Flavonoids are naturally occurring compounds found in fruits, vegetables, and other plant-based foods, and they are known for their health benefits, such as UV protection, antioxidant, anti-inflammatory, and antiproliferative properties. This study investigates whether flavonoids, such as quercetin and 2,3-dehydrosilybin, can act as photoactivatable carbon monoxide (CO)-releasing molecules under physiological conditions. CO has been recently recognized as an important signaling molecule. Here, we show that upon direct irradiation, CO was released from both flavonoids in PBS with chemical yields of up to 0.23 equiv, which increased to almost unity by sensitized photooxygenation involving singlet oxygen. Photoreleased CO reduced cellular toxicity caused by high flavonol concentrations, partially restored mitochondrial respiration, reduced superoxide production induced by rotenone and high flavonol levels, and influenced the G0/G1 and G2/M phases of the cell cycle, showing antiproliferative effects. The findings highlight the potential of quercetin and 2,3-dehydrosilybin as CO-photoreleasing molecules with chemopreventive and therapeutic implications in human pathology and suggest their possible roles in plant biology.

• Klíčová slova
• 2,3-dehydrosilybin, carbon monoxide, cell cycle, mitochondrial respiration, oxidative stress, photoCORM, photoinduced release, quercetin,
• MeSH
• buněčný cyklus účinky léků   MeSH
• flavonoidy * chemie   farmakologie   MeSH
• lidé MeSH
• mitochondrie metabolismus   účinky léků   MeSH
• oxid uhelnatý * chemie   metabolismus   MeSH
• proliferace buněk účinky léků   MeSH
• quercetin chemie   farmakologie   MeSH
• rostlinné extrakty * chemie   farmakologie   MeSH
• Check Tag
• lidé MeSH
• Publikační typ
• časopisecké články MeSH
• Názvy látek
• flavonoidy * MeSH
• oxid uhelnatý * MeSH
• quercetin MeSH
• rostlinné extrakty * MeSH

This current study seeks to examine the pre-protective function of Quercetin in Cadmium (Cd)-induced liver damage, along with its modulation of the PI3K/Akt/NF-kappaB signaling pathway. A total of 60 male C57BL/6J mice were randomly assigned to four groups: control (C), quercetin (Q, 100 mg/kg/day), Cd (Cd, 2.5 mg/kg/day), and quercetin and Cd (Q+Cd). Before receiving Cd treatment, quercetin was administered intragastrically for 4 weeks. In the present study, liver markers, oxidative stress parameters, pro-inflammatory cytokines, liver histopathology, apoptotic markers and PI3K/Akt/NF-kappaB signaling molecules were examined. We observed that the body weight of the Cd-treated mice dramatically rise after 4 weeks of quercetin pre-administration, and the Cd concentration was significantly decreased. Liver function markers like alanine transaminase (ALT), aspartate transaminase (AST), alkaline phosphatase (ALP), and lactate dehydrogenase (LDH) were significantly reduced in quercetin treatment in Cd-induced mice. Additionally, we observed that quercetin reduced Cd-mediated liver injury in mice by assessing the level of malondialdehyde (MDA), and the activities of superoxide dismutase (SOD), catalase (CAT), glutathione peroxidase (GPx), and glutathione (GSH) concentrations and the histological alterations. By monitoring tumor necrosis factor-alpha (TNF-alpha), interleukin-6 (IL-6), and interleukin-1beta (IL-1beta), quercetin successfully reduced the inflammatory cytokines that the Cd metal caused in the liver. Additionally, in the liver tissues of Cd-mediated, quercetin could enhance the expression of Bcl-2 and decrease the expression of p-Akt, p-PI3K, Bax, Caspase-9, Caspase-3, NF-kappaB. In conclusion, quercetin protects against Cd induced liver injury via several pathways, including oxidative stress, inflammation and apoptosis, and its protective effect correlates with antioxidant activity.

• MeSH
• antioxidancia * farmakologie   MeSH
• fosfatidylinositol-3-kinasy * metabolismus   MeSH
• játra účinky léků   patologie   metabolismus   MeSH
• kadmium * toxicita   MeSH
• lékové postižení jater * prevence a kontrola   metabolismus   patologie   MeSH
• myši inbrední C57BL * MeSH
• myši MeSH
• NF-kappa B * metabolismus   MeSH
• oxidační stres účinky léků   MeSH
• protoonkogenní proteiny c-akt * metabolismus   MeSH
• quercetin * farmakologie   terapeutické užití   MeSH
• signální transdukce * účinky léků   MeSH
• zvířata MeSH
• Check Tag
• mužské pohlaví MeSH
• myši MeSH
• zvířata MeSH
• Publikační typ
• časopisecké články MeSH
• Názvy látek
• antioxidancia * MeSH
• fosfatidylinositol-3-kinasy * MeSH
• kadmium * MeSH
• NF-kappa B * MeSH
• protoonkogenní proteiny c-akt * MeSH
• quercetin * MeSH

Dietary polyphenols have been associated with many beneficial cardiovascular effects. However, these effects are rather attributed to small phenolic metabolites formed by the gut microbiota, which reach sufficient concentrations in systemic circulation. 4-Methylcatechol (4-MC) is one such metabolite. As it is shown to possess considerable vasorelaxant effects, this study aimed to unravel its mechanism of action. To this end, experimental in vitro and in silico approaches were employed. In the first step, isometric tension recordings were performed on rat aortic rings. 4-MC potentiated the effect of cyclic nucleotides, but the effect was not mediated by either soluble guanylyl cyclase (sGC), modification of cyclic adenosine monophosphate levels, or protein kinase G. Hence, downstream targets such as calcium or potassium channels were considered. Inhibition of voltage-gated K+ channels (KV) markedly decreased the effect of 4-MC, and vasodilation was partly decreased by inhibition of the KV7 isoform. Contrarily, other types of K+ channels or L-type Ca2+ channels were not involved. In silico reverse docking confirmed that 4-MC binds to KV7.4 through hydrogen bonding and hydrophobic interactions. In particular, it interacts with two crucial residues for KV7.4 activation: Trp242 and Phe246. In summary, our findings suggested that 4-MC exerts vasorelaxation by opening KV channels with the involvement of KV7.4.

• MeSH
• aorta účinky léků   metabolismus   MeSH
• draslíkové kanály řízené napětím * metabolismus   MeSH
• katecholy * farmakologie   MeSH
• krysa rodu Rattus MeSH
• potkani Wistar MeSH
• quercetin * farmakologie   MeSH
• simulace molekulového dockingu MeSH
• vazodilatace * účinky léků   MeSH
• vazodilatancia farmakologie   MeSH
• zvířata MeSH
• Check Tag
• krysa rodu Rattus MeSH
• mužské pohlaví MeSH
• zvířata MeSH
• Publikační typ
• časopisecké články MeSH
• Názvy látek
• 4-methylcatechol MeSH Prohlížeč
• draslíkové kanály řízené napětím * MeSH
• katecholy * MeSH
• quercetin * MeSH
• vazodilatancia MeSH

Flavonoids are considered as health-protecting food constituents. The testing of their biological effects is however hampered by their low oral absorption and complex metabolism. In order to investigate the direct effect(s) of unmetabolized flavonoid, a preparation in a biologically friendly solvent for intravenous administration is needed. Isorhamnetin, a natural flavonoid and a human metabolite of the most frequently tested flavonoid quercetin, has very low water solubility (<3.5 μg/mL). The aim of this study was to improve its solubility to enable intravenous administration and to test its pharmacokinetics in an animal model. By using polyvinylpyrrolidone (PVP10) and benzalkonium chloride, we were able to improve the solubility approximately 600 times to 2.1 mg/mL. This solution was then administered intravenously at a dose of 0.5 mg/kg of isorhamnetin to rats and its pharmacokinetics was analyzed. The pharmacokinetics of isorhamnetin corresponded to two compartmental model with a rapid initial distribution phase (t1/2α: 5.7 ± 4.3 min) and a slower elimination phase (t1/2β: 61 ± 47.5 min). Two sulfate metabolites were also identified. PVP10 and benzalkonium did not modify the properties of isorhamnetin (iron chelation and reduction, and cell penetration) substantially. In conclusion, the novel preparation reported in this study is suitable for future testing of isorhamnetin effects under in vivo conditions.

• Klíčová slova
• Flavonoid, Isorhamnetin, Pharmacokinetics, Quercetin, Solid dispersion, Solubility,
• MeSH
• benzalkoniové sloučeniny farmakokinetika   chemie   MeSH
• intravenózní podání * MeSH
• krysa rodu Rattus MeSH
• potkani Wistar MeSH
• povidon * chemie   MeSH
• quercetin * farmakokinetika   analogy a deriváty   aplikace a dávkování   chemie   MeSH
• rozpustnost * MeSH
• voda * chemie   MeSH
• zvířata MeSH
• Check Tag
• krysa rodu Rattus MeSH
• mužské pohlaví MeSH
• zvířata MeSH
• Publikační typ
• časopisecké články MeSH
• Názvy látek
• 3-methylquercetin MeSH Prohlížeč
• benzalkoniové sloučeniny MeSH
• povidon * MeSH
• quercetin * MeSH
• voda * MeSH

Organic anion transporting polypeptides (OATPs), OATP1B1 and OATP2B1 are membrane proteins mediating the cellular uptake of chemically diverse organic compounds. OATP1B1 is exclusively expressed in hepatocytes and plays a key role in hepatic detoxification. The ubiquitously expressed OATP2B1 promotes the intestinal absorption of orally administered drugs. Flavonoids are widely found in foods and beverages, and many of them can inhibit OATP function, resulting in food-drug interactions. In our previous work, we have shown that not only luteolin (LUT) and quercetin (Q), but also some of their metabolites can inhibit OATP1B1 and OATP2B1 activity. However, data about the potential direct transport of these flavonoids by OATPs have been incomplete. Hence, in the current study, we developed a simple, fluorescence-based method for the measurement of intracellular flavonoid levels. The method applies a cell-permeable small molecule (2-aminoethyl diphenylborinate, 2-APB), that, upon forming a complex with flavonoids, results in their fluorescence enhancement. This way the direct uptake of LUT and Q, and also their metabolites' could be investigated both by confocal microscopy and in a fluorescence plate reader in living cells. With this approach we identified quercetin-3'-O-sulfate, luteolin-3'-O-glucuronide, luteolin-7-O-glucuronide and luteolin-3'-O-sulfate as substrates of both OATP1B1 and OATP2B1. Our results highlight that OATP1B1 and OATP2B1 can be key participants in the transmembrane movement of LUT and Q conjugates with otherwise low cell permeability. In addition, the novel method developed in this study can be a good completion to existing fluorescence-based assays to investigate OATP function.

• Klíčová slova
• Fluorescence enhancer, Fluorescence-based direct transport, Luteolin metabolite, Organic anion transporting polypeptide, Quercetin metabolite,
• MeSH
• fluorescenční barviva * chemie   MeSH
• HEK293 buňky MeSH
• lidé MeSH
• luteolin * metabolismus   MeSH
• polypeptid C přenášející organické anionty * metabolismus   MeSH
• přenašeče organických aniontů * metabolismus   MeSH
• quercetin * metabolismus   MeSH
• zvířata MeSH
• Check Tag
• lidé MeSH
• zvířata MeSH
• Publikační typ
• časopisecké články MeSH
• Názvy látek
• fluorescenční barviva * MeSH
• luteolin * MeSH
• polypeptid C přenášející organické anionty * MeSH
• přenašeče organických aniontů * MeSH
• quercetin * MeSH
• SLCO1B1 protein, human MeSH Prohlížeč
• SLCO2B1 protein, human MeSH Prohlížeč

Nanomedicine for treating post-viral infectious disease syndrome is at an emerging stage. Despite promising results from preclinical studies on conventional antioxidants, their clinical translation as a therapy for treating post-COVID conditions remains challenging. The limitations are due to their low bioavailability, instability, limited transport to the target tissues, and short half-life, requiring frequent and high doses. Activating the immune system during coronavirus (SARS-CoV-2) infection can lead to increased production of reactive oxygen species (ROS), depleted antioxidant reserve, and finally, oxidative stress and neuroinflammation. To tackle this problem, we developed an antioxidant nanotherapy based on lipid (vesicular and cubosomal types) nanoparticles (LNPs) co-encapsulating ginkgolide B and quercetin. The antioxidant-loaded nanocarriers were prepared by a self-assembly method via hydration of a lyophilized mixed thin lipid film. We evaluated the LNPs in a new in vitro model for studying neuronal dysfunction caused by oxidative stress in coronavirus infection. We examined the key downstream signaling pathways that are triggered in response to potassium persulfate (KPS) causing oxidative stress-mediated neurotoxicity. Treatment of neuronally-derived cells (SH-SY5Y) with KPS (50 mM) for 30 min markedly increased mitochondrial dysfunction while depleting the levels of both glutathione peroxidase (GSH-Px) and tyrosine hydroxylase (TH). This led to the sequential activation of apoptotic and necrotic cell death processes, which corroborates with the crucial implication of the two proteins (GSH-Px and TH) in the long-COVID syndrome. Nanomedicine-mediated treatment with ginkgolide B-loaded cubosomes and vesicular LNPs showed minimal cytotoxicity and completely attenuated the KPS-induced cell death process, decreasing apoptosis from 32.6% (KPS) to 19.0% (MO-GB), 12.8% (MO-GB-Quer), 14.8% (DMPC-PEG-GB), and 23.6% (DMPC-PEG-GB-Quer) via free radical scavenging and replenished GSH-Px levels. These findings indicated that GB-LNPs-based nanomedicines may protect against KPS-induced apoptosis by regulating intracellular redox homeostasis.

• Klíčová slova
• ginkgolide B, glutathione peroxidase, long COVID syndrome, nanomedicine, oxidative stress, quercetin,
• MeSH
• antioxidancia * farmakologie   MeSH
• COVID-19 metabolismus   MeSH
• farmakoterapie COVID-19 * MeSH
• ginkgolidy * farmakologie   MeSH
• glutathionperoxidasa * účinky léků   metabolismus   MeSH
• laktony farmakologie   MeSH
• lidé MeSH
• nanočástice * MeSH
• nanomedicína * metody   MeSH
• neurony účinky léků   virologie   MeSH
• oxidační stres * účinky léků   MeSH
• postakutní syndrom COVID-19 * farmakoterapie   metabolismus   MeSH
• quercetin farmakologie   MeSH
• reaktivní formy kyslíku metabolismus   MeSH
• SARS-CoV-2 účinky léků   MeSH
• Check Tag
• lidé MeSH
• Publikační typ
• časopisecké články MeSH
• Názvy látek
• antioxidancia * MeSH
• ginkgolide B MeSH Prohlížeč
• ginkgolidy * MeSH
• glutathionperoxidasa * MeSH
• laktony MeSH
• quercetin MeSH
• reaktivní formy kyslíku MeSH

BACKGROUND AND AIM: Osmotic changes represent a burden for the body and their limitation would be beneficial. We hypothesized that ubiquitous natural compounds could guard against cytotoxic effects of osmotic stress. We evaluated the anti-hypertonic mechanism of quercetin and 2,3-dehydrosilybin in H9c2 cells in vitro. EXPERIMENTAL PROCEDURE: Protective effect of both compounds was determined by neutral red assay, cell apoptosis was estimated by measuring caspase-3 activity and verified by western blot and annexin V assay. Phosphorylation level of selected proteins was also detected. Mitochondrial membrane potential was evaluated using dye JC-1. Ca2+ signals were evaluated using genetically encoded fluorescent Ca2+ biosensor GCaMP7f. Formation of reactive oxygen species was measured using an oxidant-sensing probe dihydrofluorescein diacetate. KEY RESULTS: Quercetin protected H9c2 cells against hypertonic stress-induced cell death. We observed a significant increase in intracellular Ca2+ levels ([Ca2+]cyto) when cells originally placed in a hypertonic solution were returned to a normotonic environment. Quercetin was found to prevent this increase in [Ca2+]cyto and also the depolarization of mitochondrial membrane potential. CONCLUSIONS AND IMPLICATIONS: Quercetin, but not 2,3-dehydrosilybin, reduced adverse effects of osmotic stress mainly by dampening the elevation of [Ca2+]cyto and mitochondrial Ca2+ overload. This may consequently prevent MPTP pore opening and activation of apoptosis.

• Klíčová slova
• 2,3-dehydrosilybin, Calcium, H9c2 cells, Hypertonic stress, Quercetin,
• MeSH
• apoptóza * MeSH
• buněčná smrt MeSH
• membránový potenciál mitochondrií MeSH
• mitochondrie metabolismus   MeSH
• oxidační stres MeSH
• quercetin * farmakologie   MeSH
• reaktivní formy kyslíku metabolismus   MeSH
• Publikační typ
• časopisecké články MeSH
• práce podpořená grantem MeSH
• Názvy látek
• quercetin * MeSH
• reaktivní formy kyslíku MeSH

Aspirin supplemented with quercetin was reported to enhance the therapeutic effects of aspirin in a rat model of preeclampsia. In this study, the underlying mechanisms were further explored. Preeclampsia was induced by L-NAME (50 mg/kg/day) via oral gavage from gestation day (GD)14 to GD19. Aspirin (1.5 mg/kg/day) administration was performed using aspirin mixed with rodent dough from GD0 to GD19. The administration of quercetin (2 mg/kg/day) was performed by intraperitoneal infusion from GD0 to GD19. Protein levels were evaluated using ELISA or Western blot, and microRNA (miRNA) level was evaluated by RT-PCR. Aspirin supplemented with quercetin ameliorated the increase of systolic blood pressure (SBP), proteinuria, tumor necrosis factor-alpha (TNF-alpha) and interleukin-6 (IL-6) levels, and improved the pregnancy outcomes in preeclampsia rats. Aspirin supplemented with quercetin inhibited miR-155 expression in preeclampsia rats. The decreased miR-155 level in placenta further increased the protein level of SOCS1 and inhibited the phosphorylation of p65. In this study, we demonstrated that aspirin supplemented with quercetin enhanced the effects of aspirin for the treatment of preeclampsia.

• MeSH
• Aspirin škodlivé účinky   MeSH
• krysa rodu Rattus MeSH
• lidé MeSH
• mikro RNA * metabolismus   MeSH
• NG-nitroargininmethylester farmakologie   MeSH
• placenta metabolismus   MeSH
• preeklampsie * chemicky indukované   farmakoterapie   prevence a kontrola   MeSH
• quercetin farmakologie   terapeutické užití   MeSH
• těhotenství MeSH
• zvířata MeSH
• Check Tag
• krysa rodu Rattus MeSH
• lidé MeSH
• těhotenství MeSH
• ženské pohlaví MeSH
• zvířata MeSH
• Publikační typ
• časopisecké články MeSH
• Názvy látek
• Aspirin MeSH
• mikro RNA * MeSH
• MIRN155 microRNA, rat MeSH Prohlížeč
• NG-nitroargininmethylester MeSH
• quercetin MeSH

Immune checkpoints regulate the immune system response. Recent studies suggest that flavonoids, known as phytoestrogens, may inhibit the PD-1/PD-L1 axis. We explored the potential of estrogens and 17 Selective Estrogen Receptor Modulators (SERMs) as inhibiting ligands for immune checkpoint proteins (CTLA-4, PD-L1, PD-1, and CD80). Our docking studies revealed strong binding energy values for quinestrol, quercetin, and bazedoxifene, indicating their potential to inhibit PD-1 and CTLA-4. Quercetin and bazedoxifene, known to modulate EGFR and IL-6R alongside estrogen receptors, can influence the immune checkpoint functionality. We discuss the impact of SERMs on PD-1 and CTLA-4, suggesting that these SERMs could have therapeutic effects through immune checkpoint inhibition. This study highlights the potential of SERMs as inhibitory ligands for immune checkpoint proteins, emphasizing the importance of considering PD-1 and CTLA-4 inhibition when evaluating SERMs as therapeutic agents. Our findings open new avenues for cancer immunotherapy by exploring the interaction between various SERMs and immune checkpoint pathways.

• MeSH
• antigen CTLA-4 MeSH
• antigeny CD274 MeSH
• antigeny CD279 MeSH
• imunoterapie MeSH
• lidé MeSH
• modulátory estrogenních receptorů MeSH
• nádory * terapie   MeSH
• proteiny kontrolních bodů imunitní reakce * MeSH
• quercetin MeSH
• selektivní modulátory estrogenních receptorů farmakologie   MeSH
• Check Tag
• lidé MeSH
• Publikační typ
• časopisecké články MeSH
• Názvy látek
• antigen CTLA-4 MeSH
• antigeny CD274 MeSH
• antigeny CD279 MeSH
• modulátory estrogenních receptorů MeSH
• proteiny kontrolních bodů imunitní reakce * MeSH
• quercetin MeSH
• selektivní modulátory estrogenních receptorů MeSH

Alternaria alternata is a common fungus strongly related with severe allergic asthma, with 80% of affected individuals being sensitized solely to its major allergen Alt a 1. Here, we assessed the function of Alt a 1 as an innate defense protein binding to micronutrients, such as iron-quercetin complexes (FeQ2), and its impact on antigen presentation in vitro. Binding of Alt a 1 to FeQ2 was determined in docking calculations. Recombinant Alt a 1 was generated, and binding ability, as well as secondary and quaternary structure, assessed by UV-VIS, CD, and DLS spectroscopy. Proteolytic functions were determined by casein and gelatine zymography. Uptake of empty apo- or ligand-filled holoAlt a 1 were assessed in human monocytic THP1 cells under the presence of dynamin and clathrin-inhibitors, activation of the Arylhydrocarbon receptor (AhR) using the human reporter cellline AZ-AHR. Human PBMCs were stimulated and assessed for phenotypic changes in monocytes by flow cytometry. Alt a 1 bound strongly to FeQ2 as a tetramer with calculated Kd values reaching pico-molar levels and surpassing affinities to quercetin alone by a factor of 5000 for the tetramer. apoAlt a 1 but not holoAlta 1 showed low enzymatic activity against casein as a hexamer and gelatin as a trimer. Uptake of apo- and holo-Alt a 1 occurred partly clathrin-dependent, with apoAlt a 1 decreasing labile iron in THP1 cells and holoAlt a 1 facilitating quercetin-dependent AhR activation. In human PBMCs uptake of holoAlt a 1 but not apoAlt a 1 significantly decreased the surface expression of the costimulatory CD86, but also of HLADR, thereby reducing effective antigen presentation. We show here for the first time that the presence of nutritional iron complexes, such as FeQ2, significantly alters the function of Alt a 1 and dampens the human immune response, thereby supporting the notion that Alt a 1 only becomes immunogenic under nutritional deprivation.

• Klíčová slova
• enzymatic, holo–Alt a 1, immune response, iron, major allergen Alt a 1, nutritional immunity, quercetin,
• MeSH
• alergeny * MeSH
• Alternaria metabolismus   MeSH
• bronchiální astma * MeSH
• kaseiny MeSH
• klathrin MeSH
• lidé MeSH
• quercetin MeSH
• železo metabolismus   MeSH
• Check Tag
• lidé MeSH
• Publikační typ
• časopisecké články MeSH
• Názvy látek
• alergeny * MeSH
• kaseiny MeSH
• klathrin MeSH
• quercetin MeSH
• železo MeSH