Myricetin protects keratinocyte damage induced by UV through IκB/NFκb signaling pathway

Myricetin attenuates hypoxia-induced inflammation in human adipocytes

BACKGROUND

Adipose tissue hypoxia plays a crucial role in the development of chronic low-grade systemic inflammation which has been associated with the pathogenesis of obesity-related diseases. Myricetin is a natural compound present in numerous plant-based foods with presumed anti-inflammatory and beneficial health effects. The impact of this flavonoid on hypoxia-induced expression of inflammatory adipokines and hypoxia-regulated pathways is unknown so far and has been addressed in the present study.

METHODS

Differentiated human Simpson-Golabi-Behmel syndrome (SGBS) adipocytes were cultured with or without myricetin under normoxic and hypoxic conditions for varying time periods. The effect of hypoxia and myricetin on the expression of the investigated adipokines was measured by real-time RT-PCR. Western blot analysis was used for the detection of transcription factors involved in hypoxia-regulated pathways.

RESULTS

Myricetin interfered in the hypoxia-induced regulation of adipokines and the underlying pathways, which are involved in transmitting the inflammatory response. It strongly repressed hypoxia-induced expression of apelin, leptin, chemerin, asprosin, and DPP-4 and HIF-1α accumulation in the nucleus was diminished. Furthermore, the activation of the key regulators in the inflammatory response NF-κB, Akt, and CREB was suppressed by myricetin under hypoxic conditions. Myricetin also decreased hypoxia-induced accumulation of the pro-tumorigenic transcription factors Snail and Slug in the nucleus.

CONCLUSION

Taken together, our results indicated that myricetin regulated hypoxia-induced expression of adipokines and hypoxia-regulated pathways in human adipocytes. Our study therefore provided evidence of the anti-inflammatory effects of myricetin in hypoxia-treated human adipocytes.

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.

Photochemoprevention of topical formulation containing purified fraction of Inga edulis leaves extract

Natural antioxidants have attracted attention for their therapeutic use as photochemopreventive agents. Inga edulis leaves extract and its purified fraction have high polyphenolic content and high antioxidant capacity. In addition, they presented UV photostability and low citotoxicity in fibroblast cells. In this context, this study first aimed at development of topical formulation containing purified fraction of I. edulis extract and the evaluation of skin penetration of the compounds. Moreover, the photoprotective/photochemopreventive potential of the formulation containing I. edulis purified fraction were investigated in vitro and in vivo. The topical formulation containing 1% of the purified fraction of I. edulis increased the endogenous antioxidant potential of the skin, and vicenin-2 and myricetin compounds were able to penetrate the epidermis and dermis. Additionally, the purified fraction (25 and 50 mg/mL) showed a photoprotective effect against UVA and UVB radiation in L929 fibroblast cells. In vivo studies have shown that the formulation added with purified fraction provided an anti-inflammatory effect on the skin of animals after UVB exposure, since it was observed a reduction in MPO activity, IL-1β and TNF-α cytokines, and CXCL1/KC chemokine concentrations. In conclusion, the purified fraction of I. edulis, rich in phenolic compounds, when incorporated in topical formulation, appears as an alternative to prevent skin damages induced by UV radiation, due to its antioxidant and anti-inflammatory properties.

Effect of the natural flavonoids myricetin and dihydromyricetin on the wound healing process in vitro

Myricetin (MYR) and dihydromyricetin (DHM) are classified as natural flavonoids. Both substances are known for their anti-inflammatory and antioxidant properties. In this study, an in vitro model of inflammation was demonstrated on monolayers of scratched fibroblasts or keratinocytes exposed to LPS from Pseudomonas aeruginosa for six hours. MYR and DHM were subsequently applied to the cells for 24 hours at sub toxic concentrations (5-15 µM). Inflammatory parameters were analysed in collected cell medium and lysate after the incubation period using the Enzyme-Linked ImmuneSorbent Assay (ELISA) and Western blot. Both flavonoids inhibit the production of pro-inflammatory cytokines (IL-6, IL-8) in LPS-stimulated skin cells as well as the decreased level of MMP-1 in fibroblasts. However, the application of MYR and DHM dose dependently increased the level of MMP-1 in keratinocytes. In our experiments, we focused on the anti-glycation activity of MYR and DHM, where the higher concentration of MYR seems to be more effective.

Myricetin: A comprehensive review on its biological potentials

Myricetin is a critical nutritive component of diet providing immunological protection and beneficial for maintaining good health. It is found in fruits, vegetables, tea, and wine. The families Myricaceae, Polygonaceae, Primulaceae, Pinaceae, and Anacardiaceae are the richest sources of myricetin. Different researchers explored the therapeutic potential of this valuable constituent such as anticancer, antidiabetic, antiobesity, cardiovascular protection, osteoporosis protection, anti-inflammatory, and hepatoprotective. In addition to these, the compound has been tested for cancer and diabetic mellitus during clinical trials. Health benefits of myricetin are related to its impact on different cell processes, such as apoptosis, glycolysis, cell cycle, energy balance, lipid level, serum protein concentrations, and osteoclastogenesis. This review explored the potential health benefits of myricetin with a specific emphasis on its mechanism of action, considering the most updated and novel findings in the field.

Myricetin: A review of the most recent research

Myricetin(MYR) is a flavonoid compound widely found in many natural plants including bayberry. So far, MYR has been proven to have multiple biological functions and it is a natural compound with promising research and development prospects. This review comprehensively retrieved and collected the latest pharmacological abstracts on MYR, and discussed the potential molecular mechanisms of its effects. The results of our review indicated that MYR has a therapeutic effect on many diseases, including tumors of different types, inflammatory diseases, atherosclerosis, thrombosis, cerebral ischemia, diabetes, Alzheimer's disease and pathogenic microbial infections. Furthermore, it regulates the expression of Hippo, MAPK, GSK-3β, PI3K/AKT/mTOR, STAT3, TLR, IκB/NF-κB, Nrf2/HO-1, ACE, eNOS / NO, AChE and BrdU/NeuN. MYR also enhances the immunomodulatory functions, suppresses cytokine storms, improves cardiac dysfunction, possesses an antiviral potential, can be used as an adjuvant treatment against cancer, cardiovascular injury and nervous system diseases, and it may be a potential drug against COVID-19 and other viral infections. Generally, this article provides a theoretical basis for the clinical application of MYR and a reference for its further use.

Liquid crystalline nanodispersion functionalized with cell-penetrating peptides improves skin penetration and anti-inflammatory effect of lipoic acid after in vivo skin exposure to UVB radiation

In this study, the development and the performance of a new targeted liquid crystalline nanodispersion (LCN) by the attachment of cell-penetrating peptides (CPP) onto their surfaces to improve skin delivery of lipoic acid (LA) were evaluated. For that, the synthesis and characterization of this new platform as well as its spatiotemporal analysis from in vitro and in vivo topical application were explored and extensively discussed in this paper. The TAT or D4 peptides were chosen as CPP due to specific target strategies by the charge grouping on the skin surface or target the overexpressed epidermal growth factor receptor (EGFR) of cell membrane of keratinocytes, respectively. Thus, the nanoparticle characterization results when taken together suggested that designed LCNs maintained their hexagonal phase structure, nanoscale particle size, and low polydispersity index even after drug, lipopolymers, and peptide additions, which are proved to be favorable for topical skin delivery. There were no statistical differences among the LCNs investigated, except for superficial charge of LCN conjugated with TAT which may have altered the LCN zeta potential due to cationic charge of TAT amino acid sequence compared with D4. The cumulative amounts of LA retained into the skin were determined to be even higher coming from the targeted LCNs. Moreover, the exogenous antioxidant application of the LA from the LCNs can prevent ROS damage, which was demonstrated by this study with the less myeloperoxidase (MPO) activity and decrease in cytokine levels (TNF-alpha and IL-1β) generated by the oxidative stress modulation. Together, the data presented highlights the potential of these targeted LCNs, and overall, opens new frontiers for preclinical trials.

A review on myricetin as a potential therapeutic candidate for cancer prevention

Myricetin, one of the most extensively studied polyphenols, is present abundantly in various fruits and vegetables and exhibits diverse pharmacological properties. The multifaceted biological action of myricetin against tumor heterogeneity makes it an impressive anticancer agent whose efficacy has been confirmed by an overwhelming number of studies. Myricetin shows its therapeutic potential by targeting and modulating the expression of various molecular target which are involved in inflammation, cell proliferation, apoptosis, angiogenesis, invasion, and metastasis. Myricetin deters tumor progression by inducing apoptosis via both intrinsic and extrinsic pathway, activating/inactivating several signaling pathways, and reactivating various tumor suppressor genes. This comprehensive review represents the effect of myricetin on various hallmarks of cancer with insight into the molecular mechanism employed by myricetin to mitigate cell proliferation, angiogenesis, metastasis, and induce apoptosis. In addition, enhanced bioavailability of myricetin through conjugation and its increased efficacy as an anticancer agent when used in combination are also highlighted.

Myricetin inhibits endometriosis growth through cyclin E1 down-regulation in vitro and in vivo

Endometriosis is a benign gynecological condition prevalent among reproductive-aged women. Although active research and studies have been carried out to discover new drugs, surgery and hormone therapy are still the gold standard for endometriosis treatment. Nowadays, various flavonoids are considered long-term supplements for different diseases. Myricetin, a flavonol, has antiproliferative, anti- or pro-oxidant, and anticancer effects in gynecological diseases. Here, we reveal for the first time, to our knowledge, the antigrowth effects of myricetin in endometriosis. Myricetin inhibited cell proliferation and cell cycle progression of human VK2/E6E7 and End1/E6E7 cells and induced apoptosis, with the loss of mitochondrial membrane potential and accumulation of reactive oxygen species and calcium ions. Additionally, myricetin decreased the activation of AKT and ERK1/2 proteins, whereas it induced p38 activation in both cell lines. Moreover, myricetin decreased lesion size in the endometriosis mouse model via Ccne1 inhibition. Thus, myricetin has antiproliferative effects on endometriosis through cell cycle regulation.

Myricetin ameliorates high glucose-induced endothelial dysfunction in human umbilical vein endothelial cells

Endothelial dysfunction is recognized as the initial detectable stage of cardiovascular disease, a serious complication of diabetes. In this study, we evaluated effects of myricetin on high glucose (HG)-elicited oxidative damage in human umbilical vein endothelial cells (HUVECs). The cells were pre-incubated with myricetin and then treated with HG to induce apoptosis. The effect of myricetin on viability was investigated by MTT assay. The levels of lipid peroxidation (LPO) were determined by thiobarbituric acid (TBA) method. The protein expression of Bax, Bcl-2 and caspase-3 was measured by western blot analysis. Moreover, the effect of myricetin on total antioxidant capacity (TAC) and total thiol molecules was also determined. Our results showed that myricetin was able to markedly restore the viability of endothelial cells under oxidative stress. Myricetin reduced HG-caused increase in LPO levels. Also, TAC and total thiol molecules were notably elevated by myricetin. Incubation with myricetin decreased the protein expression levels of Bax, whereas it increased the expression levels of the Bcl-2, compared with HG treatment alone. Furthermore, myricetin significantly decreased cleaved caspase-3 protein expression. It is concluded that myricetin may protect HUVECs from oxidative stress induced by HG via increasing cell TAC and reducing Bax/Bcl-2 protein ratio, and caspase-3 expression.

Isolation of Myricitrin and 3,5-di-O-Methyl Gossypetin from Syzygium samarangense and Evaluation of their Involvement in Protecting Keratinocytes against Oxidative Stress via Activation of the Nrf-2 Pathway

The wax apple (Syzygium samarangense) is traditionally employed as an antibacterial and immunostimulant drug in traditional medicine. This plant is rich in different flavonoids and tannins. In this study, we isolated two compounds from S. samarangense leaves: myricitrin and 3,5-di-O-methyl gossypetin. Then, we investigated the mechanisms of action of the two compounds against oxidative stress (induced by sodium arsenite) and inflammation (induced by UV light) on human keratinocytes. We could clearly demonstrate that the pre-treatment of cells with both compounds was able to mitigate the negative effects induced by oxidative stress, as no alteration in reactive oxygen species (ROS) production, glutathione (GSH) level, or protein oxidation was observed. Additionally, both compounds were able to modulate mitogen-activated protein kinase (MAPK) signaling pathways to counteract oxidative stress activation. Finally, we showed that 3,5-di-O-methyl gossypetin exerted its antioxidant activity through the nuclear transcription factor-2 (Nrf-2) pathway, stimulating the expression of antioxidant proteins, such as HO-1 and Mn-SOD-3.