Tea and its components reduce the production of uric acid by inhibiting xanthine oxidase

Phytochemical compounds for treating hyperuricemia associated with gout: a systematic review

Gout is a prevalent metabolic disorder characterized by increased uric acid (UA) synthesis or decreased UA clearance from the bloodstream, leading to the formation of urate crystals in joints and surrounding tissues. Hyperuricemia (HUA), the underlying cause of gout, poses a growing challenge for healthcare systems in developed and developing countries. Currently, the most common therapeutic approaches for gouty HUA primarily involve the use of allopathic or modern medicine. However, these treatments are often accompanied by adverse effects and may not be universally effective for all patients. Therefore, this systematic review aims to provide a comprehensive outline of phytochemical compounds that have emerged as alternative treatments for HUA associated with gout and to examine their specific mechanisms of action. A systematic search was conducted to identify phytochemicals that have previously been evaluated for their effectiveness in reducing HUA. From a review of > 800 published articles, 100 studies reporting on 50 phytochemicals associated with the management of HUA and gout were selected for analysis. Experimental models were used to investigate the effects of these phytochemicals, many of which exhibited multiple mechanisms beneficial for managing HUA. This review offers valuable insights for identifying and developing novel compounds that are safer and more effective for treating HUA associated with gout.

Preparation of immobilized xanthine oxidase with magnetic metal-organic framework and its application in screening of active ingredients in traditional Chinese medicine

Enzymes play a crucial role in the development and progression of various diseases, making them important targets for drug development. However, the stability issues associated with natural enzymes limit their broader application. Traditional methods for screening enzyme inhibitors from natural products are often time-consuming and labor-intensive. In this study, we designed and employed magnetic metal-organic frameworks (MOFs) to immobilize xanthine oxidase for the first time. By leveraging the porous structure and high specific surface area of MOFs, combined with the magnetic responsiveness of nanoparticles, we successfully developed a novel method for the efficient screening of potential enzyme inhibitors derived from natural products. By using 1-ethyl-3-(3-dimethylaminopropyl)carbodiimide/N-hydroxysuccinimide (EDC/NHS) as a cross-linking agent, we achieved efficient immobilization of xanthine oxidase and identified baicalin as a potential inhibitor from the extract of Scutellaria baicalensis. In addition, we confirmed the adsorption capacity of this method for hordenine, demonstrated the specific adsorption of allopurinol, and also performed in vitro activity validation for baicalein. We not only successfully prepared the immobilized enzyme but also showcased that this method can efficiently screen and isolate potential enzyme inhibitors from traditional Chinese medicine, which provides a rapid and efficient new strategy for identifying enzyme inhibitors in natural products. This innovative approach offers a fresh perspective on the application of botanical medicine and the pharmacological treatment of hyperuricemia, which has important theoretical and practical significance. Graphical abstract Schematic diagram of synthesis of XO@MMOF (A) and ligand fishing process (B).

Study on the synergistical effects of characteristic compounds in Osmanthus black tea against xanthine oxidase based on multispectral analysis combined with in silico studies

With the worldwide prevalence of hyperuricemia (HUA), safe and effective natural xanthine oxidase (XOD) inhibitors are in need. This research was aimed to reveal the promising XOD inhibitors in Osmanthus black tea. Here, the combination index (CI) values for TF3 and acteoside were below 0.9, confirming the synergistic inhibitory effects on XOD. Further research confirmed that TF3-acteoside was stronger in inducing static quenching of XOD fluorescence than TF3 or acteoside. Besides, the secondary structure of XOD was significant changed by TF3-acteoside, specifically a decrease in the content of α-Helix and random coil, accompanied by an increase in β-Sheet and β-Turn contents, ultimately its structural stability and rigidity was enhanced. Molecular docking and molecular dynamics simulation analysis verified that TF3-acteoside stably bound to XOD by multiple hydrogen bonds. This study will lay important theoretical basis for the advancement of novel XOD inhibitors and the application of osmanthus black tea in lowering uric acid (UA).

Effects and mechanisms of theabrownin from black tea in improving hyperuricemia: Evidence from animal study and clinical trial

Hyperuricemia (HUA) is a metabolic disease characterized by disorders of uric acid synthesis and excretion. Theabrownin (TB), a macromolecular water-soluble pigment from black tea, can bring beneficial effects on human health. The effects and underlying molecular mechanisms of TB on HUA animals and patients are still unclear. This study aimed to explore the potential function and the possible mechanisms of TB in improving HUA. Our results demonstrated that TB could reduce the levels of serum uric acid and improve renal pathological damage in HUA mice by inhibiting xanthine oxidase (XOD) activity in the liver and increasing the expression of uric acid transporter proteins in the kidney. Furthermore, TB was proven to suppress autophagy, inflammation, and fibrosis in the kidney of HUA mice. Moreover, a self-controlled clinical trial showed that TB drinking daily for 12 weeks could decrease serum uric acid levels in HUA patients without any adverse effects. In conclusion, TB exhibits significant potential in decreasing serum uric acid levels both in HUA mice and patients, offering a novel approach to HUA treatment.

Hesperetin acts as a potent xanthine oxidase inhibitor: New evidence from its reactive oxygen suppression and enzyme binding

Xanthine oxidase (XO) plays a crucial role in purine metabolism, catalyzing the oxidation of hypoxanthine to xanthine and subsequently to uric acid. Elevated uric acid levels can lead to hyperuricemia, a condition linked to gout, kidney stones, and other chronic diseases. Inhibiting XO activity represents a promising strategy for managing hyperuricemia. This study investigated the inhibitory effects of the flavonoid hesperetin enriched in citrus fruits on XO activity, its antioxidant properties against reactive oxygen species (ROS) generated by the XO reaction, and the underlying mechanisms of enzyme inhibition. Enzyme kinetics and spectroscopy revealed that hesperetin competitively inhibited XO at an inhibition constant of (2.15 ± 0.05) × 10-6 mol/L through its binding to the molybdopterin active center of XO, preventing the entry of xanthine and the transfer of electrons, effectively scavenging superoxide radicals by inhibiting uric acid production and oxygen reduction, and inducing conformational changes in XO's structure. Fluorescence quenching indicated that hesperetin interacted with XO through a combination of static and dynamic quenching mechanisms. Molecular docking simulations demonstrated that hesperetin binded tightly to XO's active site, blocking substrate entry. Molecular dynamics confirmed that hesperetin stabilized the XO-hesperetin complex through reinforced hydrophobic and hydrogen-bond interactions. The results suggest that hesperetin can act as a potent natural xanthine oxidase inhibitor or a functional food supplement to alleviate hyperuricemia.

A Bidirectional Mendelian Randomization Study of Tea-Drinking Habits and Risk of Elevated Serum Uric Acid Levels

BACKGROUND

Although recent animal experiments have revealed that tea intake improves elevated serum uric acid (SUA) levels, a causal link between the consumption of different types of tea and SUA levels remains undetermined.

METHODS

Bidirectional Mendelian randomization (MR) analysis based on genome-wide association studies was used to assess the causal relationship between consumption of different types of tea and the risk of elevated SUA levels in European and Asian populations.

RESULTS

Forward MR analysis showed that tea intake was significantly associated with lower SUA levels (p = 0.0013). The estimated effect value (β $$ \beta $$  = $$ = $$  -0.0440) suggests that for every 1-unit increase in tea intake, there is a 0.044-unit decrease in SUA levels. However, there is no reverse causality between SUA and tea intake (p = 0.2824). No causal relationship was found between the consumption of different types of tea and risk of elevated SUA levels (p > 0.05).

CONCLUSION

Although this bidirectional MR study provided evidence of a causal relationship between tea intake and SUA levels, however, due to limitations associated with the sample size and strength of instrumental variables, a definite conclusion was not possible.

Recent Advances in the Application of Foodborne Substances in Hyperuricemia

Hyperuricemia (HUA) is a purine metabolism disorder characterized by the excessive production or inadequate excretion of uric acid. Current pharmacological strategies targeting uric acid reduction have potential adverse effects. Following the concept of "homology of medicine and food", food ingredients are increasingly being explored to prevent HUA and gout, with xanthine oxidase (XOD) emerging as a crucial therapeutic target in managing HUA. Recent scientific investigations have determined that uric acid-lowering substances come from various food sources, such as seafood, dairy products, and agricultural products. These bioactive substances have attracted wide attention because of their effective antihyperuricemia and XOD inhibitory ability. In this study, the pathogenesis, many side effects of uric acid-lowering drugs, and some components of uric acid-lowering drugs are mainly described, with emphasis on the source, composition, preparation technology, and mechanism of uric acid-lowering peptides.

Regulation of redox enzymes by nutraceuticals: a review of the roles of antioxidant polyphenols and peptides

Redox enzymes are essential components of the cellular defence system against oxidative stress, which is a common factor in various diseases. Therefore, understanding the role of bioactive nutraceuticals in modulating the activity of these enzymes holds immense therapeutic potential. This paper provides a comprehensive review of the regulation of redox enzymes in cell and animal models by food-derived bioactive nutraceuticals, focusing on polyphenols and peptides. Specifically, this paper discusses the regulation of superoxide dismutase (SOD), glutathione peroxidase (GPx), catalase (CAT), NAPDH oxidase, xanthine oxidase (XO), myeloperoxidase (MPO), and haem oxygenase (HO) in cell and animal models. Polyphenols, which are abundant in fruits, vegetables, and beverages, have diverse antioxidant properties, including direct scavenging of reactive oxygen species and regulation of transcription factors such as nuclear factor erythroid 2-related factor 2, which leads to the increased expression of the redoxenzymes SOD, HO, and GPx. Similarly, bioactive peptides from various food proteins can enhance antioxidative enzyme activity by regulating gene expression and directly activating the enzyme CAT. In other cases, an antioxidative response requires the downregulation or inhibition of the redox enzymes XO, MPO, and NAPDH oxidase. This paper highlights the potential of bioactive nutraceuticals in mitigating oxidative stress-related diseases and their mechanisms in modulating the redox enzyme expression or activity. Furthermore, the review highlights the need for further research to uncover new therapeutic strategies using nutraceuticals for enhancing cellular antioxidant defence mechanisms and improving health outcomes.

From a Cup of Tea to Cardiovascular Care: Vascular Mechanisms of Action

Tea consumption is increasingly recognized for its potential benefits to cardiovascular health. This study reviews the available research, concentrating on the major components of tea and their mechanisms of action in the cardiovascular system. Tea is abundant in bioactive compounds, such as flavonoids and polysaccharides, which possess significant antioxidant and anti-inflammatory properties. These compounds play a crucial role in mitigating oxidative stress and inflammation, thereby supporting cardiovascular health. They enhance endothelial function, leading to improved vascular relaxation and reduced arterial stiffness, and exhibit antithrombotic effects. Additionally, regular tea consumption is potentially associated with better regulation of blood pressure, improved cholesterol profiles, and effective blood sugar control. It has been suggested that incorporating tea into daily dietary habits could be a practical strategy for cardiovascular disease prevention and management. Despite the promising evidence, more rigorous clinical trials are needed to establish standardized consumption recommendations and fully understand long-term effects. This review offers a more comprehensive analysis of the current evidence based on endothelium function and identifies the gaps that future research should address.

Distinguishable short-term effects of tea and water drinking on human saliva redox

Food consumption can alter the biochemistry and redox status of human saliva, and the serving temperature of food may also play a role. The study aimed to explore the immediate (3 min) and delayed (30 min) effects of hot tea (57 ± 0.5 °C) ingestion and cold tea (8 ± 0.5 °C) ingestion on the salivary flow rate and salivary redox-relevant attributes. The saliva was collected from 20 healthy adults before, 3-min after and 30-min after the tea ingestion. The hot or cold deionised water at the same temperatures were used as control. The salivary flow rate and redox markers in hot tea (HBT), cold tea (CBT), hot water (HW) and cold water (CW) group were analysed and compared. The results demonstrated that neither the black tea nor the water altered the salivary flow rate; the black tea immediately increased the salivary thiol (SH) and malondialdehyde (MDA) content while reduced salivary uric acid (UA) significantly. The tea ingestion showed a tendency to elevate the ferric reducing antioxidant power (FRAP) in saliva, although not significantly. The water ingestion decreased the MDA content immediately and increased the UA level significantly. Cold water was found to induce a greater delayed increase in total salivary total protein (TPC) than the hot water. In conclusion, the black tea ingestion affects the redox attributes of human saliva acutely and significantly, while the temperature of drink makes the secondary contribution.

Integrating Network Pharmacology and Experimental Validation to Reveal the Mechanism of Vine Grape Tea Polyphenols on Hyperuricemia-Induced Renal Injury in Mice

Hyperuricemia (HUA) is a metabolic disease and contributes to renal injury (RI). Vine grape tea polyphenols (VGTP) have been widely used to treat HUA and RI. However, the potential mechanism of VGTP activity remains unclear. To explore the underlying mechanism of VGTP treatment for HUA-induced RI based on network pharmacology that is confirmed by an in vivo study. All ingredients of VGTP were retrieved using a Traditional Chinese Medicine Systems Pharmacology Database and Analysis Platform and Comparative Toxicogenomics Database systems. The related targets of HUA and RI were obtained from GeneCards and National Center for Biotechnology Information (NCBI) databases. Some ingredients and targets were selected for molecular docking verification. One hour after administering potassium oxonate (300 mg/kg), VGTP (50, 100, and 200 mg/kg/d) was orally administered to HUA mice for 4 weeks. Histopathology and western blotting were performed in renal tissue. Our results showed that VGTP significantly reduced blood urea nitrogen, creatinine, uric acid, and significantly improved the RI and fibrosis of HUA mice. There were 54 active ingredients and 62 targets of HUA-induced RI. Further studies showed that VGTP decreased the expression of Bax, cleaved caspase 3, transforming growth factor-β (TGF-β1), CHOP, p-STAT3, and P53, and increased Bcl-2 expression in renal tissue. The related signaling pathways have apoptosis, TGF-β1, P53 and STAT, and endoplasmic reticulum stress (ERS). In this study, VGTP exerted antihyperuricemic and anti fibrosis effects by regulating the apoptosis and ERS signaling pathways. VGTP is expected to become a drug for combating HUA and RI.

Microbial Fermentation Enhances the Effect of Black Tea on Hyperlipidemia by Mediating Bile Acid Metabolism and Remodeling Intestinal Microbes

Black tea (BT), the most consumed tea worldwide, can alleviate hyperlipidemia which is a serious threat to human health. However, the quality of summer BT is poor. It was improved by microbial fermentation in a previous study, but whether it affects hypolipidemic activity is unknown. Therefore, we compared the hypolipidemic activity of BT and microbially fermented black tea (EFT). The results demonstrated that BT inhibited weight gain and improved lipid and total bile acid (TBA) levels, and microbial fermentation reinforced this activity. Mechanistically, both BT and EFT mediate bile acid circulation to relieve hyperlipidemia. In addition, BT and EFT improve dyslipidemia by modifying the gut microbiota. Specifically, the increase in Lactobacillus johnsonii by BT, and the increase in Mucispirillum and Colidextribacter by EFT may also be potential causes for alleviation of hyperlipidemia. In summary, we demonstrated that microbial fermentation strengthened the hypolipidemic activity of BT and increased the added value of BT.

Effect of tea intake on genetic predisposition to gout and uric acid: a Mendelian randomization study

Objective

The effect of tea on gout and uric acid is still controversial. This study aims to analyze the effect of tea intake on genetic predisposition to gout, idiopathic gout, gout due to impairment of renal function as well as uric acid by Mendelian randomization (MR).

Methods

Forty independent single nucleotide polymorphisms (SNPs) associated with tea intake were selected from UK Biobank. SNPs for uric acid were obtained from BioBank Japan, SNPs for gout were obtained from UK Biobank, and SNPs for gout due to impairment of renal function and idiopathic gout were derived from FinnGen. The causal relationship of exposure-outcome was tested using inverse variance weighted, MR-Egger and weighted median. MR-Egger intercept was employed to assess horizontal pleiotropy, Cochran's Q test was used to assess heterogeneity, and leave-one-out sensitivity analysis was utilized to analyze the stability of the results.

Results

The results of MR analysis showed that tea intake was negatively associated with gout due to impairment of renal function (OR 0.997, 95% CI 0.994 to 0.999, P = 0.017), whereas there was no causal association with gout, idiopathic gout, and uric acid (P > 0.05), for which sensitivity analysis suggested that these results were robust.

Conclusions

There was a genetic predisposition effect of increased tea intake on the reduced risk of gout due to impairment of renal function, whereas there was no such effect on gout, idiopathic gout, and uric acid. Tea intake may become an important option in the dietary treatment of gout due to impairment of renal function.

Pairwise synthetic cytotoxicity between Paxlovid and 100 frequently prescribed FDA-approved small molecule drugs on liver cells

Paxlovid is a recent FDA approved specific drug for COVID-19. Extensive prescription of Paxlovid could induce potential synthetic cytotoxicity with drugs. Herein, we aimed to examine pairwise synthetic cytotoxicity between Paxlovid and 100 frequently FDA approved small molecule drugs. Liver cell line HL-7702 or L02 was adopted to evaluate synthetic cytotoxicity between Paxlovid and the 100 small molecule drugs. Inhibitory concentration IC-10 and IC-50 doses for all the 100 small molecule drugs and Paxlovid were experimentally acquired. Then, pairwise synthetic cytotoxicity was examined with the fixed dose IC-10 for each drug. The most 4 significant interactive pairs (2 positively interactive and 2 negatively interactive) were further subjected to molecular docking simulation to reveal the structural modulation with Caspase-8, a key mediator for cell apoptosis.

Therapeutic Activity of Green Tea Epigallocatechin-3-Gallate on Metabolic Diseases and Non-Alcoholic Fatty Liver Diseases: The Current Updates

Green tea polyphenols have numerous functions including antioxidation and modulation of various cellular proteins and are thus beneficial against metabolic diseases including obesity, type 2 diabetes, cardiovascular and non-alcoholic fatty liver diseases, and their comorbidities. Epigallocatechin-3-gallate (EGCG) is the most abundant polyphenol in green tea and is attributed to antioxidant and free radical scavenging activities, and the likelihood of targeting multiple metabolic pathways. It has been shown to exhibit anti-obesity, anti-inflammatory, anti-diabetic, anti-arteriosclerotic, and weight-reducing effects in humans. Worldwide, the incidences of metabolic diseases have been escalating across all age groups in modern society. Therefore, EGCG is being increasingly investigated to address the problems. This review presents the current updates on the effects of EGCG on metabolic diseases, and highlights evidence related to its safety. Collectively, this review brings more evidence for therapeutic application and further studies on EGCG and its derivatives to alleviate metabolic diseases and non-alcoholic fatty liver diseases.

Protective effects and molecular mechanisms of tea polyphenols on cardiovascular diseases

Aging is the most important factor contributing to cardiovascular diseases (CVDs), and the incidence and severity of cardiovascular events tend to increase with age. Currently, CVD is the leading cause of death in the global population. In-depth analysis of the mechanisms and interventions of cardiovascular aging and related diseases is an important basis for achieving healthy aging. Tea polyphenols (TPs) are the general term for the polyhydroxy compounds contained in tea leaves, whose main components are catechins, flavonoids, flavonols, anthocyanins, phenolic acids, condensed phenolic acids and polymeric phenols. Among them, catechins are the main components of TPs. In this article, we provide a detailed review of the classification and composition of teas, as well as an overview of the causes of aging-related CVDs. Then, we focus on ten aspects of the effects of TPs, including anti-hypertension, lipid-lowering effects, anti-oxidation, anti-inflammation, anti-proliferation, anti-angiogenesis, anti-atherosclerosis, recovery of endothelial function, anti-thrombosis, myocardial protective effect, to improve CVDs and the detailed molecular mechanisms.

Research progress on the prevention and treatment of hyperuricemia by medicinal and edible plants and its bioactive components

Hyperuricemia is another common metabolic disease, which is considered to be closely related to the development of many chronic diseases, in addition to the "three highs." Currently, although drugs show positive therapeutic effects, they have been shown to produce side effects that can damage the body. There is growing evidence that medicinal and edible plants and their bioactive components have a significant effect on hyperuricemia. In this paper, we review common medicinal and edible plants with uric acid-lowering effects and summarize the uric acid-lowering mechanisms of different bioactive components. Specifically, the bioactive components are divided into five categories: flavonoids, phenolic acids, alkaloids, polysaccharides, and saponins. These active substances exhibit positive uric acid-lowering effects by inhibiting uric acid production, promoting uric acid excretion, and improving inflammation. Overall, this review examines the potential role of medicinal and edible plants and their bioactive components as a means of combating hyperuricemia, with the hope of providing some reference value for the treatment of hyperuricemia.

Mechanisms of theaflavins against gout and strategies for improving the bioavailability

BACKGROUND

Gout is a crystal related arthropathy caused by monosodium urate deposition. At present, the identification of appropriate treatments and new drugs to reduce serum uric acid levels and gout risk is a major research area.

PURPOSE

Theaflavins are naturally occurring compounds characterized by a benzodiazepine skeleton. The significant benefits of theaflavins have been well documented. A large number of studies have been carried out and excellent anti-gout results have been achieved in recent years.

STUDY DESIGN

A comprehensive analysis of the mechanism of the anti-gout effect of theaflavins is presented through a literature review and network pharmacology prediction, and strategies for increasing the bioavailability of theaflavins are summarized.

METHODS

In this review, the active components and pharmacological mechanisms of theaflavins in the treatment of gout were summarized, and the relationship between theaflavins and gout, the relevant components, and the potential mechanisms of anti-gout action were clarified by reviewing the literature on the anti-gout effects of theaflavins and network pharmacology.

RESULTS

Theaflavins exert anti-gout effects by down regulating the gene and protein expression of glucose transporter 9 (GLUT9) and uric acid transporter 1 (URAT1), while upregulating the mRNA expression levels of organic anion transporter 1 (OAT1), organic cation transporter N1 (OCTN1), organic cation transporters 1/2 (Oct1/2), and organic anion transporter 2 (OAT2). Network pharmacology prediction indicate that theaflavins can regulate the AGE-RAGE and cancer signaling pathways through ATP-binding cassette subfamily B member 1 (ABCB1), recombinant mitogen activated protein kinase 14 (MAPK14), telomerase reverse tranase (TERT), signal transducer and activator of transcription 1 (STAT1), matrix metalloproteinase 2 (MMP2), B-cell lymphoma-2 (BCL2), and matrix metalloproteinase 14 (MMP14) targets for anti-gout effects.

CONCLUSION

This review presents the mechanisms of anti-gout action of theaflavins and strategies for improving the bioavailability of theaflavins, as well as providing research strategies for anti-gout treatment measures and the development of novel anti-gout drugs.

Yellow tea: more than turning green leaves to yellow

Yellow tea (YT), a slightly-fermented tea originated from Ming Dynasty with distinctive "Three yellows," mild-sweet smell, and mellow taste attributed to the unique yellowing process. Based on current literature and our previous work, we aim to comprehensively illustrate the key processing procedures, characteristic chemical compounds, health benefits and applications, as well as the interlocking relationships among them. Yellowing is the most vital procedure anchored on the organoleptic quality, characteristic chemical components, and bioactivities of YT, which is influenced by temperature, moisture content, duration, and ventilation conditions. Pheophorbides, carotenoids, thearubigins and theabrownins are the major pigments contributing to the "three yellows" appearance. Alcohols, such as terpinol and nerol, are attributed to the refreshing and sweet aroma of bud and small-leaf YT, while heterocyclics and aromatics forming during roasting result in the crispy rice-like large-leaf YT. Hygrothermal effects and enzymatic reactions during yellowing result in the decline of astringent substances. Meanwhile, multiple bioactive compounds such as catechins, ellagitannins, and vitexin, endow YT with antioxidant, anti-metabolic syndrome, anti-cancer, gut microbiota regulation, and organ injury protection effects. Future studies focusing on the standard yellowing process technology, quality evaluation system, and functional factors and mechanisms, possible orientations, and perspectives are guaranteed.

Caffeine and Its Antioxidant Properties-It Is All about Dose and Source

Caffeine is the most frequently used substance with a central nervous system stimulant effect, but its consumption is most often due to the intake of foods and drinks that contain it (coffee, tea, chocolate, food supplements with plant extracts of Guarana, Mate herba, Cola nuts). Due to its innocuity, caffeine is a safe xanthine alkaloid for human consumption in a wide range of doses, being used for its central nervous stimulating effect, lipolytic and diuresis-enhancing properties, but also as a permitted ergogenic compound in athletes. In addition to the mechanisms that explain the effects of caffeine on the targeted organ, there are many proposed mechanisms by which this substance would have antioxidant effects. As such, its consumption prevents the occurrence/progression of certain neurodegenerative diseases as well as other medical conditions associated with increased levels of reactive oxygen or nitrogen species. However, most studies that have assessed the beneficial effects of caffeine have used pure caffeine. The question, therefore, arises whether the daily intake of caffeine from food or drink has similar benefits, considering that in foods or drinks with a high caffeine content, there are other substances that could interfere with this action, either by potentiating or decreasing its antioxidant capacity. Natural sources of caffeine often combine plant polyphenols (phenol-carboxylic acids, catechins) with known antioxidant effects; however, stimulant drinks and dietary supplements often contain sugars or artificial sweeteners that can significantly reduce the effects of caffeine on oxidative stress. The objective of this review is to clarify the effects of caffeine in modulating oxidative stress and assess these benefits, considering the source and the dose administered.

Anti-Inflammatory and Hypouricemic Effect of Bioactive Compounds: Molecular Evidence and Potential Application in the Management of Gout

Gout is caused by the deposition of monosodium urate crystals in the joint and represents the most common form of inflammatory arthritis in men. Its prevalence is rising worldwide mainly due to the increase of risk factors associated with the disease, in particular hyperuricemia. Besides gout, hyperuricemia leads to an increased inflammatory state of the body with consequent increased risk of comorbidities such as cardiovascular diseases. Increasing evidence shows that bioactive compounds have a significant role in fighting inflammatory and immune chronic conditions. In gout and hyperuricemia, these molecules can exert their effects at two levels. They can either decrease serum uric acid concentrations or fight inflammation associated with monosodium urate crystals deposits and hyperuricemia. In this view, they might be considered valuable support to the pharmacological therapy and prevention of the disease. This review aims to provide an overview of the beneficial role of bioactive compounds in hyperuricemia, gout development, and inflammatory pathways of the disease.

Tea (Camellia sinensis) Ameliorates Hyperuricemia via Uric Acid Metabolic Pathways and Gut Microbiota

Hyperuricemia (HUA) is a metabolic disease that threatens human health. Tea is a healthy beverage with an abundance of benefits. This study revealed the uric acid-lowering efficacy of six types of tea water extracts (TWEs) on HUA in mice. The results revealed that under the intervention of TWEs, the expression of XDH, a key enzyme that produces uric acid, was significantly downregulated in the liver. TWE treatment significantly upregulated the expression of uric acid secretion transporters ABCG2, OAT1, and OAT3, and downregulated the expression of uric acid reabsorption transporter URAT1 in the kidney. Furthermore, HUA-induced oxidative stress could be alleviated by upregulating the Nrf2/HO-1 pathway. The intervention of TWEs also significantly upregulated the expression of the intestinal ABCG2 protein. On the other hand, TWE intervention could significantly upregulate the expression of intestinal ABCG2 and alleviate HUA by modulating the gut microbiota. Taken together, tea can comprehensively regulate uric acid metabolism in HUA mice. Interestingly, we found that the degree of fermentation of tea was negatively correlated with the uric acid-lowering effect. The current study indicated that tea consumption may have a mitigating effect on the HUA population and provided a basis for further research on the efficacy of tea on the dosage and mechanism of uric acid-lowering effects in humans.