Effects of green tea polyphenols against metal-induced genotoxic damage: underlying mechanistic pathways

Dose-response effect of polyphenon-60 from green tea (P60-GT) on hexavalent chromium-induced genotoxic damage and apoptosis in mice

This study aimed to examine the dose-response effects of polyphenon-60 derived from green tea (P60-GT) on hexavalent chromium [Cr(VI)]-induced genotoxic damage and apoptosis. Male Hsd:ICR mice were divided into 4 groups: (1) Control (vehicle only), (2) P60-GT (15, 30, or 45 mg/kg gavage), (3) Cr(VI) (20 mg/kg of CrO3 intraperitoneally), and (4) P60-GT+CrO3 (P60-GT administered 4 hr before CrO3). Peripheral blood samples were collected at 24, 48, and 72 hr to assess the number of micronuclei (MN), apoptosis, and cell viability, while plasma 8-hydroxy-2'-deoxyguanosine (8-OHdG) levels were measured at 0 and 48 hr. Cr(VI) significantly increased MN frequency, suppressed 8-OHdG repair, and reduced cell viability. Pre-treatment with P60-GT reduced MN frequency by up to 74%, with the 30 mg/kg dose demonstrating the highest efficacy. This dose restored cell viability, enhanced 8-OHdG repair, and enhanced apoptosis, suggesting activation of DNA repair and apoptotic pathways as potential antigenotoxic mechanisms. The 15 mg/kg dose exhibited anti-apoptotic effects, while the 30 and 45 mg/kg doses promoted apoptosis. However, the 45 mg/kg dose resulted in 100% lethality by 72 hr, likely due to synergistic toxicity with Cr(VI). These findings demonstrate the dose-dependent protective effects of P60-GT and emphasize the need for dosage optimization to maximize therapeutic benefits while minimizing toxicity.

Green tea catechins: protectors or threats to DNA? A review of their antigenotoxic and genotoxic effects

This review examines the dual behavior of green tea catechins (GTCs), demonstrating the compound's ability to protect against oxidative stress and DNA damage while also potentially inducing genotoxicity under certain conditions. This duality may be attributed to their capacity both to scavenge free radicals and to generate these species via autooxidation. GTCs' antigenotoxic activities are mediated by multiple mechanisms, including reactive oxygen species (ROS) scavenging, regulation of endogenous antioxidant system (EAS), DNA repair, selective apoptosis of genetically compromised cells, epigenetic modulation, and metal ion (Cu, Fe, Zn) chelation-all of which collectively maintain cellular homeostasis and help reduce inflammation. However, at specific concentrations and in certain cellular conditions, GTCs' prooxidant effects-i.e., high ROS levels-might damage DNA and promote pro-apoptotic processes, potentially benefiting elimination of malignant cells. In contrast, lower ROS levels might stimulate antioxidant defenses via Nrf2 activation. Although evidence from both in vitro and in vivo studies indicates that GTCs consumption offers significant protection against diseases linked to oxidative DNA injury, the prooxidant properties of GTCs warrant careful consideration. Future research might focus on (1) optimizing GTC formulations for improved bioavailability, (2) assessing long-term outcomes, (3) evaluating toxicity at higher doses, and (4) investigating gut microbiome interactions. The dual antigenotoxic and genotoxic actions of GTCs indicate the potential role in preventive and complementary medicine, aligning with sustainable beneficial health strategies utilizing natural compounds.

Natural Copper Ion Scavenger: Investigation of the Hepatoprotective Effects of Green Tea Extract in Toxic-Milk Mice with Wilson's Disease Model

Wilson's disease (WD) is an inherited disorder characterized by abnormal copper metabolism with complex pathological features. Currently, the mechanism of copper overload-induced hepatic injury is unclear. Green tea is a natural chelator, and its main ingredients, green tea polyphenol (GTP) and L-theanine (L-TA) are good at binding to heavy metals like iron and copper. There have been no reports on green tea extracts (GTE) for the treatment of Wilson's disease. This study investigated the hepatoprotective effect of GTE on WD model mice. Initially, we examined the impact of green tea extract on copper metabolism, excretion, and hepatoprotective effects in WD model toxic milk mice. Then, Ultra performance liquid chromatography (UPLC-DAD) was established to analyze GTP and L-TA in green tea extract. Further screening of eight active components and copper complex active components in green tea extract was carried out by ion analyzer. Finally, we verified the pharmacodynamic effects of these active ingredients at the animal level. The results showed that GTE improves liver function and attenuates liver injury in TX mice by promoting tissue copper excretion and inhibiting oxidative stress, which provides a theoretical basis for green tea's potential to improve the clinical symptoms of WD.

Tea Polyphenols Relieve the Fluoride-Induced Oxidative Stress in the Intestinal Porcine Epithelial Cell Model

Prolonged excessive intake of fluoride (F) can result in fluorosis, leading to a range of tissue oxidative damages. Therefore, mitigating the oxidative stress induced by fluorosis has become a significant research concern. Consequently, how to relieve oxidative stress caused by fluorosis is an urgent matter. In the present study, intestinal porcine epithelial (IPEC-J2) cells were chosen to explore the underlying mechanism of tea polyphenols (TPs) on F-induced oxidative stress. The results show that the cytotoxicity of IPEC-J2 cells induced by F presented a dose-dependent manner according to cell viability. Additionally, F treatment inhibited the activity of T-SOD, CAT, and GSH-Px as well as their transcription levels, increased the reactive oxygen (ROS) formation and cell damage rates, and then promoted cell apoptosis through the results of TUNEL and mitochondrial membrane potential detection when compared with the IPEC-J2 cells from the control group. As the main antioxidant ingredient in tea, TPs alleviated F-induced cell oxidation and apoptosis via blocking F-induced ROS generation and LDH's release, as well as promoting the transcription of tight junction (TJ) proteins and the activities of antioxidant enzymes in IPEC-J2 cells. These results provide a new treatment strategy for F-induced intestinal oxidative impairment.

New Insights into Aspirin's Anticancer Activity: The Predominant Role of Its Iron-Chelating Antioxidant Metabolites

Epidemiological studies have suggested that following long-term, low-dose daily aspirin (LTLDA) administration for more than 5 years at 75-100 mg/day, 20-30% of patients (50-80 years old) had a lower risk of developing colorectal cancer (CRC) and about the same proportion in developing iron deficiency anemia (IDA). In cases of IDA, an increase in iron excretion is suspected, which is caused by aspirin chelating metabolites (ACMs): salicylic acid, salicyluric acid, 2,5-dihydroxybenzoic acid, and 2,3-dihydroxybenzoic acid. The ACMs constitute 70% of the administered aspirin dose and have much longer half-lives than aspirin in blood and tissues. The mechanisms of cancer risk reduction in LTLDA users is likely due to the ACM's targeting of iron involved in free radical damage, iron-containing toxins, iron proteins, and associated metabolic pathways such as ferroptosis. The ACMs from non-absorbed aspirin (about 30%) may also mitigate the toxicity of heme and nitroso-heme and other iron toxins from food, which are responsible for the cause of colorectal cancer. The mode of action of aspirin as a chelating antioxidant pro-drug of the ACMs, with continuous presence in LTLDA users, increases the prospect for prophylaxis in cancer and other diseases. It is suggested that the anticancer effects of aspirin depend primarily on the iron-chelating antioxidant activity of the ACMs. The role of aspirin in cancer and other diseases is incomplete without considering its rapid biotransformation and the longer half-life of the ACMs.

Short-term dietary teprenone improved thermal tolerance and mitigated liver damage caused by heat stress in juvenile largemouth bass (Micropterus salmoides)

Heat stress seriously threatens fish survival and health, demanding immediate attention. Teprenone is a gastric mucosal protective agent that can induce heat shock protein expression. This research investigated the effects of teprenone on largemouth bass (Micropterus salmoides) subjected to heat stress. Juvenile fish were assigned to different groups: group C (control group, 0 mg teprenone/kg diet), T0, T200, T400, and T800 (0, 200, 400, and 800 mg teprenone/kg diet, respectively), which were fed for 3 days, followed by a day without the diet. All groups except group C were subjected to acute heat stress (from 24 °C to 35 °C at 1 °C per hour and then maintained at 35 °C for 3 h). The results were as follows: The critical thermal maxima were significantly higher in the T200, T400, and T800 groups compared with the T0 group (P < 0.05). Heat stress caused severe damage to the tissue morphology of the liver, while teprenone significantly reduced this injury (P < 0.05). Serum cortisol concentration decreased gradually as teprenone concentration increased, and the lowest concentration was observed in the T800 group (P < 0.05). Compared with the T0 group, the serum activities of aspartate aminotransferase, alanine aminotransferase, and gamma-glutamyl transferase were significantly lower in the T200, T400, and T800 groups (P < 0.05). The liver activities of catalase, total superoxide dismutase, and peroxidase were significantly higher in the T200 group than in the T0 group (P < 0.05). Transcript levels of the heat shock proteins (hsp90, hsp70, hspa5, and hsf1) and caspase family (caspase3 and caspase9) in the liver of the T200 group were significantly higher than those of the T0 group (P < 0.05). Western blot results showed that HSP70 and HSPA5 in the liver were significantly upregulated in the T200 group compared with the T0 group (P < 0.05). In summary, dietary teprenone improved thermal tolerance, alleviated heat stress damage in the liver, enhanced antioxidant capacity, and upregulated heat shock proteins in juvenile largemouth bass. This study offers theoretical support for applying teprenone in aquaculture to reduce financial losses caused by abiotic factors.

Green tea polyphenols inhibit TBBPA-induced lung injury via enhancing antioxidant capacity and modulating the NF-κB pathway in mice

Tetrabromobisphenol A (TBBPA) is a global pollutant. When TBBPA is absorbed by the body through various routes, it can have a wide range of harmful effects on the body. Green tea polyphenols (GTPs) can act as antioxidants, resisting the toxic effects of TBBPA on animals. The effects and mechanisms of GTP and TBBPA on oxidative stress, inflammation and apoptosis in the mouse lung are unknown. Therefore, we established in vivo and in vitro models of TBBPA exposure and GTP antagonism using C57 mice and A549 cells and examined the expression of factors related to oxidative stress, autophagy, inflammation and apoptosis. The results of the study showed that the increase in reactive oxygen species (ROS) levels after TBBPA exposure decreased the expression of autophagy-related factors Beclin1, LC3-II, ATG3, ATG5, ATG7 and ATG12 and increased the expression of p62; oxidative stress inhibits autophagy levels. The increased expression of the pro-inflammatory factors IL-1β, IL-6 and TNF-α decreased the expression of the anti-inflammatory factor IL-10 and activation of the NF-κB p65/TNF-α pathway. The increased expression of Bax, caspase-3, caspase-7 and caspase-9 and the decreased expression of Bcl-2 activate apoptosis-related pathways. The addition of GTP attenuated oxidative stress levels, restored autophagy inhibition and reduced the inflammation and apoptosis levels. Our results suggest that GTP can attenuate the toxic effects of TBBPA by modulating ROS, reducing oxidative stress levels, increasing autophagy and attenuating inflammation and apoptosis in mouse lung and A549 cells. These results provide fundamental information for exploring the antioxidant mechanism of GTP and further for studying the toxic effects of TBBPA.

A comparative study on chromium-induced micronuclei assessment in the peripheral blood of Hsd:ICR mice

This study investigated the genotoxic effects of chromium (Cr) in Hsd:ICR mice, considering factors such as oxidative state, apoptosis, exposure pathway, duration, pregnancy, and transplacental exposure. Genotoxicity was assessed using the erythrocytes' micronucleus (MN) assay, while apoptosis was evaluated in nucleated blood cells. The results showed that Cr(III) (CrK(SO4 )2 and CrCl3 ) did not induce any marked genotoxic damage. However, Cr(VI) (CrO3 , K2 Cr2 O7 , Na2 Cr2 O7 , and K2 CrO4 ) produced varying degrees of genotoxicity, with CrO3 being the most potent. MN frequencies increased following 24-h exposure, with a greater effect in male mice. Administering 20 mg/kg of CrO3 via gavage did not lead to significant effects compared to intraperitoneal administration. Short-term oral treatment with a daily dose of 8.5 mg/kg for 49 days elevated MN levels only on day 14 after treatment. Pregnant female mice exposed to CrO3 on day 15 of pregnancy exhibited reduced genotoxic effects compared to nonpregnant animals. However, significant increases in MN levels were found in their fetuses starting 48 h after exposure. In summary, data indicate the potential genotoxic effects of Cr, with Cr(VI) forms inducing higher genotoxicity than Cr(III). These findings indicate that gender, exposure route, and pregnancy status might influence genotoxic responses to Cr.

Masson pine pollen aqueous extract ameliorates cadmium-induced kidney damage in rats

Introduction: Cadmium (Cd) is a hazardous environmental pollutant present in soil, water, and food. Accumulation of Cd in organisms can cause systematic injury and damage to the kidney. The Masson pine pollen aqueous extract (MPPAE) has attracted increasing attention due to its antioxidant activity and ability to enhance immunity. Methods: In this study, we investigated the potential of MPPAE to protect against Cd-induced kidney damage in rats and the underlying mechanism. The transcriptome and metabolome of rats with Cd-induced kidney damage, following treatment with MPPAE, were explored. Results: The concentrations of superoxide dismutase (SOD) and malondialdehyde (MDA) were both significantly altered after treatment with MPPAE. Furthermore, sequencing and analysis of the transcriptome and metabolome of rats with Cd-induced kidney damage, following treatment with MPPAE, revealed differential expression of numerous genes and metabolites compared with the untreated control rats. These differentially expressed genes (DEGs) included detoxification-related genes such as cytochrome P450 and the transporter. The differentially expressed metabolites (DEMs) included 4-hydroxybenzoic acid, L-ascorbate, and ciliatine. Conjoint transcriptome and metabolome analysis showed that several DEGs were correlated with DEMs. Conclusion: These preliminary findings indicate the potential of MPPAE for the treatment of toxic metal poisoning.

Iron Load Toxicity in Medicine: From Molecular and Cellular Aspects to Clinical Implications

Iron is essential for all organisms and cells. Diseases of iron imbalance affect billions of patients, including those with iron overload and other forms of iron toxicity. Excess iron load is an adverse prognostic factor for all diseases and can cause serious organ damage and fatalities following chronic red blood cell transfusions in patients of many conditions, including hemoglobinopathies, myelodyspasia, and hematopoietic stem cell transplantation. Similar toxicity of excess body iron load but at a slower rate of disease progression is found in idiopathic haemochromatosis patients. Excess iron deposition in different regions of the brain with suspected toxicity has been identified by MRI T2* and similar methods in many neurodegenerative diseases, including Alzheimer's disease and Parkinson's disease. Based on its role as the major biological catalyst of free radical reactions and the Fenton reaction, iron has also been implicated in all diseases associated with free radical pathology and tissue damage. Furthermore, the recent discovery of ferroptosis, which is a cell death program based on free radical generation by iron and cell membrane lipid oxidation, sparked thousands of investigations and the association of iron with cardiac, kidney, liver, and many other diseases, including cancer and infections. The toxicity implications of iron in a labile, non-protein bound form and its complexes with dietary molecules such as vitamin C and drugs such as doxorubicin and other xenobiotic molecules in relation to carcinogenesis and other forms of toxicity are also discussed. In each case and form of iron toxicity, the mechanistic insights, diagnostic criteria, and molecular interactions are essential for the design of new and effective therapeutic interventions and of future targeted therapeutic strategies. In particular, this approach has been successful for the treatment of most iron loading conditions and especially for the transition of thalassemia from a fatal to a chronic disease due to new therapeutic protocols resulting in the complete elimination of iron overload and of iron toxicity.