Caffeic acid, a phyto polyphenol mitigates fluoride induced hepatotoxicity in rats: A possible mechanism

Grape seed proanthocyanins protect fluoride-induced hepatotoxicity via the Nrf2 signaling pathway in male rats

Background

Fluoride is a necessary element for human health, but excessive fluoride intake is found toxic to the liver. Previous studies confirmed that Grape seed procyanidin extract (GSPE) protects against fluoride-induced hepatic injury. However, the mechanism underlying this protective effect remains obscure. To evaluate the protective effect of GSPE against fluoride-induced hepatic injury and explore the possible hepatoprotective role of the Nrf2 signaling pathway to find effective strategies for the treatment and prevention of fluoride-induced hepatotoxicity. This study aims to explore the mechanisms by which GSPE attenuates fluoride-induced hepatotoxicity through a rat drinking water poisoning model.

Methods

Hepatic injury was determined by serum biochemical parameters, oxidative parameters, HE, and TUNEL analysis. The protein expression levels of apoptosis-related proteins like Bax, B-cell lymphoma-2 (Bcl-2), and Caspase-3 and the nuclear factor, erythroid 2 like 2 (Nrf2) were analyzed by Western blot.

Resluts

Our results showed that GSPE administration reduced fluoride-induced elevated serum ALT and AST and enhanced the antioxidant capacity of the liver. In addition, GSPE mitigated fluoride-induced histopathological damage and reduced the liver cell apoptosis rate. Furthermore, GSPE significantly up-regulated the expression and nuclear translocation of the Nrf2 and decreased apoptosis-related proteins like Bax and caspase-3 in the hepatic.

Conclusion

Taken together, GSPE exerts protective effects on the oxidative damage and apoptosis of fluoride-induced hepatic injury via the activation of the Nrf2 signaling pathway. This study provides a new perspective for the mechanism study and scientific prevention and treatment of liver injury induced by endemic fluorosis.

Fluoride-Induced Mitochondrial Dysfunction and Approaches for Its Intervention

Fluoride is present everywhere in nature. The primary way that individuals are exposed to fluoride is by drinking water. It's interesting to note that while low fluoride levels are good for bone and tooth growth, prolonged fluoride exposure is bad for human health. Additionally, preclinical studies link oxidative stress, inflammation, and programmed cell death to fluoride toxicity. Moreover, mitochondria play a crucial role in the production of reactive oxygen species (ROS). On the other hand, little is known about fluoride's impact on mitophagy, biogenesis, and mitochondrial dynamics. These actions control the growth, composition, and organisation of mitochondria, and the purification of mitochondrial DNA helps to inhibit the production of reactive oxygen species and the release of cytochrome c, which enables cells to survive the effects of fluoride poisoning. In this review, we discuss the different pathways involved in mitochondrial toxicity and dysfunction induced by fluoride. For therapeutic approaches, we discussed different phytochemical and pharmacological agents which reduce the toxicity of fluoride via maintained by imbalanced cellular processes, mitochondrial dynamics, and scavenging the ROS.

Fluoride promotes the secretion of inflammatory factors in microglia through NLRP3/Caspase-1/GSDMD pathway

It is widespread of endemic fluorosis in China, and the exposure of excessive fluoride will cause nervous system disease and activate microglia. However, the mechanism of the damage is not clear. It is well-known that NLRP3/Caspase-1/GSDMD pathway, a classic pyroptosis pathway, is widely involved in the occurrence and development of nervous system-related diseases, infectious diseases, and atherosclerotic diseases. This research aimed to explore the molecular mechanism of sodium fluoride on inflammation and pyroptosis in BV2 microglia based on the NLRP3/Caspase-1/GSDMD signaling pathway. BV2 microglia was treated with sodium fluoride at the dose of 0.25, 1, and 2 mmol/L for 24, 48, and 72 h, respectively. Cell viability, cell morphology, lactate dehydrogenase content, and related proteins and genes were examined to investigate if sodium fluoride caused damage to BV2 microglia through the pyroptosis pathway. Dithiolam (5 μmol/L), a pyroptosis inhibitor, was added for further verification. NaF could induced BV2 cells injury in a dose-dependent fashion through disrupting the integrity of cell membranes and increasing IL-1β via upregulating NLRP3, Caspase-1, and its downstream protein GSDMD. Disulfiram could improve these changes caused by NaF. In conclusion, our results suggested that NLRP3/Caspase-1/GSDMD-mediated classical pyroptosis pathway was involved in fluoride-induced BV2 microglia damage.

Effects of Treadmill Exercise on Liver Apoptosis in Fluoride-Exposed Mice

Hepatotoxicity induced by excessive fluoride (F) exposure has been extensively studied in both humans and animals. Chronic fluorosis can result in liver apoptosis. Meanwhile, moderate exercise alleviates apoptosis caused by pathological factors. However, the effect of moderate exercise on F-induced liver apoptosis remains unclear. In this research, sixty-four three-week-old Institute of Cancer Research (ICR) mice, half male and half female, were randomly divided into four groups: control group (distilled water); exercise group (distilled water and treadmill exercise); F group [100 mg/L sodium fluoride (NaF)]; and exercise plus F group (100 mg/L NaF and treadmill exercise). The liver tissues of mice were taken at 3 months and 6 months, respectively. Hematoxylin-eosin (HE) staining and situ terminal deoxynucleotidyl transferase-mediated dUTP nick end labeling (TUNEL) results showed that nuclear condensation and apoptotic hepatocytes occurred in the F group. However, this phenomenon could be reversed with the intervention of treadmill exercise. The results of QRT-PCR and western blot displayed NaF- induced apoptosis via tumor necrosis factor recpter 1 (TNFR1) signaling pathway, while treadmill exercise could restore the molecular changes caused by excessive NaF exposure.

An interventional clinical trial investigating the effects of Spirulina platensis on dental fluorosis and antioxidant system in lambs reared in endemic areas

This study aimed to evaluate the protective effect of Spirulina platensis primary against dental fluorosis and secondary against oxidative stress in lambs reared in endemic fluorosis areas. Forty-eight lambs aged 5 months were divided into four equal groups (each one including 6 males and 6 females). Groups I and II served as controls belonging respectively to fluorosis-free (Settat) and endemic fluorosis (El Fokra) areas, while the other two Groups III and IV (belonging to El Fokra) received respectively a fixed daily intake of 250 and 500 mg/kg bodyweight (BW) of Spirulina platensis. The experiment was carried out for 13 months until the adult incisors appeared for all animals. According to the Dean's Fluorosis Index (DFI), 500 mg/kg BW/day of Spirulina platensis (Group IV) protected against dental fluorosis. Moreover, in both male and female lambs, this dose significantly (p < 0.0001) reduced the plasmatic levels of fluoride, proteins, GSH, and MDA compared to the Group II. Furthermore, enzymatic activities of catalase and SOD increased significantly (p < 0.0001) in male and female lambs of the Group IV as compared to Group II. In conclusion, our findings support the potential use of Spirulina platensis as a valuable solution for addressing fluorosis in sheep, warranting further clinical trials.

Fluoride Binding Potential of Selected Phytochemicals: A Pilot Study

Fluoride (F-) contamination in drinking water is a major global concern. According to several studies, India and China are the most affected by the presence of excess F-. Long-time exposure to F- concentrations above 1.5 ppm can lead to hard and soft tissue fluorosis (F- toxicity). There are no effective cure or treatment for fluorosis and the condition is almost irreversible. Considering water to be the prime media through which F- reaches humans, maintaining optimal F- levels in water remains the only possible remedy. F- endemic areas have adapted several conventional defluoridation techniques to resolve the issue. Among these, adsorption with plant compounds is widely used for F- removal. Studies have shown that plant metabolites can ameliorate the toxic effects of F-. Based on this, we attempt to elucidate the potential binding and electrochemical bio-sensing properties of selected phytochemicals towards F-. The focus of the present work is to evaluate the interactions of phytochemicals with F-; for which, the binding studies of phytochemicals with F- have been elaborated by UV-visible spectroscopy and emission techniques. Benesi-Hildebrand's (BH) plot was used to calculate the binding constant (CUR - 34.9 × 103 (M-1), QUER - 13 × 103 (M-1), ESC -6.3 × 103 (M-1), FIS - 5.36 × 103 (M-1) and PCA -1.5 × 103 (M-1), and detection limit (CUR - 1.54 × 10-7 M, QUER - 0.156 × 10-6 M, ESC - 0.221 × 10-6 M, FIS - 0.175 × 10-6 M, and PCA - 5.8 × 10-6 M) for the F-:phytochemical mixtures. Further, the binding characteristics were confirmed using 1H-NMR titration experiments. Our findings highlight the potential of phytochemicals as effective binding agents for F-, thereby reducing its bioavailability.

Chlorogenic acids: A pharmacological systematic review on their hepatoprotective effects

BACKGROUND

Liver diseases have a negative impact on global health and are a leading cause of death worldwide. Chlorogenic acids (CGAs), a family of esters formed between certain trans-cinnamic acids and quinic acid, are natural polyphenols abundant in coffee, tea, and a variety of traditional Chinese medicines (TCMs). They are reported to have good hepatoprotective effects against various liver diseases.

PURPOSE

This review aims to analyze the available literature on the hepatoprotective effect of CGAs, with particular emphasis on their mechanisms.

METHODS

Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) guidelines were followed. PubMed and Web of Science databases were adopted to retrieve all relevant literature on CGAs for liver disease from 2013 to March 2023.

RESULTS

Research has indicated that CGAs play a crucial role in improving different types of liver diseases, including drug-induced liver injury (DILI), alcoholic liver disease (ALD), metabolic (dysfunction)-associated fatty liver disease (MAFLD), cholestatic liver disease (CLD), liver fibrosis, and liver cancer. CGAs display remarkable antioxidant and anti-inflammatory effects by activating erythroid 2-related factor 2 (Nrf2) and inhibiting toll-like receptor 4 (TLR4)/nuclear factor-κB (NF-κB) signaling pathways. Some important molecules such as AMP-activated protein kinase (AMPK) and extracellular signal-regulated kinases 1 and 2 (ERK1/2), and other key physiological processes like intestinal barrier and gut microbiota have also been discovered to participate in CGAs-provided amelioration on various liver diseases.

CONCLUSION

In this review, different studies indicate that CGAs have an excellent protective effect against various liver diseases associated with various signaling pathways.

Fluoride Induced Neurobehavioral Impairments in Experimental Animals: a Brief Review

Fluoride is one of the major toxicants in the environment and is often found in drinking water at higher concentrations. Living organisms including humans exposed to high fluoride levels are found to develop mild-to-severe detrimental pathological conditions called fluorosis. Fluoride can cross the hematoencephalic barrier and settle in various brain regions. This accumulation affects the structure and function of both the central and peripheral nervous systems. The neural ultrastructure damages are reflected in metabolic and cognitive activities. Hindrances in synaptic plasticity and signal transmission, early neuronal apoptosis, functional alterations of the intercellular signaling pathway components, improper protein synthesis, dyshomeostasis of the transcriptional and neurotrophic factors, oxidative stress, and inflammatory responses are accounted for the fluoride neurotoxicity. Fluoride causes a decline in brain functions that directly influence the overall quality of life in both humans and animals. Animal studies are widely used to explore the etiology of fluoride-induced neurotoxicity. A good number of these studies support a positive correlation between fluoride intake and toxicity phenotypes closely associated with neurotoxicity. However, the experimental dosages highly surpass the normal environmental concentrations and are difficult to compare with human exposures. The treatment procedures are highly dependent on the dosage, duration of exposure, sex, and age of specimens among other factors which make it difficult to arrive at general conclusions. Our review aims to explore fluoride-induced neuronal damage along with associated histopathological, behavioral, and cognitive effects in experimental models. Furthermore, the correlation of various molecular mechanisms upon fluoride intoxication and associated neurobehavioral deficits has been discussed. Since there is no well-established mechanism to prevent fluorosis, phytochemical-based alleviation of its characteristic indications has been proposed as a possible remedial measure.

Morphological, ultrastructural, and biochemical changes induced by sodium fluoride in the tongue of adult male albino rat and the ameliorative effect of resveratrol

Little knowledge is available about the effects of fluoride exposure on the tongue. This study evaluated the effects of sodium fluoride (NaF) on the tongue ultrastructure and detected the ameliorative effects of resveratrol. Forty adult albino rats were separated into 4 groups: the control group was given a balanced diet and purified water. The NaF treated group: received 10 mg/kg/d dissolved in 2.5 ml distilled water once daily for 30 days orally. The NaF+resveratrol group: received NaF 10 mg/kg/d orally together with resveratrol in a dose of 30 mg/kg daily for 30 days. The resveratrol group was subjected to resveratrol in a dose of 30 mg/kg/d by oral gavage for 30 days. Sections were stained with hematoxylin & eosin, and Masson's trichrome. Tumor necrosis factor α immunohistochemical study and electron microscopic examinations were done. The oxidative stress markers malondialdehyde, antioxidant reduced glutathione, and the total antioxidant capacity were measured. The NaF group revealed ulceration, necrotic muscle fibers, distorted papillae and a significant increase in malondialdehyde level, and a significant decrease in glutathione and the total antioxidant levels. In the NaF+resveratrol group, pathological changes were less, and the oxidant levels were decreased by the administration of resveratrol with NaF. In conclusion, NaF adversely affects the ultrastructure of the adult rat tongue and resveratrol can ameliorate this effect.

Virgin coconut oil: A comprehensive review of antioxidant activity and mechanisms contributed by phenolic compounds

Virgin coconut oil (VCO) is obtained by processing mature coconut cores with mechanical or natural methods. In recent years, VCO has been widely used in the food, pharmaceutical, and cosmetic industries because of its excellent functional activities. VCO has biological functions such as antioxidant, anti-inflammatory, antibacterial, and antiviral, and also has potential therapeutic effects on many chronic degenerative diseases. Among these functions, the antioxidant is the most basic and important function, which is mainly determined by phenolic compounds and medium-chain fatty acids (MCFAs). This review aims to elucidate the antioxidant functions of each phenolic compound in VCO, and discuss the antioxidant mechanisms of VCO in terms of the role of phenolic compounds with fat, intestinal microorganisms, and various organs. Besides, the composition of VCO and its application in various industries are summarized, and the biological functions of VCO are generalized, which should lay a foundation for further research on the antioxidant activity of VCO and provide a theoretical basis for the development of food additives with antioxidant activity.

Role of oxidative stress-mediated cell death and signaling pathways in experimental fluorosis

Free radicals and other oxidants have enticed the interest of researchers in the fields of biology and medicine, owing to their role in several pathophysiological conditions, including fluorosis (Fluoride toxicity). Radical species affect cellular biomolecules such as nucleic acids, proteins, and lipids, resulting in oxidative stress. Reactive oxygen species-mediated oxidative stress is a common denominator in fluoride toxicity. Fluorosis is a global health concern caused by excessive fluoride consumption over time. Fluoride alters the cellular redox homeostasis, and its toxicity leads to the activation of cell death mechanisms like apoptosis, autophagy, and necroptosis. Even though a surfeit of signaling pathways is involved in fluorosis, their toxicity mechanisms are not fully understood. Thus, this review aims to understand the role of reactive species in fluoride toxicity with an outlook on the effects of fluoride in vitro and in vivo models. Also, we emphasized the signal transduction pathways and the mechanism of cell death implicated in fluoride-induced oxidative stress.

A systematic review on fluoride-induced epigenetic toxicity in mammals

Fluoride, one of the global groundwater contaminants, is ubiquitous in our day-to-day life from various natural and anthropogenic sources. Numerous in vitro, in vivo, and epidemiological studies are conducted to understand the effect of fluoride on biological systems. A low concentration of fluoride is reported to increase oral health, whereas chronic exposure to higher concentrations causes fluoride toxicity (fluorosis). It includes dental fluorosis, skeletal fluorosis, and fluoride toxicity in soft tissues. The mechanism of fluoride toxicity has been reviewed extensively. However, epigenetic regulation in fluoride toxicity has not been reviewed. This systematic review summarizes the current knowledge regarding fluoride-induced epigenetic toxicity in the in vitro, in vivo, and epidemiological studies in mammalian systems. We examined four databases for the association between epigenetics and fluoride exposure. Out of 932 articles (as of 31 March 2022), 39 met our inclusion criteria. Most of the studies focused on different genes, and overall, preliminary evidence for epigenetic regulation of fluoride toxicity was identified. We further highlight the need for epigenome studies rather than candidate genes and provide recommendations for future research. Our results indicate a correlation between fluoride exposure and epigenetic processes. Further studies are warranted to elucidate and confirm the mechanism of epigenetic alterations mediated fluoride toxicity.

Nanoparticles for active combination radio mitigating agents of zinc coumarate and zinc caffeinate in a rat model

Zinc coumarate and zinc caffeinate nanoparticles (ZnCoNPs, ZnCaNPs) affect different biological processes. This study aimed to evaluate the mitigating action of ZnCoNPs in combination with ZnCaNPs against liver damage induced by gamma rays (γ-rays). Rats were exposed to 7 Gy of γ-rays and then injected intraperitoneally (i.p) with ZnCoNPs [2U/rat/day (5 mg/kg)] and ZnCaNPs [2U/rat/day (15 mg/kg)] for 7 consecutive days. The results showed that irradiated rats treated with ZnCoNPs (5 mg/kg/body weight) in combination with ZnCaNPs (15 mg/kg/body weight) for 7 days had a significant increases in body weight, antioxidant levels, T helper cell 4 (cluster of differentiation 4 (CD4)), and T cytotoxic cell 8 (cluster of differentiation 8 (CD8)), associated with a marked decrease in lipid peroxidation (LP), nitric oxide(NOx), total free radicals concentrate (TFRC), and DNA fragmentation. There were positive alterations in the morphological state, hematological parameters and the cell cycle phases. Additionally, the histopathological study demonstrated an improvement in the liver tissue of irradiated rats after treatment. Thus, ZnCoNPs and ZnCaNPs could be used as natural mitigating agents to reduce the hazards of ionizing radiation.

Potential Protective Effect of Riboflavin Against Pathological Changes in the Main Organs of Male Mice Induced by Fluoride Exposure

Long-term exposure to excessive fluorine could cause damage to various tissues and organs in human and animals. However, there is no effective antidote to prevent and cure fluorosis except for avoiding fluoride intake. As an essential nutrient, riboflavin (VB₂) has been identified to relieve oxidative stress and inflammation in animal tissues caused by other toxic substances, whether it can alleviate the damage caused by fluoride is unknown. For this, 32 ICR male mice were allocated to four groups of eight each. They were treated with 0 (distilled water), 100 mg/L sodium fluoride (NaF), 40 mg/L VB₂, and their combination (100 mg/L NaF plus 40 mg/L VB₂) via the drinking water for 90 consecutive days, respectively. The content of bone fluoride and the histomorphology of the main organs including liver, kidney, cerebral cortex, epididymis, small intestine, and colon were evaluated and pathologically scored. The results found that fluoride caused the pathological changes in liver, kidney, cerebral cortex, epididymis, small intestine, and colon at varying degrees, while riboflavin supplementation reduced significantly the accumulation of fluoride in bone, alleviated the morphological damage to cerebral cortex, epididymis, ileum, and colon. This study provides new clues for deeply exploring the mechanism of riboflavin intervention in fluorosis.

Mitochondriotropic antioxidant based on caffeic acid AntiOxCIN4 activates Nrf2-dependent antioxidant defenses and quality control mechanisms to antagonize oxidative stress-induced cell damage

Mitochondria are key organelles involved in cellular survival, differentiation, and death induction. In this regard, mitochondrial morphology and/or function alterations are involved in stress-induced adaptive pathways, priming mitochondria for mitophagy or apoptosis induction. We have previously shown that the mitochondriotropic antioxidant AntiOxCIN₄ (100 μM; 48 h) presented significant cytoprotective effect without affecting the viability of human hepatoma-derived (HepG2) cells. Moreover, AntiOxCIN₄ (12.5 μM; 72 h) caused a mild increase of reactive oxygen species (ROS) levels without toxicity to primary human skin fibroblasts (PHSF). As Nrf2 is a master regulator of the oxidative stress response inducing antioxidant-encoding gene expression, we hypothesized that AntiOxCIN₄ could increase the resistance of human hepatoma-derived HepG2 to oxidative stress by Nrf2-dependent mechanisms, in a process mediated by mitochondrial ROS (mtROS). Here we showed that after an initial decrease in oxygen consumption paralleled by a moderate increase in superoxide anion levels, AntiOxCIN₄ led to a time-dependent Nrf2 translocation to the nucleus. This was followed later by a 1.5-fold increase in basal respiration and a 1.2-fold increase in extracellular acidification. AntiOxCIN₄ treatment enhanced mitochondrial quality by triggering the clearance of defective organelles by autophagy and/or mitophagy, coupled with increased mitochondrial biogenesis. AntiOxCIN₄ also up-regulated the cellular antioxidant defense system. AntiOxCIN₄ seems to have the ability to maintain hepatocyte redox homeostasis, regulating the electrophilic/nucleophilic tone, and preserve cellular physiological functions. The obtained data open a new avenue to explore the effects of AntiOxCIN₄ in the context of preserving hepatic mitochondrial function in disorders, such as NASH/NAFLD and type II diabetes.

Recent advances in cellular effects of fluoride: an update on its signalling pathway and targeted therapeutic approaches

Fluoride is a natural element essential in minute quantities in human's to maintain dental and skeletal health. However, the disease fluorosis manifests itself due to excessive fluoride intake mostly through drinking water and sometimes through food. At the cellular energetics level, fluoride is a known inhibitor of glycolysis. At the tissue level, the effect of fluoride has been more pronounced in the musculoskeletal systems due to its ability to retain fluoride. Fluoride alters dentinogenesis, thereby affecting the tooth enamel formation. In bones, fluoride alters the osteogenesis by replacing calcium, thus resulting in bone deformities. In skeletal muscles, high concentration and long term exposure to fluoride causes loss of muscle proteins leading to atrophy. Although fluorosis is quite a familiar problem, the exact molecular pathway is not yet clear. Extensive research on the effects of fluoride on various organs and its toxicity was reported. Indeed, it is clear that high and chronic exposure to fluoride causes cellular apoptosis. Accordingly, in this review, we have highlighted fluoride-mediated apoptosis via two vital pathways, mitochondrial-mediated and endoplasmic reticulum stress pathways. This review also elaborates on new cellular energetic, apoptotic pathways and therapeutic strategies targeted to treat fluorosis.

Synergistic effect of docosahexaenoic acid or conjugated linoleic acid with caffeic acid on ameliorating oxidative stress of HepG2 cells

Exploring the synergistic effect of docosahexaenoic acid (DHA) or conjugated linoleic acid (CLA) with caffeic acid (CA) on ameliorating oxidative stress, thereby introducing CA to DHA or CLA will contribute significantly to enhance the bioactivity. We observed that DHA or CLA with CA promoted the recovery of intact individual morphology and the decline of cavities inside the nucleus and apoptosis under the observation of confocal laser scanning microscopy and fluorescent inverted microscope. The activity of intracellular antioxidant enzymes catalase (CAT) and glutathione peroxidase (GSH-Px), lactate dehydrogenase (LDH) leakage, pyruvate and malondialdehyde and reactive oxygen species (ROS), cellular morphology, and cell cycle were analyzed. Our results showed that DHA or CLA with CA enhanced the activity of CAT and GSH-Px, decreased LDH leakage and the number of apoptotic, significantly inhibited (ROS-induced cellular injury. Cell arrest in G1 and G2 phase during cell mitosis was reduced by the measurement of flow cytometry. DHA or CLA combined with CA could markedly strengthen the free radical scavenging and endogenous antioxidant defense capacity on HepG2 cells. This study provides a new direction in the application of synergies to antioxidant compounds. PRACTICAL APPLICATION: Caffeic acid (CA) can synergize with docosahexaenoic acid (DHA) or conjugated linoleic acid (CLA) to enhance antioxidant capacity. This study highlighted an effect of ameliorating oxidative stress injury DHA or CLA with CA on HepG2 cells. The data indicated that DHA or CLA with CA might be used to relieve oxidative stress damage.

Apoptotic and Oxidative Mechanisms in Liver and Kidney Tissues of Sheep with Fluorosis

This study was planned to determine the molecular basis and causes of damage to the kidney and the liver, which are the most affected tissues in sheep exposed to chronic fluoride. For this purpose, liver and kidney tissues were obtained from sheep with signs of fluorosis in the age range of 4-6 years. The control group consisted of clinically healthy sheep without fluorosis. The apoptotic and oxidative genes expression of target genes was determined using the real qRT-PCR method. According to the control gene (Gapdh) that was detected that in the liver, the apoptotic genes caspase-8, caspase-9, and Bim increased and caspase-3, Bcl-2, and Bak decreased, while in the kidney, caspase-3 and Bax and caspase-8, Bcl-2, Bcl2l-1, Bim, and Bak decreased. According to the 2-ΔCt values of the oxidative stress genes, it was determined that Cygb, Gstp1, and Ncf1 genes increased significantly in the fluorosis group and Gpx1, sod1, and sod2 genes decreased significantly. In the kidney tissue, Cygb and Gpx1 increased in the fluorosis group, while sod1, sod2, Gstp1, Ncf1 and Ccs, and Nos2 were found to decrease significantly. As a result, it was shown that apoptosis and oxidative mechanisms are activated in the liver and the kidney tissues of sheep with fluorosis and these parameters have an important role in understanding the molecular basis of tissue damage in fluorosis.

Argan oil ameliorates sodium fluoride-induced renal damage via inhibiting oxidative damage, inflammation, and intermediate filament protein expression in male rats

Fluoride is widely distributed in the environment and has been associated with the development of different health hazards in animals and humans. Argan oil (AO) is a natural vegetable oil with various beneficial pharmacological effects. This study was designed to investigate the potential protective effect of AO supplementation as pre-treatment or co-treatment on sodium fluoride (NaF)-induced nephrotoxicity in rats. Male Sprague Dawley rats (n = 50) were randomly assigned to one of five equal groups: control group, AO-treated group (6 ml/kg b.wt.), NaF-treated group (20 mg/kg b.wt.), pre-treated group, and co-treated group. All rats were daily administered by oral gavage for duration of 30 days. The results showed that AO administration significantly improved renal function and antioxidant status and decreased the lipid peroxidation in NaF-treated rats. Additionally, AO normalized the renal levels of inflammatory markers and mRNA expression level of the intermediate filament protein genes, indicating NaF-induced podocyte damage was ameliorated. Histopathological evaluation of the kidney confirmed the before mentioned biochemical results. AO counteracted the nephrotoxic effects of NaF in rats particularly at co-exposure. These results concluded that AO administration exhibited a significant nephroprotective effect against renal injury induced by NaF in rats.

Phenolic acids from vegetables: A review on processing stability and health benefits

Phenolic acids are the most prominent group of bioactive compounds present in various plant sources. Hydroxybenzoic acids and hydroxycinnamic acids, the aromatic secondary metabolites imparting typical organoleptic characteristics to food are the major phenolic acids, and they are linked to several health benefits. Fruit and beverage crops being the richer sources of phenolic acids have been studied in depth, but phenolic acids from vegetables are largely overlooked. Though lesser in quantity in many vegetables, there is a need to explore the health benefits of the phenolic acids present in them. In this review, the importance of vegetables as a significant source of phenolic acids is emphasized. Vegetables being easily accessible throughout the year and consumed in larger quantities compared to fruits in our daily diet will probably contribute to significant health benefits. Since vegetables are often processed before consumption, the changes in phenolic acids as influenced by processing methods are highlighted. Best processing methods, pre-treatments and storage conditions for higher retention of phenolic acids have been highlighted to minimize their losses. The phenolic acids in vegetables and their health benefits have been cluster mapped, which may facilitate further research for nutraceutical development for specific health concerns. The processing stability of phenolic acids coupled with higher consumption indicates that they may be a potential source of phenolic acids in the diet. It is expected that the popularization of vegetables as a source of phenolic acids in daily diet will help in ameliorating the adverse effect of some of the lifestyle diseases.

Hydroxycinnamic acids and human health: recent advances

There is an urgent need to improve human diet globally. Compelling evidence gathered over the past several decades suggests that a suboptimal diet is associated with many chronic diseases and may be responsible for more deaths than any other risks worldwide. The main components in our diet that need higher intake are whole grains, fruit and vegetables, and nuts and seeds; all of these are important sources of dietary fiber and polyphenols. The health benefits of dietary fiber and polyphenols are also supported by several decades of valuable research. However, the conclusions drawn from interventional human trials are not straightforward and the action mechanisms in improving human health are not fully understood. Moreover, there is a great inter-individual variation caused by different individual capabilities of processing, absorbing and using these compounds effectively. Data on the bioavailability and bioefficacy of hydroxycinnamic acids (HCAs) are limited when compared to other classes of polyphenols (e.g. anthocyanins). This review aims to summarize the latest research advances related to HCA bioavailability and their biological effects revealed by epidemiological data, pre-clinical and clinical studies. Moreover, we aim to review the effects of HCAs on gut microbiota diversity and function and its respective influence on host health. © 2019 Society of Chemical Industry.

Liquiritigenin and liquiritin alleviated monocrotaline-induced hepatic sinusoidal obstruction syndrome via inhibiting HSP60-induced inflammatory injury

Hepatic sinusoidal obstruction syndrome (HSOS) is a life-threatening liver disease caused by the damage to liver sinusoidal endothelial cells (LSECs). Liquiritigenin and liquiritin are two main compounds in Glycyrrhizae Radix et Rhizoma (Gan-cao). Our previous study has shown that both liquiritigenin and liquiritin alleviated monocrotaline (MCT)-induced HSOS in rats via inducing the activation of nuclear factor erythroid 2-related factor 2 (Nrf2) antioxidant signaling pathway. This study aims to further investigate whether inhibiting liver inflammatory injury also contributed to the liquiritigenin and liquiritin-provided alleviation on MCT-induced HSOS. The results of serum alanine/aspartate aminotransferases (ALT/AST) activities and total bilirubin (TBil) amount, liver histological evaluation, scanning electron microscope observation and hepatic metalloproteinase-9 (MMP9) expression showed that liquiritigenin and liquiritin both alleviated MCT-induced HSOS in rats. Liquiritigenin and liquiritin reduced the increased liver myeloperoxidase (MPO) activity, mRNA expression of pro-inflammatory factors, hepatic infiltration of immune cells, hepatic toll-like receptor 4 (TLR4) expression and nuclear factor κB (NFκB) nuclear accumulation induced by MCT in rats. Furthermore, liquiritigenin and liquiritin attenuated MCT-induced liver mitochondrial injury, increased the decreased Lon protein expression and reduced the release of heat shock protein 60 (HSP60). Moreover, liquiritigenin and liquiritin also reduced NFκB nuclear accumulation and decreased the elevated cellular mRNA expression of NFκB-downstream pro-inflammatory cytokines induced by HSP60 in macrophage RAW264.7 cells. In conclusion, our study revealed that both liquiritigenin and liquiritin alleviated MCT-induced HSOS by inhibiting hepatic inflammatory responses triggered by HSP60.

Chemical and Pharmacological Aspects of Caffeic Acid and Its Activity in Hepatocarcinoma

Caffeic acid (CA) is a phenolic compound synthesized by all plant species and is present in foods such as coffee, wine, tea, and popular medicines such as propolis. This phenolic acid and its derivatives have antioxidant, anti-inflammatory and anticarcinogenic activity. In vitro and in vivo studies have demonstrated the anticarcinogenic activity of this compound against an important type of cancer, hepatocarcinoma (HCC), considered to be of high incidence, highly aggressive and causing considerable mortality across the world. The anticancer properties of CA are associated with its antioxidant and pro-oxidant capacity, attributed to its chemical structure that has free phenolic hydroxyls, the number and position of OH in the catechol group and the double bond in the carbonic chain. Pharmacokinetic studies indicate that this compound is hydrolyzed by the microflora of colonies and metabolized mainly in the intestinal mucosa through phase II enzymes, submitted to conjugation and methylation processes, forming sulphated, glucuronic and/or methylated conjugates by the action of sulfotransferases, UDP-glucotransferases, and o-methyltransferases, respectively. The transmembrane flux of CA in intestinal cells occurs through active transport mediated by monocarboxylic acid carriers. CA can act by preventing the production of ROS (reactive oxygen species), inducing DNA oxidation of cancer cells, as well as reducing tumor cell angiogenesis, blocking STATS (transcription factor and signal translation 3) and suppression of MMP2 and MMP-9 (collagen IV metalloproteases). Thus, this review provides an overview of the chemical and pharmacological parameters of CA and its derivatives, demonstrating its mechanism of action and pharmacokinetic aspects, as well as a critical analysis of its action in the fight against hepatocarcinoma.

Fluoride Exposure Induces Inhibition of Sodium/Iodide Symporter (NIS) Contributing to Impaired Iodine Absorption and Iodine Deficiency: Molecular Mechanisms of Inhibition and Implications for Public Health

The sodium iodide symporter (NIS) is the plasma membrane glycoprotein that mediates active iodide transport in the thyroid and other tissues, such as the salivary, gastric mucosa, rectal mucosa, bronchial mucosa, placenta and mammary glands. In the thyroid, NIS mediates the uptake and accumulation of iodine and its activity is crucial for the development of the central nervous system and disease prevention. Since the discovery of NIS in 1996, research has further shown that NIS functionality and iodine transport is dependent on the activity of the sodium potassium activated adenosine 5'-triphosphatase pump (Na+, K+-ATPase). In this article, I review the molecular mechanisms by which F inhibits NIS expression and functionality which in turn contributes to impaired iodide absorption, diminished iodide-concentrating ability and iodine deficiency disorders. I discuss how NIS expression and activity is inhibited by thyroglobulin (Tg), tumour necrosis factor alpha (TNF-α), transforming growth factor beta 1 (TGF-β1), interleukin 6 (IL-6) and Interleukin 1 beta (IL-1β), interferon-γ (IFN-γ), insulin like growth factor 1 (IGF-1) and phosphoinositide 3-kinase (PI3K) and how fluoride upregulates expression and activity of these biomarkers. I further describe the crucial role of prolactin and megalin in regulation of NIS expression and iodine homeostasis and the effect of fluoride in down regulating prolactin and megalin expression. Among many other issues, I discuss the potential conflict between public health policies such as water fluoridation and its contribution to iodine deficiency, neurodevelopmental and pathological disorders. Further studies are warranted to examine these associations.

Protective effect of isochlorogenic acid B on liver fibrosis in non-alcoholic steatohepatitis of mice

Liver fibrosis is a common symptom of non-alcoholic steatohepatitis (NASH) and a worldwide clinical issue. The miR-122/HIF-1α signalling pathway is believed to play an important role in the genesis of progressive fibrosis. Isochlorogenic acid B (ICAB), naturally isolated from Laggera alata, is verified to have antioxidative and hepatoprotective properties. The aim of this study was to investigate the effect of ICAB on liver fibrosis in NASH and its potential protective mechanisms. NASH was induced in a mouse model with a methionine- and choline-deficient (MCD) diet for 4 weeks, and ICAB was orally administered every day at three doses (5, 10 and 20 mg/kg). Pathological results indicated that ICAB significantly improved the pathological lesions of liver fibrosis. The levels of serum alanine aminotransferase (ALT), aspartate aminotransferase (AST) and hepatic hydroxyproline (Hyp), cholesterol (CHO) and triglyceride (TG) were also significantly decreased by ICAB. In addition, ICAB inhibited hepatic stellate cells (HSCs) activation and the expressions of hepatic genes involved in liver fibrosis including LOX, TGF-β1, MCP-1, COL1α1 and TIMP-1. ICAB also attenuated liver oxidative stress through Nrf2 signalling pathway. What is more, the decreased levels of miR-122 and over-expression of hepatic HIF-1α could be reversed by ICAB treatment. These results simultaneously confirmed that ICAB had a significant protective effect on fibrosis in NASH by inhibiting oxidative stress via Nrf2 and suppressing multiple profibrogenic factors through miR-122/HIF-1α signalling pathway.

Tamarind seed coat extract restores fluoride-induced hematological and biochemical alterations in rats

Fluoride (F^-) is becoming an ineluctable environmental pollutant causing deleterious effects in humans. In the present study, we examined whether tamarind seed coat extract (TSCE) is beneficial against the F^--induced systemic toxicity and hematological changes. Wistar rats were randomly grouped as follows: group I served as control; group II intoxicated with sodium fluoride (NaF, 300 ppm) in drinking water; group III was administered through oral intubation with TSCE (100 mg/kg bw); group IV was treated with NaF (300 ppm) in association with TSCE (100 mg/kg bw) for 30 days. The results indicated that F^- exposure induced oxidative stress as evidenced by elevated levels of reactive oxygen species and lipid peroxidation in the brain, liver, and kidney. F^- administration modulates hematological indices-WBC, RBC, and mean corpuscular volume. Moreover, aspartate aminotransferase, alanine aminotransferase, alkaline phosphatase, acetylcholinesterase, and monoamine oxidase significantly increased on F^- exposure. Conversely, δ-aminolevulinic acid dehydratase and glutathione/reduced glutathione ratio were decreased. Activity of antioxidants-superoxide dismutase, catalase, glutathione peroxidase, and vitamin C-was also significantly decreased due to F^- administration. Treatment with TSCE effectively mitigated the alterations through its antioxidant potential. The data suggested that the TSCE had beneficial effects in alleviating the F^--induced toxicity and hence can serve as a promising neutraceutical agent.

Melatonin-mediated upregulation of Sirt3 attenuates sodium fluoride-induced hepatotoxicity by activating the MT1-PI3K/AKT-PGC-1α signaling pathway

Mitochondrial reactive oxygen species (ROS) production has been implicated in the pathogenesis of fluoride toxicity in liver. Melatonin, an indolamine synthesized in the pineal gland, was previously shown to protect against sodium fluoride (NaF)-induced hepatotoxicity. This study investigated the protective effects of melatonin pretreatment on NaF-induced hepatotoxicity and elucidates the potential mechanism of melatonin-mediated protection. Reducing mitochondrial ROS by melatonin substantially attenuated NaF-induced NADPH oxidase 4 (Nox4) upregulation and cytotoxicity in L-02 cells. Melatonin exerted its hepatoprotective effects by upregulating Sirtuin 3 (Sirt3) expression level and its activity. Melatonin increased the activity of manganese superoxide dismutase (SOD2) by promoting Sirt3-mediated deacetylation and promoted SOD2 expression through Sirt3-regulated DNA-binding activity of forkhead box O3 (FoxO3a), thus inhibiting the production of mitochondrial ROS induced by NaF. Notably, increased peroxisome proliferator-activated receptor gamma coactivator 1α (PGC-1α) by melatonin activated the Sirt3 expression, which was regulated by an estrogen-related receptor (ERR) binding element (ERRE) mapped to Sirt3 promoter region. Analysis of the cell signaling pathway profiling systems and specific pathway inhibition indicated that melatonin enhances PGC-1α expression by activating the PI3K/AKT signaling pathway. Importantly, inhibition of melatonin receptor (MT)-1 blocked the melatonin-activated PI3K/AKT-PGC-1α-Sirt3 signaling. Mechanistic study revealed that the protective effects of melatonin were associated with down-regulation of JNK1/2 phosphorylation. Our findings provided a theoretical basis that melatonin mitigated NaF-induced hepatotoxicity, which, in part, was mediated through the activation of the Sirt3 pathway.

Restoration of plasma markers of liver and kidney functions/integrity in alloxan-induced diabetic rabbits by aqueous extract of Pleurotus tuberregium sclerotia

The effect of aqueous extract of the sclerotia of Pleurotus tuberregium on the plasma electrolytes, and markers of liver and kidney functions/integrity of normal and alloxan-induced rabbits was investigated. Diabetes mellitus was induced by injection of alloxan (120mg/kg body weight), via the marginal ear vein. The extract was administered orally at 100, 200 and 300mg/kg (both to normal and diabetic rabbits), and metformin at 50mg/kg. Gas chromatographic-flame ionization detector analysis of the extract revealed the presence of twelve known phenolic acids, consisting mainly of caffeic acid (80.24%), chlorogenic acid (11.08%), piperic acid (6.11%), sinapinic acid (2.14%) and ferulic acid (0.34%). Compared to test control, the treatment significantly (p<0.05) lowered plasma activities of alkaline phosphatase, gamma glutamyltransferase, and alanine and aspartate transaminases. Also lowered were plasma unconjugated/conjugated bilirubin ratio and concentrations of urea, blood urea nitrogen, creatinine, sodium, and total and unconjugated bilirubin. It however, significantly (p<0.05) raised plasma potassium and calcium levels. Therefore, the modulation of plasma sodium and potassium is an indication of the diuretic potential of the extract. In addition, the extract had no deleterious effect on the liver and kidney of the treated animals, at least at the doses administered in this study.

Caffeic acid attenuates the inflammatory stress induced by glycated LDL in human endothelial cells by mechanisms involving inhibition of AGE-receptor, oxidative, and endoplasmic reticulum stress

Type 2 diabetes mellitus is a worldwide epidemic and its atherosclerotic complications determine the high morbidity and mortality of diabetic patients. Caffeic acid (CAF), a phenolic acid present in normal diets, is known for its antioxidant properties. The aim of this study was to investigate CAF's anti-inflammatory properties and its mechanism of action, using cultured human endothelial cells (HEC) incubated with glycated low-density lipoproteins (gLDL). Levels of the receptor for advanced glycation end-products (RAGE), inflammatory stress markers (C reactive protein, CRP; vascular cell adhesion molecule-1, VCAM-1; monocyte chemoattractant protein-1, MCP-1), and oxidative stress and endoplasmic reticulum stress (ERS) markers were evaluated in gLDL-exposed HEC, in the presence/absence of CAF. RAGE silencing or blocking, specific inhibitors for oxidative stress (apocynin, N-acetyl-cysteine), and ERS (salubrinal) were used. The results showed that: (i) gLDL induced CRP synthesis and secretion through mechanisms involving NADPH oxidase-dependent oxidative stress and ERS in HEC; (ii) gLDL-RAGE interaction, oxidative stress, and ERS stimulated the secretion of VCAM-1 and MCP-1 in HEC; and (iii) CAF reduced the secretion of CRP, VCAM-1, and MCP-1 in gLDL-exposed HEC by inhibiting RAGE expression, oxidative stress, and ERS. In conclusion, CAF might be a promising alternative to ameliorate a wide spectrum of disorders due to its complex mechanisms of action resulting in anti-inflammatory and antioxidative properties. © 2017 BioFactors, 43(5):685-697, 2017.

Differential expression of myocardial heat shock proteins in rats acutely exposed to fluoride

Acute fluoride (F-) toxicity is known to cause severe cardiac complications and leads to sudden heart failure. Previously, we reported that increased myocardial oxidative damage, apoptosis, altered cytoskeleton and AMPK signaling proteins associated with energy deprivation in acute F- induced cardiac dysfunction. The present study was aimed to decipher the status of myocardial heat shock proteins (Hsps-Hsp27, Hsp32, Hsp40, Hsp60, Hsp70, Hsp90) and heat shock transcription factor 1 (Hsf1) in acute F--intoxicated rats. In order to study the expression of myocardial Hsps, male Wistar rats were treated with single oral doses of 45 and 90 mg/kg F- for 24 h. The expression levels of myocardial Hsps were determined using RT-PCR, western blotting, and immunohistochemical studies. Acute F--intoxicated rats showed elevated levels of both the transcripts and protein expression of Hsf1, Hsp27, Hsp32, Hsp60, and Hsp70 when compared to control. In addition, the expression levels of Hsp40 and Hsp90 were significantly declined in a dose-dependent fashion in F--treated animals. Our result suggests that differential expression of Hsps in the rat myocardium could serve as a balance between pro-survival and death signal during acute F--induced heart failure.

Changes in Liver Antioxidant Status of Offspring Mice Induced by Maternal Fluoride Exposure During Gestation and Lactation

Excessive fluoride intake for a long time has been demonstrated to provoke hepatic oxidative stress in adults. However, the response to fluoride toxicity of liver in newborns exposed to fluoride during embryonic and suckling stages remains unclear. In this study, female Kunming mice were administrated with 25, 50, and 100 mg/L sodium fluoride (NaF) from prenatal day 0 to day 21 after delivery, and the antioxidative status in the liver of their pups at postnatal day 21 was evaluated. The results showed that compared with the control group, NaF significantly increased malondialdehyde (MDA) level and reduced catalase (CAT) activity, while no statistical difference was observed in activities and mRNA expressions of superoxide dismutase (SOD), glutathione peroxidase (GPx), and glutathione reductase (GR). Notably, with comparison to the controls, the protein level of CAT was significantly reduced in medium- and high-fluoride groups, while its relative mRNA abundance was enhanced which could result from the encouragement of the lowered CAT protein expression. These findings suggested that CAT was more susceptible to low-fluoride exposure in early life.