Antioxidant effects of green tea and its polyphenols on bladder cells

Exploring the protective role of green tea extract against cardiovascular alterations induced by chronic REM sleep deprivation via modulation of inflammation and oxidative stress

BACKGROUND

Chronic Rapid eye movement (REM) sleep deprivation has been associated with various cardiovascular alterations, including disruptions in antioxidant defense mechanisms, lipid metabolism, and inflammatory responses. This study investigates the therapeutic potential of green tea extract (GTE) in mitigating these adverse effects.

METHODS

A total of 24 male Wistar albino rats were used in this study and divided into the control group (n = 8), Chronic-REM Sleep Deprivation (CRSD) Group (n = 8) and Chronic-REM SD + Green Tea 200 (CRSD + GTE200) Group (n = 8). After 21 days, a comprehensive analysis of paraoxonase (PON1), arylesterase (ARE), malondialdehyde (MDA), glutathione (GSH), nitric oxide (NOx), proinflammatory cytokines, and lipid profiles in aortic tissue, heart tissue, and serum was conducted in a sleep-deprived rat model.

RESULTS

Chronic REM sleep deprivation led to a significant reduction in PON1 and ARE levels in aortic (p = 0.046, p = 0.035 respectively) and heart tissues (p = 0.020, p = 0.019 respectively), indicative of compromised antioxidant defenses. MDA levels increased, and NOx levels decreased, suggesting oxidative stress and impaired vascular function. Lipid profile alterations, including increased triglycerides and total cholesterol, were observed in serum. Elevated levels of inflammatory cytokines (IL-6 and TNF-alpha) further indicated an inflammatory response (p = 0.007, p = 0.018 respectively). GTE administration demonstrated a protective role, restoring antioxidant enzyme levels, suppressing lipid peroxidation, and improving NOx levels.

CONCLUSION

These findings suggest the therapeutic potential of GTE in alleviating the cardiovascular impairments of chronic REM sleep deprivation, emphasizing its candidacy for further clinical exploration as a natural intervention in sleep-related disorders and associated cardiovascular risks.

Epigallocatechin-3-gallate attenuates the sulfamethoxazole-induced immunotoxicity and reduces SMZ residues in Procambarus clarkii

Sulfamethoxazole (SMZ) is a commonly used antibiotic in aquaculture, and its residues in water bodies pose a significant threat to aquatic organisms in the water environment. In the present study, epigallocatechin-3-gallate (EGCG), a catecholamine, was used to mitigate the immunotoxicity caused by SMZ exposure in Procambarus clarkii. EGCG reduced the apoptosis rate, which was elevated by SMZ exposure, and increased the total hemocyte count. Simultaneously, EGCG enhanced the activities of enzymes related to antibacterial and antioxidant activities, such as superoxide dismutase (SOD), catalase (CAT), lysozyme (LZM), acid phosphatase (ACP), and GSH, which were decreased following SMZ exposure. Hepatopancreatic histology confirmed that EGCG ameliorated SMZ-induced tissue damage caused by SMZ exposure. In addition to EGCG attenuating SMZ-induced immunotoxicity in crayfish, we determined that EGCG can effectively reduce SMZ residues in crayfish exposed to SMZ. In addition, at the genetic level, the expression levels of genes related to the immune response in hemocytes were disrupted after SMZ exposure, and EGCG promoted their recovery and stimulated an increase in the expression levels of metabolism-related transcripts in hemocytes. The transcriptome analysis was conducted, and "phagosome" and "apoptosis" pathways were shown to be highlighted using Kyoto Encyclopedia of Genes and Genomes (KEGG) analyses. To the best of our knowledge, this is the first study to confirm that EGCG attenuates SMZ-induced immunotoxicity in aquatic animals and reduces SMZ residues in aquatic animals exposed to SMZ. Our study contributes to the understanding of the mechanisms by which EGCG reduces the immunotoxicity of antibiotic residues in aquatic animals.

Methylglyoxal and Advanced Glycation End Products (AGEs): Targets for the Prevention and Treatment of Diabetes-Associated Bladder Dysfunction?

Methylglyoxal (MGO) is a highly reactive α-dicarbonyl compound formed endogenously from 3-carbon glycolytic intermediates. Methylglyoxal accumulated in plasma and urine of hyperglycemic and diabetic individuals acts as a potent peptide glycation molecule, giving rise to advanced glycation end products (AGEs) like arginine-derived hydroimidazolone (MG-H1) and carboxyethyl-lysine (CEL). Methylglyoxal-derived AGEs exert their effects mostly via activation of RAGE, a cell surface receptor that initiates multiple intracellular signaling pathways, favoring a pro-oxidant environment through NADPH oxidase activation and generation of high levels of reactive oxygen species (ROS). Diabetic bladder dysfunction is a bothersome urological complication in patients with poorly controlled diabetes mellitus and may comprise overactive bladder, urge incontinence, poor emptying, dribbling, incomplete emptying of the bladder, and urinary retention. Preclinical models of type 1 and type 2 diabetes have further confirmed the relationship between diabetes and voiding dysfunction. Interestingly, healthy mice supplemented with MGO for prolonged periods exhibit in vivo and in vitro bladder dysfunction, which is accompanied by increased AGE formation and RAGE expression, as well as by ROS overproduction in bladder tissues. Drugs reported to scavenge MGO and to inactivate AGEs like metformin, polyphenols, and alagebrium (ALT-711) have shown favorable outcomes on bladder dysfunction in diabetic obese leptin-deficient and MGO-exposed mice. Therefore, MGO, AGEs, and RAGE levels may be critically involved in the pathogenesis of bladder dysfunction in diabetic individuals. However, there are no clinical trials designed to test drugs that selectively inhibit the MGO-AGEs-RAGE signaling, aiming to reduce the manifestations of diabetes-associated bladder dysfunction. This review summarizes the current literature on the role of MGO-AGEs-RAGE-ROS axis in diabetes-associated bladder dysfunction. Drugs that directly inactivate MGO and ameliorate bladder dysfunction are also reviewed here.

Rutaecarpine alleviates migraine in nitroglycerin-induced mice by regulating PTEN/PGK1 signaling pathway to activate NRF2 antioxidant system

BACKGROUND

Due to its widespread prevalence, migraine is a common neurovascular condition that has a major impact on people's health and quality of life. Rutaecarpine (RUT) is one of the main effective components of Evodia rutaecarpa, which has a wide range of biological activities. However, the exact mechanism by which RUT improves migraine remain unknown.

PURPOSE

The purpose of this study was to investigate whether RUT improves migraine by inhibiting oxidative stress via activating the Nrf2 antioxidant system through the PTEN/PGK1 signaling pathway.

METHODS

In vivo, a mouse model of chronic migraine (CM) was established by repeated intraperitoneal injection of nitroglycerin (NTG). After treatment with RUT and Sumatriptan, behavioral tests were performed, followed by measurements of oxidative stress-related indicators in the trigeminal nucleus caudalis, expression of proteins associated with the Nrf2 antioxidant system, and the PTEN/PGK1 pathway. In vitro, PC12 cells were stimulated by 100 μM H2O2 for 24 h to induce oxidative stress, which was then treated with RUT. Furthermore, the role of PTEN in antioxidant stress of RUT was elucidated by knockout of the PTEN gene.

RESULTS

The results showed that RUT treatment improved NTG-induced migraine in mice by inhibiting oxidative stress. Importantly, RUT inhibited oxidative stress in NTG-induced mice or H2O2-induced PC12 cells via activating the Nrf2 antioxidant system by inhibiting PGK1 activity through PTEN. These results provide evidence that RUT improves migraine by activation of the Nrf2 antioxidant system through the PTEN/PGK1 pathway and provide new insights into the potential use of RUT as an effective drug development candidate for migraine.

Tea polyphenols alleviate hydrogen peroxide-induced oxidative stress damage through the Mst/Nrf2 axis and the Keap1/Nrf2/HO-1 pathway in murine RAW264.7 cells

Tea polyphenols (TPs) are the major bioactive extract from green tea that have been extensively reported to prevent and treat oxidative stress damage. In previous studies, TPs have been demonstrated to protect cells against oxidative injury induced by hydrogen peroxide (H₂O₂). However, the underlying mechanism remains unclear. The aim of the current study was to investigate whether the protective and regulatory effects of TPs on oxidative stress damage were dependent on the mammalian STE20-like protein kinase (Mst)/nuclear factor (erythroid-derived 2)-like 2 (Nrf2) axis and the Kelch-like ECH-associated protein 1 (Keap1)/Nrf2/heme oxygenase 1 (HO-1) pathway in RAW264.7 cells, a murine macrophage cell line. Maintaining a certain range of intracellular reactive oxygen species (ROS) levels is critical to basic cellular activities, while excessive ROS generation can override the antioxidant capacity of the cell and result in oxidative stress damage. The inhibition of ROS generation offers an effective target for preventing oxidative damage. The results of the present study revealed that pretreatment with TPs inhibited the production of intracellular ROS and protected RAW264.7 cells from H₂O₂-induced oxidative damage. TPs was also demonstrated to attenuate the production of nitric oxide and malondialdehyde and increase the levels of antioxidant enzymes (superoxide dismutase, catalase and glutathione peroxidase). In addition, following TPs treatment, alterations in Mst1/2 at the mRNA and protein level inhibited the production of ROS and promoted the self-regulation of antioxidation. TPs-induced Keap1 gene downregulation also increased the expression of Nrf2 and HO-1. Collectively, the results of the present study demonstrated that TPs provided protection against H₂O₂-induced oxidative injury in RAW264.7 cells.

Isolation, purification, and characterization of antioxidant peptides from fresh mare's milk

In this study, the whey protein of fresh mare's milk was used as raw material. The antioxidant peptide liquid XMNDT was extracted from fresh mare's milk solution and purified. The peptide had a molecular weight of 1594.89 kDa and was mainly composed of VAPFPQPVVPYPQR. Antioxidant peptide XMNDT could inhibit the proliferation of A549 lung cancer cells in the G1 phase, accelerate cell apoptosis, increase the activity of SOD and the amount of GSH, and reduce the secretion of MDA. It also exhibited certain antioxidant capacity and free radical scavenging. These data can provide a basis for research on new antioxidant properties by reducing the inflammation caused by aging.

Bladder Hyperactivity Induced by Oxidative Stress and Bladder Ischemia: A Review of Treatment Strategies with Antioxidants

Overactive bladder (OAB) syndrome, including frequency, urgency, nocturia and urgency incontinence, has a significantly negative impact on the quality-of-life scale (QoL) and can cause sufferer withdrawal from social activities. The occurrence of OAB can result from an imbalance between the production of pro-oxidants, such as free radicals and reactive species, and their elimination through protective mechanisms of antioxidant-induced oxidative stress. Several animal models, such as bladder ischemia/reperfusion (I/R), partial bladder outlet obstruction (PBOO) and ovarian hormone deficiency (OHD), have suggested that cyclic I/R during the micturition cycle induces oxidative stress, leading to bladder denervation, bladder afferent pathway sensitization and overexpression of bladder-damaging molecules, and finally resulting in bladder hyperactivity. Based on the results of previous animal experiments, the present review specifically focuses on four issues: (1) oxidative stress and antioxidant defense system; (2) oxidative stress in OAB and biomarkers of OAB; (3) OAB animal model; (4) potential nature/plant antioxidant treatment strategies for urinary dysfunction with OAB. Moreover, we organized the relationships between urinary dysfunction and oxidative stress biomarkers in urine, blood and bladder tissue. Reviewed information also revealed the summary of research findings for the effects of various antioxidants for treatment strategies for OAB.

Effects of Epigallocatechin Gallate (EGCG) on Urinary Bladder Urothelial Carcinoma-Next-Generation Sequencing and Bioinformatics Approaches

Background and objectives: Bladder urothelial carcinoma is the most common type of genitourinary cancer. Patients with bladder cancer may have limited treatment efficacy related to drug toxicity, resistance or adverse effects, and novel therapeutic strategies to enhance treatment efficacy or increase sensitivity to drugs are of high clinical importance. Epigallocatechin gallate (EGCG) is a polyphenolic compound found in green tea leaves, and a potential anti-cancer agent in various cancer types through modulating and regulating multiple signaling pathways. The current study aimed to explore the role and novel therapeutic targets of EGCG on bladder urothelial carcinoma. Materials and Methods: The BFTC-905 cells, human urinary bladder transitional cell carcinoma (TCC) cell line, were treated with EGCG or water for 24 hours, and the expression profiles of mRNAs and microRNAs were analyzed using next generation sequencing (NGS). The enriched biological functions were determined using different bioinformatics databases. Results: A total of 108 differentially expressed genes in EGCG-treated bladder TCC cells were identified, which were mainly involved in nicotinamide adenine dinucleotide (NAD) biogenesis, inflammatory response and oxidation-reduction metabolism. Moreover, several microRNA-mRNA interactions that potentially participated in the response of bladder TCC to EGCG treatment, including miR-185-3p- ARRB1 (arrestin beta 1), miR-3116- MGAT5B (alpha-1,6-mannosylglycoprotein 6-beta-N-acetylglucosaminyltransferase B), miR-31-5p-TNS1 (tensin 1), miR-642a-5p-TNS1, miR-1226-3p- DLG2 (discs large homolog 2), miR-484-DLG2, and miR-22-3p- PPM1K (protein phosphatase 1K). Conclusions: The current findings provide insights into novel therapeutic targets and underlying mechanisms of action of EGCG treatment in bladder cancer.

Synergistic effect of herbal plant extract (Hibiscus sabdariffa) in maintain the antioxidant activity of decaffeinated green tea from various parts of Assam

In the present study, two extraction methods, hot water extraction and ethyl acetate extraction were used to decaffeinate fresh green tea leaf (Camellia assamica) collected from four parts of Assam, NE-India. Both type of extraction methods have significant effect on the antioxidant activity of decaffeinated green tea. Amongst the four samples, Dhekiajuli sample have highest antioxidant activity and total polyphenol as well as flavonoid contents. During hot water extraction (100 °C for 3 min), in decaffeinated green tea, the antioxidant activity decreases to 996.1 ± 26.12 mM TE/g green tea and 1165 ± 31.25 mM TE/g green tea from 1403.07 ± 70.15 mM TE/g and 1587.1 ± 79.355 mM TE/g green tea as observed for caffeinated green tea by DPPH and FRAP assay respectively. Again more antioxidant activity (ranges from 996.1 ± 15.8 to 1421.3 ± 71.06 mM TE/g) was recorded for ethyl acetate extracts compared to hot water extracts of samples. However, the loss in antioxidant activity, due to decaffeination of green tea in our study was minimize by using herbal plant extract, Hibiscus sabdariffa along with the tea extract which shows a synergistic effect.

Decaffeinated Green Tea Extract Does Not Elicit Hepatotoxic Effects and Modulates the Gut Microbiome in Lean B6C3F₁ Mice

The main purpose of this study was to investigate the hepatotoxic potential and effects on the gut microbiome of decaffeinated green tea extract (dGTE) in lean B6C3F₁ mice. Gavaging dGTE over a range of 1X–10X mouse equivalent doses (MED) for up to two weeks did not elicit significant histomorphological, physiological, biochemical or molecular alterations in mouse livers. At the same time, administration of dGTE at MED comparable to those consumed by humans resulted in significant modulation of gut microflora, with increases in Akkermansia sp. being most pronounced. Results of this study demonstrate that administration of relevant-to-human-consumption MED of dGTE to non-fasting mice does not lead to hepatotoxicity. Furthermore, dGTE administered to lean mice, caused changes in gut microflora comparable to those observed in obese mice. This study provides further insight into the previously reported weight management properties of dGTE; however, future studies are needed to fully evaluate and understand this effect.

Recent Advances in the Understanding of the Health Benefits and Molecular Mechanisms Associated with Green Tea Polyphenols

Tea, leaf, or bud from the plant Camellia sinensis, make up some of the beverages popularly consumed in different parts of the world as green tea, oolong tea, or black tea. More particularly, as a nonfermented tea, green tea has gained more renown because of the significant health benefits assigned to its rich content in polyphenols. As a main constituent, green tea polyphenols were documented for their antioxidant, anti-inflammation, anticancer, anticardiovascular, antimicrobial, antihyperglycemic, and antiobesity properties. Recent reports demonstrate that green tea may exert a positive effect on the reduction of medical chronic conditions such as cardiovascular disease, cancer, Alzheimer's disease, Parkinson's disease, and diabetes. The health benefits of green teas, in particular EGCG, are widely investigated, and these effects are known to be primarily associated with the structure and compositions of its polyphenols. This Review focuses on the diverse constituents of green tea polyphenols and their molecular mechanisms from the perspective of their potential therapeutic function. Recent advances of green tea polyphenols on their bioavailability, bioaccessibility, and microbiota were also summarized in this article. Dietary supplementation with green tea represents an attractive alternative toward promoting human health.

Litsea japonica Leaf Extract Suppresses Proinflammatory Cytokine Production in Periodontal Ligament Fibroblasts Stimulated with Oral Pathogenic Bacteria or Interleukin-1β

Periodontal disease, a chronic disease caused by bacterial infection, eventually progresses to severe inflammation and bone loss. Regulating excessive inflammation of inflamed periodontal tissues is critical in treating periodontal diseases. The periodontal ligament (PDL) is primarily a connective tissue attachment between the root and alveolar bone. PDL fibroblasts (PDLFs) produce pro-inflammatory cytokines in response to bacterial infection, which could further adversely affect the tissue and cause bone loss. In this study, we determined the ability of Litsea japonica leaf extract (LJLE) to inhibit pro-inflammatory cytokine production in PDLFs in response to various stimulants. First, we found that LJLE treatment reduced lipopolysaccharide (LPS)-induced pro-inflammatory cytokine (interleukin-6 and interleukin-8) mRNA and protein expression in PDLFs without cytotoxicity. Next, we observed the anti-inflammatory effect of LJLE in PDLFs after infection with various oral bacteria, including Fusobacterium nucleatum, Porphyromonas gingivalis, Treponema denticola, and Tannerella forsythia. These anti-inflammatory effects of LJLE were dose-dependent, and the extract was effective following both pretreatment and posttreatment. Moreover, we found that LJLE suppressed the effect of interleukin-1 beta-induced pro-inflammatory cytokine production in PDLFs. Taken together, these results indicate that LJLE has anti-inflammatory activity that could be exploited to prevent and treat human periodontitis by controlling inflammation.

Anticancer Effects of Green Tea and the Underlying Molecular Mechanisms in Bladder Cancer

Green tea and green tea polyphenols (GTPs) are reported to inhibit carcinogenesis and malignant behavior in several diseases. Various in vivo and in vitro studies have shown that GTPs suppress the incidence and development of bladder cancer. However, at present, opinions concerning the anticancer effects and preventive role of green tea are conflicting. In addition, the detailed molecular mechanisms underlying the anticancer effects of green tea in bladder cancer remain unclear, as these effects are regulated by several cancer-related factors. A detailed understanding of the pathological roles and regulatory mechanisms at the molecular level is necessary for advancing treatment strategies based on green tea consumption for patients with bladder cancer. In this review, we discuss the anticancer effects of GTPs on the basis of data presented in in vitro studies in bladder cancer cell lines and in vivo studies using animal models, as well as new treatment strategies for patients with bladder cancer, based on green tea consumption. Finally, on the basis of the accumulated data and the main findings, we discuss the potential usefulness of green tea as an antibladder cancer agent and the future direction of green tea-based treatment strategies for these patients.

Epigallocatechin-3-gallate alleviates bladder overactivity in a rat model with metabolic syndrome and ovarian hormone deficiency through mitochondria apoptosis pathways

Metabolic syndrome (MetS) and ovarian hormone deficiency could affect bladder storage dysfunction. Epigallocatechin-3-gallate (EGCG), a polyphenolic compound in green tea, has been shown to protect against ovarian hormone deficiency induced overactive bladder (OAB). The present study investigated oxidative stress induced by MetS and bilateral ovariectomy (OVX), and elucidated the mechanism underlying the protective effect of EGCG (10 umol/kg/day) on bladder overactivity. Rats were fed with high fat high sugar (HFHS) diet to induce MetS and received ovariectomy surgery to deprive ovarian hormone. By dieting with HFHS for 6 months, rats developed MetS and OAB. MetS + OVX deteriorated bladder storage dysfunction more profound than MetS alone. MetS and MetS + OVX rats showed over-expression of inflammatory and fibrosis markers (1.7~3.8-fold of control). EGCG pretreatment alleviated storage dysfunction, and protected the bladders from MetS and OVX - induced interstitial fibrosis changes. Moreover, OVX exacerbated MetS related bladder apoptosis (2.3~4.5-fold of control; 1.8~2.6-fold of Mets group), enhances oxidative stress markers (3.6~4.3-fold of control; 1.8~2.2-fold of Mets group) and mitochondrial enzyme complexes subunits (1.8~3.7-fold of control; 1.5~3.4-fold of Mets group). EGCG pretreatment alleviated bladder apoptosis, attenuated oxidative stress, and reduced the mitochondrial and endoplasmic reticulum apoptotic signals. In conclusions, HFHS feeding and ovarian hormone deficiency enhances the generation of oxidative stress mediated through mitochondrial pathway. EGCG reduced the generation of oxidative stress and lessened bladder overactivity.

Tea Polyphenols Protect Against Methylmercury-Induced Cell Injury in Rat Primary Cultured Astrocytes, Involvement of Oxidative Stress and Glutamate Uptake/Metabolism Disorders

Methylmercury (MeHg) is an extremely dangerous environmental contaminant, accumulating preferentially in CNS and causing a series of cytotoxic effects. However, the precise mechanisms are still incompletely understood. The current study explored the mechanisms that contribute to MeHg-induced cell injury focusing on the oxidative stress and Glu uptake/metabolism disorders in rat primary cultured astrocytes. Moreover, the neuroprotective effects of tea polyphenols (TP), a natural antioxidant, against MeHg cytotoxicity were also investigated. Astrocytes were exposed to 0, 2.5, 5, 10, and 20 μM MeHgCl for 6-30 h, or pretreated with 50, 100, 200, and 400 μM TP for 1-12 h; cell viability and LDH release were then determined. For further experiments, 50, 100, and 200 μM of TP pretreatment for 6 h followed by 10 μM MeHgCl for 24 h were performed for the examination of the responses of astrocytes, specifically addressing NPSH levels, ROS generation, ATPase activity, the expressions of Nrf2 pathway as well as Glu metabolism enzyme GS and Glu transporters (GLAST and GLT-1). Exposure of MeHg resulted in damages of astrocytes, which were shown by a loss of cell viability, and supported by high levels of LDH release, morphological changes, apoptosis rates, and NPSH depletion. In addition, astrocytes were sensitive to MeHg-mediated oxidative stress, a finding that is consistent with ROS overproduction; Nrf2 as well as its downstream genes HO-1 and γ-GCSh were markedly upregulated. Moreover, MeHg significantly inhibited GS activity, as well as expressions of GS, GLAST, and GLT-1. On the contrary, pretreatment with TP presented a concentration-dependent prevention against MeHg-mediated cytotoxic effects of astrocytes. In conclusion, the findings clearly indicated that MeHg aggravated oxidative stress and Glu uptake/metabolism dysfunction in astrocytes. TP possesses some abilities to prevent MeHg cytotoxicity through its antioxidative properties.

Chronic treatment with resveratrol improves overactive bladder in obese mice via antioxidant activity

The objective of the present work was to evaluate whether oral intake with resveratrol ameliorates overactive bladder in high-fat fed mice. Male C57BL6 mice fed with standard chow or high-fat diet to induce obesity received a two-week therapy with resveratrol (100mg/kg, given as a daily gavage). Weight and metabolic profile, together with cystometry and in vitro bladder contractions were evaluated. Measurements of gp91phox and SOD1 mRNA expressions and reactive-oxygen species (ROS) in bladder tissues, and serum TBARS were performed. Obese mice exhibited increases in body weight and epididymal fat mass, which were significantly reduced by oral treatment with resveratrol. Cystometric study in obese mice showed increases in non-voiding contractions, post-voiding pressure and voiding frequency that were reversed by resveratrol treatment. Likewise, the in vitro bladder overactivity in response to electrical-field stimulation (80V, 1-32Hz) or carbachol (1nM to 10mM) were normalized by resveratrol. The gp91phox and SOD1 mRNA expressions in bladder tissues were markedly higher in obese mice compared with lean group. In addition, ROS levels in bladder tissues and serum lipid peroxidation (TBARS assay) were markedly higher in obese compared with lean mice, all of which were reduced by resveratrol treatment. In lean group, resveratrol had no effect in any parameter evaluated. Our results show that two-week therapy of obese mice with resveratrol reduces the systemic and bladder oxidative stress, and greatly ameliorated the cystometry alterations and in vitro bladder overactivity. Resveratrol treatment could be an option to prevent obesity-associated overactive bladder.

Screening of cytoprotectors against methotrexate-induced cytogenotoxicity from bioactive phytochemicals

As a well known anti-neoplastic drug, the cytogenotoxicity of methotrexate (MTX) has received more attention in recent years. To develop a new cytoprotector to reduce the risk of second cancers caused by methotrexate, an umu test combined with a micronucleus assay was employed to estimate the cytoprotective effects of ten kinds of bioactive phytochemicals and their combinations. The results showed that allicin, proanthocyanidins, polyphenols, eleutherosides and isoflavones had higher antimutagenic activities than other phytochemicals. At the highest dose tested, the MTX genetoxicity was suppressed by 34.03%∼67.12%. Of all the bioactive phytochemical combinations, the combination of grape seed proanthocyanidins and eleutherosides from Siberian ginseng as well as green tea polyphenols and eleutherosides exhibited stronger antimutagenic effects; the inhibition rate of methotrexate-induced genotoxicity separately reached 74.7 ± 6.5% and 71.8 ± 4.7%. Pretreatment of Kunming mice with phytochemical combinations revealed an obvious reduction in micronucleus and sperm abnormality rates following exposure to MTX (p < 0.01). Moreover, significant increases in thymus and spleen indices were observed in cytoprotector candidates in treated groups. The results indicated that bioactive phytochemicals combinations had the potential to be used as new cytoprotectors.

Epigallocatechin-3-gallate enhances the therapeutic effects of leptomycin B on human lung cancer a549 cells

Our previous studies have shown Leptomycin B (LMB) is a promising antilung cancer drug. Epigallocatechin-3-gallate (EGCG) has antitumor properties but a debatable clinical application. The objective of this study is to evaluate the combination therapeutic effect of LMB and EGCG and its molecular mechanisms in human lung cancer A549 cells. Increased cytotoxicity was observed in LMB+EGCG-treated cells compared to LMB-treated cells. Elevated ROS was maximized 2 h after treatment, and LMB+EGCG-treated cells had higher ROS levels compared to LMB. N-Acetyl-L-cysteine (NAC) studies confirmed the oxidative role of LMB and/or EGCG treatment. In comparison to the control, CYP3A4, SOD, GPX1, and p21 mRNA expression levels were increased 7.1-, 2.0-, 4.6-, and 13.1-fold in LMB-treated cells, respectively, while survivin was decreased 42.6-fold. Additionally, these increases of CYP3A4, SOD, and GPX1 were significantly reduced, while p21 was significantly increased in LMB+EGCG-treated cells compared to LMB-treated cells. The qRT-PCR results for p21 and survivin were further confirmed by Western blot. Our study first shows that LMB produces ROS and is possibly metabolized by CYP3A4, GPX1, and SOD in A549 cells, and combination treatment of LMB and EGCG augments LMB-induced cytotoxicity through enhanced ROS production and the modulation of drug metabolism and p21/survivin pathways.

Excitotoxicity and oxidative damages induced by methylmercury in rat cerebral cortex and the protective effects of tea polyphenols

Methylmercury (MeHg) is a highly neurotoxic environmental pollutant that has a high appetency to the central nervous system. The underlying mechanisms of MeHg-induced neurotoxicity have not been elucidated clearly until now. Therefore, to explore the mechanisms contribute to MeHg-induced neurotoxicity, rats were exposed to different dosage of methylmercury chloride (CH3 ClHg) (0, 4, and 12 μmol kg(-1)) for 4 weeks to evaluate the neurotoxic effects of MeHg. In addition, considering the antioxidative properties of tea polyphenols (TP), 1 mmol kg(-1) TP was pretreated to observe the possible protective effects on MeHg-induced neurotoxicity. Then Hg, glutamate (Glu) and glutamine (Gln) levels, glutamine synthetase (GS), phosphate-activated glutaminase (PAG), Na(+)-K(+)-ATPase, and Ca(2+)-ATPase activities, intracellular Ca(2+) level were examined, glutathione (GSH), malondialdehyde (MDA), protein sulfhydryl, carbonyl, 8-hydroxy-2-deoxyguanosine (8-OHdG), and reactive oxygen species (ROS) levels, N-methyl-D-aspartate receptors (NMDARs) mRNA and protein expressions, apoptosis level and morphological changes in the cerebral cortex were also investigated. Study results showed that compared with those in control, exposure to CH3 ClHg resulted in excitotoxicity in a concentration-dependent manner, which was shown by the Glu-Gln cycle disruption and intracellular Ca(2+) homeostasis disturbance. On the other hand, CH3 ClHg exposure resulted in oxidative damages of brain, which were supported by the significant changes on GSH, MDA, sulfhydryl, carbonyl, 8-OHdG, and ROS levels. Moreover, apoptosis rate increased obviously and many morphological changes were found after CH3 ClHg exposure. Furthermore, this research indicated that TP pretreatment significantly mitigated the toxic effects of MeHg. In conclusion, findings from this study indicated that exposure to MeHg could induce excitotoxicity and oxidative damage in cerebral cortex while TP might antagonize the MeHg-induced neurotoxicity.

Molecular evidence of cryptotanshinone for treatment and prevention of human cancer

Cryptotanshinone is one of the major tanshinones isolated from the roots of the plant Salvia miltiorrhiza Bunge (Danshen). Danshen has been widely used in traditional Chinese medicine for treatment of a variety of diseases, including coronary artery disease, acute ischemic stroke, hyperlipidemia, chronic renal failure, chronic hepatitis, and Alzheimer's disease, showing no serious adverse effects. Recent studies have shown that cryptotanshinone not only possesses the potential for treatment and prevention of the above-mentioned diseases, but also is a potent anticancer agent. Here we briefly summarize the physical and chemical properties and the pharmacokinetic profiles of cryptotanshinone, and then comprehensively review its anticancer activities as well as the underlying mechanisms.

Effect of Epigallocatechin Gallate on shear bond strength of composite resin to bleached enamel: an in vitro study

Objectives

The aim of this study was to determine the effect of epigallocatechin gallate (EGCG) on the shear bond strength of composite resin to bleached enamel.

Materials and Methods

Ninety enamel surfaces of maxillary incisors were randomly divided into 9 groups as follows: G1: control (no bleaching); G2: bleaching; G3: bleaching and storage for seven days; G4 - 6: bleaching and application of 600, 800 and 1,000 µmol of EGCG-containing solution for 10 minutes, respectively; G7 - 9: bleaching and application of 600, 800 and 1,000 µmol of EGCG-containing solution for 20 minutes, respectively. The specimens were bleached with 30% hydrogen peroxide gel and a composite resin cylinder was bonded on each specimen using a bonding agent. Shear bond strength of the samples were measured in MPa. Data was analyzed using the two-way ANOVA and Tukey HSD tests (α = 0.05).

Results

The maximum and minimum mean shear bond strength values were observed in G1 and G2, respectively. Time and concentration of EGCG showed no significant effects on bond strength of the groups (p > 0.05). Multiple comparison of groups did not reveal any significant differences between the groups except for G2 and all the other groups (p < 0.05).

Conclusions

There is a significant decrease in bond strength of composite resin to enamel immediately after bleaching. A delay of one week before bonding and the use of EGCG increased bond strength of composite resin to bleached enamel.

Targeting oxidative stress response by green tea polyphenols: clinical implications

Green tea polyphenols, the most interesting constituent of green tea leaves, have been shown to have both pro-oxidant and antioxidant properties. Both pro-oxidant and antioxidant properties are expected to contribute to modulation of oxidative stress response under ideal optimal dosage regimens. Exposure to a low concentration of a pro-oxidant prior to exposure to oxidative stress induces the expression of genes that code for proteins that induce adaptation in a subsequent oxidative stress. On the other hand, exposure to an antioxidant concurrently with exposure to the oxidative stress affords protection through free radical scavenging or through other indirect antioxidant mechanisms. In any case, the optimal conditions that afford protection from oxidative stress should be defined for any substance with redox properties. Green tea polyphenols, being naturally occurring substances, seem to be an ideal option for the modulation of oxidative stress response. This paper reviews available data on the pro-oxidant and antioxidant properties of green tea polyphenols focusing on their potential on the modulation of oxidative stress response.

Effects of molecular structure of polyphenols on their noncovalent interactions with oat β-glucan

Few data were available on the interactions between polyphenols and polysaccharides. The effects of the chemical structure of polyphenols on their interactions with oat β-glucan were analyzed. Ultrafiltration was applied to determine the adsorption capacities of polyphenols into oat β-glucan. Hydroxylation favored the adsorption of flavonoids with three or fewer hydroxyl groups but deteriorated those with four or more hydroxyl groups. Among flavonoid isomers, the adsorption capacities increased in the order flavonol > flvaone > flavanone > isoflavone. Glycosylation exerted complicated influences on the adsorption capacities of flavonoids into oat β-glucan. In most cases, methylation and methoxylation of phenolic acids lowered their adsorption capacities into oat β-glucan. Esterification of gallic acid weakened its adsorption capacity into oat β-glucan, whereas o-coumaric acid presented higher adsorption capacity into oat β-glucan than p- and m-coumaric acids. Galloylation improved the adsorption capacities of catechins into oat β-glucan.

Artificial neural network modeling and optimization of ultrahigh pressure extraction of green tea polyphenols

In this study, the ultrahigh pressure extraction of green tea polyphenols was modeled and optimized by a three-layer artificial neural network. A feed-forward neural network trained with an error back-propagation algorithm was used to evaluate the effects of pressure, liquid/solid ratio and ethanol concentration on the total phenolic content of green tea extracts. The neural network coupled with genetic algorithms was also used to optimize the conditions needed to obtain the highest yield of tea polyphenols. The obtained optimal architecture of artificial neural network model involved a feed-forward neural network with three input neurons, one hidden layer with eight neurons and one output layer including single neuron. The trained network gave the minimum value in the MSE of 0.03 and the maximum value in the R(2) of 0.9571, which implied a good agreement between the predicted value and the actual value, and confirmed a good generalization of the network. Based on the combination of neural network and genetic algorithms, the optimum extraction conditions for the highest yield of green tea polyphenols were determined as follows: 498.8 MPa for pressure, 20.8 mL/g for liquid/solid ratio and 53.6% for ethanol concentration. The total phenolic content of the actual measurement under the optimum predicated extraction conditions was 582.4 ± 0.63 mg/g DW, which was well matched with the predicted value (597.2mg/g DW). This suggests that the artificial neural network model described in this work is an efficient quantitative tool to predict the extraction efficiency of green tea polyphenols.

Decrease in the antioxidant capacity in beverages containing tea extracts during storage

The aim of this work was to determine antioxidant capacity of beverages containing black, white, and green tea extracts using the photochemiluminescence method, and to monitor its changes based on the storage temperature and time. Samples were stored at two different temperatures (refrigerated at 4°C and laboratory temperature 22°C), analyzed after opening of the original package, and consequently after 4 and 7 days. Results of the antioxidant capacity are expressed as the standard equivalents, that is, ascorbic acid in mmol/L. The highest mean value of the antioxidant capacity was found after opening of the original package in fruit-juice-enriched samples and totaled 9.793 mmol/L. This group revealed significant dependence (P < 0.05) not only on the storage time, but also temperature. In samples without added fruit juices containing preservatives the value was 0.428 mmol/L. This group showed significant dependence (P < 0.05) on the decrease of antioxidant capacity only when based on the storage time. Samples without fruit juices or preservatives showed significant decrease in the antioxidant capacity (P < 0.05) after 4 days of storage based on the storage time. The dependence on temperature was revealed only after 7 days of storage.

Rice protein improves oxidative stress by regulating glutathione metabolism and attenuating oxidative damage to lipids and proteins in rats

AIMS

To evaluate the effects of rice protein (RP) on glutathione metabolism and oxidative damage.

MAIN METHODS

Seven-week-old male Wistar rats were fed diets containing casein and RP without cholesterol for 3weeks. Plasma and liver lipid levels, hepatic accumulation of total glutathione (T-GSH), oxidized glutathione (GSSG), reduced glutathione (GSH), malondialdehyde (MDA) and protein carbonyl (PCO) were measured. In the liver, the total antioxidative capacity (T-AOC), mRNA levels of glutamate cysteine ligase catalytic subunit (GCLC) and glutamate cysteine ligase modulatory subunit (GCLM), and the activities of hepatic catalase (CAT), total superoxide dismutase (T-SOD), γ-glutamylcysteine synthetase (γ-GCS), glutathione S-transferase (GST), glutathione reductase (GR) and glutathione peroxidase (GSHPx) were also measured.

KEY FINDINGS

T-AOC, GCLC and GCLM mRNA levels, antioxidative enzyme activities (T-SOD and CAT) and glutathione metabolism related enzyme activities (γ-GCS, GST, GR and GSHPx) were effectively stimulated by RP feeding compared to casein, and RP significantly reduced the hepatic accumulation of MDA and PCO in rats. These results indicate that lipid-lowering activity was induced by RP feeding.

SIGNIFICANCE

The present study demonstrates that RP improves oxidative stress primarily through enzymatic and non-enzymatic antioxidative defense mechanisms, reflected by enhancing the antioxidative status and attenuating the oxidative damage to lipids and proteins. These results suggest that RP can prevent hyperlipidemia in part through modifying glutathione metabolism, and sulfur amino acids may be the main modulator of this antioxidative mechanism.

Chemopreventive efficacy of Atorvastatin against nitrosamine-induced rat bladder cancer: antioxidant, anti-proliferative and anti-inflammatory properties

To investigate the anti-carcinogenic effects of Atorvastatin (Atorva) on a rat bladder carcinogenesis model with N-butyl-N-(4-hydroxibutil)nitrosamine (BBN), four male Wistar rat groups were studied: (1) Control: vehicle; (2) Atorva: 3 mg/kg bw/day; (3) Carcinogen: BBN (0.05%); (4) Preventive Atorva: 3 mg/kg bw/day Atorva + BBN. A two phase protocol was used, in which the drug and the carcinogen were given between week 1 and 8 and tumor development or chemoprevention were expressed between week 9 and 20, when the bladders were collected for macroscopic, histological and immunohistochemical (p53, ki67, CD31) evaluation. Serum was assessed for markers of inflammation, proliferation and redox status. The incidence of bladder carcinoma was: control 0/8 (0%); Atorva 0/8 (0%); BBN 13/20 (65%) and Atorva + BBN 1/8 (12.5%). The number and volume of tumors were significantly lower in the Atorva + BBN group, with a marked reduction in hyperplasia, dysplasia and carcinoma in situ lesions. An anti-proliferative, anti-inflammatory and antioxidant profile was also observed in the preventive Atorva group. p53 and ki67 immunostaining were significantly increased in the BBN-treated rats, which was prevented in the Atorva + BBN group. No differences were found for CD31 expression. In conclusion, Atorvastatin had a clear inhibitory effect on bladder cancer development, probably due to its antioxidant, anti-proliferative and anti-inflammatory properties.

Cryptotanshinone activates p38/JNK and inhibits Erk1/2 leading to caspase-independent cell death in tumor cells

Cryptotanshinone (CPT), a natural compound isolated from the plant Salvia miltiorrhiza Bunge, is a potential anticancer agent. However, the underlying mechanism is not well understood. Here, we show that CPT induced caspase-independent cell death in human tumor cells (Rh30, DU145, and MCF-7). Besides downregulating antiapoptotic protein expression of survivin and Mcl-1, CPT increased phosphorylation of p38 mitogen-activated protein kinase (MAPK) and c-jun N-terminal kinase (JNK), and inhibited phosphorylation of extracellular signal-regulated kinases 1/2 (Erk1/2). Inhibition of p38 with SB202190 or JNK with SP600125 attenuated CPT-induced cell death. Similarly, silencing p38 or c-Jun also in part prevented CPT-induced cell death. In contrast, expression of constitutively active mitogen-activated protein kinase kinase 1 (MKK1) conferred resistance to CPT inhibition of Erk1/2 phosphorylation and induction of cell death. Furthermore, we found that all of these were attributed to CPT induction of reactive oxygen species (ROS). This is evidenced by the findings that CPT induced ROS in a concentration- and time-dependent manner; CPT induction of ROS was inhibited by N-acetyl-L-cysteine (NAC), a ROS scavenger; and NAC attenuated CPT activation of p38/JNK, inhibition of Erk1/2, and induction of cell death. The results suggested that CPT induction of ROS activates p38/JNK and inhibits Erk1/2, leading to caspase-independent cell death in tumor cells.

Green tea extract alleviates arsenic-induced biochemical toxicity and lipid peroxidation in rats

The present work was undertaken to evaluate the protective effect of an aqueous extract of green tea (GT, Camellia sinensis) leaves against arsenic (NaAsO2)-induced biochemical toxicity and lipid peroxidation production in experimental rats. The treatment with arsenic exhibited a significant increase in some serum hepatic and renal biochemical parameters (alanine aminotransferase, aspartate aminotransferase, alkaline phosphatase, total protein, albumin, bilirubin, cholesterol, urea and creatinine). But the co-administration of GT has increased the level of plasmatic concentration of biochemical parameters. Exposure of rats to arsenic caused also a significant increase in liver, kidney and testicular thiobarbituric acid reactive substances compared to control. However, the co-administration of GT was effective in reducing its level. To conclude, our data suggest that arsenic exposure enhanced an oxidative stress by disturbing the tissue antioxidant defense system, but the GT co-administration alleviates the toxicity induced by arsenic exposure.

The protective effects of tea polyphenols and schisandrin B on nephrotoxicity of mercury

Mercury (Hg) is an occupational and environmental contaminant that is a well-recognized health hazard. To approach the concrete mechanisms of mercury nephrotoxicity and find out a new way to prevent it, the rats were subcutaneously injected with different dosages of mercuric chloride (HgCl(2))--0, 2.2, 4.4, and 8.8 μmol/kg. The levels of Hg, blood urea nitrogen (BUN), urine protein, glutathione (GSH), malondialdehyde (MDA) and activities of N-acetyl-beta-D-glucosaminidase (NAG), alkaline phosphatase (ALP), lactate dehydrogenase (LDH), superoxide dismutase (SOD), and glutathione peroxidase (GSH-Px) were investigated, and the levels of reactive oxygen species (ROS) and apoptosis and the pathological changes were also observed. In addition, the effects of 1 mmol/kg tea polyphenols (TP) and 0.04 mmol/kg schisandrin B (Sch B) were studied at 8.8 μmol/kg HgCl(2). It was observed that the levels of Hg, BUN, urine protein, GSH, and MDA and activities of NAG, ALP, and LDH increased significantly; the activities of SOD and GSH-Px decreased significantly; the levels of ROS and apoptosis increased obviously; and many pathological changes occurred dose-dependently in the HgCl(2) injection groups. Further investigation indicated that pretreatment with TP and Sch B significantly reversed the toxic effects of HgCl(2). These results suggested that TP and Sch B might antagonize the nephrotoxicity caused by HgCl(2) exposure.

Antioxidant and potential anti-inflammatory activity of extracts and formulations of white tea, rose, and witch hazel on primary human dermal fibroblast cells

BACKGROUND

Numerous reports have identified therapeutic roles for plants and their extracts and constituents. The aim of this study was to assess the efficacies of three plant extracts for their potential antioxidant and anti-inflammatory activity in primary human skin fibroblasts.

METHODS

Aqueous extracts and formulations of white tea, witch hazel and rose were subjected to assays to measure anti-collagenase, anti-elastase, trolox equivalent and catalase activities. Skin fibroblast cells were employed to determine the effect of each extract/formulation on IL-8 release induced by the addition of hydrogen peroxide. Microscopic examination along with Neutral Red viability testing was employed to ascertain the effects of hydrogen peroxide directly on cell viability.

RESULTS

Considerable anti-collagenase, anti-elastase, and antioxidant activities were measured for all extracts apart from the witch hazel distillate which showed no activity in the collagenase assay or in the trolox equivalence assay. All of the extracts and products tested elicited a significant decrease in the amount of IL-8 produced by fibroblast cells compared to the control (p < 0.05). None of the test samples exhibited catalase activity or had a significant effect on the spontaneous secretion of IL-8 in the control cells which was further corroborated with the microscopy results and the Neutral Red viability test.

CONCLUSIONS

These data show that the extracts and products tested have a protective effect on fibroblast cells against hydrogen peroxide induced damage. This approach provides a potential method to evaluate the claims made for plant extracts and the products in which these extracts are found.

The role of antioxidant versus pro-oxidant effects of green tea polyphenols in cancer prevention

Consumption of green tea (Camellia sinensis) may provide protection against chronic diseases, including cancer. Green tea polyphenols are believed to be responsible for this cancer preventive effect, and the antioxidant activity of the green tea polyphenols has been implicated as a potential mechanism. This hypothesis has been difficult to study in vivo due to metabolism of these compounds and poor understanding of the redox environment in vivo. Green tea polyphenols can be direct antioxidants by scavenging reactive oxygen species or chelating transition metals as has been demonstrated in vitro. Alternatively, they may act indirectly by upregulating phase II antioxidant enzymes. Evidence of this latter effect has been observed in vivo, yet more work is required to determine under which conditions these mechanisms occur. Green tea polyphenols can also be potent pro-oxidants, both in vitro and in vivo, leading to the formation of hydrogen peroxide, the hydroxyl radical, and superoxide anion. The potential role of these pro-oxidant effects in the cancer preventive activity of green tea is not well understood. The evidence for not only the antioxidant, but also pro-oxidant, properties of green tea is discussed in the present review.

White tea (Camellia sinensis Kuntze) exerts neuroprotection against hydrogen peroxide-induced toxicity in PC12 cells

Tea is a popular beverage whose consumption is associated with prevention of certain disorders. The objective of the study was to investigate the potential neuroprotective effect of white tea extract (WTE) on hydrogen peroxide induced toxicity in PC12 cells. Cells were treated with various doses of WTE (10-250 μg/ml) before exposition to 250 μM hydrogen peroxide and cell survival was determined through the MTT and LDH assays. Oxidative stress was quantified in the cells after treatments as intracellular reactive oxygen species (ROS) production and the antioxidant activity of the extract was assessed in a cell free system in terms of free radical scavenging capacity. Results showed that WTE has a significant protective effect in the PC12 cell line against hydrogen peroxide as cell survival was significantly superior in WTE-treated cells compared to hydrogen peroxide-treated cells. A reduction on intracellular oxidative stress as well as radical scavenging properties were produced by WTE. Results suggest that WTE protects PC12 cells against H(2)O(2)-induced toxicity, and that an antioxidant mechanism through ROS scavenging may be in part responsible for cells neuroprotection.

Multistage carcinogenesis process as molecular targets in cancer chemoprevention by epicatechin-3-gallate

The consumption of green tea has long been associated with a reduced risk of cancer development. (-)-Epicatechin-3-gallate (ECG) or (-)-epigallocatechin-3-gallate (EGCG) are the major antioxidative polyphenolic compounds of green tea. They have been shown to exert growth-inhibitory potential of various cancer cells in culture and antitumor activity in vivo models. ECG or EGCG could interact with various molecules like proteins, transcription factors, and enzymes, which block multiple stages of carcinogenesis via regulating intracellular signaling transduction pathways. Moreover, ECG and EGCG possess pharmacological and physiological properties including induction of phase II enzymes, mediation of anti-inflammation response, regulation of cell proliferation and apoptosis effects and prevention of tumor angiogenesis, invasion and metastasis. Numerous review articles have been focused on EGCG, however none have been focused on ECG despite many studies supporting the cancer preventive potential of ECG. To develop ECG as an anticarcinogenic agent, more clear understanding of the cell signaling pathways and the molecular targets responsible for chemopreventive and chemotherapeutic effects are needed. This review summarizes recent research on the ECG-induced cellular signal transduction events which implicate in cancer management.

Oxidative stress and antioxidants in hepatic pathogenesis

Long term hepatitis B virus (HBV) infection is a major risk factor in pathogenesis of chronic liver diseases, including hepatocellular carcinoma (HCC). The HBV encoded proteins, hepatitis B virus X protein and preS, appear to contribute importantly to the pathogenesis of HCC. Both are associated with oxidative stress, which can damage cellular molecules like lipids, proteins, and DNA during chronic infection. Chronic alcohol use is another important factor that contributes to oxidative stress in the liver. Previous studies reported that treatment with antioxidants, such as curcumin, silymarin, green tea, and vitamins C and E, can protect DNA from damage and regulate liver pathogenesis-related cascades by reducing reactive oxygen species. This review summarizes some of the relationships between oxidative stress and liver pathogenesis, focusing upon HBV and alcohol, and suggests antioxidant therapeutic approaches.