Anti‐neuroinflammatory effects of tannic acid against lipopolysaccharide‐induced BV2 microglial cells via inhibition of NF‐κB activation

Fennel seeds extract prevents fructose-induced cardiac dysfunction in a rat model of metabolic syndrome via targeting abdominal obesity, hyperuricemia and NF-κβ inflammatory pathway

BACKGROUND

Metabolic syndrome (MetS) is commonly associated with increased risk of cardiac disease that affects a large number of world populations.

OBJECTIVE

This research attempted to investigate the efficacy of fennel seeds extract (FSE) in preventing development of cardiac dysfunction in rats on fructose enriched diet for 3 months, as a model of MetS.

MATERIALS & METHODS

Thirty adult Wistar male rats (160-170 g) were assigned into 5 groups including control, vehicle, FSE (200 mg/kg BW) and fructose (60%) fed rats with and without FSE. Following the last treatment, blood pressure, ECG and heart rate were measured. Next, blood and cardiac tissues were taken for biochemical and histological investigations.

RESULTS

Feeding fructose exhibited characteristic features of MetS involving, hypertension, abnormal ECG, elevated heart rate, serum glucose, insulin, lipids and insulin resistance, accompanied by abdominal obesity, cardiac hypertrophy and hyperuricemia. Fructose fed rats also showed significant reduction in cardiac antioxidants (GSH, SOD, CAT) with elevation in oxidative stress indices (NADPH oxidase, O2.-, H2O2, MDA, PCO), NF-κβ, pro-inflammatory cytokines (TNF-α, IL-1β, IL-6), adhesion molecules (ICAM-1, VCAM-1) and serum cardiac biomarkers (AST, LDH, CK-MB, cTn-I). Histopathological changes evidenced by destruction of cardiac myofibrils, cytoplasmic vacuolization, and aggregation of inflammatory cells were also detected. Consumption of FSE showed high ability to alleviate fructose-induced hypertension, ECG abnormalities, cardiac hypertrophy, metabolic alterations, oxidative stress, inflammation and histological injury.

CONCLUSION

Findings could suggest FSE as a complementary supplement for preventing MetS and associated cardiac outcomes. However, well controlled clinical studies are still needed.

Tannin-albumin particles as stable carriers of medicines

Background: The effectiveness of a drug is dependent on its accumulation at the site of therapeutic action, as well as its time in circulation. The aim of the research was the creation of stable albumin/tannin (punicalagin, punicalin) particles, which might serve for the delivery of medicines. Methods: Numerous chromatographic and analytical methods, docking analyses and in vivo testing were applied and used. Results: Stable tannin-albumin/medicine particles with a diameter of ∼100 nm were obtained. The results of in vivo experiments proved that tannin-albumin particles are more stable than albumin particles. Conclusion: Based on the experiments and docking analyses, these stable particles can carry an extended number of medicines, with diverse chemical structures.

Neuroprotective Potential of Tannic Acid Against Neurotoxic Outputs of Monosodium Glutamate in Rat Cerebral Cortex

Glutamate in monosodium glutamate (MSG), which is widely used in the food industry, has an important role in major brain functions such as memory, learning, synapse formation, and stabilization. However, extensive use of MSG has been linked with neurotoxicity. Therefore, in addition to clarifying the underlying mechanisms of MSG-induced neurotoxicity, it is also important to determine safe agents that can diminish the damage caused by MSG. Tannic acid (TA) is a naturally occurring plant polyphenol that exhibits versatile physiological effects such as anti-inflammatory, anti-carcinogenic, antioxidant, and radical scavenging. This study was conducted to assess the neurotoxic and neuroprotective effects of these two dietary components in the rat cerebral cortex. Twenty-four Sprague Dawley rats were divided into 4 equal groups and were treated with MSG (2 g/kg) and TA (50 mg/kg) alone and in combination for 3 weeks. Alterations in oxidative stress indicators (MDA and GSH) were measured in the cortex tissues. In addition, changes in enzymatic activities and gene expression patterns of antioxidant system components (GST, GPx, CAT, and SOD) were investigated. Furthermore, mRNA expressions of FoxO transcription factors (Foxo1 and Foxo3) and apoptotic markers (Casp3 and Casp9) were assessed. Results revealed that dietary TA intake significantly rehabilitated MSG-induced dysregulation in cortical tissue by regulating redox balance, cellular homeostasis, and apoptosis. The present study proposes that MSG-induced detrimental effects on cortical tissue are potentially mitigated by TA via modulation of oxidative stress, cell metabolism, and programmed cell death.

Nanoarchitectonics of tannic acid based injectable hydrogel regulate the microglial phenotype to enhance neuroplasticity for poststroke rehabilitation

BACKGROUND

Stroke is the second leading cause of mortality and disability worldwide. Poststroke rehabilitation is still unsatisfactory in clinics, which brings great pain and economic burdens to stroke patients. In this study, an injectable hydrogel in which tannic acid (TA) acts as not only a building block but also a therapeutic drug, was developed for poststroke rehabilitation.

METHODS

TA is used as a building block to form an injectable hydrogel (TA gel) with carboxymethyl chitosan (CMCS) by multivalent hydrogen bonds. The morphology, rheological properties, and TA release behavior of the hydrogel were characterized. The abilities of the TA gel to modulate microglial (BV2 cells) polarization and subsequently enhance the neuroplasticity of neuro cells (N2a cells) were assessed in vitro. The TA gel was injected into the cavity of stroke mice to evaluate motor function recovery, microglial polarization, and neuroplasticity in vivo. The molecular pathway through which TA modulates microglial polarization was also explored both in vitro and in vivo.

RESULTS

The TA gel exhibited sustainable release behavior of TA. The TA gel can suppress the expression of CD16 and IL-1β, and upregulate the expression of CD206 and TGF-β in oxygen and glucose-deprived (OGD) BV2 cells, indicating the regulation of OGD BV2 cells to an anti-inflammatory phenotype in vitro. This finding further shows that the decrease in synaptophysin and PSD95 in OGD N2a cells is effectively recovered by anti-inflammatory BV2 cells. Furthermore, the TA gel decreased CD16/iNOS expression and increased CD206 expression in the peri-infarct area of stroke mice, implying anti-inflammatory polarization of microglia in vivo. The colocalization of PSD95 and Vglut1 stains, as well as Golgi staining, showed the enhancement of neuroplasticity by the TA gel. Spontaneously, the TA gel successfully recovered the motor function of stroke mice. The western blot results in vitro and in vivo suggested that the TA gel regulated microglial polarization via the NF-κB pathway.

CONCLUSION

The TA gel serves as an effective brain injectable implant to treat stroke and shows promising potential to promote poststroke rehabilitation in the clinic.

The Impact of Tannic Acid Consumption on Bone Mineralization

Tannic acid (TA) is an organic compound belonging to the tannin group. Like other tannins, it has an affinity for endogenous proteins, including digestive enzymes, which can result in the reduced digestibility and absorption of nutrients. It can also form complexes with mineral components, reducing their absorption. In some cases, this can be beneficial, such as in the case of toxic metals, but sometimes it may have a detrimental effect on the body when it involves essential mineral components like Ca, P, Mg, Na, K, or Fe. Therefore, the impact of TA on bone health should be considered from both perspectives. This relatively short review summarizes the available information and research findings on TA, with a particular focus on its potential impact on bone health. It is worth noting that future research and clinical studies may provide more detailed and precise information on this topic, allowing for a better understanding of the role of TA in maintaining the integrity of the musculoskeletal system. Despite its brevity, this paper represents a valuable contribution to the analysis of the potential benefits and challenges associated with TA in the context of bone health. We anticipate that future research will continue along this important research line, expanding our knowledge of the influence of this compound on the skeletal system and its potential therapeutic applications.

Hydrolysable tannins as a potential therapeutic drug for the human fibrosis-associated disease

Fibrosis is a pathological change with abnormal tissue regeneration due to a response to persistent injury, which is extensively related to organ damage and failure, leading to high morbidity and mortality worldwide. Although the pathogenesis of fibrosis has been comprehensively elucidated, there are few effective therapies for treating fibrotic diseases. Natural products are increasingly regarded as an effective strategy for fibrosis with numerous favorable functions. Hydrolysable tannins (HT) are a type of natural products that have the potential to treat the fibrotic disease. In this review, we describe some biological activities and the therapeutic prospects of HT in organ fibrosis. Furthermore, the underlying mechanisms of inhibition of HT on fibrotic organs in relation to inflammation, oxidative stress, epithelial-mesenchymal transition, fibroblast activation and proliferation, and extracellular matrix accumulation are discussed. Understanding the mechanism of HT against fibrotic diseases will provide a new strategy for the prevention and attenuation of fibrosis progression.

Tannic Acid Mitigates Rotenone-Induced Dopaminergic Neurodegeneration by Inhibiting Inflammation, Oxidative Stress, Apoptosis, and Glutamate Toxicity in Rats

Parkinson's disease (PD), a movement disorder, is a neurodegenerative disease characterized by the degeneration of dopaminergic neurons in the substantia nigra pars compacta (SNpc) region of the brain. The etiopathogenesis of PD involves increased oxidative stress, augmented inflammation, impaired autophagy, accumulation of α-synuclein, and α-Glutamate neurotoxicity. The treatment of PD is limited and there is a lack of agents to prevent the disease/delay its progression and inhibit the onset of pathogenic events. Many agents of natural and synthetic origin have been investigated employing experimental models of PD, mimicking human PD. In the present study, we assessed the effect of tannic acid (TA) in a rodent model of PD induced by rotenone (ROT), a pesticide and an environmental toxin of natural origin reported to cause PD in agricultural workers and farmers. Rotenone (2.5 mg/kg/day, i.p.) was administered for 28 days, and TA (50 mg/kg, orally) was administered 30 min before ROT injections. The study results showed an increase in oxidative stress, as evidenced by the depletion of endogenous antioxidants and enhanced formation of lipid peroxidation products, along with the onset of inflammation following a rise in inflammatory mediators and proinflammatory cytokines. ROT injections have also augmented apoptosis, impaired autophagy, promoted synaptic loss, and perturbed α-Glutamate hyperpolarization in rats. ROT injections also induced the loss of dopaminergic neurons subsequent to the activation of microglia and astrocytes. However, TA treatment was observed to reduce lipid peroxidation, prevent loss of endogenous antioxidants, and inhibit the release and synthesis of proinflammatory cytokines, in addition to the favorable modulation of apoptosis and autophagic pathways. Treatment with TA also attenuated the activation of microglia and astrocytes along with preservation of dopaminergic neurons following reduced loss of dopaminergic neurodegeneration and inhibition of synaptic loss and α-Glutamate cytotoxicity. The effects of TA in ROT-induced PD were attributed to the antioxidant, anti-inflammatory, antiapoptotic, and neurogenesis properties. Based on the present study findings, it can be concluded that TA may be a promising novel therapeutic candidate for pharmaceutical as well as nutraceutical development owing to its neuroprotective properties in PD. Further regulatory toxicology and translational studies are suggested for future clinical usage in PD.

Effects of dietary Galla Chinensis tannin supplementation on immune function and liver health in broiler chickens challenged with lipopolysaccharide

Herein, Galla Chinensis tannin (GCT) was examined for its influence on preventing lipopolysaccharide (LPS)-induced liver damage in broiler chickens. Approximately 486 one-day-old healthy broilers were randomly allocated to 3 treatment groups (control, LPS, and LPS + GCT). The control and LPS groups were fed a basal diet and the LPS+GCT group was fed the basal diet supplemented with 300 mg/kg GCT. LPS was intraperitoneally injected (1 mg/kg body weight BW) in broilers in the LPS and LPS+GCT groups at 17, 19, and 21 days of age. The results manifested that dietary GCT addition attenuated LPS-induced deleterious effects on serum parameters and significantly increased serum immunoglobulin and complement C3 concentrations relative to the control and LPS groups. Dietary supplementation of GCT inhibited LPS-induced increase in broiler hepatic inflammatory cytokines, caspases activities, and TLR4/NF-κB pathway-related gene mRNA expression. Therefore, 300 mg/kg GCT addition to the diet improved the immune function of broilers and inhibit liver inflammation by blocking the TLR4/NF-κB pathway. Our findings provide support for the application of GCT in poultry production.

Bioactive self-healing hydrogel based on tannic acid modified gold nano-crosslinker as an injectable brain implant for treating Parkinson's disease

BACKGROUND

Parkinson's disease (PD) is one of the most common long-term neurodegenerative diseases. Current treatments for PD are mostly based on surgery and medication because of the limitation and challenges in selecting proper biomaterials. In this study, an injectable bioactive hydrogel based on novel tannic acid crosslinker was developed to treat PD.

METHODS

The oxidized tannic acid modified gold nano-crosslinker was synthesized and used to effectively crosslink chitosan for preparation of the bioactive self-healing hydrogel. The crosslinking density, conductivity, self-healing ability, and injectability of the hydrogel were characterized. Abilities of the hydrogel to promote the proliferation and differentiation of neural stem cells (NSCs) were assessed in vitro. Anti-inflammatory property was analyzed on J774A.1 macrophages. The hydrogel was injected in the PD rat model for evaluation of the motor function recovery, electrophysiological performance improvement, and histological repair.

RESULTS

The hydrogel exhibited self-healing property and 34G (~ 80 μm) needle injectability. NSCs grown in the hydrogel displayed long-term proliferation and differentiation toward neurons in vitro. Besides, the hydrogel owned strong anti-inflammatory and antioxidative capabilities to rescue inflamed NSCs (~ 90%). Brain injection of the bioactive hydrogel recovered the motor function of PD rats. Electrophysiological measurements showed evident alleviation of irregular discharge of nerve cells in the subthalamic nucleus of PD rats administered with the hydrogel. Histological examination confirmed that the hydrogel alone significantly increased the density of tyrosine hydroxylase positive neurons and fibers as well as reduced inflammation, with a high efficacy similar to drug-loaded hydrogel.

CONCLUSION

The new bioactive hydrogel serves as an effective brain injectable implant to treat PD and a promising biomaterial for developing novel strategies to treat brain diseases.

Yomogin, Isolated from Artemisia iwayomogi, Inhibits Neuroinflammation Stimulated by Lipopolysaccharide via Regulating MAPK Pathway

Neuroinflammation causes various neurological disorders, including depression and neurodegenerative diseases. Therefore, regulation of neuroinflammation is a promising therapeutic strategy for inflammation-related neurological disorders. This study aimed to investigate whether yomogin, isolated from Artemisia iwayomogi, has anti-neuroinflammatory effects. First, we evaluated the effects of yomogin by assessing pro-inflammatory mediators and cytokines in lipopolysaccharide (LPS)-stimulated BV2 microglial cells. The results showed that yomogin inhibited the increase in neuroinflammatory factors, including nitric oxide, inducible nitric oxide synthase, cyclooxygenase-2, interleukin-6, and tumor necrosis factor-α, and suppressed phosphorylation of c-Jun N-terminal kinase, extracellular signal-regulated kinase and p38, which participate in the mitogen-activated protein kinase (MAPK) pathway. To confirm these effects in vivo, we measured the activation of astrocyte and microglia in LPS-injected mouse brains. Results showed that yomogin treatment decreased astrocyte and microglia activations. Collectively, these results suggest that yomogin suppresses neuroinflammation by regulating the MAPK pathway and it could be a potential candidate for inflammation-mediated neurological diseases.

The Role of Oxidative Stress-Mediated Inflammation in the Development of T2DM-Induced Diabetic Nephropathy: Possible Preventive Action of Tannins and Other Oligomeric Polyphenols

Diabetic nephropathy is manifested in more than 10% of people with diabetes. It is a common cause of kidney failure and end-stage kidney disease. Understanding of mechanisms underlying the initiation and development of diabetes-induced kidney injuries will allow for the development of more effective methods of prevention and treatment of the disease. Diabetic nephropathy is a wide-ranging complication of diabetes, and it is necessary to discuss the "weight" of pro-inflammatory pathways and molecules in the progress of renal injuries during the development of the disease. A large spectrum of pro-inflammatory molecules and pathways participate in different stages of the pathophysiological progression of diabetic nephropathy, including pro-inflammatory cytokines, chemokines, their receptors, adhesion molecules, and transcription factors. On the other hand, it is known that one of the consequences of hyperglycemia-induced ROS generation is the up-regulation of pro-inflammatory cascades, which, in turn, activate the transcription of genes encoding cytokines-chemokines, growth factors, and extracellular matrix proteins. It is a proven fact that a variety of plant secondary metabolites, such as tannins, flavonoids, and other polyphenols, demonstrate significant anti-diabetic, redox-modulating properties and effectively modulate the inflammatory response. Thus, this review is discussing the possible role of plant phenols in the prevention and treatment of diabetic nephropathy.

Catechin, rutin and quercetin in Quercus mongolica Fisch leaves exert inhibitory effects on multiple cancer cells

We aimed to identify anti-tumor agents in Quercus mongolica Fisch (QMF). Bioactive compounds in QMF leaves, which were extracted using ethanol as a co-solvent. Five point zero six grams of flavonoids were obtained from 100 g of QMF leaves. Catechin (18.4%), rutin (6.3%), ellagic acid (34.9%), quercetin (5.1%) and kaempferol (20.6%) are the main ingredients of the extracts and were further purified by HPLC. CCK-8 cell proliferation assay showed that catechin and ellagic acid exerted strong inhibitory effects on the proliferation of all cancer cells with lower IC₅₀ values against MCF-7 human breast cancer cell lines, SMMC-7721 human hepatocellular carcinoma cells, HeLa human cervical carcinoma cell lines and SKOV3 human ovarian carcinoma cell lines (p < .05). Catechin, rutin and quercetin induced a higher rate of apoptosis and inhibited all cancer cell proliferation by inducing the G0/G1 phase and G2/M phase arrest (p < .05). However, ellagic acid induced tumor cell death, not through apoptosis and there may be other molecular mechanisms. High levels of catechin and ellagic acid in QMF can be developed as potential drugs to treat different types of cancer cells. PRACTICAL APPLICATIONS: Quercus species have been widely studied because of their antioxidant, anti-inflammatory, antimicrobial, and anti-tumor properties. Bioactive compounds in the leaves of Quercus mongolica Fisch have high levels of catechin and ellagic acid, which exert significant inhibitory properties on the proliferation of various types of cancer cells. Therefore, the bioactive compounds may be potential natural drugs in the prevention of cancer development and progression.

Dietary Galla Chinensis tannic acid supplementation in the diets improves growth performance, immune function and liver health status of broiler chicken

This experiment was conducted to investigate the effects of Galla Chinensis tannic acid (TA) on growth performance, immune function, and liver health status in broilers. A total of 288 1-day-old Arbor Acres broiler chickens were randomly divided into two groups in a 42-days study. The two groups were a basal diet (CON group) and a basal diet supplemented with 300 mg/kg Galla Chinensis tannic acid (TA group). The results showed that the TA group had significantly decreased feed-to-gain ratio (F/G) throughout the experiment (P < 0.05). The levels of total protein, albumin, low density lipoprotein, high density lipoprotein, urea, total cholesterol, and glucose in the TA group were significantly higher than in the CON group (P < 0.05). In addition, the serum immunoglobulin G, immunoglobulin M, and complements (C3, C4) levels in the TA group were significantly higher than those in the CON group (P < 0.05). Compared with the CON group, the hepatic interleukin-6, interleukin-18, NLRs family pyrin domain containing 3 (NLRP3), caspase-1, and caspase-3 in the TA group were significantly decreased (P < 0.05). Besides, TA group had significantly lower mRNA expression levels of toll-like receptor 4 (TLR4), myeloid differentiation primary response 88 (MyD88), nuclear factor-kappa B (NF-κB), and NLRP3 in liver (P < 0.05). The TA group had significantly higher the mRNA expression levels of Bcl-2 than CON group in liver (P < 0.05). Moreover, TA group tended to decrease Bax/Bcl-2 ratio in liver (P < 0.10). To sum up, dietary supplemented with microencapsulated TA from Galla Chinensis had beneficial effects on growth performance, immune function, and liver health status in broilers. The protective role of TA from Galla Chinensis in liver health of broilers might be related to the inhibition of hepatic apoptosis and pyroptosis via inactivation of TLR4/MyD88/NF-κB signaling pathway.

Tannic Acid Extracted from Galla chinensis Supplementation in the Diet Improves Intestinal Development through Suppressing Inflammatory Responses via Blockage of NF-κB in Broiler Chickens

The objective of this study was to investigate the effects of adding tannic acid (TA) extracted from Galla chinensis to the diet of broiler chickens on intestinal development. A total of 324 healthy 1-day-old broilers were used in a 42 d study, and divided into two treatment groups at random (six replicates per group). Broilers were either received a basal diet or a basal diet supplemented with 300 mg/kg microencapsulated TA extracted from Galla chinensis. The results showed that dietary supplemented with 300 mg/kg TA from Galla chinensis improved intestinal morphology, promoted intestinal mucosal barrier integrity, and elevated mucosal expressions of nutrients transporters and tight junction protein CLDN3 in broilers. Besides, 300 mg/kg TA from Galla chinensis supplementation decreased the concentrations of inflammatory cytokines in serum and intestinal mucosa and reduced the mRNA expression of NF-κB in intestinal mucosa. Above all, supplementation of 300 mg/kg microencapsulated TA extracted from Galla chinensis showed beneficial effects in improving intestinal development, which might be attributed to the suppression of inflammatory responses via blockage of NF-κB in broiler chickens. These findings will support the use of TA sourced from Galla chinensis in poultry industry.

Pharmacological effects and mechanisms of tannic acid

In recent years, increasing attention has been paid to the pharmacological efficacy of tannins. Tannic acid (TA), the simplest hydrolysable tannin that has been approved by the FDA as a safe food additive, is one of the most important components of these traditional medicines. Studies have shown that TA displays a wide range of pharmacological activities, such as anti-inflammatory, neuroprotective, antitumor, cardioprotective, and anti-pathogenic effects. Here, we summarize the known pharmacological effects and associated mechanisms of TA. We focus on the effect and mechanism of TA in various animal models of inflammatory disease and organ, brain, and cardiovascular injury. Moreover, we discuss the possible molecular targets and signaling pathways of TA, in addition to the pharmacological effects of TA-based nanoparticles and TA in combination with chemotherapeutic drugs.

Investigation of the multi-targeted protection potential of tannic acid against doxorubicin-induced kidney damage in rats

Doxorubicin (DOX) is an antitumor drug that is powerful but can cause worse outcomes, including nephrotoxicity, and therefore has limited clinical use. Therefore, it is necessary to identify safer agents that can minimize the damage caused by the drug without shifting the treatment performance, in addition to clarifying the underlying mechanisms of DOX-induced aberrant in vivo renal activation. In this study, we tested the prophylactic capacity and mechanisms of action of tannic acid (TA) against DOX-mediated kidney damage in rats and evaluated the nephrotoxic activity of DOX when used with TA. Rats were treated during the two weeks with cumulative (18 mg/kg with six different injections) DOX, daily TA (50 mg/kg), and the DOX + TA combination. Changes in major metabolites and components involved in antioxidant metabolism were evaluated in the kidney tissues of all animals. Further, the gene expression levels of regulatory factors that have critical importance in cell metabolism, inflammation, and apoptosis were investigated. Both biochemical and molecular examinations showed that TA improved DOX-induced dysregulations at both protein and gene levels in the kidneys. Increased lipid peroxidation and decreased glutathione levels were reversed. Consistent with oxidative stress marker metabolites, suppressed antioxidant enzyme activities and transcript levels of antioxidant system members were restored. Of note, combination treatment with TA could overcome doxorubicin-induced gene expressions markedly altered by DOX, suggesting that nephroprotection conferred by TA involved the remodeling of stress resistance, cell metabolism, inflammation, and apoptosis. Collectively, the present in vivo study suggests that TA could be used as a multitarget and effective agent for the mitigation of doxorubicin-induced nephrotoxicity without changing the therapeutic efficacy of the drug.

Multifunctional chitosan/gelatin@tannic acid cryogels decorated with in situ reduced silver nanoparticles for wound healing

Background

Most traditional wound dressings only partially meet the needs of wound healing because of their single function. Patients usually suffer from the increasing cost of treatment and pain resulting from the frequent changing of wound dressings. Herein, we have developed a mutifunctional cryogel to promote bacterial infected wound healing based on a biocompatible polysaccharide.

Methods

The multifunctional cryogel is made up of a compositive scaffold of chitosan (CS), gelatin (Gel) and tannic acid (TA) and in situ formed silver nanoparticles (Ag NPs). A liver bleeding rat model was used to evaluate the dynamic hemostasis performance of the various cryogels. In order to evaluate the antibacterial properties of the prepared cryogels, gram-positive bacterium Staphylococcus aureus (S. aureus) and gram-negative bacterium Escherichia coli (E. coli) were cultured with the cryogels for 12 h. Meanwhile, S. aureus was introduced to cause bacterial infection in vivo. After treatment for 2 days, the exudates from wound sites were dipped for bacterial colony culture. Subsequently, the anti-inflammatory effect of the various cryogels was evaluated by western blotting and enzyme-linked immunosorbent assay. Finally, full-thickness skin defect models on the back of SD rats were established to assess the wound healing performances of the cryogels.

Results

Due to its porous structure, the multifunctional cryogel showed fast liver hemostasis. The introduced Ag NPs endowed the cryogel with an antibacterial efficiency of >99.9% against both S. aureus and E. coli. Benefited from the polyphenol groups of TA, the cryogel could inhibit nuclear factor-κB nuclear translocation and down-regulate inflammatory cytokines for an anti-inflammatory effect. Meanwhile, excessive reactive oxygen species could also be scavenged effectively. Despite the presence of Ag NPs, the cryogel did not show cytotoxicity and hemolysis. Moreover, in vivo experiments demonstrated that the biocompatible cryogel displayed effective bacterial disinfection and accelerated wound healing.

Conclusions

The multifunctional cryogel, with fast hemostasis, antibacterial and anti-inflammation properties and the ability to promote cell proliferation could be widely applied as a wound dressing for bacterial infected wound healing.

Preparation of chitosan-tannic acid coating and its anti-osteoclast and antibacterial activities in titanium implants

INTRODUCTION

Bacterial infection and aseptic loosening caused by bone resorption at the implant interface are major clinical complications during bone defect implantation surgery, and surface modification of the implant to address the aforementioned problems has long been a research focus.

MATERIALS AND METHODS

In this paper, a chitosan (CTS)-tannic acid (TA) colloid coating with a negative charge and excellent hydrophilicity was prepared on a Ti6Al4V (TC4) surface using a layer-by-layer assembly method. The physical properties, anti-osteoclast activity, and antimicrobial activity of the coatings were investigated.

RESULTS

The findings showed that when the pH value was 5 and the ratio of CTS:TA was 0.8, the carrying rate of TA was the best. Furthermore, the CTS-TA coating had no cytotoxicity on the morphology and proliferation of BMSCs cells and effectively inhibited the differentiation of RAW264.7 cells into osteoclasts and the proliferation of Staphylococcus aureus and Escherichia coli. With the increase in the immersion time of TC4 in CTS-TA colloid solution, the inhibitory effects will also enhance.

CONCLUSION

Therefore, the preparation of the CTS-TA coating provides a revolutionary technique for implant surface modification to avoid postoperative bacterial infection and aseptic loosening.

Dietary Polyphenols as Therapeutic Intervention for Alzheimer’s Disease: A Mechanistic Insight

Dietary polyphenols encompass a diverse range of secondary metabolites found in nature, such as fruits, vegetables, herbal teas, wine, and cocoa products, etc. Structurally, they are either derivatives or isomers of phenol acid, isoflavonoids and possess hidden health promoting characteristics, such as antioxidative, anti-aging, anti-cancerous and many more. The use of such polyphenols in combating the neuropathological war raging in this generation is currently a hotly debated topic. Lately, Alzheimer’s disease (AD) is emerging as the most common neuropathological disease, destroying the livelihoods of millions in one way or another. Any therapeutic intervention to curtail its advancement in the generation to come has been in vain to date. Using dietary polyphenols to construct the barricade around it is going to be an effective strategy, taking into account their hidden potential to counter multifactorial events taking place under such pathology. Besides their strong antioxidant properties, naturally occurring polyphenols are reported to have neuroprotective effects by modulating the Aβ biogenesis pathway in Alzheimer’s disease. Thus, in this review, I am focusing on unlocking the hidden secrets of dietary polyphenols and their mechanistic advantages to fight the war with AD and related pathology.

Molecular Interactions of Tannic Acid with Proteins Associated with SARS-CoV-2 Infectivity

The overall impact of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) on our society is unprecedented. The identification of small natural ligands that could prevent the entry and/or replication of the coronavirus remains a pertinent approach to fight the coronavirus disease (COVID-19) pandemic. Previously, we showed that the phenolic compounds corilagin and 1,3,6-tri-O-galloyl-β-D-glucose (TGG) inhibit the interaction between the SARS-CoV-2 spike protein receptor binding domain (RBD) and angiotensin-converting enzyme 2 (ACE2), the SARS-CoV-2 target receptor on the cell membrane of the host organism. Building on these promising results, we now assess the effects of these phenolic ligands on two other crucial targets involved in SARS-CoV-2 cell entry and replication, respectively: transmembrane protease serine 2 (TMPRSS2) and 3-chymotrypsin like protease (3CLpro) inhibitors. Since corilagin, TGG, and tannic acid (TA) share many physicochemical and structural properties, we investigate the binding of TA to these targets. In this work, a combination of experimental methods (biochemical inhibition assays, surface plasmon resonance, and quartz crystal microbalance with dissipation monitoring) confirms the potential role of TA in the prevention of SARS-CoV-2 infectivity through the inhibition of extracellular RBD/ACE2 interactions and TMPRSS2 and 3CLpro activity. Moreover, molecular docking prediction followed by dynamic simulation and molecular mechanics Poisson-Boltzmann surface area (MMPBSA) free energy calculation also shows that TA binds to RBD, TMPRSS2, and 3CLpro with higher affinities than TGG and corilagin. Overall, these results suggest that naturally occurring TA is a promising candidate to prevent and inhibit the infectivity of SARS-CoV-2.

Neuroprotective effects of tannic acid against kainic acid-induced seizures in mice

BACKGROUND

Epileptic seizures are associated with the release of potentially neurotoxic amount of glutamate, which results in the over-production of free radicals and inflammatory factors, and induction of neuronal cell death. Current study evaluated the effect of tannic acid (TA) on Kainic acid (KA)-induced seizures in mice.

METHODS

Mice were divided into the six groups. Group I was administrated with normal saline (NS; 1 mL/kg, intraperitoneally (i.p.)), Group II was injected with KA (15 mg/kg, i.p.), Groups III was treated with diazepam (DZ; 20 mg/kg, i.p.) and KA (15 mg/kg, i.p.), Groups IV-VI were treated with TA (25, 50 and 100 mg/kg, i.p.) and KA (15 mg/kg, i.p.). Animals received all treatments 30 min before injection of KA. After the injection of KA, mice were observed for seizure (latency, activity and duration) and mortality for 2 h. In the brain tissue, oxidative stress, apoptosis, and inflammatory markers were evaluated in addition to the determination of histological alterations in the CA1 molecular layer of hippocampus.

RESULTS

Treatment with TA significantly increased seizure latency and decreased seizure duration and activity, but could not significantly decrease mice mortality. This effect was associated with the reduction of oxidative stress, inflammation, and apoptosis. Furthermore, treatment with TA significantly improved KA-induced pyramidal cell loss and change in the arrangement of CA1 molecular layer.

CONCLUSIONS

Tannic acid may be useful in the control of epileptic seizures through regulating oxidative stress, inflammation and apoptosis.

In Vitro and In Silico Interaction Studies with Red Wine Polyphenols against Different Proteins from Human Serum

Previous reports have shown that consumption of wine has several health benefits; however, there are different types of wine. In the present study, red wines were investigated for their compositions of active ingredients. The interaction of each component in terms of its binding mode with different serum proteins was unraveled, and the components were implicated as drug candidates in clinical settings. Overall, the study indicates that red wines have a composition of flavonoids, non-flavonoids, and phenolic acids that can interact with the key regions of proteins to enhance their biological activity. Among them, rutin, resveratrol, and tannic acid have shown good binding affinity and possess beneficial properties that can enhance their role in clinical applications.

Tannic acid repair of zearalenone-induced damage by regulating the death receptor and mitochondrial apoptosis signaling pathway in mice

Zearalenone (ZEA) is an estrogenic toxin produced by Fusarium strains, that is widely present in crops, and endangers the reproductive system of animals. Tannic acid (TA) is a natural polyphenolic substance that is widespread in the roots, stems, and leaves of plants, and has special pharmacological activity. This study was designed to investigate the therapeutic effect of TA on ZEA-induced ovarian damage in mice and to explore the molecular mechanism involved. Ninety healthy Kunming female mice were divided into six equal groups. All the groups but the control group were administered daily with ZEA [10 mg/kg body weight (bw)] orally, for 7 days, to induce damage to the reproductive system. Some groups were also administered with TA (50, 100, and 200 mg/bw) for 7 days. Mice were euthanized 24 h later to allow for collection of serum and ovaries. TA can effectively alleviate the appearance of congestion and redness of the ovary, caused by ZEA, and increase the number of healthy growing follicles. Moreover, the estrogen content and the levels of MDA and ROS in the ovaries can be effectively reduced by TA. It can also reduce the apoptosis of ovarian cells, decreases the protein expression of the estrogen receptor, Fas, Fasl, caspase-3, caspase-8, caspase-9, and Bax, and increases the protein expression of Bcl-2. Our study indicates that TA reduces the strong estrogen and oxidative damage induced by ZEA, and these therapeutic effects may be partially mediated by the death receptor and mitochondrial apoptosis signaling pathway.

In-Situ-Sprayed Dual-Functional Immunotherapeutic Gel for Colorectal Cancer Postsurgical Treatment

Surgery remains the most preferred treatment options for colorectal cancer (CRC). Paradoxically, local recurrence and distant metastasis are usually accelerated postsurgery as a consequence of local and systemic immunosuppression caused by surgery. Therefore, modulating tumor postoperative immune microenvironment and activating systemic antitumor immunity are necessary supplementaries for CRC therapy. Here, an in-situ-sprayed immunotherapeutic gel loaded with anti-OX40 antibody (iSGels@aOX40) is reported for CRC postsurgical treatment. The iSGel is formed instantly after spraying with strong adhesion ability via crosslinking between tannic acid (TA) and poly(l-glutamic acid)-g-methoxy poly(ethylene glycol)/phenyl boronic acid (PLG-g-mPEG/PBA). TA not only serves as one component of the iSGel but also relieves the postsurgical immunosuppressive microenvironment by inhibiting the activity of cyclo-oxygenase-2 (COX-2). The aOX40 serves as an immune agonistic antibody and is released from the iSGel in a constant manner lasting for over 20 days. In a subcutaneous murine CRC model, the iSGels@aOX40 results in complete inhibition on tumor recurrence. In addition, the cured mice show resistance to tumor re-challenge, suggesting that immune memory effects are established after the iSGels@aOX40 treatment. In an orthotopic CRC peritoneal metastatic model, the iSGels@aOX40 also remarkably inhibits the growth of the abdominal metastatic tumors, suggesting great potential for clinical CRC therapy.

The Enhancing Immune Response and Anti-Inflammatory Effects of Caulerpa lentillifera Extract in RAW 264.7 Cells

Background: Caulerpa lentillifera (CL) is a green seaweed, and its edible part represents added value as a functional ingredient. CL was dried and extracted for the determination of its active compounds and the evaluation of its biological activities. The major constituents of CL extract (CLE), including tannic acid, catechin, rutin, and isoquercetin, exhibited beneficial effects, such as antioxidant activity, anti-diabetic activity, immunomodulatory effects, and anti-cancer activities in in vitro and in vivo models. Whether CLE has an anti-inflammatory effect and immune response remains unclear. Methods: This study examined the effect of CLE on the inflammatory status and immune response of lipopolysaccharide (LPS)-stimulated RAW 264.7 cells and the mechanisms involved therein. RAW264.7 cells were treated with different concentrations of CLE (0.1–1000 µg/mL) with or without LPS (1 µg/mL) for 24 h. Expression and production of the inflammatory cytokines, enzymes, and mediators were evaluated. Results: CLE suppressed expression and production of the pro-inflammatory cytokines IL-6 and TNF-α. Moreover, CLE inhibited expression and secretion of the inflammatory enzyme COX-2 and the mediators PGE2 and NO. CLE also reduced DNA damage. Furthermore, CLE stimulated the immune response by modulating the cell cycle regulators p27, p53, cyclin D2, and cyclin E2. Conclusions: CLE inhibits inflammatory responses in LPS-activated macrophages by downregulating inflammatory cytokines and mediators. Furthermore, CLE has an immunomodulatory effect by modulating cell cycle regulators.

Anti-asthmatic effects of tannic acid from Chinese natural gall nuts in a mouse model of allergic asthma

Asthma is a chronic inflammatory disease of the airways, which is characterized by infiltration of inflammatory cells, airway hyperresponsiveness (AHR), and airway remodeling. This study aimed to explore the role and mechanism of tannic acid (TA), a naturally occurring plant-derived polyphenol, in murine asthma model. BALB/c mice were given ovalbumin (OVA) to establish an allergic asthma model. The results revealed that TA treatment significantly decreased OVA-induced AHR, inflammatory cells infiltration, and the expression of various inflammatory mediators (Th2 and Th1 cytokines, eotaxin, and total IgE). Additionally, TA treatment also attenuated increases in mucins (Muc5ac and Muc5b) expression, mucus production in airway goblet cells, mast cells infiltration, and airway remodeling induced by OVA exposure. Furthermore, OVA-induced NF-κB (nuclear factor- kappa B) activation and cell adhesion molecules expression in the lungs was suppressed by TA treatment. In conclusion, TA effectively attenuated AHR, inflammatory response, and airway remodeling in OVA-challenged asthmatic mice. Therefore, TA may be a potential therapeutic option against allergic asthma in clinical settings.

Nephroprotective activity of natural products against chemical toxicants: The role of Nrf2/ARE signaling pathway

Nephropathy can occur following exposure of the kidneys to oxidative stress. Oxidative stress is the result of reactive oxygen species (ROS) formation due to intracellular catabolism or exogenous toxicant exposure. Many natural products (NPs) with antioxidant properties have been used to demonstrate that oxidative damage-induced nephrotoxicity can be ameliorated or at least reduced through stimulation of the nuclear factor erythroid 2-related factor 2 (Nrf2) signaling pathway. Nrf2 is a basic leucine zipper (bZip) transcription factor that regulates gene expression of the antioxidant response elements (ARE). Nrf2 is involved in the cellular antioxidant-detoxification machinery. Nrf2 activation is a major mechanism of nephroprotective activity for these NPs, which facilitates its entry into the nucleus, primarily by inhibiting Kelch like-ECH-associated protein 1 (Keap1). The purpose of this article was to review the peer-reviewed literature of NPs that have shown mitigating effects on renal disorder by stimulating Nrf2 and thereby suggesting potential new therapeutic or prophylactic strategies against kidney-damaging xenobiotics.

Impact of dietary polyphenols on neuroinflammation-associated disorders

Neurodegenerative disorders like Alzheimer's, Parkinson's, and associated dementia typically originate with altered protein folding and aggregation of their β structures in the neurons. This self-aggregation leads to glial activation in the brain, causing neuroinflammation and leads to neuronal death. According to statistics provided by WHO, there are around 50 million people with dementia worldwide and every year, 10 million more cases are projected to increase. Also, around 5-8 percentage of people who are aged above 60 globally has dementia or associated disorders. Over 82 million in 2030 and 152 in 2050 are expected to have dementia. Most of these patients fall into low-middle-income countries which makes it even more essential to find an affordable and effective treatment method. Polyphenols of different origin are studied for their potential role as anti-neuro-inflammatory molecules. This review would summarize recent advances in three widely researched dietary polyphenols projected as potential therapeutic agents for disorders like Alzheimer's, Parkinson's, etc. They are Resveratrol, Catechins, and Tannins. The review would discuss the recent advances and challenges in using these polyphenols using specific examples as potential therapeutic agents against neuroinflammation associated disorders. An abstract of neuroinflammation-associated events and the effects by selected polyphenols.

Effects of chestnut tannins supplementation of prepartum moderate yielding dairy cows on metabolic health, antioxidant and colostrum indices

This study investigated the effects of dietary supplementation with chestnut tannins (CNT) on metabolic and antioxidant status of prepartum cows along with their colostrum quality. Pregnant multiparous Holstein cows were paired according to parity and body condition score, and assigned either to a diet supplemented with 20 g/d of commercially available product containing chestnut tannins (CNT, n=20) or to an unsupplemented control diet (CON, n=20) for the last 25±2 d of pregnancy. Serum metabolite, insulin and antioxidant capacity indices were measured in blood samples taken at d 25 and d 5 before expected parturition. Chemical composition and IgG concentration were determined in colostrum samples collected from the first milking postpartum. The addition of CNT led to lower BUN (P=0.02) and consequently higher serum glucose (P=0.02) and insulin (P<0.01) concentrations which were associated with lower circulating NEFA (P<0.01) and BHBA (P<0.01) in CNT group than those of CON. The serum paraoxonase 1 (PON 1) activity and total antioxidant capacity (TAOC) were higher at -5 d in CNT than in CON (P<0.01, P=0.03; respectively). Close-up CNT improved lactose percentage and IgG concentration (P=0.03, P=0.04; respectively) and tended to improve percentage of protein and SNF (Solid Not Fat) in primary colostrum (P=0.06, respectively), without affecting colostrum fat and total solid (P=0.98, P=0.43; respectively). Supplementation of CNT in the diet during close-up period did not have adverse effects on metabolic profiles prepartum. Instead, this feeding regimen was more beneficial to antioxidant capacity and colostrum quality than feeding the control diet.

Tannylated Calcium Carbonate Materials with Antacid, Anti-Inflammatory, and Antioxidant Effects

Calcium carbonate (CaCO3)-based materials have received notable attention for biomedical applications owing to their safety and beneficial characteristics, such as pH sensitivity, carbon dioxide (CO2) gas generation, and antacid properties. Herein, to additionally incorporate antioxidant and anti-inflammatory functions, we prepared tannylated CaCO3 (TA-CaCO3) materials using a simple reaction between tannic acid (TA), calcium (Ca2+), and carbonate (CO32-) ions. TA-CaCO3 synthesized at a molar ratio of 1:75 (TA:calcium chloride (CaCl2)/sodium carbonate (Na2CO3)) showed 3-6 μm particles, comprising small nanoparticles in a size range of 17-41 nm. The TA-CaCO3 materials could efficiently neutralize the acid solution and scavenge free radicals. In addition, these materials could significantly reduce the mRNA levels of pro-inflammatory factors and intracellular reactive oxygen species, and protect chondrocytes from toxic hydrogen peroxide conditions. Thus, in addition to their antacid property, the prepared TA-CaCO3 materials exert excellent antioxidant and anti-inflammatory effects through the introduction of TA molecules. Therefore, TA-CaCO3 materials can potentially be used to treat inflammatory cells or diseases.

Ameliorative effect of tannic acid on hypermethioninemia-induced oxidative and nitrosative damage in rats: biochemical-based evidences in liver, kidney, brain, and serum

We investigated the ability of tannic acid (TA) to prevent oxidative and nitrosative damage in the brain, liver, kidney, and serum of a rat model of acute hypermethioninemia. Young Wistar rats were divided into four groups: I (control), II (TA 30 mg/kg), III (methionine (Met) 0.4 g/kg + methionine sulfoxide (MetO) 0.1 g/kg), and IV (TA/Met + MetO). Rats in groups II and IV received TA orally for seven days, and rats of groups I and III received an equal volume of water. After pretreatment with TA, rats from groups II and IV received a single subcutaneous injection of Met + MetO, and were euthanized 3 h afterwards. In specific brain structures and the kidneys, we observed that Met + MetO led to increased reactive oxygen species (ROS), nitrite, and lipid peroxidation levels, followed by a reduction in thiol content and antioxidant enzyme activity. On the other hand, pretreatment with TA prevented both oxidative and nitrosative damage. In the serum, Met + MetO caused a decrease in the activity of antioxidant enzymes, which was again prevented by TA pretreatment. In contrast, in the liver, there was a reduction in ROS levels and an increase in total thiol content, which was accompanied by a reduction in catalase and superoxide dismutase activities in the Met + MetO group, and pretreatment with TA was able to prevent only the reduction in catalase activity. Conclusively, pretreatment with TA has proven effective in preventing oxidative and nitrosative changes caused by the administration of Met + MetO, and may thus represent an adjunctive therapeutic approach for treatment of hypermethioninemia.

Antidepressant Effect and Modulation of the Redox System Mediated by Tannic Acid on Lipopolysaccharide-Induced Depressive and Inflammatory Changes in Mice

Depression is an emotional disorder that causes mental and physical changes, and has limited pharmacotherapy. Tannic acid (TA) is a polyphenol with previously described antioxidant and neuroprotective properties. The aim of this study was to evaluate the effects of TA on lipopolysaccharide (LPS)-induced depressive-like behavior, as well as oxidative stress parameters and TNF-α levels in the brains of mice. Animals were pretreated once daily, with TA (30 or 60 mg/kg), fluoxetine (20 mg/kg) or vehicle for 7 days. On the 7th day, the animals received a single injection of LPS (830 μg/kg). After 24 h, open field, forced swimming, tail suspension, and splash tests were conducted. The endotoxin induced depressive-like behavior in these mice and this was attenuated by TA. In the cerebral cortex, hippocampus, and striatum, LPS increased lipid peroxidation and reactive oxygen species production, and this was also prevented by TA administration. TA treatment also prevented a decrease in catalase activity within the striatum. Further, LPS administration caused increased levels of TNF-α in all brain structures, and this was prevented in the cortex by TA treatment. In conclusion, TA shows many neuroprotective properties, with demonstrated antioxidant, anti-inflammatory and antidepressant effects in this animal model of acute depressive-like behavior. Therefore, this compound could provide an alternative therapeutic approach for the treatment of depression.

Spirogyra neglecta Aqueous Extract Attenuates LPS-Induced Renal Inflammation

Spirogyra neglecta (SN), commonly named "Tao" in Thai, is a genus of filamentous green macroalgae. SN contains polyphenols such as isoquercetin, catechin, hydroquinone and kaempferol. These constituents exhibit beneficial effects including anti-oxidant, anti-gastric ulcer, anti-hyperglycaemia and anti-hyperlipidaemia in both in vitro and in vivo models. Whether SN extract (SNE) has an anti-inflammatory effect in vivo remains unclear. This study examined the effect of SNE on renal function and renal organic transport in lipopolysaccharide (LPS)-induced renal inflammation in rats. Rats were randomised and divided into normal saline (NS), NS supplemented with 1000 mg/kg body weight (BW) of SNE (NS + SNE), intraperitoneally injected with 12 mg/kg BW of LPS and LPS treated with 1000 mg/kg BW of SNE (LPS + SNE). Biochemical parameters in serum and urine, lipid peroxidation concentration, kidney function and renal organic anion and cation transports were determined. LPS-injected rats developed renal injury and inflammation by increasing urine microalbumin, total malondialdehyde (MDA) and inflammatory cytokines, tumor necrosis factor (TNF)-α and interleukin (IL)-1β protein expression, respectively. In addition, uptake of renal organic anion, [³H]-oestrone sulphate (ES), was reduced in LPS-injected rats together with increased expression of organic anion transporter 3 (Oat3). However, the renal injury and inflammation, as well as impaired Oat3 function and protein expression, were restored in LPS + SNE rats. Accordingly, SNE could be developed as nutraceutical product to prevent inflammation-induced nephrotoxicity.

Tannic acid ameliorates arsenic trioxide-induced nephrotoxicity, contribution of NF-κB and Nrf2 pathways

BACKGROUND AND PURPOSE

Tannic acid (TA), a group of polyphenolic compounds, has multiple anticancer, antimutagenic, antioxidant and anti-inflammatory activities. However, the effects of TA on arsenic trioxide (ATO)-induced nephrotoxicity are still relatively unknown. This study investigated the protective effects and potential mechanisms of TA on ATO-induced nephrotoxicity in rats.

METHODS

Rats were intragastrically administered TA with concurrent ATO infused intraperitoneally over 10 days. Renal morphology changes were observed through light microscopy. The levels of antioxidants and pro-inflammatory factors were measured in the serum and renal tissue, respectively. Further, expression of B-cell lymphoma-2, B-cell lymphoma-extra large, p53, and Bcl-2-associated X protein were measured using an immunohistochemical method. The protein expression of nuclear factor kappa B (NF-κB), nuclear factor-erythroid-2-related factor 2 (Nrf2), and kelch-like ECH-associated protein 1 (Keap1) were measured by Western blot.

RESULTS

The data showed that ATO exposure significantly increased the serum nephritic, oxidative stress, apoptosis and inflammatory markers in the renal tissue of rats. Conversely, pretreatment with TA reversed these changes. Furthermore, TA treatment caused a significant decrease in NF-κB expression (P < 0.05), while increasing Nrf2 and Keap1 expressions (P < 0.05).

CONCLUSION

TA ameliorates ATO-induced nephrotoxicity, which is related to the inhibition of oxidative stress, inflammation and apoptosis, potentially through the NF-κB/Nrf2 pathway.

Antioxidant Nanoparticles for Concerted Inhibition of α-Synuclein Fibrillization, and Attenuation of Microglial Intracellular Aggregation and Activation

Parkinson’s Disease is characterized by the loss of dopaminergic neurons in the substantia nigra pars compacta, the extracellular accumulation of toxic α-synuclein (αSYN) aggregates, and neuroinflammation. Microglia, resident macrophages of the brain, are one of the critical cell types involved in neuroinflammation. Upon sensing extracellular stimuli or experiencing oxidative stress, microglia become activated, which further exacerbates neuroinflammation. In addition, as the first line of defense in the central nervous system, microglia play a critical role in αSYN clearance and degradation. While the role of microglia in neurodegenerative pathologies is widely recognized, few therapeutic approaches have been designed to target both microglial activation and αSYN aggregation. Here, we designed nanoparticles (NPs) to deliver aggregation-inhibiting antioxidants to ameliorate αSYN aggregation and attenuate activation of a pro-inflammatory microglial phenotype. Ferulic acid diacid with an adipic acid linker (FAA) and tannic acid (TA) were used as shell and core molecules to form NPs via flash nanoprecipitation. These NPs showed a strong inhibitory effect on αSYN fibrillization, significantly diminishing αSYN fibrillization in vitro compared to untreated αSYN using a Thioflavin T assay. Treating microglia with NPs decreased overall αSYN internalization and intracellular αSYN oligomer formation. NP treatment additionally lowered the in vitro secretion of pro-inflammatory cytokines TNF-α and IL-6, and also attenuated nitric oxide and reactive oxygen species production induced by αSYN. NP treatment also significantly decreased Iba-1 expression in αSYN-challenged microglia and suppressed nuclear translocation of nuclear factor kappa B (NF-κB). Overall, this work lays the foundation for an antioxidant-based nanotherapeutic candidate to target pathological protein aggregation and neuroinflammation in neurodegenerative diseases.

Tannic Acid Ameliorates STZ-Induced Alzheimer's Disease-Like Impairment of Memory, Neuroinflammation, Neuronal Death and Modulates Akt Expression

Tannic acid (TA) is a hydrolysable glycosidic polyphenol polymer of gallic acid, which possesses neuroprotective properties. The aim of this study was to evaluate the effect of TA treatment on cognitive performance and neurochemical changes in an experimental model of sporadic dementia of Alzheimer's type (SDAT) induced by intracerebroventricular (ICV) injection of streptozotocin (STZ) and to explore the potential cellular and molecular mechanisms underlying these effects. Adult male rats were divided into four groups: control, TA, STZ, and TA + STZ. Animals from TA and TA + STZ groups were treated with TA (30 mg/kg) daily, by gavage, for 21 days; others groups received water (1 mL/kg). Subsequently, an ICV injection of STZ (3 mg/kg) was administered into the lateral ventricles of animals from STZ and TA + STZ groups, while other groups received citrate buffer. Cognitive deficits (short-term memory), neuronal survival, neuroinflammation as well as expression of SNAP-25, Akt, and pAkt were evaluated in the cerebral cortex. TA treatment protected against the impairment of memory in STZ-induced SDAT. STZ promoted an increase in neuronal death and the levels of proinflammatory cytokines (IL-6 and TNF-α) and a decrease in Akt and pAkt expression; TA was able to restore these changes. Neither STZ nor TA altered SNAP-25 expression or the levels of IL-12 and IL-4 in the cerebral cortex. Our study highlights that treatment with TA prevents memory deficits and reestablishes Akt and pAkt expression, protecting against neuronal death and neuroinflammation in STZ-induced SDAT in rats.

Roles of Toll-like receptor 2/4, monoacylglycerol lipase, and cyclooxygenase in social defeat stress-induced prostaglandin E2 synthesis in the brain and their behavioral relevance

Inflammation in the brain and periphery has been associated with stress-related pathology of mental illness. We have shown that prostaglandin (PG) E₂, an arachidonic acid-derived lipid mediator, and innate immune receptors Toll-like receptor (TLR) 2/4 are crucial for repeated stress-induced behavioral changes in rodents. However, how the stress induces PGE₂ synthesis in the brain and whether TLR2/4 are involved in the PGE₂ synthesis remain unknown. Using mice lacking TLR2 and TLR4 in combination, here we show that social defeat stress (SDS) induced the PGE₂ synthesis in subcortical, but not cortical, tissues in a TLR2/4-dependent manner. It is known that PGE₂ in the brain is mainly derived by monoacylglycerol lipase (MAGL)-mediated conversion of endocannabinoid 2-arachidonoylglycerol to free-arachidonic acid, a substrate for cyclooxygenase (COX) for PGE₂ synthesis. We found that TLR2/4 deletion reduced the mRNA expression of MAGL and COX1 in subcortical tissues after repeated SDS. Perturbation of MAGL and COX1 as well as COX2 abolished SDS-induced PGE₂ synthesis in subcortical tissues. Furthermore, systemic administration of JZL184, an MAGL inhibitor, abolished repeated SDS-induced social avoidance. These results suggest that SDS induces PGE₂ synthesis in subcortical regions of the brain via the MAGL-COX pathway in a TLR2/4-dependent manner, thereby leading to social avoidance.