Effects of polyphenol compounds melanin on NAFLD/NASH prevention

Protective effect of vaginal resveratrol administration on joint tissues in ovariectomized rats: Targeting mTOR and сaspase 3

INTRODUCTION

Estrogens play a considerable role in maintaining bone and articular cartilage homeostasis. Menopause provokes joint disorders due to metabolic syndrome and altered signaling pathways. Phytoestrogen resveratrol was demonstrated to provide chondroprotective and osteoprotective effects. However, the mechanisms of such action of Resveratrol are still being explored.

AIM

The study aims to determine the effect of Resveratrol on the joints and its therapeutic mechanism in ovariectomized rats.

MATERIAL AND METHODS

The study was carried out on Wistar female rats that were divided into three groups, including control animals; ovariectomized rats (OVX); and the OVX group treated with an intravaginal gel containing Resveratrol (0.5 % 0.1 mL, daily 28 days). Knee joint tissues (articular cartilage, subchondral plate, subchondral bone) were assessed by histomorphometry. The expression of mTOR, PTEN, Caspase 3 and BCL-2 in articular cartilage and subchondral bone were evaluated immunohistochemically.

RESULTS

Resveratrol treatment of OVX rats prevented weight gain by 17 % (P < 0.001), demonstrating the systemic effect on metabolic pathways. Although there were no statistically significant differences in the thickness of articular cartilage between groups, OVX rats possessed degenerative changes in chondrocytes, associated with the enhanced expression of mTOR (P < 0.001) and Casp-3 (P = 0.005). Resveratrol decreased mTOR (P = 0.007) and Casp-3 (P = 0.011) expression in chondrocytes, reducing degenerative changes. At the same time, resveratrol attenuated the deterioration of trabecular bone in OVX rats (P = 0.002). This effect was through the up-regulation of BCL-2 (P = 0.018) and down-regulation of Casp-3 expression (P < 0.001).

CONCLUSIONS

Intravaginal administration of resveratrol provided systemic effects and ameliorated joint tissue structure and signaling in OVX rats through stimulation of BCL-2 and reduced Casp-3 expression.

Resveratrol Effects on the Reproductive System in Ovariectomized Rats: Deciphering Possible Mechanisms

Phytoestrogen resveratrol (R) has been demonstrated to benefit human reproductive health. However, R bioavailability and pharmacokinetics are still problematic under oral supplementation. We used an experimental vaginal gel with R and hyaluronic acid (HA) to improve bioavailability and pharmacokinetic properties. The study aimed to assess the impact of vaginal R-HA gel on the reproductive system in ovariectomized rats. Methods: The study was carried out on Wistar female rats. It investigated the body weight, tail temperature, vaginal pH, estrogen and progesterone blood levels, and immunohistochemical biomarkers (COX2, Casp-3, Bcl-2, and VEGF). Animals were divided into control animals; ovariectomized rats (OVX); and OVX group treated with vaginal 0.5% R-HA gel (0.5%, 0.1 mL, daily 28 days). Results: The R-HA gel’s therapeutic effect was manifested by slowing weight gain by 17% (p < 0.001), less pronounced symptom of fever at the root of the tail by 9% (p < 0.001) and lowering the vaginal pH to 4.4−4.5 compared with OVX rats. The anti-inflammatory effect and the reduction of COX-2 expression in vagina were accompanied by antiapoptotic impact of RA-H on endometrium, associated with the decreased Casp-3 expression (p < 0.001) and elevated Bcl-2 score in endometrial glands (p = 0.01). Together with enhanced VEGF expression in endometrial glands (p < 0.001) and stromal cells (p = 0.007), these changes prevented endometrial atrophy (p < 0.001) after ovariectomy. Thus, this study substantiates the feasibility of developing an innovative topical drug with R and HA for treating hypoestrogenic disorders.

Melanin and Melanin-Functionalized Nanoparticles as Promising Tools in Cancer Research-A Review

Cancer poses an ongoing global challenge, despite the substantial progress made in the prevention, diagnosis, and treatment of the disease. The existing therapeutic methods remain limited by undesirable outcomes such as systemic toxicity and lack of specificity or long-term efficacy, although innovative alternatives are being continuously investigated. By offering a means for the targeted delivery of therapeutics, nanotechnology (NT) has emerged as a state-of-the-art solution for augmenting the efficiency of currently available cancer therapies while combating their drawbacks. Melanin, a polymeric pigment of natural origin that is widely spread among many living organisms, became a promising candidate for NT-based cancer treatment owing to its unique physicochemical properties (e.g., high biocompatibility, redox behavior, light absorption, chelating ability) and innate antioxidant, photoprotective, anti-inflammatory, and antitumor effects. The latest research on melanin and melanin-like nanoparticles has extended considerably on many fronts, allowing not only efficient cancer treatments via both traditional and modern methods, but also early disease detection and diagnosis. The current paper provides an updated insight into the applicability of melanin in cancer therapy as antitumor agent, molecular target, and delivery nanoplatform.

Auricularia auricula Melanin Protects against Alcoholic Liver Injury and Modulates Intestinal Microbiota Composition in Mice Exposed to Alcohol Intake

The potential effects of Auricularia auricula melanin (AAM) on the intestinal flora and liver metabolome in mice exposed to alcohol intake were investigated for the first time. The results showed that oral administration of AAM significantly reduced the abnormal elevation of serum total triglyceride (TG), cholesterol (TC), low density lipoprotein cholesterol (LDL-C), aspartate aminotransferase (AST) and alanine aminotransferase (ALT), and significantly inhibited hepatic lipid accumulation and steatosis in mice exposed to alcohol intake. Besides, the abnormally high levels of bile acids (BAs) and lactate dehydrogenase (LDH) in the liver of mice with alcohol intake were significantly decreased by AAM intervention, while the hepatic levels of glutathione (GSH) and superoxide dismutase (SOD) were appreciably increased. Compared with the model group, AAM supplementation significantly changed the composition of intestinal flora and up-regulated the levels of Akkermansia, Bifidobacterium, Romboutsia, Muribaculaceae, Lachnospiraceae_NK4A136_group, etc. Furthermore, liver metabolomics demonstrated that AAM had a significant regulatory effect on the composition of liver metabolites in mice with alcohol intake, especially the metabolites involved in phosphatidylinositol signaling system, ascorbate and aldarate metabolism, starch and sucrose metabolism, galactose metabolism, alpha-linolenic acid metabolism, glycolysis/gluconeogenesis, and biosynthesis of unsaturated fatty acids. At the gene level, AAM treatment regulated the mRNA levels of lipid metabolism and inflammatory response related genes in liver, including ACC-1, FASn, CPT-1, CD36, IFN-γ, LDLr and TNF-α. Conclusively, these findings suggest that AAM has potential beneficial effects on alleviating alcohol-induced liver injury and is expected to become a new functional food ingredient.

Dietary Polyphenols to Combat Nonalcoholic Fatty Liver Disease via the Gut-Brain-Liver Axis: A Review of Possible Mechanisms

Polyphenols are a group of micronutrients widely existing in plant foods including fruits, vegetables, and teas that can improve nonalcoholic fatty liver disease (NAFLD). In this review, the existing knowledge of dietary polyphenols for the development of NAFLD regulated by intestinal microecology is discussed. Polyphenols can influence the vagal afferent pathway in the central and enteric nervous system to control NAFLD via gut-brain-liver cross-talk. The possible mechanisms involve in the alteration of microbial community structure, effects of gut metabolites (short-chain fatty acids (SCFAs), bile acids (BAs), endogenous ethanol (EnEth)), and stimulation of gut-derived hormones (ghrelin, cholecystokinin (CCK), glucagon-like peptide-1 (GLP-1), and leptin) based on the targets excavated from the gut-brain-liver axis. Consequently, the communication among the intestine, brain, and liver paves the way for new approaches to understand the underlying roles and mechanisms of dietary polyphenols in NAFLD pathology.

Whole Red Raspberry (Rubus idaeus)-Enriched Diet Is Hepatoprotective in the Obese Zucker Rat, a Model of the Metabolic Syndrome

Non-alcoholic fatty liver disease is a major risk factor of the metabolic syndrome (MetS). The effect of whole red raspberry (WRR) consumption on lipid metabolism was investigated in the obese Zucker rat (OZR), a model for the MetS. Male OZRs (n = 16) and their lean littermates (lean Zucker rat) (n = 16) at 8 weeks of age were placed on a control or an 8% WRR-enriched diet for 8 weeks. Plasma triglycerides (TGs), total cholesterol, high-density lipoprotein cholesterol (HDL-C), and non-HDL-C levels, and hepatic concentration of TG were measured. The expression of nine genes related to lipid metabolism was evaluated, both in liver and adipose tissue. A WRR-enriched diet reduced plasma cholesterol and HDL-C and increased plasma TG, while it decreased hepatic TG accumulation in the OZR. The OZR assigned to a WRR exhibited upregulation of microsomal triglyceride transfer protein (Mttp) and downregulation of fatty acid synthase (Fas) expression in the liver. Results showed a decrease in accumulation of liver TG and gene expression modulation of enzymes and transcription factors associated with lipid metabolism, suggesting a possible hepatoprotective role of a WRR-enriched diet.

Melanin nanoparticles as a promising tool for biomedical applications - a review

Melanin is a biopolymer of easy and cheap availability that can be found among the living organisms and excels for its biocompatibility and biodegradability properties, along with scavenging abilities, metal chelation and electronic conductance. This biomaterial can act as a nanocarrier or agent itself to be used in diverse biomedical applications, such as imaging, controlled drug release, bioengineering and bioelectronics, antioxidant applications and theranostics. In this review, the melanin source and structure, its physicochemical properties, melanin-like polymers as well as the differences among those will be elucidated. The focus will be the discussion of the current approaches that apply melanin nanoparticles (MNPs) and melanin-like nanoparticles (MLNPs) in the biomedical field, to which promising capabilities have been attributed, regarding optoelectronic, photoconductivity and photoacoustic. The use of these nanoparticles, in the last 10 years, in topics as drug delivery or theranostics will be detailed and the major achievements will be discussed. Overall, we anticipate that melanin can drive us toward a new paradigm in medical diagnostics and treatments, since applying melanin features possibly its use as a theranostics nanocarrier agent, not only for diagnostics, but also for photothermal therapy and controlled drug release through chemotherapy. STATEMENT OF SIGNIFICANCE: We present here a timely and opportune review article focusing the significant potential of melanin nanoparticles in biomedical applications, which will be discussed thoroughly. This biomaterial presents multiple capabilities that may be taken into consideration towards cancer theranostics, expecting a high future impact in the nanosized-platforms design and performance.

Efficiency comparison of PGBR extract and γ-oryzanol in antioxidative stress and anti-inflammatory properties against metabolic syndrome

This research aims to delineate the anti-inflammatory effect of pregerminated brown rice extract (PE) and γ-oryzanol on improving metabolic features of high-fat diet (HFD)-induced metabolic syndrome (MetS) mouse model. C57BL/6 mice were randomly divided into eight groups: regular diet (RD), HFD, HFD-combined treatment of 0.5, 5, or 10 mg kg^-1  day^-1 oral gavage γ-oryzanol, and 30, 300, or 600 mg kg^-1  day^-1 PE for 18 weeks. HFD-fed mice showed overweight, hyperglycemia, hyperlipidemia signs of metabolic disorder, and elevation of inflammatory cytokines such as IL-6, TNF-α, IFN-γ, NO, PGE2 in serum and MAPKs, transcription factor p65, iNOS, and MDA in the liver. In contrast, HFD-fed mice showed lower levels of adiponectin in serum and antiperoxidation enzymes GPx, SOD, and catalase in the liver. While HFD-fed mice cotreated with PE or γ-oryzanol, HFD-induced metabolic disorders, ROS, and inflammation were improved. The anti-MetS, antioxidative stress and anti-inflammation properties of PE were more potent than γ-oryzanol. PRACTICAL APPLICATIONS: Our study showed that PE or γ-oryzanol supplement could help control metabolic disorders, oxidative stress, chronic inflammation, and related complications.

Functional polarization of macrophages of rats with progesterone-induced obesity treated with melanin from the Antarctic yeast Nadsoniella nigra

Progesterone-induced obesity develops in women who use this drug for contraception and the menopause treatment, though its mechanisms remain poorly understood. We studied functional M1 and M2 polarizations of the abdominal cavity macrophages of rats with progesterone induced obesity during 28 days of administration. The effect of melanin from the Antarctic yeast Nadsoniella nigra (Chaetothyriales, Herpotrichiellaceae, Nadsoniella Issatsch, 1914) was investigated. The NO level was determined by the accumulation of nitrites, ROS level was estimated by the NBT-test, arginase activity was assayed by the reaction of L-arginine hydrolysis. The body weights of rats administrated progesterone increased by 27% and continued to increase one month after withdrawal of progesterone (55% higher than control). Melanin prevents the weight gain when administered during one month after progesterone withdrawal. The NO production by peritoneal macrophages of obese animals intensified by 31% indicating their polarization towards pro-inflammatory M1 type. Production of ROS did not change. A 14% increase in arginase activity was observed, indicating the inhibition of M2 (anti-inflammatory) polarization. In the progesterone withdrawal group all these rates significantly decreased, indicating a reduction in the functional activity of peritoneal macrophages’. Melanin decreased the NO and ROS production by 60% and 18% respectively in comparison with the progesterone group and unexpectedly reduced arginase activity. Our data provide evidence of the spread of inflammation in response to progesterone-induced obesity. Peritoneal macrophages are involved in the inflammation in obesity, undergoing polarization towards the pro-inflammatory phenotype. The long-term consequences of such inflammation include the continuation of weight gain and likely the development of systemic inflammation associated with the exhaustion of the functional capacity of peritoneal cavity macrophages. Melanin has an anti-obesity effect and exhibits anti-inflammatory properties preventing progesterone-induced weight gain and macrophage M1 polarization. This requires detailed elucidation and can be valuable in designing countermeasures to prevent obesity outcomes.

Bergamot Polyphenols Boost Therapeutic Effects of the Diet on Non-Alcoholic Steatohepatitis (NASH) Induced by "Junk Food": Evidence for Anti-Inflammatory Activity

Wrong alimentary behaviors and so-called “junk food” are a driving force for the rising incidence of non-alcoholic fatty liver disease (NAFLD) among children and adults. The “junk food” toxicity can be studied in “cafeteria” (CAF) diet animal model. Young rats exposed to CAF diet become obese and rapidly develop NAFLD. We have previously showed that bergamot (Citrus bergamia Risso et Poiteau) flavonoids, in the form of bergamot polyphenol fraction (BPF), effectively prevent CAF diet-induced NAFLD in rats. Here, we addressed if BPF can accelerate therapeutic effects of weight loss induced by a normocaloric standard chow (SC) diet. 21 rats fed with CAF diet for 16 weeks to induce NAFLD with inflammatory features (NASH) were divided into three groups. Two groups were switched to SC diet supplemented or not with BPF (CAF/SC±BPF), while one group continued with CAF diet (CAF/CAF) for 10 weeks. BPF had no effect on SC diet-induced weight loss, but it accelerated hepatic lipid droplets clearance and reduced blood triglycerides. Accordingly, BPF improved insulin sensitivity, but had little effect on leptin levels. Interestingly, the inflammatory parameters were still elevated in CAF/SC livers compared to CAF/CAF group after 10 weeks of dietary intervention, despite over 90% hepatic fat reduction. In contrast, BPF supplementation decreased hepatic inflammation by reducing interleukin 6 (Il6) mRNA expression and increasing anti-inflammatory Il10, which correlated with fewer Kupffer cells and lower inflammatory foci score in CAF/SC+BPF livers compared to CAF/SC group. These data indicate that BPF mediates a specific anti-inflammatory activity in livers recovering from NASH, while it boosts lipid-lowering and anti-diabetic effects of the dietary intervention.

Polyphenol Compounds Melanin Prevented Hepatic Inflammation in Rats with Experimental Obesity

Melanin produced by yeast Nadsoniella nigra strain X-1 lead to significant reduction of steatosis, lobular inflammation and ballooning degeneration, according to NAFLD activity score (NAS), in liver of rats with monosodium glutamate (MSG) induced obesity. These histological changes were associated with substantial decrease of TNF-α expression in sinusoid cells that prevented NF-kB activation in hepatocytes.

Wogonin mitigates nonalcoholic fatty liver disease via enhancing PPARα/AdipoR2, in vivo and in vitro

Wogonin has been reported to attenuate hyperglycemia in diabetic mice via anti-adipogenic effect on adipocytes. The potential therapeutic role of wogonin in nonalcoholic fatty liver disease (NAFLD) remains obscure. The aim of the present study was to explore the protective effect of wogonin on NAFLD mice and cultured NCTC 1469 cells exposed to palmitate. Wogonin supplementation significantly improved metabolic parameters in NAFLD mice, including body weight, blood glucose, insulin resistance, adiponectin, blood lipids, aminotransferases and hepatic histopathology. Further research in liver tissues from NAFLD mice and NCTC 1469 cells stressed by lipotoxicity showed wogonin treatment reduced inflammatory response by lowering interleukin-6 (IL-6) and tumor necrosis factor α (TNFα), alleviated oxidative stress by preventing the accumulation of oxidative product malondialdehyde (MDA) and strengthening the anti-oxidative capacity of glutathione (GSH), Superoxide Dismutase (SOD) and Glutathione Peroxidase (GPX). In addition, wogonin repaired the lipotoxicity-induced decline of peroxisome proliferator- activated receptor α (PPARα) and adiponectin receptor 2 (AdipoR2) in hepatocytes, in vivo and in vitro. Knock-down of PPARα abolished the protective effect of wogonin on NCTC 1469 cells, including the up-regulation of AdipoR2. Taken together, the current study demonstrated wogonin might be a potential therapeutic agent for NAFLD via up-regulation of hepatic PPARα/AdipoR2.