Myricetin inhibits IL-1beta-induced inflammatory mediators in SW982 human synovial sarcoma cells

Extra Virgin Olive Oil Polyphenol-Enriched Extracts Exert Antioxidant and Anti-Inflammatory Effects on Peripheral Blood Mononuclear Cells from Rheumatoid Arthritis Patients

Rheumatoid arthritis (RA) is a long-term systemic autoimmune disorder that causes joint inflammation, swelling, pain, bone erosion, and deformities. Recent findings emphasize the anti-inflammatory and antioxidant properties of bioactive natural compounds, such as polyphenols extracted from plants and fruits, and their possible synergistic effect when used in combination with current therapies to improve the prognosis and symptoms of inflammatory rheumatic diseases. Here, we report that Sicilian extra virgin olive oil polyphenol-enriched extracts (PE-EVOOs) reduce intracellular reactive oxygen species (ROS) and pro-inflammatory cytokines, such as tumor necrosis factor-α (TNF-α) and interleukin-1 β (IL-1β), in peripheral mononuclear cells (PBMCs) obtained from both RA patients and healthy subjects (HSs) treated with lipopolysaccharides (LPS) as a control. HPLC-ESI-MS analysis highlighted that PE-EVOOs are rich in different polyphenolic compounds responsible for many of the observed biological effects. At molecular levels, Western blotting analyses revealed that PE-EVOO treatment is associated with the downregulation of the phosphorylated and active form of the inflammatory transcription factor NF-κB and the pro-inflammatory enzyme cyclooxygenase 2 (COX2). In addition, PE-EVOOs upregulated the transcription factor Nrf2 and its target antioxidant enzyme catalase and manganese superoxide dismutase (MnSOD). Collectively, these results suggest a possible use of PE-EVOOs as potential adjuvants for the treatment of RA.

Myricetin Protects Against Rat Intervertebral Disc Degeneration Partly Through the Nrf2/HO-1/NF-κB Signaling Pathway

Intervertebral disc (IVD) degeneration (IDD) is a prevalent musculoskeletal disorder. Nucleus pulposus cells (NPCs) play a significant role in the normal functioning of the IVD. Myricetin is an agent that exerts anti-inflammatory and antioxidant effects in various pathological conditions. Here, we investigated the ameliorative effects of myricetin on the IVD degeneration. NPCs were obtained from the IVD of rats, and were treated with myricetin (0, 5, 10, 15, 20 μM) for 24 h before 20 ng/mL IL-1β stimulation. RT-qPCR, western blotting, and ELISA were applied to evaluate the levels of inflammatory factors (iNOS, COX-2, TNF-α, IL-6, PGE2, and Nitrite) and extracellular matrix (ECM)-associated components (MMP13, ADAMTS-5, aggrecan, and collagen II) in NPCs. Activation status of related signaling pathways (NF-κB and Nrf2) was determined using western blotting and immunofluorescence staining. Experimental rat models of IDD were established using a needle puncture method. Myricetin (20 mg/kg) was administrated intraperitoneally, and the degeneration was evaluated using histopathological analysis. Myricetin treatment attenuated the IL-1β-induced production of inflammatory factors in NPCs. Downregulation of aggrecan and collagen II as well as upregulation of MMP-13 and ADAMTS-5 in NPCs caused by IL-1β was reversed by myricetin treatment. Mechanistically, myricetin blocked NF-κB signaling by activation of Nrf2 in IL-1β-stimulated NPCs. Moreover, inhibition of Nrf2 reversed the protective effects of myricetin in NPCs. The in vivo experiments showed that myricetin ameliorated the IDD progression in rats. The present work suggests that Nrf2 is involved in the pathogenesis of IDD and shows the protective effects as well as the underlying mechanism of myricetin on Nrf2 activation in NPCs.

Rheumatoid arthritis molecular targets and their importance to flavonoid-based therapy

Rheumatoid arthritis (RA) is a progressive, chronic, autoimmune, inflammatory, and systemic condition that primarily affects the synovial joints and adjacent tissues, including bone, muscle, and tendons. The World Health Organization recognizes RA as one of the most prevalent chronic inflammatory diseases. In the last decade, there was an expansion on the available RA therapeutic options which aimed to improve patient's quality of life. Despite the extensive research and the emergence of new therapeutic approaches and drugs, there are still significant unwanted side effects associated to these drugs and still a vast number of patients that do not respond positively to the existing therapeutic strategies. Over the years, several references to the use of flavonoids in the quest for new treatments for RA have emerged. This review aimed to summarize the existing literature about the flavonoids' effects on the major pathogenic/molecular targets of RA and their potential use as lead compounds for the development of new effective molecules for RA treatment. It is demonstrated that flavonoids can modulate various players in synovial inflammation, regulate immune cell function, decrease synoviocytes proliferation and balance the apoptotic process, decrease angiogenesis, and stop/prevent bone and cartilage degradation, which are all dominant features of RA. Although further investigation is necessary to determine the effectiveness of flavonoids in humans, the available data from in vitro and in vivo models suggest their potential as new disease-modifying anti-rheumatic drugs. This review highlights the use of flavonoids as a promising avenue for future research in the treatment of RA.

The Wound-Healing Potential of the Endemic Plant Helianthemum canum (L.) Baumg: Preclinical Studies Supported with Phytochemical Profiling

The study's objective is to clarify the probable mechanisms underlying the wound-healing properties of Helianthemum canum L. (Cistaceae), a traditional anti-inflammatory and wound-healing medicine. LC/MS-MS was used to perform phytochemical analyses on a 70 % methanol extract of the plant's aerial parts. In vivo, linear incision and circular excision models were used to evaluate the wound healing activity. For anti-inflammatory effect, in vivo acetic acid capillary permeability assay and in vitro Interleukin 1, Interleukin 6, and Interferon ɣ levels in LPS-induced FR skin fibroblast cell line were also evaluated. The extract significantly improved wound healing in experimental models, with tensile strength values of 27.8 % and a contraction value of 35.09 %. Histopathological examinations, hydroxyproline estimation, hyaluronidase, collagenase, and elastase enzyme inhibitory assays confirmed wound healing potential. Inflammatory cytokines were significantly inhibited in the LPS-induced FR cell line, with the highest effect seen on IL-6 (34.5±2.12 pg/mL). This study offered the first concrete proof that H. canum can be used to treat wounds by suggesting that the myricetin and quinic acid content identified by LCMS-MS analysis may be accountable for the effect of H. canum on wound contraction and hydroxyproline production.

Myricetin: a potential plant-derived anticancer bioactive compound-an updated overview

The globe is currently confronting a global fight against the deadliest cancer sickness. Chemotherapy, hormonal therapy, surgery, and radiation therapy are among cancer treatment options. Still, these treatments can induce patient side effects, including recurrence, multidrug resistance, fever, and weakness. As a result, the scientific community is always working on natural phytochemical substances. Numerous phytochemical compounds, including taxol analogues, vinca alkaloids such as vincristine and vinblastine, and podophyllotoxin analogues, are currently undergoing testing and have shown promising results against a number of the deadliest diseases, as well as considerable advantages due to their safety and low cost. According to research, secondary plant metabolites such as myricetin, a flavonoid in berries, herbs, and walnuts, have emerged as valuable bio-agents for cancer prevention. Myricetin and its derivatives have antiinflammatory, anticancer, apoptosis-inducing, and anticarcinogenic properties and can prevent cancer cell proliferation. Multiple studies have found that myricetin has anticancer characteristics in various malignancies, including colon, breast, prostate, bladder, and pancreatic cancers. Current knowledge of the anticancer effects of myricetin reveals its promise as a potentially bioactive chemical produced from plants for the prevention and treatment of cancer. This review aimed to study the numerous bioactivities, mode of action, and modification of several cellular processes that myricetin possesses to impede the spread of cancer cells. This review also addresses the challenges and future prospects of using myricetin as a anticancer drug.

Myricetin ameliorates experimental autoimmune myocarditis in mice by modulating immune response and inhibiting MCP-1 expression

Myocarditis is defined as an inflammatory disease of the myocardium, and the autoimmune response specific to myocardium plays an important role in chronic myocarditis. Inhibiting myocardial-specific autoimmune response and inflammation is crucial to treat myocarditis. Myricetin is a plant-derived flavonoid in nature which has potent anti-inflammatory and cardiovascular protective properties. However, the pharmacological effect of myricetin in autoimmune myocarditis is undefined. It is necessary to investigate the role and potential mechanisms of myricetin in autoimmune myocarditis. Therefore, purified cardiac myosin was subcutaneously injected to mice to establish the experimental autoimmune myocarditis (EAM) model. Myricetin was solubilized in normal saline and administered everyday by gavage from the day of immunization. After 21 days of treatment, it was found that myricetin significantly alleviated myocardial injury in EAM mice. The serum anti-cardiac myosin antibody, immunoglobulin (Ig) G, IgM levels and the proportion of T helper 17 (Th17) cells were decreased and the proportion of regulatory T (Treg) cells was increased with the treatment of myricetin in EAM mice. The myosin-specific T cell proliferation was inhibited by myricetin. Meanwhile, myricetin suppressed the expressions of monocyte chemoattractant protein-1 (MCP-1), phospho (p)-p65, p-c-Jun and Act1/TRAF6/TAK1 in H9C2 cells and myocardial tissues of EAM mice. These results revealed that myricetin inhibited the autoimmune response specific to myocardium and the expression of MCP-1 in cardiomyocytes, which suggested that myricetin ameliorated autoimmune myocarditis by modulating immune response and the expression of MCP-1. Therefore, myricetin may be a promising therapeutic strategy for autoimmune myocarditis.

Myricetin (3,3',4',5,5',7-Hexahydroxyflavone) Prevents 5-Fluorouracil-Induced Cardiotoxicity

5-Fluorouracil (5-FU) is a strong anti-cancer drug used to manage numerous cancers. Cardiotoxicity, renal toxicity, and liver toxicity are some of the adverse effects which confine its clinical use to some extent. 5-FU-induced organ injuries are associated with redox imbalance, inflammation, and damage to heart functioning, particularly in the present study. Myricetin is an abundant flavonoid, commonly extracted from berries and herbs having anti-oxidative and anti-cancer activities. We planned the current work to explore the beneficial effects of myricetin against 5-FU-induced cardiac injury in Wistar rats through a biochemical and histological approach. Prophylactic myricetin treatment at two doses (25 and 50 mg/kg) was given to rats orally for 21 days against cardiac injury induced by a single injection of 5-FU (150 mg/kg b.wt.) given on the 20th day intraperitoneally. The 5-FU injection induced oxidative stress, inflammation, and extensive cardiac damage. Nevertheless, myricetin alleviated markers of inflammation, apoptosis, cardiac toxicity, oxidative stress, and upregulated anti-oxidative machinery. The histology of heart further supports our biochemical findings mitigated by the prophylactic treatment of myricetin. Henceforth, myricetin mitigates 5-FU-induced cardiac damage by modulating oxidative stress, inflammation, and cardiac-specific markers, as found in the present study.

Myricetin: a Multifunctional Flavonol in Biomedicine

PURPOSE OF REVEIW

The root cause of many diseases like CVD, cancer, and aging is free radicals which exert their effect by interfering with different metabolic pathways. The sources of free radicals can be exogenous, like UV rays from sunlight, and endogenous due to different metabolic by-products.In our body, there are defense mechanisms present, such as antioxidant enzymes and antioxidant molecules to combat these free radicals, but if there is an overload of these free radicals in our body, the defense system may not be sufficient to neutralize these free radicals. In such situations, we are exposed to a chronic low dose of oxidants creating oxidative stress, which is responsible for eliciting different diseases.

RECENT FINDINGS

Pubmed and Google Scholar are the search engines used to sort out relevant papers on myricetin and its role in combating many diseases. Myricetin is present in many fruits and vegetables and is a known antioxidant. It can elevate the antioxidant enzyme levels; reduces the lipid peroxidation; and is known to protect against cancer. In the case of myocardial dysfunction, myricetin has been shown to suppress the inflammatory cytokines and reduced the mortality rate. Myricetin has also been found to reduce platelet aggregation and control the viral infections by interfering in the DNA replication pathways.

SUMMARY

In this paper, we have briefly reviewed about the different type and site of free radicals and the role of myricetin in addressing the ROS and different diseases.

The role of flavonoids in inhibiting IL-6 and inflammatory arthritis

Rheumatoid arthritis (RA) is a chronic autoimmune disease that primarily affects the synovial joints. RA has well-known clinical manifestations and can cause progressive disability and premature death along with socioeconomic burdens. Interleukin-6 (IL-6) has been implicated in the pathology of RA where it can stimulate pannus formation, osteoclastogenesis, and oxidative stress. Flavonoids are plant metabolites with beneficial pharmacological effects, including anti-inflammatory, antioxidant, antidiabetic, anticancer, and others. Flavonoids are polyphenolic compounds found in a variety of plants, vegetables, and fruits. Many flavonoids have demonstrated anti-arthritic activity mediated mainly through the suppression of pro-inflammatory cytokines. This review thoroughly discusses the accumulate data on the role of flavonoids on IL-6 in RA.

Recent advances in research on vine tea, a potential and functional herbal tea with dihydromyricetin and myricetin as major bioactive compounds

Vine tea has been used as an herbal tea by several ethnic minorities for hundreds of years in China. Flavonoids, a kind of indispensable component in a variety of nutraceutical, pharmaceutical and cosmetic applications, are identified to be the major metabolites and bioactive ingredients in vine tea. Interestingly, vine tea exhibits a wide range of significant bioactivities including anti-oxidant, anti-inflammatory, anti-tumor, antidiabetic, neuroprotective and other activities, but no toxicity. These bioactivities, to some extent, enrich the understanding about the role of vine tea in disease prevention and therapy. The health benefits of vine tea, particularly dihydromyricetin and myricetin, are widely investigated. However, there is currently no comprehensive review available on vine tea. Therefore, this report summarizes the most recent studies investigating bioactive constituents, pharmacological effects and possible mechanisms of vine tea, which will provide a better understanding about the health benefits and preclinical assessment of novel application of vine tea.

Role of natural products in alleviation of rheumatoid arthritis-A review

Rheumatoid arthritis (RHA) is one of the most prevalent complex, chronic, inflammatory diseases, manifested by elevated oxidative stress and inflammatory biomarkers. Prolonged administration of NSAIDs, steroids, and DMARDs, used in the treatment of RHA, is associated with deleterious side effects. This necessitates the urge of new and safe approaches for RHA management, based on the complementary and alternative system of medicine. Documented evidences have suggested that supplementation with nutritional, dietary, and herbal components; can play a crucial role as an adjuvant, in the alleviation of the RHA symptoms, through their influence on the pathological inflammatory processes. Dietary phenolic compounds, flavonoids, carotenoids, and alkaloids with their ability to modulate prooxidant and pro-inflammatory pathways, have been effective in delaying the arthritic disease progression. Moreover, in scientific explorations, herbs containing phenolic compounds, alkaloids, carotenoids flavonoids, spices such as ginger, turmeric, Ayurvedic formulations, different diets such as Mediterranean diet, vegan diet, beverages, and oils such as sesame oil, rice bran oil, vitamins, and probiotics are proven to modulate the action of inflammatory molecules, involved in RHA pathology. Subsequently, the purpose of this review article is to summarize various in vitro, in vivo, and clinical studies in RHA, which have documented remarkable insights into the anti-inflammatory, antioxidant, analgesic, and immunomodulatory, bone erosion preventing properties of dietary, nutritional, and herbal components with the focus on their molecular level mechanisms involved in RHA. Even though major findings were derived from in vitro studies, several in vivo and clinical studies have established the use of diet, herbal, and nutritional management in RHA treatment. PRACTICAL APPLICATIONS: Thickening of the synovial membrane, bone erosion, and cartilage destruction is known to trigger rheumatoid arthritis causing inflammation and pain in bone joints. Continuous intake of NSAIDs, steroids, and DMARD therapy are associated with detrimental side effects. These side effects can be overcome by the use of dietary, nutritional, and herbal interventions based on the complementary and alternative therapy. This concept portrays the food components and other natural components having the potential to promote health, improve general well-being, and reduce the risk of RHA.

Nimbolide exerts protective effects in complete Freund's adjuvant induced inflammatory arthritis via abrogation of STAT-3/NF-κB/Notch-1 signaling

AIM

Activation of transmembrane Notch-1 receptors through inflammatory cytokines is highly regulated by STAT-3 and NF-κB phosphorylation. Nimbolide (NMB) exhibits potent anti-inflammatory, anti-fibrotic, anticancer activities by targeting various pathways. Here, we have investigated the effect of NMB in regulation of STAT-3/NF-κB/Notch-1 axis in complete Freund's adjuvant (CFA) induced inflammatory arthritis (IA) model.

MAIN METHODS

The anti-inflammatory and anti-arthritic activity of NMB was evaluated both in vitro (IL-1β stimulated HIG-82 synovial fibroblasts) and in vivo (CFA induced rat model of IA) models. In vitro anti-arthritic activity was assessed by anti-migratory effect, while in vivo effects were evaluated through radiological and histological analysis. The effect of NMB on STAT-3, NF-κB, Notch-1 signaling pathways and proinflammatory cytokines were studied using western blot, immunohistochemistry and ELISA methods. Key findings NMB attenuated the migration of synovial fibroblasts in vitro. It reduced the progression of arthritis as evidenced from the improved radiological and histological abnormalities in arthritic rats. NMB significantly suppressed the nitrosooxidative stress and levels of pro-inflammatory cytokines. NMB also exhibited remarkable protective activity against upregulation of MAPK, STAT-3 and NF-κB phosphorylation mediated Notch-1 signaling pathway in synovial tissue of arthritic rats.

SIGNIFICANCE

NMB may have clinical therapeutic value in rheumatoid arthritis by inhibiting STAT-3/NF-κB/Notch-1 axis and also by reducing the levels of proinflammatory cytokines.

Topical Wound Healing Activity of Myricetin Isolated from Tecomaria capensis v. aurea

Wounds and burn injury are major causes of death and disability worldwide. Myricetin is a common bioactive flavonoid isolated naturally from the plant kingdom. Herein, a topical application of naturally isolated myricetin from the shoots of Tecomaria capensis v. aurea on excisional wound healing that was performed in albino rats. The wounded rats were treated every day with 10 and 20% myricetin for 14 days. During the experiment, the wound closure percentage was estimated at days 0, 7, and 14. Effects of myricetin on the inflammatory cytokines (tumor necrosis factor-α (TNF-α), interleukin-1β (IL-1β), and cluster of differentiation 68 (CD68) in the serum were evaluated using immunosorbent assay kits. The percentage of wound closure and contraction was delayed in wounded rats (67.35%) and was remarkably increased after treatment of wounded rats with myricetin; the treatment with 20% myricetin was the most potent (98.76%). Histological findings exhibited that 10% myricetin caused the formation of a large area of scarring at the wound enclosure and stratified squamous epithelium without the formation of papillae as in the control group. Treatment with 20% myricetin exhibited less area of scarring at the wound enclosure as well as re-epithelialization with a high density of fibroblasts and blood capillaries in the wound. Level elevations of serum pro-inflammatory cytokines, IL-1β, and TNF-α and macrophage CD68 were decreased in wounded rats treated with myricetin. Thus, it can be suggested that the enhancements in inflammatory cytokines as well as systemic reorganization after myricetin treatment may be recommended to play a crucial part in the promotion of wound healing. The findings suggest that treatment with a higher dose of myricetin was better in improving wound curing in rats. It could serve as a potent anti-inflammatory agent and can be used as an adjunctive or alternative agent in the future.

Anti-hyperuricemic and Anti-inflammatory Effects of Marantodes pumilum as Potential Treatment for Gout

Marantodes pumilum (Primulaceae) has been used in Malaysian folk medicine to help women regain strength after delivery and for “sickness in the bones.” It was previously revealed that its extracts inhibited xanthine oxidase (XO) activity in vitro. The leaves and roots of M. pumilum var. alata (MPA), var. pumila (MPP), and var. lanceolata (MPL) were individually extracted in ethanol (80%). The anti-hyperuricemic activity was initially assessed by XO inhibition with a spectrophotometric in vitro assay. The most active extract was further investigated on hyperuricemic rat model induced by potassium oxonate to determine serum uric acid levels and liver XO effect. The in vitro anti-inflammatory activity was carried out on monosodium urate (MSU) crystal-induced pro-inflammatory cytokines (i.e., interleukin (IL)1α, IL-1β, IL-6, IL-8, and tumor necrosis factor (TNF)-α) secretion using human peripheral blood mononuclear cells and ELISA technique, and prostaglandin E₂ (PGE₂)secretion using radioimmunoassay. The active extract was then investigated on gout-induced inflammation with MSU crystals to determine pro-inflammatory cytokines and PGE₂ secretion levels in the synovial fluid of rat knee joint. Quantitative analysis using validated HPLC was performed on the extracts to determine presence of bioactive flavonoids. The findings revealed that extract of MPP leaves gave the highest inhibitory activity on XO (IC₅₀ 130.5 μg/mL) compared to other extracts tested. However, all extracts possessed significantly lower activity compared to allopurinol (IC₅₀ 0.13 μg/mL). Oral administration of MPP leaf extract (200 mg/kg) significantly reduced serum uric acid level in hyperuricemic rats in time-dependent manner to the baseline level and it was as effective as allopurinol (5 mg/kg). The extract also inhibited liver XO activity (25%) compared to allopurinol (45%). In vitro anti-inflammatory assay showed that extract of MPP roots inhibited MSU crystals-induced secretion of IL-1α, IL-1β, IL-8, TNF-α, and PGE₂ with IC₅₀ values of 36, 25, 38, 18, and 46 μg/mL, respectively. Oral administration of the MPP root extract (200 mg/kg) significantly decreased IL-1α, IL-1β, IL-6, TNF-α, and PGE₂ levels in rat’s synovial fluid as effective as indomethacin. There were no significant body weight changes of all experimental animals. MPP extracts showed presence of myricetin, quercetin and kaempferol. Myricetin was detected with values of 0.2 and 0.6 mg/g for root and leaf extracts, respectively. The anti-hyperuricemic of MPP leaf and anti-inflammatory of MPP root indicated that MPP may be promising for complementary therapy of gout.

Myricetin Abrogates Cisplatin-Induced Oxidative Stress, Inflammatory Response, and Goblet Cell Disintegration in Colon of Wistar Rats

Cisplatin [cis-diamminedichloroplatinum II] is an extensively prescribed drug in cancer chemotherapy; it is also useful for the treatment of diverse types of malignancies. Conversely, cisplatin is associated with a range of side effects such as nephrotoxicity, hepatotoxicity, gastrointestinal toxicity, and so on. Myricetin (3,5,7-trihydroxy-2-(3,4,5-trihydroxyphenyl)-4chromenone) is a very common natural flavonoid found in fruits, tea, and plants. It has been found to have high-value pharmacological properties and strong health benefits. To examine the role of myricetin in colon toxicity induced by cisplatin, we conducted a concurrent prophylactic study in experimental animals that were treated orally with myricetin for 14 days at two doses—25 and 50 mg/kg of body weight. On the 14th day, a single intraperitoneal injection of cisplatin (7.5 mg/kg body weight) was administered in all groups except control. The effects of myricetin in cisplatin-induced toxicity in the colon were assessed in terms of antioxidant status, phase-II detoxification enzymes, the level of inflammatory markers, and goblet cell disintegration. Myricetin was found to restore the level of all the antioxidant enzymes analyzed in the study. In addition, the compound ameliorated cisplatin-induced lipid peroxidation, increase in xanthine oxidase activity, and phase-II detoxifying enzyme activity. Myricetin also attenuated deteriorative effects induced by cisplatin by regulating the level of molecular markers of inflammation (NF-κB, Nrf-2, IL-6, and TNF-α), restoring Nrf-2 levels, and controlling goblet cell disintegration. The current study reinforces the conclusion that myricetin exerts protection in colon toxicity via up-regulation of inflammatory markers, improving anti-oxidant status, and protecting tissue damage.

Myricetin Alleviates Pathological Cardiac Hypertrophy via TRAF6/TAK1/MAPK and Nrf2 Signaling Pathway

Myricetin (Myr) is a common plant-derived polyphenol and is well recognized for its multiple activities including antioxidant, anti-inflammation, anticancer, and antidiabetes. Our previous studies indicated that Myr protected mouse heart from lipopolysaccharide and streptozocin-induced injuries. However, it remained to be unclear whether Myr could prevent mouse heart from pressure overload-induced pathological hypertrophy. Wild type (WT) and cardiac Nrf2 knockdown (Nrf2-KD) mice were subjected to aortic banding (AB) surgery and then administered with Myr (200 mg/kg/d) for 6 weeks. Myr significantly alleviated AB-induced cardiac hypertrophy, fibrosis, and cardiac dysfunction in both WT and Nrf2-KD mice. Myr also inhibited phenylephrine- (PE-) induced neonatal rat cardiomyocyte (NRCM) hypertrophy and hypertrophic markers' expression in vitro. Mechanically, Myr markedly increased Nrf2 activity, decreased NF-κB activity, and inhibited TAK1/p38/JNK1/2 MAPK signaling in WT mouse hearts. We further demonstrated that Myr could inhibit TAK1/p38/JNK1/2 signaling via inhibiting Traf6 ubiquitination and its interaction with TAK1 after Nrf2 knockdown in NRCM. These results strongly suggested that Myr could attenuate pressure overload-induced pathological hypertrophy in vivo and PE-induced NRCM hypertrophy via enhancing Nrf2 activity and inhibiting TAK1/P38/JNK1/2 phosphorylation by regulating Traf6 ubiquitination. Thus, Myr might be a potential strategy for therapy or adjuvant therapy for malignant cardiac hypertrophy.

Potential of myricetin to restore the immune balance in dextran sulfate sodium-induced acute murine ulcerative colitis

OBJECTIVES

Myricetin is a bioactive compound in many edible plants with anti-inflammatory and anticarcinogenic activity. The current study aimed to determine the protective effects and mechanism of myricetin against ulcerative colitis (UC).

METHODS

Myricetin was orally administered at doses of 40 and 80 mg/kg to C57BL/6 mice with UC induced using dextran sulfate sodium. The disease-associated index and colon length were determined at the end of the experiment, the proportion of Treg, Th1 and Th17 was analysed by cytometry, and cytokines were detected using ELISA.

KEY FINDINGS

Myricetin (80 mg/kg) ameliorated the severity of inflammation in acute UC and significantly improved the condition. Myricetin (80 mg/kg) elevated the levels of IL-10 and transforming growth factor β. In addition, the proportion of regulatory T cells significantly increased in mice in the myricetin treatment group.

CONCLUSIONS

Taking together, these results suggest that myricetin exhibits significant protective effects against UC and it could be used as a potential treatment for UC.

Anti-tumor effects and associated molecular mechanisms of myricetin

Myricetin (3, 5, 7, 3', 4', 5'-hexahydroxyflavone) is a natural flavonol compound found in a large variety of plants, including berries, oranges, grapes, herbs, teas, and wine. In the last decade, a convergence of evidence has demonstrated that myricetin has good biological activity as an anti-tumor, anti-inflammatory, and anti-oxidation agent. In studies involving various types of cancer cells, myricetin has been shown to suppress cancer cell invasion and metastasis, to induce cell cycle arrest and apoptosis of cancer cells, and to inhibit their proliferation. These findings have raised interest in myricetin as a potential tumor inhibitor in human patients. In this review, evidence of myricetin's anti-tumor activity and its underlying molecular mechanisms published in the last decade are summarized.

Protective functions of myricetin in LPS-induced cardiomyocytes H9c2 cells injury by regulation of MALAT1

BACKGROUND

Metastasis-associated lung adenocarcinoma transcript 1 (MALAT1) is a crucial mediator in response to inflammation. Myricetin protects cardiomyocytes against inflammatory injury. However, it's still unexplored whether myricetin exerted anti-inflammatory properties via MALAT1. The purpose of our study was to validate the cardio-protective function of myricetin against myocarditis and its underlying mechanism in vitro.

METHODS

H9c2 cells were pre-incubated with myricetin before stimulation with lipopolysaccharide (LPS). Enforced silence of MALAT1 was achieved by transducing short hairpin (sh)-MALAT1 into H9c2 cells. Next, cell viability and apoptotic cells were detected with cell counting kit-8 (CCK-8) and Annexin V-fluorescein isothiocyanate/propidium iodide (Annexin V-FITC/PI) apoptosis detection kit, respectively. Western blot assay was conducted to examine apoptosis-relative proteins, pro-inflammatory factors, and signaling regulators. Quantitative real-time PCR (qRT-PCR) was performed to quantify pro-inflammatory factors and MALAT1 at mRNA levels. Enzyme-linked immune sorbent assay (ELISA) was employed to determine protein concentration of pro-inflammatory factors.

RESULTS

Myricetin ameliorated LPS-elicited reduction of cell viability, augment of apoptosis, and overexpression of monocyte chemo-attractant protein-1 (MCP-1) and interleukin-6 (IL-6) in H9c2 cells. Meanwhile, phosphorylation of p65 and inhibitor of nuclear factor kappa B alpha (IκBα) were suppressed. Besides, myricetin enhanced the expression of MALAT1 which was originally down-regulated by LPS. However, the protective effects of myricetin against LPS-caused inflammatory lesions were abrogated in MALAT1-deficiency cells, with the restored phosphorylation of p65 and IκBα.

CONCLUSION

Myricetin possessed an anti-inflammatory function against LPS-induced lesions in cardiomyocytes. Mechanically, myricetin up-regulated MALAT1, blocked LPS-evoked activation of nuclear factor-κB (NF-κB) inflammatory pathway, and, finally, exerted cardio-protective effects.

Myricetin Protects Against High Glucose-Induced β-Cell Apoptosis by Attenuating Endoplasmic Reticulum Stress via Inactivation of Cyclin-Dependent Kinase 5

BACKGROUND

Chronic hyperglycemia has deleterious effects on pancreatic β-cell function and turnover. Recent studies support the view that cyclin-dependent kinase 5 (CDK5) plays a role in β-cell failure under hyperglycemic conditions. However, little is known about how CDK5 impair β-cell function. Myricetin, a natural flavonoid, has therapeutic potential for the treatment of type 2 diabetes mellitus. In this study, we examined the effect of myricetin on high glucose (HG)-induced β-cell apoptosis and explored the relationship between myricetin and CDK5.

METHODS

To address this question, we subjected INS-1 cells and isolated rat islets to HG conditions (30 mM) in the presence or absence of myricetin. Docking studies were conducted to validate the interaction between myricetin and CDK5. Gene expression and protein levels of endoplasmic reticulum (ER) stress markers were measured by real-time reverse transcription polymerase chain reaction and Western blot analysis.

RESULTS

Activation of CDK5 in response to HG coupled with the induction of ER stress via the down regulation of sarcoendoplasmic reticulum calcium ATPase 2b (SERCA2b) gene expression and reduced the nuclear accumulation of pancreatic duodenal homeobox 1 (PDX1) leads to β-cell apoptosis. Docking study predicts that myricetin inhibit CDK5 activation by direct binding in the ATP-binding pocket. Myricetin counteracted the decrease in the levels of PDX1 and SERCA2b by HG. Moreover, myricetin attenuated HG-induced apoptosis in INS-1 cells and rat islets and reduce the mitochondrial dysfunction by decreasing reactive oxygen species production and mitochondrial membrane potential (ΔΨm) loss.

CONCLUSION

Myricetin protects the β-cells against HG-induced apoptosis by inhibiting ER stress, possibly through inactivation of CDK5 and consequent upregulation of PDX1 and SERCA2b.

Progress in active compounds effective on ulcerative colitis from Chinese medicines

Ulcerative colitis (UC), a chronic inflammatory disease affecting the colon, has a rising incidence worldwide. The known pathogenesis is multifactorial and involves genetic predisposition, epithelial barrier defects, dysregulated immune responses, and environmental factors. Nowadays, the drugs for UC include 5-aminosalicylic acid, steroids, and immunosuppressants. Long-term use of these drugs, however, may cause several side effects, such as hepatic and renal toxicity, drug resistance and allergic reactions. Moreover, the use of traditional Chinese medicine (TCM) in the treatment of UC shows significantly positive effects, low recurrence rate, few side effects and other obvious advantages. This paper summarizes several kinds of active compounds used in the experimental research of anti-UC effects extracted from TCM, mainly including flavonoids, acids, terpenoids, phenols, alkaloids, quinones, and bile acids from some animal medicines. It is found that the anti-UC activities are mainly focused on targeting inflammation or oxidative stress, which is associated with increasing the levels of anti-inflammatory cytokine (IL-4, IL-10, SOD), suppressing the levels of pro-inflammatory cytokines (TNF-α, IL-1β, IL-6, IL-8, IL-23, NF-κB, NO), reducing the activity of MPO, MDA, IFN-γ, and iNOS. This review may offer valuable reference for UC-related studies on the compounds from natural medicines.

Protective effects of apigenin and myricetin against cisplatin-induced nephrotoxicity in mice

CONTEXT

Currently, the outcomes of the use of cisplatin in cancer therapy is limited by nephrotoxicity.

OBJECTIVE

This study aims to investigate the nephroprotective role of apigenin and myricetin against cisplatin-induced nephrotoxicity in mice.

MATERIALS AND METHODS

Adult female Wistar Albino mice were divided into eight groups (n = 8). Group I served as normal control. Groups II, III and IV received apigenin (3 mg/kg, i.p.), myricetin (3 mg/kg, i.p.) or their combination respectively, for seven days. Group V served as positive control group, received vehicles for seven days and cisplatin (7.5 mg/kg, i.p.) for three days starting at day five. Groups VI, VII and VIII received apigenin, myricetin or their combination, respectively for seven days as well as cisplatin injection for three days starting at day five. by the end of the experimental period, a biochemical study involving, nephrotoxicity markers [serum creatinine (Cr) and blood urea nitrogen (BUN)], apoptotic marker [caspase 3], inflammatory mediators [tumour necrosis factor alpha (TNF-α), interleukin 6 (IL-6), cyclooxygenase I and II (COXI, COXII)] and oxidative stress biomarkers [malondialdehyde (MDA), reduced glutathione (GSH) and catalase] was conducted. In addition, renal histopathological alterations were evaluated.

RESULTS

Apigenin, myricetin and their combination significantly reduced blood BUN, serum Cr, caspase-3TNF-α, IL-6, COXI and COXII, MDA levels and significantly increased GSH level and catalase activity parallel to, histopathological improvement in kidney tissues.

DISCUSSION AND CONCLUSION

Apigenin and myricetin exhibited a protective and promising preventive strategy against cisplatin-induced nephrotoxicity due to their antioxidant and anti-inflammatory effects.

Myricetin: A Dietary Molecule with Diverse Biological Activities

Myricetin is a common plant-derived flavonoid and is well recognised for its nutraceuticals value. It is one of the key ingredients of various foods and beverages. The compound exhibits a wide range of activities that include strong anti-oxidant, anticancer, antidiabetic and anti-inflammatory activities. It displays several activities that are related to the central nervous system and numerous studies have suggested that the compound may be beneficial to protect against diseases such as Parkinson's and Alzheimer's. The use of myricetin as a preserving agent to extend the shelf life of foods containing oils and fats is attributed to the compound's ability to protect lipids against oxidation. A detailed search of existing literature revealed that there is currently no comprehensive review available on this important molecule. Hence, the present work includes the history, synthesis, pharmaceutical applications and toxicity studies of myricetin. This report also highlights structure-activity relationships and mechanisms of action for various biological activities.

An update on dietary phenolic compounds in the prevention and management of rheumatoid arthritis

Certain nutritional components influence the cellular metabolism and interfere in the pathological inflammatory process, so that they may act as a coadjuvant in the treatment of many chronic inflammatory diseases, including rheumatoid arthritis (RA).

The treatment of rheumatoid arthritis using Chinese medicinal plants: From pharmacology to potential molecular mechanisms

ETHNOPHARMACOLOGICAL RELEVANCE

Rheumatoid arthritis (RA) is a common worldwide public health problem. Traditional Chinese Medicine (TCM) achieved some results to some extent in the treatment of rheumatoid arthritis (RA). Especially in China, TCM formulas are used in the clinic because of their advantages. Some of these TCM formulas have been used for thousands of years in ancient China, they pays much attention to strengthening healthy qi, cleaning heat, and wet, activating blood, etc. So TCM in anti-RA drug is considered as a simple and effective method. In addition, TCM are also traditionally used as extracts and many Chinese herbs which are considered to be effective for RA. With the advancement of technologies and research methods, researchers have devoted themselves to exploring new therapeutic materials from troves of TCM. The components of TCM are identified and purified, which include alkaloids, coumarins, flavonoids, saponins and so on. However, little or no review works are found in the research literature on the anti-RA drugs from TCM. The present review aims to provide systematically reorganized information on the ethnopharmacology, phytochemistry and pharmacology of TCM used traditionally against RA. The information recorded in this review will provide new directions for researchers in the future.

MATERIALS AND METHODS

Relevant scientific literatures were collected from Chinese traditional books and Chinese Pharmacopoeia. Several important pharmacology data, clinical observations, animal experiments on effects of anti-RA drugs from TCM and their mechanisms were extracted from a library and electric search (Pubmed, PubChem Compound, Science Direct, Spring Link, Elsevier, Web of Science, CNKI, Wan Fang, Bai du, The Plant List, etc.). We collected information published between 2002 and 2015 on Chinese medicine in the treatment of RA. Information was also acquired from local classic herbal literature, conference papers, government reports, and PhD and MSc dissertations.

RESULTS

This review mainly introduces the current research on anti-RA TCM formulas, extracts and compounds from TCM, pharmacological data and potential mechanisms (inhibit osteoclast proliferation, suppress fibroblast-like synoviocytes (FLSs) growth, decrease the expression of inflammatory cytokines, blocking signal pathways, etc.).

CONCLUSIONS

TCM, as a multi-component and multi-target approach, which is a perfect match with the holistic concept of systems biology, is applicable in the treatment of RA. The synergistic connections of Chinese herbs and mechanisms of related active compounds on RA increase the trust for TCM. TCM as alternative remedies for RA not only has an important position in the world market, but also has an irreplaceable role in the treatment of RA in future.

Biflavonoids as Potential Small Molecule Therapeutics for Alzheimer's Disease

Flavonoids are naturally occurring phytochemicals found in a variety of fruits and vegetables and offer color, flavor, aroma, nutritional and health benefits. Flavonoids have been found to play a neuroprotective role by inhibiting and/or modifying the self-assembly of the amyloid-β (Aβ) peptide into oligomers and fibrils, which are linked to the pathogenesis of Alzheimer's disease. The neuroprotective efficacy of flavonoids has been found to strongly depend on their structure and functional groups. Flavonoids may exist in monomeric, as well as di-, tri-, tetra- or polymeric form through C-C or C-O-C linkages. It has been shown that flavonoids containing two or more units, e.g., biflavonoids, exert greater biological activity than their respective monoflavonoids. For instance, biflavonoids have the ability to distinctly alter Aβ aggregation and more effectively reduce the toxicity of Aβ oligomers compared to the monoflavonoid moieties. Although the molecular mechanisms remain to be elucidated, flavonoids have been shown to alter the Aβ aggregation pathway to yield non-toxic, unstructured Aβ aggregates, as well as directly exerting a neuroprotective effect to cells. In this chapter, we review biflavonoid-mediated Aβ aggregation and toxicity, and highlight the beneficial roles biflavonoids can potentially play in the prevention and treatment of Alzheimer's disease.

Myricetin suppresses lipoteichoic acid-induced interleukin-1β and cyclooxygenase-2 expression in human gingival fibroblasts

Periodontitis is an inflammatory disease affecting the connective tissue and supporting bone surrounding the teeth. In periodontitis, human gingival fibroblasts (HGFs) synthesize IL-1β, causing a progressive inflammatory response. Flavones demonstrate a variety of biological activity: among others, they possess anti-inflammatory properties. Myricetin is a flavone with a strong anti-inflammatory activity. The objective of this study was to evaluate the effect of the flavonoid myricetin on HGFs under inflammatory conditions induced by lipoteichoic acid (LTA). the effect of myricetin on HGFs was assessed by measuring cell viability, signaling pathways and IL-1β expression and synthesis. It was found that, over time, myricetin did not affect cell viability. However, it inhibited activation of p38 and extracellular-signal-regulated kinase-1/2 in LTA-treated HGFs and also blocked IκB degradation and cyclooxygenase-2 and prostaglandin E2 synthesis and expression. These findings suggest that myricetin has therapeutic effects in the form of controlling LTA-induced inflammatory responses.

Ameliorative effect of myricetin on insulin resistance in mice fed a high-fat, high-sucrose diet

BACKGROUND/OBJECTIVES

Obesity-associated insulin resistance is a strong risk factor for type 2 diabetes mellitus. The aim of this study was to investigate the effect of myricetin on adiposity, insulin resistance, and inflammatory markers in mice with diet-induced insulin resistance.

MATERIALS/METHODS

Five-week-old male C57BL/6J mice were fed a basal diet, a high-fat, high-sucrose (HFHS) diet, or the HFHS diet containing 0.06% myricetin or 0.12% myricetin for 12 weeks after a 1-week adaptation, and body weight and food intake were monitored. After sacrifice, serum lipid profiles, glucose, insulin, adipocyte-derived hormones, and proinflammatory cytokines were measured. The homeostasis model assessment for insulin resistance (HOMA-IR) was determined.

RESULTS

Myricetin given at 0.12% of the total diet significantly reduced body weight, weight gain, and epidydimal white adipose tissue weight, and improved hypertriglyceridemia and hypercholesterolemia without a significant influence on food intake in mice fed the HFHS diet. Serum glucose and insulin levels, as well as HOMA-IR values, decreased significantly by 0.12% myricetin supplementation in mice fed the HFHS diet. Myricetin given at 0.12% of the total diet significantly reduced serum levels of leptin, tumor necrosis factor-α (TNF-α) and interleukin-6 (IL-6) in mice fed the HFHS diet.

CONCLUSIONS

These findings suggest that myricetin may have a protective effect against diet-induced obesity and insulin resistance in mice fed HFHS diet, and that alleviation of insulin resistance could partly occur by improving obesity and reducing serum proinflammatory cytokine levels.

Evaluation of anti-inflammatory and mechanism of action of extract of Macrosiphonia longiflora (Desf.) Müll. Arg

ETHNOPHARMACOLOGICAL RELEVANCE

Macrosiphonia longiflora (Desf.) Müll. Arg (Apocynaceae), popularly known as 'velame' and 'velame branco', is a native subshrub that grows in the Brazilian Cerrado. This plant is widely used in traditional medicine in the form of decoction and infusion, particularly as anti-inflammatory, depurative, anti-rheumatic, antisyphilitic and antiulcer remedy. There is no available information in the literature that has addressed its pharmacological activity and phytochemical analysis.

AIM OF THE STUDY

This study aimed to evaluate the anti-inflammatory pharmacological profile of the hydroethanolic extract of Macrosiphonia longiflora, using in vivo and in vitro acute inflammation experimental models, as well as investigate the roles of cytokines and nitric oxide in its mechanism of action, and including phytochemical analysis constitution of its hydroethanolic extract.

MATERIALS AND METHODS

Hydroethanolic (70%) extract of Macrosiphonia longiflora (HEMl) was prepared by maceration. The preliminary phytochemical analysis was performed according to procedures described in the literature. Selected secondary metabolites detected were quantified by spectrophotometry and high performance liquid chromatography (HPLC). Its cytotoxic potential in Chinese hamster ovary (CHO-k1) epithelial cell lines was evaluated using Alamar Blue. in vivo anti-inflammatory activity was evaluated with carrageenan- and dextran-induced paw edemas, carrageenan-induced pleurisy in rats and lipopolysaccharide (LPS)-induced peritonitis in mice. The in vitro anti-inflammatory activity was evaluated using RAW 264.7 cells stimulated with LPS and interferon (INF)-γ. Effects of HEMl on the inflammatory cytokines (IL-1β, IL-10, IL-17, INF-γ and TNF-α) concentrations in the peritoneal lavage were evaluated using commercial ELISA kits, while the Griess method was employed to determine nitric oxide (NO) concentrations in the peritoneal lavage, as well as in the supernatants of RAW 264.7 cells.

RESULTS

Preliminary phytochemical analysis, revealed the presence of phenolics compounds, terpenoids, alkaloids and flavonoids. Spectrophotometric analysis revealed the presence of relatively high content of phenolics and flavonoids in HEMl. HPLC analysis confirmed the presence of the quantified compounds and demonstrated the presence of ellagic acid in the detected matrix of compounds. HEMl appeared to be non-cytotoxic. It effectively inhibited (p<0.05) paw edema induced by carrageenan and dextran. Furthermore, HEMl also significantly reduced exudates volume and leukocyte migration in the carrageenan-induced pleurisy and LPS-induced peritonitis, neutrophils counts in LPS-induced peritonitis. HEMl also acts by effectively inhibiting the following inflammatory cytokines: IL-1β and IL-10 levels in the peritoneal lavage, but had no effect on IL-17 level in the peritonitis model. In addition, HEMl had no effect on the levels of tumor necrosis factor alpha (TNF-α) present in the peritoneal lavage and cells supernatants. The concentration of NO, as assessed by measurement of nitrite (NO2(-)), showed that pretreatment with HEMl reduced NO significantly in the peritoneal lavage and in RAW 264.7 cells co-stimulated with LPS and INF-γ.

CONCLUSION

The results obtained in this study indicate that HEMl possesses very low cytotoxic potential. In addition, it demonstrated a potent anti-inflammatory activity in both the in vivo and in vitro models of acute inflammation. The anti-inflammatory effect is partly related to the inhibition of IL-1β, IL-10, and nitric oxide releases, but independent of TNF-α and IL-17 modulation. Phytochemical analysis revealed the predominant presence of the flavonoids (naringin, rutin, myricetin, morin, quercetin, (±)-naringenin, and luteolin) and phenols (ellagic acid), which are possibly involved in the anti-inflammatory effect of HEMl. The current study provided supportive evidence for the popular use of HEMl in the treatment of inflammatory conditions, and shed more light on the possible roles of the inflammatory cytokines in its mechanisms of action as anti-inflammatory agent.

The potential for dietary factors to prevent or treat osteoarthritis

Osteoarthritis (OA) is a degenerative joint disease for which there are no disease-modifying drugs. It is a leading cause of disability in the UK. Increasing age and obesity are both major risk factors for OA and the health and economic burden of this disease will increase in the future. Focusing on compounds from the habitual diet that may prevent the onset or slow the progression of OA is a strategy that has been under-investigated to date. An approach that relies on dietary modification is clearly attractive in terms of risk/benefit and more likely to be implementable at the population level. However, before undertaking a full clinical trial to examine potential efficacy, detailed molecular studies are required in order to optimise the design. This review focuses on potential dietary factors that may reduce the risk or progression of OA, including micronutrients, fatty acids, flavonoids and other phytochemicals. It therefore ignores data coming from classical inflammatory arthritides and nutraceuticals such as glucosamine and chondroitin. In conclusion, diet offers a route by which the health of the joint can be protected and OA incidence or progression decreased. In a chronic disease, with risk factors increasing in the population and with no pharmaceutical cure, an understanding of this will be crucial.

Acidic environments enhance the inhibitory effect of statins on proliferation of synovial cells

Many previous studies in animal models and clinical investigations have suggested that statins are useful chemotherapeutics against rheumatoid arthritis, whereas in vitro experiments using synovial cell lines showed no significant effect of statins on cell proliferation until now. Since synovial fluid in rheumatoid joint knee was found to be acidic, we examined the effect of statins on human synovial sarcoma cell line SW982 cells in acidic medium. Statins suppressed the proliferation of SW982 cells at pH6.7, while the suppression was very weak in pH7.5 medium. It was shown that the suppression was caused by the decrease in geranylgeranyl diphosphate, suggesting that a geranylgeranylated protein(s) has an essential role in cell proliferation of SW982 cells under acidic conditions. Our present data clearly implied that statins had high efficacy against SW982 cells in acidic medium whose pH is close to that of rheumatoid arthritis loci in patients. These results lead us to anticipate that screening of chemicals having high therapeutic efficacy in acidic medium promotes the development of new microenvironment-dependent medicines for chemotherapies against rheumatoid arthritis.

Myricetin attenuates lipopolysaccharide-stimulated activation of mouse bone marrow-derived dendritic cells through suppression of IKK/NF-κB and MAPK signalling pathways

BACKGROUND

Myricetin is a naturally occurring flavonoid that is found in many fruits, vegetables, teas and medicinal herbs. It has been demonstrated to have anti-inflammatory properties, but, to date, no studies have described the immunomodulatory effects of myricetin on the functions of dendritic cells (DCs). The aim of this study was to evaluate the potential for myricetin to modulate lipopolysaccharide (LPS)-stimulated activation of mouse bone marrow-derived DCs.

RESULTS

Our experimental data showed that treatment with myricetin up to 10 µg mL(-1) does not cause cytotoxicity in cells. Myricetin significantly decreased the secretion of tumour necrosis factor-α, interleukin-6 and interleukin-12p70 by LPS-stimulated DCs. The expression of LPS-induced major histocompatibility class II, CD40 and CD86 on DCs was also inhibited by myricetin, and the endocytic and migratory capacity of LPS-stimulated DCs was blocked by myricentin. In addition, LPS-stimulated DC-elicited allogeneic T-cell proliferation was reduced by myricetin. Moreover, our results confirmed that myricetin attenuates the responses of LPS-stimulated activation of DCs via suppression of IκB kinase/nuclear factor-κB and mitogen-activated protein kinase-dependent pathways.

CONCLUSION

Myricetin has novel immunopharmacological activity, and modulation of DCs by myricetin may be an attractive strategy for the treatment of inflammatory and autoimmune disorders, and for transplantation.

Analysis of Flavonoids from Eugenia uniflora Leaves and Its Protective Effect against Murine Sepsis

Eugenia uniflora, referred to as Pitanga cherry shrub, is largely distributed in tropical and subtropical America. This plant is cultivated in many countries and it is suitable for the production of juice, frozen pulp, and tea. Besides, it can be used as treatment for inflammatory diseases. We reported that a flavonoid-rich fraction (HE-Bu) obtained from leaves decreased the lethality induced by cecal ligation and puncture (CLP), a clinically relevant model of sepsis. The oral administration of HE-Bu reduced the late mortality rate by 30%, prevented neutrophil accumulation in lungs, decreased TNF-α and IL-1β serum levels, and markedly decreased iNOS and COX-2 protein expression by ileum cells. Chemical investigation showed myricetin and quercetin rhamnosides as the major components of this fraction. The results showed that HE-Bu protected mice from sepsis and indicated that this edible plant produces compounds that could be considered as potential adjuvants for sepsis treatment.

Myricetin protects against cytokine-induced cell death in RIN-m5f β cells

Cytokine-induced cell death is recognized as a major cause of progressive β-cell loss. Tumor necrosis factor α (TNF-α), interleukin 1β (IL-1β), and interferon γ (IFN-γ) in combination trigger a series of events that lead to β-cell death. In the past few decades, the use of myricetin as an anti-inflammatory and cytoprotective agent has gained much attention. The present study focused on the protective roles of myricetin against cytokine-induced cell death in insulin-secreting RIN-m5f β cells. The results showed that myricetin (especially at concentrations of 10 μM and 20 μM) increased cell viability and decreased cell apoptosis induced by the cytokine mixture of TNF-α (10 ng/mL), IL-1β (5 ng/mL), and IFN-γ (1000 IU/mL) for 3 days. Moreover, the cytokines increased the total and p65 subunit levels of nuclear factor κB, decreased inhibitor κB α levels, stimulated the accumulation of nitric oxide, increased cytochrome c release from mitochondria, and induced reactive oxygen species generation; myricetin (especially at the concentration of 20 μM) abolished all of these parameters. These results suggest that myricetin might have therapeutic value for preventing β-cell death.