. The intake of TFs can be translated into a novel dietary intervention approach against aging-induced cognitive decline.

New Perspectives on Sleep Regulation by Tea: Harmonizing Pathological Sleep and Energy Balance under Stress

Sleep, a conservative evolutionary behavior of organisms to adapt to changes in the external environment, is divided into natural sleep, in a healthy state, and sickness sleep, which occurs in stressful environments or during illness. Sickness sleep plays an important role in maintaining energy homeostasis under an injury and promoting physical recovery. Tea, a popular phytochemical-rich beverage, has multiple health benefits, including lowering stress and regulating energy metabolism and natural sleep. However, the role of tea in regulating sickness sleep has received little attention. The mechanism underlying tea regulation of sickness sleep and its association with the maintenance of energy homeostasis in injured organisms remains to be elucidated. This review examines the current research on the effect of tea on sleep regulation, focusing on the function of tea in modulating energy homeostasis through sickness sleep, energy metabolism, and damage repair in model organisms. The potential mechanisms underlying tea in regulating sickness sleep are further suggested. Based on the biohomology of sleep regulation, this review provides novel insights into the role of tea in sleep regulation and a new perspective on the potential role of tea in restoring homeostasis from diseases.

Review of Herbal Medicines for the Treatment of Depression

Depression, a mental illness that is receiving increasing attention, is caused by multiple factors and genes and adversely affects social life and health. Several hypotheses have been proposed to clarify the pathogenesis of depression, and various synthetic antidepressants have been introduced to treat patients with depression. However, these drugs are effective only in a proportion of patients and fail to achieve complete remission. Recently, herbal medicines have received much attention as alternative treatments for depression because of their fewer side effects and lower costs. In this review, we have mainly focused on the herbal medicines that have been proven in clinical studies (especially randomized controlled trials and preclinical studies) to have antidepressant effects; we also describe the potential mechanisms of the antidepressant effects of those herbal medicines; the cellular and animal model of depression; and the development of novel drug delivery systems for herbal antidepressants. Finally, we objectively elaborate on the challenges of using herbal medicines as antidepressants and describe the benefits, adverse effects, and toxicity of these medicines.

Alleviating Effects of Black Soybean Peptide on Oxidative Stress Injury Induced by Lead in PC12 Cells via Keap1/Nrf2/TXNIP Signaling Pathway

Many researchers have found that Pb exposure can cause oxidative stress damage to the body’s tissue. Black soybean peptide (BSP) has a variety of physiological functions, especially in terms of oxidative stress. Nevertheless, the mitigation function of BSPs on Pb-induced oxidative stress damage in PC12 cells has not been clearly defined. In this study, cell viability was detected by CCK8. Oxidative stress indicators, such as ROS, GSH/GSSG, MDA, SOD, CAT, GPx, and GR, were tested with biochemical kit. Protein expression of Keap1, Nrf2, and TXNIP was measured by Western blot. Compared with the control group, Pb reduced the cell viability of PC12 cells. However, BSP treatment significantly increased the viability of PC12 cells induced by lead exposure (p < 0.05). Lead can enrich the contents of MDA and ROS, but decrease the amount of CAT, SOD, GR, GPx, and GSH/GSSG in PC12 cells, while BSP can alleviate it (p < 0.05). Lead can enhance the expression of Keap1 and TXNIP proteins, but reduce Nrf2 expression. In contrast, BSPs reversed this phenomenon (p < 0.05). BSPs can alleviate oxidative stress injury induced by lead in PC12 cells through the Keap1/Nrf2/TXNIP signaling pathway.

Antioxidative, Anti-Inflammatory, Anti-Obesogenic, and Antidiabetic Properties of Tea Polyphenols-The Positive Impact of Regular Tea Consumption as an Element of Prophylaxis and Pharmacotherapy Support in Endometrial Cancer

Endometrial cancer (EC) is second only to cervical carcinoma among the most commonly diagnosed malignant tumours of the female reproductive system. The available literature provides evidence for the involvement of 32 genes in the hereditary incidence of EC. The physiological markers of EC and coexisting diet-dependent maladies include antioxidative system disorders but also progressing inflammation; hence, the main forms of prophylaxis and pharmacotherapy ought to include a diet rich in substances aiding the organism’s response to this type of disorder, with a particular focus on ones suitable for lifelong consumption. Tea polyphenols satisfy those requirements due to their proven antioxidative, anti-inflammatory, anti-obesogenic, and antidiabetic properties. Practitioners ought to consider promoting tea consumption among individuals genetically predisposed for EC, particularly given its low cost, accessibility, confirmed health benefits, and above all, suitability for long-term consumption regardless of the patient’s age. The aim of this paper is to analyse the potential usability of tea as an element of prophylaxis and pharmacotherapy support in EC patients. The analysis is based on information available from worldwide literature published in the last 15 years.

Long noncoding RNA Gm31629 promotes bone regeneration by maintaining bone marrow mesenchymal stem cells activity

Background

Long noncoding RNA Gm31629 can regulate hypothalamic neural stem cells (htNSCs) senescence and the aging process. However, the effect of Gm31629 on the senescence of bone marrow mesenchymal stem cells (BMSCs) and bone regeneration is unclear. In the present study, we investigated the effects of Gm31629 on the senescence of BMSCs and bone regeneration.

Methods

Gm31629 knockout (Gm31629-KO) and wild-type (WT) mice were used to establish a bone regeneration model. The Brdu labelling, CCK8 assay, wound healing assay, β-gal staining and osteogenic differentiation assay were used to assess the effects of Gm31629 on the functions of BMSCs. Micro-computed tomography (CT), histochemical and immunohistochemical staining were used to evaluate the ability of bone regeneration. The mimic of Gm31629, theaflavin 3-gallate, was used to investigate its role on the senescence of BMSCs and bone regeneration.

Results

The expression of Gm31629 reduced in BMSCs of middle-aged mice was compared with that of young mice. The deletion of Gm31629 was sufficient to drive the senescence of BMSCs, resulting in impaired bone regeneration in mice. Mechanistically, Gm31629 could interact with Y-box protein 1(YB-1) and delay its degradation, decreasing the transcription of p16^INK4A of BMSCs. We also found that theaflavin 3-gallate could alleviate the senescence of BMSCs and promote bone regeneration in middle-aged mice.

Conclusion

These results indicated that Gm31629 played an important role on BMSCs senescence and bone regeneration and provided a therapeutic target to promote bone regeneration.

Theaflavin Chemistry and Its Health Benefits

Huge epidemiological and clinical studies have confirmed that black tea is a rich source of health-promoting ingredients, such as catechins and theaflavins (TFs). Furthermore, TF derivatives mainly include theaflavin (TF1), theaflavin-3-gallate (TF2A), theaflavin-3'-gallate (TF2B), and theaflavin-3,3'-digallate (TF3). All of these TFs exhibit extensive usages in pharmaceutics, foods, and traditional medication systems. Various indepth studies reported that how TFs modulates health effects in cellular and molecular mechanisms. The available literature regarding the pharmacological activities of TFs has revealed that TF3 has remarkable anti-inflammatory, antioxidant, anticancer, antiobesity, antiosteoporotic, and antimicrobial properties, thus posing significant effects on human health. The current manuscript summarizes both the chemistry and various pharmacological effects of TFs on human health, lifestyle or aging associated diseases, and populations of gut microbiota. Furthermore, the biological potential of TFs has also been focused to provide a deeper understanding of its mechanism of action.

Cellular Defensive Mechanisms of Tea Polyphenols: Structure-Activity Relationship

Tea is particularly rich in polyphenols, including catechins and theaflavins, thearubigins, flavonols, and phenolic acids, which are believed to contribute to the health benefits of tea. The health-promoting effects of tea polyphenols are believed to be related to their cellular defensive properties. This review is intended to briefly summarize the relationship between the chemical structures of tea polyphenols and their biological activities. Tea polyphenols appear as direct antioxidants by scavenging reactive oxygen/nitrogen species; chelating transition metals; and inhibiting lipid, protein, and DNA oxidations. They also act directly by suppressing “pro-oxidant” enzymes, inducing endogenous antioxidants, and cooperating with vitamins. Moreover, tea polyphenols regulate cellular signaling transduction pathways, importantly contributing to the prevention of chronic diseases and the promotion of physiological functions. Apparently, the features in the chemical structures of tea polyphenols are closely associated with their antioxidant potentials.

Theaflavin protects chondrocytes against apoptosis and senescence via regulating Nrf2 and ameliorates murine osteoarthritis

Oxidative stress-mediated excessive apoptosis and senescence of chondrocytes are the main pathological alterations in the osteoarthritis (OA) development. The protective effects of theaflavin (TF), a common group of polyphenols in black tea, against many degenerative diseases by attenuating oxidative stress are well reported. Nevertheless, its role in the OA treatment is still scantily understood. In the current research, by applying enzyme-linked immunosorbent assay (ELISA) kits and immunofluorescent staining, TF treatment was found to inhibit tert-Butyl hydroperoxide (TBHP)-induced imbalance of anabolism and catabolism in primary mouse chondrocytes. Then, according to western blot, live-dead staining, and SA-β-gal staining, the dramatically increased level of apoptosis and senescence of chondrocytes in response to TBHP was also found to be reduced by TF administration. With regard to upstream signaling investigation, the in vitro molecular binding analysis indicated that the beneficial effects of TF might be related to the regulation of the Keap1/Nrf2/HO-1 axis. Furthermore, the Silencing of Nrf2 resulted in the abolishment of the anti-apoptosis and anti-senescence effects of TF. In addition, the oral administration of TF was demonstrated to ameliorate osteoarthritis development in a surgically induced mouse OA model. Taken together, these results suggest that TF might be a promising therapeutic option for the treatment of OA.

Natural Phytochemicals as Novel Therapeutic Strategies to Prevent and Treat Parkinson's Disease: Current Knowledge and Future Perspectives

Parkinson's disease (PD) is the second-most common neurodegenerative chronic disease affecting both cognitive performance and motor functions in aged people. Yet despite the prevalence of this disease, the current therapeutic options for the management of PD can only alleviate motor symptoms. Research has explored novel substances for naturally derived antioxidant phytochemicals with potential therapeutic benefits for PD patients through their neuroprotective mechanism, targeting oxidative stress, neuroinflammation, abnormal protein accumulation, mitochondrial dysfunction, endoplasmic reticulum stress, neurotrophic factor deficit, and apoptosis. The aim of the present study is to perform a comprehensive evaluation of naturally derived antioxidant phytochemicals with neuroprotective or therapeutic activities in PD, focusing on their neuropharmacological mechanisms, including modulation of antioxidant and anti-inflammatory activity, growth factor induction, neurotransmitter activity, direct regulation of mitochondrial apoptotic machinery, prevention of protein aggregation via modulation of protein folding, modification of cell signaling pathways, enhanced systemic immunity, autophagy, and proteasome activity. In addition, we provide data showing the relationship between nuclear factor E2-related factor 2 (Nrf2) and PD is supported by studies demonstrating that antiparkinsonian phytochemicals can activate the Nrf2/antioxidant response element (ARE) signaling pathway and Nrf2-dependent protein expression, preventing cellular oxidative damage and PD. Furthermore, we explore several experimental models that evaluated the potential neuroprotective efficacy of antioxidant phytochemical derivatives for their inhibitory effects on oxidative stress and neuroinflammation in the brain. Finally, we highlight recent developments in the nanodelivery of antioxidant phytochemicals and its neuroprotective application against pathological conditions associated with oxidative stress. In conclusion, naturally derived antioxidant phytochemicals can be considered as future pharmaceutical drug candidates to potentially alleviate symptoms or slow the progression of PD. However, further well-designed clinical studies are required to evaluate the protective and therapeutic benefits of phytochemicals as promising drugs in the management of PD.

Rapid screening of neuroprotective components from Huang-Lian-Jie-Du Decoction by living cell biospecific extraction coupled with HPLC-Q-Orbitrap-HRMS/MS analysis

Huang-Lian-Jie-Du Decoction (HLJDD), a well-known traditional Chinese formulation, has been proved to exert neuroprotective effects, however, the bioactive components in HLJDD still remain to be elucidated. In the present study, a rapid and effective method involving live cell biospecific extraction and HPLC-Q-Orbitrap HRMS/MS was utilized to rapidly screen and identify the neuroprotective compounds from the HLJDD crude extract directly. Firstly, sixteen principal components in HLJDD crude extract were identified by HPLC-Q-Orbitrap HRMS/MS analysis. After co-incubation with PC12 cells, which have been validated as the key target cells for neurodegenerative diseases, seven compounds of them were demonstrated to exhibit binding affinity to the target cells. Furthermore, three representative compounds named baicalin, wogonoside, and berberine were subsequently verified to exert cytoprotective effects on PC12 cells injured by hydrogen peroxide via inhibiting oxidative stress and cell apoptosis, indicating that these screened compounds may possess a potential for the treatment of neurodegenerative diseases and were responsible, in part at least, for the neuroprotective beneficial effects of HLJDD. Taken together, our study provides evidence that live cell biospecific extraction coupled with LC-HRMS/MS technique is an efficient method for rapid screening potential bioactive components in traditional Chinese medicines.

Evaluation of antityrosinase activity and mechanism, antioxidation, and UV filter properties of theaflavin

Tyrosinase is a key metalloenzyme for the biosynthesis of melanin that plays a critical role in the prevention of skin damage caused by ultraviolet (UV) radiation. However, the overproduction of melanin may cause a variety of skin diseases. Due to the toxicity and inefficiency of existing tyrosinase inhibitors, it is urgent to identify safe and potent alternatives from natural sources. Theaflavin, a single-component extracted from black tea, has been found to possess a variety of pharmacological activities. Herein, the inhibition kinetics of theaflavin on tyrosinase and inhibitory mechanism were determined using spectroscopy, molecular docking, and zebrafish model. The results showed that theaflavin inhibited the diphenolase activity of tyrosinase in a reversible mixed type manner with IC₅₀ of 229.75 μmol/L and hindered the synthesis of melanin in zebrafish. This may be due to the formation of eight hydrogen bonds and hydrophobic effects between theaflavin and tyrosinase according to the results of molecular docking. To study the possible effects on the prevention of free radical-mediated skin cancer and photoaging caused by UV radiation, the antioxidation and UV filter properties of theaflavin were further verified. This study demonstrates that theaflavin is a potential multifunctional compound that can be used in cosmetic and medicinal products.

Theaflavin protects against oxalate calcium-induced kidney oxidative stress injury via upregulation of SIRT1

Renal tubular cell injury induced by calcium oxalate (CaOx) is a critical initial stage of kidney stone formation. Theaflavin (TF) has been known for its strong antioxidative capacity; however, the effect and molecular mechanism of TF against oxidative stress and injury caused by CaOx crystal exposure in kidneys remains unknown. To explore the potential function of TF on renal crystal deposition and its underlying mechanisms, experiments were conducted using a CaOx nephrocalcinosis mouse model established by glyoxylate intraperitoneal injection, and HK-2 cells were subjected to calcium oxalate monohydrate (COM) crystals, with or without the treatment of TF. We discovered that TF treatment remarkably protected against CaOx-induced kidney oxidative stress injury and reduced crystal deposition. Additionally, miR-128-3p expression was decreased and negatively correlated with SIRT1 level in mouse CaOx nephrocalcinosis model following TF treatment. Moreover, TF suppressed miR-128-3p expression and further abolished its inhibition on SIRT1 to attenuate oxidative stress in vitro. Mechanistically, TF interacted with miR-128-3p and suppressed its expression. In addition, miR-128-3p inhibited SIRT1 expression by directly binding its 3'-untranslated region (UTR). Furthermore, miR-128-3p activation partially reversed the acceerative effect of TF on SIRT1 expression. Taken together, TF exhibits a strong nephroprotective ability to suppress CaOx-induced kidney damage through the recovery of the antioxidant defense system regulated by miR-128-3p/SIRT1 axis. These findings provide novel insights for the prevention and treatment of renal calculus.

The role of Nrf2 in neural stem/progenitors cells: From maintaining stemness and self-renewal to promoting differentiation capability and facilitating therapeutic application in neurodegenerative disease

Neurodegenerative diseases (NDs) cause progressive loss of neurons in nervous system. NDs are categorized as acute NDs such as stroke and head injury, besides chronic NDs including Alzheimer's, Parkinson's, Huntington's diseases, Friedreich's Ataxia, Multiple Sclerosis. The exact etiology of NDs is not understood but oxidative stress, inflammation and synaptic dysfunction are main hallmarks. Oxidative stress leads to free radical attack on neural cells which contributes to protein misfolding, glia cell activation, mitochondrial dysfunction, impairment of DNA repair system and subsequently cellular death. Neural stem cells (NSCs) support adult neurogenesis in nervous system during injuries which is limited to certain regions in brain. NSCs can differentiate into the neurons, astrocytes or oligodendrocytes. Impaired neurogenesis and inadequate induction of neurogenesis are the main obstacles in treatment of NDs. Protection of neural cells from oxidative damages and supporting neurogenesis are promising strategies to treat NDs. Nuclear factor-erythroid 2-related factor 2 (Nrf2) is a transcriptional master regulator that maintains the redox homeostasis in cells by provoking expression of antioxidant, anti-inflammatory and cytoprotective genes. Nrf2 can strongly influence the NSCs function and fate determination by reducing levels of reactive oxygen species in benefit of NSC survival and neurogenesis. In this review we will summarize the role of Nrf2 in NSC function, and exogenous and endogenous therapeutic strategies in treatment of NDs.

Theaflavin ameliorates renal ischemia/reperfusion injury by activating the Nrf2 signalling pathway in vivo and in vitro

Studies have demonstrated that oxidaive stress-induced apoptosis may be the main pathogenic mechanism of renal ischemia/reperfusion (I/R) injury. Theaflavin, a polyphenolic compound extracted from black tea, has been proven to exert strong antioxidant biological function. The objective of the present study was to investigate the potential role of theaflavin on renal I/R injury and its potential molecular mechanism both in vitro and in vivo. C57/BL6 J mice were used to create a model of I/R injury wherein mice were ligated with bilateral renal pedicles for 45 min, and then reperfused for 24 h. A hypoxia/reoxygenation (H/R) model of TCMK-1 cells was used to simulate I/R in vitro. Theaflavin were administered to the treatment group first and then established the model. Kidney Injury Molecule-1 (KIM-1), serum creatinine, urea nitrogen, and 24-h urinary protein levels were evaluated and changes in mitochondrial membrane potential and the ultrastructure of mitochondria were observed. Cell viability, oxidative stress damage, and apoptosis were assessed. The expression levels of nuclear factor erythroid 2-related factor 2 (Nrf2) and its downstream target genes HO-1 and NQO1 were evaluated. Our results revealed that pretreatment with theaflavin significantly inhibited I/R- and H/R-induced renal injury and cell apoptosis. Theaflavin improved mitochondrial dysfunction by attenuating mitochondrial damage and promoting mitochondrial membrane potential. Theaflavin pretreatment significantly reduced malondialdehyde content, while enhancing superoxide dismutase activity in vivo and in vitro. It also reduced oxidative stress and apoptosis mainly by upregulating Nrf2 and its downstream targets in TCMK-1 cells. Thus, theaflavin exerted a protective effect against renal I/R injury by inhibiting oxidative stress and apoptosis via activation of the Nrf2-NQO1/HO-1 pathway as well as correcting mitochondrial dysfunction, thereby presenting its potential as a clinical therapeutic in cases of acute kidney injury.

Anti-melanogenic effects of epigallocatechin-3-gallate (EGCG), epicatechin-3-gallate (ECG) and gallocatechin-3-gallate (GCG) via down-regulation of cAMP/CREB /MITF signaling pathway in B16F10 melanoma cells

Tea catechins, the main bioactive polyphenols in green tea, are well known for their health promoting effects. Previous studies have shown that gallocatechin-3-gallate (GCG), epigallocatechin-3-gallate (EGCG) and epicatechin-3-gallate (ECG) exerted strong inhibitory effects on mushroom tyrosinase activity in vitro, whilst EGCG inhibited melanogenesis in vivo, yet the underlying mechanisms are not entirely clear. In this study, we (i) evaluated and compared the inhibitory effects of the main tea catechins (GCG, EGCG, and ECG) on melanogenesis in B16F10 melanoma cells, and (ii) explain the underlying mechanisms. The results showed that the tea catechins significantly suppressed tyrosinase activity and melanin synthesis in B16F10 cells, where the effects of ECG > EGCG > GCG. Interestingly, the inhibitory effects of the catechins were stronger than those of arbutin (AT), a well-known depigmenting agent. Moreover, GCG, EGCG, and ECG regulated the melanogenesis of B16F10 cells through the cAMP/CREB/MITF pathway. These results revealed catechins could be used as anti-melanogenic agents to protect cells from abnormal melanogenesis.

Protective effects of bovine milk exosomes against oxidative stress in IEC-6 cells

PURPOSE

Bovine milk exosomes, which are enriched with microRNAs (miRNAs) and proteins, regulate immune response and growth. In the present study, we aimed to assess the protective effects of bovine milk exosomes against oxidative stress of intestinal crypt epithelial cells (IEC-6).

METHODS

Bovine milk exosomes were isolated and characterized. To assess the protective effects of exosomes, IEC-6 cells were pretreated with exosomes, followed by H₂O₂. Cell viability and levels of superoxide dismutase (SOD), malondialdehyde (MDA), glutathione peroxidase (GPX), reactive oxidative species (ROS), and lactate dehydrogenase (LDH) were measured. The expression levels of nuclear factor erythroid 2-related factor 2 (Nrf2) and heme oxygenase 1 (Ho1) genes, and miR-146a, miR-155, and the HO-1 protein were also determined.

RESULTS

The isolated bovine milk exosome were positive for CD63 and CD9 expression. The exosomes were approximately circular and had a diameter of about 67.23 nm. Pretreatment of IEC-6 cells with bovine milk exosomes enhanced cell viability; increased SOD and GPX activities; and reduced LDH, ROS, and MDA levels after H₂O₂ challenge. Further analysis showed that exosome pretreatment increased intracellular miR-146a and miR-155 levels. Exosome pretreatment inhibited the elevation of Nrf2 and Ho1 gene expression induced by H₂O₂, but promoted HO-1 protein expression.

CONCLUSION

The results indicated that bovine milk exosomes exerted protective effects against oxidative stress in IEC-6 cells.

Theaflavin attenuates cerebral ischemia/reperfusion injury by abolishing miRNA‑128‑3p‑mediated Nrf2 inhibition and reducing oxidative stress

Theaflavin has been proven to own strong antioxidative capacity; however, the molecular mechanism underlying its protective effect against cerebral ischemia-reperfusion (I/R) injury remains unclear. Therefore, the present study was designed to elucidate the neuroprotective effects of theaflavin on cerebral I/R injury and its underlying molecular mechanisms. To investigate the effects of theaflavin on neurological function, neurogenesis, and oxidative stress, experiments were performed using a cerebral I/R injury rat model, and neural stem cells (NSCs) were subjected to oxygen-glucose deprivation and reoxygenation (OGD/R). Further, the expression profiles of miRNA-128-3p and the regulatory function of nuclear factor (erythroid-derived 2)-related factor 2 (Nrf2) were evaluated in these models. We found that theaflavin treatment significantly reduced infarct volume and neuronal injury, and thus improved the impaired memory and learning ability. Furthermore, theaflavin treatment significantly enhanced the increase in NSC proliferation, reduction in the apoptotic rate and inhibition of oxidative stress. Mechanistically, theaflavin targeted miRNA-128-3p and further activated the Nrf2 pathway to reduce oxidative stress. In summary, theaflavin has a strong ability to attenuate cerebral I/R injury through miRNA-128-3p-mediated recovery of the impaired antioxidant defense system, which suggests that it could be a potential drug candidate for ischemic stroke.

Theaflavins alleviate sevoflurane-induced neurocytotoxicity via Nrf2 signaling pathway

Aim: Sevoflurane could induce apoptosis of rat hippocampal neurons, while theaflavins (TFs) have antioxidant and anti-inflammatory properties. This study aims to explore whether TFs could alleviate sevoflurane-induced neuronal cell injury.Materials and methods: Cells were treated by concentration gradient of sevoflurane and TFs. Cell viability, level of reactive oxygen species (ROS) and apoptosis rate were determined by cell counting kit-8 (CCK-8) and flow cytometry, respectively. Quantitative PCR (qPCR) and western blot were performed to determine mRNA and protein expressions.Results: TFs promoted viability of cells under the treatment of sevoflurane, while it suppressed apoptosis and down-regulated ROS level in a concentration-dependent manner. TFs could also down-regulate expression levels of caspase-3 and caspase-9 and cytosol and intranuclear nuclear factor E2-related factor 2 (Nrf2) in rat hippocampal nerve cells, while it up-regulated those of heme oxygenase 1 (HO-1), NADPH quinine oxidoreductase 1 (NQO1), glutamate cysteine ligase (GCL) and peroxiredoxin 1 (Prx1).Conclusions: Our study suggests that TFs exert protective effects on sevoflurane-induced neurocytotoxicity and therefore could be used as a potential drug for treatment of neuronal injury.

Theaflavin 3,3'-digallate reverses the downregulation of connexin 43 and autophagy induced by high glucose via AMPK activation in cardiomyocytes

Theaflavin 3,3'-digallate (TF3), is reported to protect cardiomyocytes from lipotoxicity and reperfusion injury. However, the role of TF3 in the protection of high-glucose injury is still poorly understood. This study investigated the protective effects of TF3 on gap junctions and autophagy in neonatal cardiomyocytes (NRCMs). NRCMs preincubated with high glucose were coincubated with TF3. The expression of connexins and autophagy-related proteins was determined. The functioning of gap-junctional intercellular communication (GJIC) was measured by a dye transfer assay. Adenosine monophosphate-activated protein kinase (AMPK) activity was determined by western blot. Moreover, AMPK was activated with aminoimidazole-4-carboxamide-1-β-d-ribofuranoside (AICAR) or inhibited by AMPKα small interfering RNA (siRNA) to explore the role of AMPK in the modulation of connexin 43 (Cx43) and autophagy. Meanwhile, autophagy was activated or blocked to observe the change in Cx43 expression. It was found that the protein expression of Cx43 and autophagy-related proteins was increased in a TF3 dose- and time-dependent manner under high glucose. TF3 also recovered the reduced GJIC function induced by high glucose concentrations. TF3 activated phosphorylated AMPK in a time-dependent way. AMPKα siRNA abrogated the protection of TF3, while AICAR showed similar results compared to the TF3 treatment. Meanwhile, autophagy activation caused decreased Cx43, while cotreatment with baf A1 enhanced Cx43 expression further compared with the TF3 treatment alone under high glucose. We concluded that TF3 partly reversed the inhibition of Cx43 expression and autophagy induced by high glucose in NRCMs, partly by restoring AMPK activity. Inhibition of autophagy might be protective by preserving Cx43 expression in NRCMs stimulated by high glucose.

Theaflavic acid from black tea protects PC12 cells against ROS-mediated mitochondrial apoptosis induced by OGD/R via activating Nrf2/ARE signaling pathway

Cerebral ischemic stroke is a severe disease afflicting people worldwide. Phytochemicals play a pivotal role in the discovery of novel therapeutic approaches for the prevention of ischemic stroke. In our continual search for bioactive natural products for the treatment of ischemic stroke, we have evaluated the protective effects of theaflavic acid (TFA) from black tea using PC12 cells injured by oxygen and glucose deprivation/restoration (OGD/R), and investigated the possible mechanisms. The results showed that TFA can protect PC12 cells against OGD/R through increasing cell viability and decreasing intracellular lactate dehydrogenase (LDH) release. Further investigations found that TFA could inhibit the overproduction of intracellular reactive oxygen species (ROS), reduce malondialdehyde content, and elevate superoxide dismutase activity, which implied that TFA suppresses oxidative stress in PC12 cells induced by OGD/R. In addition, overload of intracellular calcium and collapse of the mitochondrial membrane potential were improved in the presence of TFA, and the activity of caspase-3 was significantly reduced by TFA. Western blot analysis showed that the expression of Bcl-2 was up-regulated while Bax was down-regulated. Therefore, it can be concluded that TFA can inhibit mitochondria-dependent apoptosis of PC12 cells induced by OGD/R. In addition, activation of the nuclear factor erythroid 2-related factor 2 (Nrf2)/antioxidant response elements (ARE) signaling pathway was explored to elucidate the mechanism by which TFA inhibits ROS-mediated apoptosis in PC12 cells. The results revealed that TFA promoted the translocation of Nrf2 into nuclei, enhanced the transcriptional activity of ARE, and up-regulated expression of downstream HO-1, which indicates that the Nrf2/ARE signaling pathway is involved in the protection by TFA of PC12 cells injured by OGD/R.

Theaflavins prevent cartilage degeneration via AKT/FOXO3 signaling in vitro

Theaflavins (TFs) are the main bioactive polyphenols in tea and contribute to protection against oxidative stress. Excessive reactive oxygen species (ROS) accumulation can lead to the disruption of cartilage homeostasis. The present study examined the potential effects of TFs on H₂O₂-induced cartilage degeneration in vitro. Cell Counting kit (CCK-8) was used to determine cell viability, and flow cytometric analysis was used to detect ROS, apoptosis and DNA damage. Reverse transcription-quantitative polymerase chain reaction (RT-qPCR) and western blotting were used to detect the expression levels of target factors. The present study revealed that TFs effectively reduced the expression of catabolic factors, including matrix metalloproteinase-13, interleukin-1 and cartilage glycoprotein 39. TFs inhibited ROS generation in cartilage degeneration, and suppressed apoptosis and DNA damage caused by oxidative stress. TFs also downregulated the expression levels of cleaved caspase-3 and B-cell lymphoma 2-associated X protein, and the DNA damage-related genes, ATR serine/threonine kinase and ATM serine/threonine kinase. Furthermore, TFs enhanced the activity of glutathione peroxidase 1 and catalase, but reduced the expression levels of phosphorylated (p)-AKT serine/threonine kinase (AKT) and p-Forkhead box O3 (FOXO3)a. Conversely, the effects of TFs on apoptosis and DNA damage were reversed by persistent activation of AKT. In conclusion, TFs prevented cartilage degeneration via AKT/FOXO3 signaling in vitro. The present study suggested that TFs may be a potential candidate drug for the prevention of cartilage degeneration.

Theaflavins attenuate ethanol‑induced oxidative stress and cell apoptosis in gastric mucosa epithelial cells via downregulation of the mitogen‑activated protein kinase pathway

Ethanol‑induced diseases of the gastric mucosa are the most common and refractory diseases of gastrointestinal system in clinic, and are mediated by oxidative stress and apoptosis pathways. Theaflavins (TFs) are considered to be antioxidants. The present study aimed to determine the molecular mechanism underlying the ability of TFs to attenuate ethanol‑induced oxidative stress and apoptosis in GES‑1 gastric mucosa epithelial cells. A Cell Counting Kit‑8 (CCK‑8) assay was performed to investigate the cell viability of GES‑1 cells following administration of ethanol (0.5 mol/l) and subsequent treatment with TFs (20, 40 and 80 µg/ml) for specific time intervals. A carboxyfluorescein diacetate succinimidyl ester assay was used to measure proliferation and further investigate the results of the CCK‑8 assay. Flow cytometry was performed to measure reactive oxygen species (ROS) levels and the apoptosis rates of GES‑1 cells. Furthermore, levels of oxidative stress‑associated factors, including malondialdehyde, superoxide dismutase and glutathione, were investigated using commercial kits. Reverse transcription‑quantitative polymerase chain reaction and western blot assays were performed to determine the expression levels of apoptosis‑associated factors, as well as the phosphorylation levels of extracellular signal‑regulated kinase (ERK), c‑Jun N‑terminal kinase (JNK) and p38 kinase (p38). The results of the present study demonstrated that treatment with ethanol inhibited GES‑1 cell proliferation, and enhanced ROS levels and apoptosis rates, potentially via downregulation of B‑cell lymphoma‑2 (Bcl‑2) expression and upregulation of Bcl‑2‑associated X and caspase‑3 expression levels, as well as enhancing the phosphorylation levels of ERK, JNK and p38. However, treatment with TFs was revealed to attenuate the effects of ethanol administration on GES‑1 cells in a dose‑dependent manner. In conclusion, TFs may attenuate ethanol‑induced oxidative stress and apoptosis in gastric mucosa epithelial cells via downregulation of various mitogen‑activated protein kinase pathways.

Neuroprotective Effects and Mechanisms of Tea Bioactive Components in Neurodegenerative Diseases

As the population ages, neurodegenerative diseases such as Parkinson's disease (PD) and Alzheimer's disease (AD) impose a heavy burden on society and families. The pathogeneses of PD and AD are complex. There are no radical cures for the diseases, and existing therapeutic agents for PD and AD have diverse side effects. Tea contains many bioactive components such as polyphenols, theanine, caffeine, and theaflavins. Some investigations of epidemiology have demonstrated that drinking tea can decrease the risk of PD and AD. Tea polyphenols can lower the morbidity of PD and AD by reducing oxidative stress and regulating signaling pathways and metal chelation. Theanine can inhibit the glutamate receptors and regulate the extracellular concentration of glutamine, presenting neuroprotective effects. Additionally, the neuroprotective mechanisms of caffeine and theaflavins may contribute to the ability to antagonize the adenosine receptor A2AR and the antioxidant properties, respectively. Thus, tea bioactive components might be useful for neuronal degeneration treatment in the future. In the present paper, the neuro protection and the mechanisms of tea and its bioactive components are reviewed. Moreover, the potential challenges and future work are also discussed.

Melatonin promotes neuroprotection of induced pluripotent stem cells-derived neural stem cells subjected to H2O2-induced injury in vitro

Melatonin is a neurohormone mainly extracted from the pineal gland with neuroprotective effects. It has antioxidant, anti-inflammatory, and antiapoptotic functions. However, the mechanism of melatonin against reactive oxygen species is unclear. Here, we explore the potential proliferative and neuroprotective mechanism of melatonin on induced pluripotent stem cells (iPSC)-derived neural stem cells (NSCs) exposed to hydrogen peroxide (H₂O₂). NSCs were induced from iPSCs, then pretreated with 500 μM H₂O₂, 1 μM melatonin, 1 μM melatonin receptor antagonist (Luzindole), or 10 μM Phosphatidylinositide 3 kinase (PI3K) inhibitor (LY294002). The results showed that melatonin stimulated proliferation of iPSC-derived NSCs on H₂O₂ exposure. Melatonin also markedly improved stabilization of the mitochondrial membrane potential and reduced the rate of apoptosis. Treatment with Luzindole or LY294002 inhibited the increasing proliferative and neuroprotective effects of melatonin on iPSC-derived NSCs with H₂O₂ treatment. Our results further demonstrated that these promotional effects of melatonin were related with the activity of phosphorylation of AKT. Therefore, these outcomes propose that melatonin protects iPSC-derived NSCs from H₂O₂-induced injury through the mediation of melatonin receptor and PI3K/AKT signaling pathway.

Ligustrazine suppresses neuron apoptosis via the Bax/Bcl-2 and caspase-3 pathway in PC12 cells and in rats with vascular dementia

The aim of this study was to examine the comprehensive neuroprotective mechanism of ligustrazine, which is extracted from Ligusticum Chuanxiong Hort., against vascular dementia (VD) in rats and apoptosis in oxygen and glucose deprivation (OGD) PC12 cells. Rats were subjected to bilateral common carotid artery occlusion (BCCAO) surgery and administered ligustrazine intragastrically for 6 weeks. At the end of the experiments, the hippocampal biomarkers brain-derived neurotrophic factor (BDNF), monocyte chemotactic protein 1 (MCP-1), and homocysteine (Hcy) were examined. In experiments in vitro, OGD PC12 cells were treated with ligustrazine for 0.5, 1, 3, 6, 12, or 24 h. The cell-released biomarkers BDNF, MCP-1, and Hcy were examined. Microscopy, acridine orange-ethidium bromide (AO/EB) staining, and flow cytometry assays were performed to investigate apoptosis. Cleaved caspase-3, Bcl-2 associated X protein (Bax), and B cell lymphoma 2 (Bcl-2) expression was examined using Western blot assays. The results showed that biomarkers, including MCP-1 and Hcy, were significantly increased in both the in vivo and in vitro models, while the BDNF level was significantly decreased compared with the sham or vehicle models. Microscopy, AO/EB staining, and flow cytometry analysis showed that severe cell damage occurred in OGD PC12 cells, and apoptosis played a major role in this environment. Further Western blot studies showed that the apoptosis-related Bax/Bcl-2 protein ratio and cleaved caspase-3 were significantly increased in the experiment. However, ligustrazine profoundly suppressed the imbalance of these biomarkers, reduced cell damage, decreased the Bax/Bcl-2, and downregulated cleaved caspase-3. Pro- and anti-apoptotic biomarkers of multiple pathways including BDNF, MCP-1, and Hcy played a joint role in triggering the activation of the mitochondria-related Bax/Bcl-2 and caspase-3 apoptosis pathway in VD. Ligustrazine attenuated VD by comprehensively regulating BDNF, MCP-1, and Hcy and inactivating the Bax/Bcl-2 and caspase-3 apoptosis pathway. Our data provide novel insight into ligustrazine, which is a promising neuroprotective agent for VD disease treatment strategies. © IUBMB Life, 70(1):60-70, 2018.

Theaflavin ameliorates ionizing radiation-induced hematopoietic injury via the NRF2 pathway

It has been well established that reactive oxygen species (ROS) play a critical role in ionizing radiation (IR)-induced hematopoietic injury. Theaflavin (TF), a polyphenolic compound from black tea, has been implicated in the regulation of endogenous cellular antioxidant systems. However, it remains unclear whether TF could ameliorate IR-induced hematopoietic injury, particularly the hematopoietic stem cell (HSC) injury. In this study, we explored the potential role of TF in IR-induced HSC injury and the underlying mechanism in a total body irradiation (TBI) mouse model. Our results showed that TF improved survival of irradiated wild-type mice and ameliorated TBI-induced hematopoietic injury by attenuating myelosuppression and myeloid skewing, increasing HSC frequency, and promoting reconstitution of irradiated HSCs. Furthermore, TF inhibited TBI-induced HSC senescence. These effects of TF were associated with a decline in ROS levels and DNA damage in irradiated HSCs. TF reduced oxidative stress mainly by up-regulating nuclear factor erythroid 2-related factor 2 (NRF2) and its downstream targets in irradiated Lineage^-c-kit⁺ positive cells. However, TF failed to improve the survival, to increase HSC frequency and to reduce ROS levels of HSCs in irradiated Nrf2^-/- mice. These findings suggest that TF ameliorates IR-induced HSC injury via the NRF2 pathway. Therefore, TF has the potential to be used as a radioprotective agent to ameliorate IR-induced hematopoietic injury.

Neuroprotective effect of Ruminococcus albus on oxidatively stressed SH-SY5Y cells and animals

Recent evidence shows that the gut microbiota has an important role in gut-brain crosstalk and is linked to neuronal disorders. The aim of this study was to investigate the effects of intestinal Ruminococcus albus with probiotic potential on neuroprotection in oxidatively stressed SH-SY5Y neuroblastoma cells and animals. To investigate these effects, conditioned medium was prepared using Caco-2 cells cultured with heat-killed R. albus (CRA-CM). Caco-2 cells cultured with heat-killed R. albus showed increased BDNF expression and BDNF protein levels increased in CRA-CM. CRA-CM up-regulated the protein expression levels of SRF, C-fos and CDK2. In addition, CRA-CM protected SH-SY5Y cells from H₂O₂-induced cell death. CRA-CM significantly decreased the Bax/Bcl-2 ratio in oxidatively stressed SH-SY5Y cells. Animal experiments showed that oral administration of heat-killed R. albus for 15 days attenuated the oxidative stress induced by sodium arsenate. Treatment with heat-killed R. albus reduced the level of ROS, and the levels of SOD and GSH increased in oxidatively stressed brains. In conclusion, the secretome prepared from Caco-2 cells cultured with heat-killed R. albus might promote neuronal proliferation through the activation of cell proliferation-related proteins, and heat-killed R. albus protects neurons from oxidative damage by reducing ROS levels and increasing SOD and GSH levels.

Neuroprotection of N-benzylcinnamide on scopolamine-induced cholinergic dysfunction in human SH-SY5Y neuroblastoma cells

Alzheimer's disease, a progressive neurodegenerative disease, affects learning and memory resulting from cholinergic dysfunction. Scopolamine has been employed to induce Alzheimer's disease-like pathology in vivo and in vitro through alteration of cholinergic system. N-benzylcinnamide (PT-3), purified from Piper submultinerve, has been shown to exhibit neuroprotective properties against amyloid-β-induced neuronal toxicity in rat cortical primary cell culture and to improve spatial learning and memory of aged rats through alleviating oxidative stress. We proposed a hypothesis that PT3 has a neuroprotective effect against scopolamine-induced cholinergic dysfunction. PT-3 (125–200 nM) pretreatment was performed in human neuroblastoma SH-SY5Y cell line following scopolamine induction. PT-3 (125–200 nM) inhibited scopolamine (2 mM)-induced generation of reactive oxygen species, cellular apoptosis, upregulation of acetylcholinesterase activity, downregulation of choline acetyltransferase level, and activation of p38 and JNK signalling pathways. These findings revealed the underlying mechanisms of scopolamine-induced Alzheimer's disease-like cellular dysfunctions, which provide evidence for developing drugs for the treatment of this debilitating disease.