BACKGROUND: Over the past two decades, the global incidence of gout has markedly increased, affecting people worldwide. Considering the side effects of xanthine oxidase (XO) inhibitor drugs (e.g. allopurinol and febuxostat) used in the treatment of hyperuricemia and gout, the potential application of phytochemicals has been widely studied. In addition, XO also takes part in the elimination of certain drugs, including 6-mercaptopurine. In the current explorative study, we aimed to examine the potential effects of tea catechins, resveratrol, silymarin flavonolignans and some of their conjugated metabolites on XO-catalyzed xanthine and 6-mercaptopurine oxidation, applying in vitro assays and modeling studies. RESULTS: Catechins, resveratrol and resveratrol conjugates exerted no or only weak inhibitory effects on XO. Silybin A, silybin B and isosilybin A were weak, silychristin was a moderate, while 2,3-dehydrosilychristin was a potent inhibitor of the enzyme. Sulfate metabolites of silybin A, silybin B and isosilybin A were considerably stronger inhibitors compared to the parent flavonolignans, and the sulfation of 2,3-dehydrosilychristin slightly increased its inhibitory potency. Silychristin was the sole flavonolignan tested, where sulfate conjugation decreased its inhibitory effect. CONCLUSION: 2,3-Dehydrosilychristin seems to be a promising candidate for examining its in vivo antihyperuricemic effects, because both the parent compound and its sulfate conjugate are highly potent inhibitors of XO. © 2024 The Author(s). Journal of the Science of Food and Agriculture published by John Wiley & Sons Ltd on behalf of Society of Chemical Industry.
- MeSH
- Enzyme Inhibitors * chemistry pharmacology MeSH
- Catalysis MeSH
- Catechin * chemistry analogs & derivatives pharmacology MeSH
- Humans MeSH
- Mercaptopurine * chemistry pharmacology metabolism MeSH
- Oxidation-Reduction * MeSH
- Resveratrol * chemistry pharmacology MeSH
- Silymarin * pharmacology chemistry MeSH
- Xanthine chemistry metabolism pharmacology MeSH
- Xanthine Oxidase * antagonists & inhibitors metabolism chemistry MeSH
- Check Tag
- Humans MeSH
- Publication type
- Journal Article MeSH
INTRODUCTION: Adrenergic activation of protein kinase A (PKA) in cardiac muscle targets the sarcolemma, sarcoplasmic reticulum, and contractile apparatus to increase contractile force and heart rate. In the thin filaments of the contractile apparatus, cardiac troponin I (cTnI) Ser22 and Ser23 in the cardiac-specific N-terminal peptide (NcTnI: residues 1 to 32) are the targets for PKA phosphorylation. Phosphorylation causes a 2-3 fold decrease of affinity of cTn for Ca2+ associated with a higher rate of Ca2+ dissociation from cTnC leading to a faster relaxation rate of the cardiac muscle (lusitropy). Cardiomyopathy-linked mutations primarily affect Ca2+ regulation or the PKA-dependent modulatory system, such that Ca2+-sensitivity becomes independent of phosphorylation level (uncoupling) and this could be sufficient to induce cardiomyopathy. A drug that could restore the phosphorylation-dependent modulation of Ca2+-sensitivity could have potential for treatment of these pathologies. We have found that a number of small molecules, including silybin B, resveratrol and EGCG, can restore coupling in single filament assays. METHODS: We did molecular dynamics simulations (5x1500ns for each condition) of the unphosphorylated and phosphorylated cardiac troponin core with the G159D DCM mutation in the presence of the 5 ligands and analysed the effects on several dynamic parameters. We also studied the effect of the ligands on the contractility of cardiac muscle myocytes with ACTC E99K and TNNT2 R92Q mutations in response to dobutamine. RESULTS: Silybin B, EGCG and resveratrol restored the phosphorylation-induced change in molecular dynamics to wild-type values, whilst silybin A, an inactive isomer of silybin B, and Epicatechin gallate, an EGCG analogue that does not recouple, did not. We analysed the atomic-level changes induced by ligand binding to explain recoupling. Mutations ACTC E99K and TNNT2 R92Q blunt the increased relaxation speed response to β1 adrenergic stimulation of cardiac myocytes and we found that resveratrol, EGCG and silybin B could restore the β1 adrenergic response, whereas silybin A did not. DISCUSSION: The uncoupling phenomenon caused by cardiomyopathy-related mutations and the ability of small molecules to restore coupling in vitro and lusitropy in myocytes is observed at the cellular, molecular and atomistic levels therefore, restoring lusitropy is a suitable target for treatment. Further research on compounds that restore lusitropy is thus indicated as treatments for genetic cardiomyopathies. Further molecular dynamics simulations could define the specific properties needed for recoupling and allow for the prediction and design of potential new drugs.
- Publication type
- Journal Article MeSH
Ostropestřec mariánský (Silybum marianum) je jednoletá nebo dvouletá bylina z čeledi hvězdnicovitých (Asteraceae). K léčbě jaterních onemocnění je používán již tisíce let. Pro tento účel se z ostropestřecových plodů vyrábí standardizovaný extrakt. Silymarin je komplex flavolignanů, hlavní složkou je silybin, silykristin a silydianin. Současný výzkum odhaluje další farmakologické účinky silymarinu včetně účinků na nervový systém. In vitro studie a experimenty na zvířatech odhalily antidepresivní, anxiolytický, neuroprotektivní a prokognitivní účinek. Klinických studií je však zatím minimum.
Milk thistle (Silybum marianum) is an annual or biennial plant of Compositae family (Asteraceae). It has been used for treatment of liver diseases for thousands of years. For this purpose, a standardized extract is made from milk thistle fruits. Silymarin is a complex of flavolignans, main active compounds are silybin, silychristin and silydianin. Current research discovers another pharmacological effects of silymarin, including effects on the nervous system. In vitro studies and animal experiments confirmed antidepressant, anxiolytic, neuroprotective, and procognitive effects. However, clinical studies ale still lacking.
CE method for the baseline separation of structurally similar flavonolignans silybin A, silybin B, isosilybin A, isosilybin B, silychristin, silydianin, and their precursor taxifolin in silymarin complex has been developed and validated. The optimized background electrolyte was 100 mmol/L boric acid (pH 9.0) containing 5 mmol/L heptakis(2,3,6-tri-O-methyl)-β-CD and 10% (v/v) of methanol. The separation was carried out in an 80.5/72 cm (50 μm id) fused silica capillary at +25 kV with UV detection at 200 nm. Genistein (10 μg/mL) was used as internal standard. The resolution between the diastereomers of silybin and isosilybin was 1.73 and 2.59, respectively. The method was validated for each analyte in a concentration range of 2.5-50 μg/mL. The calibration curves were rectilinear with correlation coefficients ≥0.9972. The method was applied to determine flavonolignans in two dietary supplements containing Silybum marianum extract. The accuracy was evaluated by comparing the results of the CE analyses of the dietary supplements with those of the reference United States Pharmacopeial HPLC method. The unpaired t-test did not show a statistically significant difference between the results of both the proposed CE and the reference method (p > 0.05, n = 3).
Metabolický syndrom je rozšířen zejména v ekonomicky vyspělých částech světa. Celosvětově je jím postiženo 20–25 % dospělé populace, ale v současnosti je pozorován častěji i u dětí a dospívajících. Standardní léčba často zahrnuje polyfarmakoterapii, která zvyšuje riziko vedlejších účinků způsobených mezilékovými (drug-drug) interakcemi. Proto je vhodné hledat alternativní zdroje pro podporu léčby komponent metabolického syndromu. Přírodní polyfenolické sloučeniny, zpravidla obsažené v tzv. funkčních potravinách, jsou vzhledem k jejich biologické aktivitě a příznivému vlivu na lidský organismus pro tuto problematiku vhodným kandidátem. Mezi aktuálně studované a užívané přírodní polyfenolické sloučeniny s pozitivním vlivem na složky metabolického syndromu patří quercetin, troxerutin, diosmin, hesperidin nebo silybin. Tyto polyfenoly, kromě antioxidačních a protizánětlivých účinků mají i další pozitivní vlastnosti, které velmi často násobně převyšují jejich vedlejší nežádoucí účinky během jejich užití ve farmakoterapii.
Metabolic syndrome is diagnosed mainly in people of economically developed parts of the world and it affects 20–25% of the adult population worldwide. Nowadays, it is also more frequently diagnosed in children and adolescents. In addition to standard treatment that often involves polypharmacotherapy, and thus increases risk of side effects caused by drugdrug interactions, it is appropriate to look for alternative tools to support the treatment of metabolic syndrome components. Natural polyphenolic compounds, usually present in the so-called functional foods, are suitable candidates for that matter, due to the bioactivity and beneficial effects on the human body. Quercetin, troxerutin, diosmin, hesperidin or silybin are among the currently studied and used natural polyphenolic compounds with a positive effect on aspects of the metabolic syndrome. In addition to their antioxidant and anti-inflammatory effects, these compounds have other positive properties that very often outweigh their side effects whilst their usage in the pharmacotherapy.
- Keywords
- troxerutin,
- MeSH
- Diosmin pharmacology therapeutic use MeSH
- Hesperidin pharmacology therapeutic use MeSH
- Humans MeSH
- Metabolic Syndrome * drug therapy pathology MeSH
- Dietary Supplements * MeSH
- Quercetin pharmacology therapeutic use MeSH
- Silybin pharmacology therapeutic use MeSH
- Check Tag
- Humans MeSH
- Publication type
- Research Support, Non-U.S. Gov't MeSH
- Review MeSH
Covering: 2015 up to 2022 (Feb)Silymarin, an extract of milk thistle (Silybum marianum) fruits, has been used in various medicinal applications since ancient times. A major component of silymarin is the flavonolignan silybin and its relatives isosilybin, silychristin, silydianin, 2,3-dehydrosilybin, and some others. Except for silydianin, they occur in nature as two stereomers. This review focuses on recent developments in chemistry, biosynthesis, modern advanced analytical methods, and transformations of flavonolignans specifically reflecting their chirality. Recently described chemotypes of S. marianum, but also the newest findings regarding the pharmacokinetics, hepatoprotective, antiviral, neuroprotective, and cardioprotective activity, modulation of endocrine functions, modulation of multidrug resistance, and safety of flavonolignans are discussed. A growing number of studies show that the respective diastereomers of flavonolignans have significantly different activities in anisotropic biological systems. Moreover, it is now clear that flavonolignans do not act as antioxidants in vivo, but as specific ligands of biological targets and therefore their chirality is crucial. Many controversies often arise, mainly due to the non-standard composition of this phytopreparation, the use of various undefined mixtures, the misattribution of silymarin vs. silybin, and also the failure to consider the chemistry of the respective components of silymarin.
Antibiotic resistance is currently a serious health problem. Since the discovery of new antibiotics no longer seems to be a sufficient tool in the fight against multidrug-resistant infections, adjuvant (combination) therapy is gaining in importance as well as reducing bacterial virulence. Silymarin is a complex of flavonoids and flavonolignans known for its broad spectrum of biological activities, including its ability to modulate drug resistance in cancer. This work aimed to test eleven, optically pure silymarin flavonolignans for their ability to reverse the multidrug resistance phenotype of Staphylococcus aureus and reduce its virulence. Silybin A, 2,3-dehydrosilybin B, and 2,3-dehydrosilybin AB completely reversed antibiotic resistance at concentrations of 20 μM or less. Both 2,3-dehydrosilybin B and AB decreased the antibiotic-induced gene expression of representative efflux pumps belonging to the major facilitator (MFS), multidrug and toxic compound extrusion (MATE), and ATP-binding cassette (ABC) families. 2,3-Dehydrosilybin B also inhibited ethidium bromide accumulation and efflux in a clinical isolate whose NorA and MdeA overproduction was induced by antibiotics. Most of the tested flavonolignans reduced cell-to-cell communication on a tetrahydrofuran-borate (autoinducer-2) basis, with isosilychristin leading the way followed by 2,3-dehydrosilybin A and AB, which halved communication at 10 μM. Anhydrosilychristin was the only compound that reduced communication based on acyl-homoserine lactone (autoinducer 1), with an IC50 of 4.8 μM. Except for isosilychristin and anhydrosilychristin, all of the flavonolignans inhibited S. aureus surface colonization, with 2,3-dehydrosilybin A being the most active (IC50 10.6 μM). In conclusion, the selected flavonolignans, particularly derivatives of 2,3-dehydrosilybin B, 2,3-dehydrosilybin AB, and silybin A are non-toxic modulators of S. aureus multidrug resistance and can decrease the virulence of the bacterium, which deserves further detailed research.
Silymarin, standardizovaný extrakt z plodu Silybum marianum, je osvědčeným přírodním doplňkem stravy, jenž je využívaný k podpoře léčby řady patologických stavů organismu. Metformin podávaný se silymarinem může zmírnit rozvoj jaterní steatózy, zejména v prediabetickém stavu. Fenofibrát v kombinaci se silymarinem může snížit lipoperoxidaci a expresi CYP2E1 (a tím i produkci ROS), což přispívá ke snížení rizika rozvoje komplikací steatózy v játrech. Mechanismus jeho hypolipidemického působení nespočívá v aktivaci PPARα receptorů (jak je tomu například u fibrátů), ale pravděpodobně ve snížení absorpce cholesterolu ze střeva (což působí i jeho polymerní frakce) nebo zvýšené expresi cytochromů P450 zapojených do metabolismu a vylučování cholesterolu. Upregulace transportních proteinů ABCG5 a ABCG8 silymarinem a n-3 PUFA snižuje hladinu triglyceridů a celkového cholesterolu, což může působit preventivně v rozvoji metabolických poruch vyvolaných hypertriglyceridemií. Uvedené závěry in vivo studií ukazují pozitivní působení silymarinu (ať už jeho komponent, nebo celku) na organismus v rámci prevence nebo podpůrné léčby řady onemocnění včetně metabolického syndromu.
Silymarin, a standardized extract from the Silybum marianum fruit, is a proven natural food supplement that is used to support the treatment of a number of pathological conditions of the organism. Metformin administered with silymarin may reduce the development of hepatic steatosis, especially in the prediabetic state. Fenofibrate in combination with silymarin can reduce lipoperoxidation and CYP2E1 expression (and thus ROS production) which contributes to reducing the risk of developing complications of steatosis in the liver. Mechanism of its hypolipidemic effect does not work via activation of PPARα receptors (as it does in the case of fibrates), but probably in the reduction of cholesterol absorption from the intestine (which is also the effect of its polymer fraction) or in the increased expression of cytochromes P450 involved in the metabolism and excretion of cholesterol. Upregulation of transport proteins ABCG5 and ABCG8 by silymarin and n-3 PUFA reduces the level of triglycerides and total cholesterol, which can act preventively in the development of metabolic disorders caused by hypertriglyceridemia. The stated conclusions of in vivo studies show a positive effect of silymarin (whether its component or whole) on the organism in the prevention or supportive treatment of a number of diseases, including metabolic syndrome.
- MeSH
- Humans MeSH
- Liver Diseases drug therapy MeSH
- Plant Extracts therapeutic use MeSH
- Silybin pharmacology therapeutic use MeSH
- Silymarin * analysis pharmacology therapeutic use MeSH
- Check Tag
- Humans MeSH
- Publication type
- Review MeSH
Silymarin is known for its hepatoprotective effects. Although there is solid evidence for its protective effects against Amanita phalloides intoxication, only inconclusive data are available for alcoholic liver damage. Since silymarin flavonolignans have metal-chelating activity, we hypothesized that silymarin may influence alcoholic liver damage by inhibiting zinc-containing alcohol dehydrogenase (ADH). Therefore, we tested the zinc-chelating activity of pure silymarin flavonolignans and their effect on yeast and equine ADH. The most active compounds were also tested on bovine glutamate dehydrogenase, an enzyme blocked by zinc ions. Of the six flavonolignans tested, only 2,3-dehydroderivatives (2,3-dehydrosilybin and 2,3-dehydrosilychristin) significantly chelated zinc ions. Their effect on yeast ADH was modest but stronger than that of the clinically used ADH inhibitor fomepizole. In contrast, fomepizole strongly blocked mammalian (equine) ADH. 2,3-Dehydrosilybin at low micromolar concentrations also partially inhibited this enzyme. These results were confirmed by in silico docking of active dehydroflavonolignans with equine ADH. Glutamate dehydrogenase activity was decreased by zinc ions in a concentration-dependent manner, and this inhibition was abolished by a standard zinc chelating agent. In contrast, 2,3-dehydroflavonolignans blocked the enzyme both in the absence and presence of zinc ions. Therefore, 2,3-dehydrosilybin might have a biologically relevant inhibitory effect on ADH and glutamate dehydrogenase.
- MeSH
- Alcohol Dehydrogenase antagonists & inhibitors MeSH
- Chelating Agents pharmacology MeSH
- Flavonolignans pharmacology MeSH
- Glutamate Dehydrogenase antagonists & inhibitors MeSH
- Horses MeSH
- Yeasts drug effects MeSH
- Silybin pharmacology MeSH
- Silymarin pharmacology MeSH
- Zinc isolation & purification metabolism MeSH
- Animals MeSH
- Check Tag
- Animals MeSH
- Publication type
- Journal Article MeSH
