Polyphenols of cocoa: inhibition of mammalian 15-lipoxygenase

Harnessing the Power of Polyphenols: A New Frontier in Disease Prevention and Therapy

There are a wide variety of phytochemicals collectively known as polyphenols. Their structural diversity results in a broad range of characteristics and biological effects. Polyphenols can be found in a variety of foods and drinks, including fruits, cereals, tea, and coffee. Studies both in vitro and in vivo, as well as clinical trials, have shown that they possess potent antioxidant activities, numerous therapeutic effects, and health advantages. Dietary polyphenols have demonstrated the potential to prevent many health problems, including obesity, atherosclerosis, high blood sugar, diabetes, hypertension, cancer, and neurological diseases. In this paper, the protective effects of polyphenols and the mechanisms behind them are investigated in detail, citing the most recent available literature. This review aims to provide a comprehensive overview of the current knowledge on the role of polyphenols in preventing and managing chronic diseases. The cited publications are derived from in vitro, in vivo, and human-based studies and clinical trials. A more complete understanding of these naturally occurring metabolites will pave the way for the development of novel polyphenol-rich diet and drug development programs. This, in turn, provides further evidence of their health benefits.

Synthesis, structural characterization and study of antioxidant and anti-PrPSc properties of flavonoids and their rhenium(I)-tricarbonyl complexes

This study aims at the synthesis and initial biological evaluation of novel rhenium-tricarbonyl complexes of 3,3',4',5,7-pentahydroxyflavone (quercetin), 3,7,4΄-trihydroxyflavone (resokaempferol), 5,7-dihydroxyflavone (chrysin) and 4΄,5,7-trihydroxyflavonone (naringenin) as neuroprotective and anti-PrP agents. Resokaempferol was synthesized from 2,2΄,4-trihydroxychalcone by H₂O₂/NaOH. The rhenium-tricarbonyl complexes of the type fac-[Re(CO)₃(Fl)(sol)] were synthesized by reacting the precursor fac-[Re(CO)₃(sol)₃]⁺ with an equimolar amount of the flavonoids (Fl) quercetin, resokaempferol, chrysin and naringenin and the solvent (sol) was methanol or water. The respective Re-flavonoid complexes were purified by semi-preparative HPLC and characterized by spectroscopic methods. Furthermore, the structure of Re-chrysin was elucidated by X-ray crystallography. Initial screening of the neuroprotective properties of these compounds included the in vitro assessment of the antioxidant properties by the DPPH assay as well as the anti-lipid peroxidation of linoleic acid in the presence of AAPH and their ability to inhibit soybean lipoxygenase. From the above studies, it was concluded that the complexes' properties are mainly correlated with the structural characteristics and the presence of the flavonoids. The flavonoids and their respective Re-complexes were also tested in vitro for their ability to inhibit the formation and aggregation of the amyloid-like abnormal prion protein, PrP^Sc, by employing the real-time quaking-induced conversion assay with recombinant PrP seeded with cerebrospinal fluid from patients with Creutzfeldt-Jakob disease. All the compounds blocked de novo abnormal PrP formation and aggregation.

Dietary proanthocyanidins promote localized antioxidant responses in porcine pulmonary and gastrointestinal tissues during Ascaris suum-induced type 2 inflammation

Proanthocyanidins (PAC) are dietary polyphenols with putative anti-inflammatory and immunomodulatory effects. However, whether dietary PAC can regulate type-2 immune function and inflammation at mucosal surfaces remains unclear. Here, we investigated if diets supplemented with purified PAC modulated pulmonary and intestinal mucosal immune responses during infection with the helminth parasite Ascaris suum in pigs. A. suum infection induced a type-2 biased immune response in lung and intestinal tissues, characterized by pulmonary granulocytosis, increased Th2/Th1 T cell ratios in tracheal-bronchial lymph nodes, intestinal eosinophilia, and modulation of genes involved in mucosal barrier function and immunity. Whilst PAC had only minor effects on pulmonary immune responses, RNA-sequencing of intestinal tissues revealed that dietary PAC significantly enhanced transcriptional responses related to immune function and antioxidant responses in the gut of both naïve and A. suum-infected animals. A. suum infection and dietary PAC induced distinct changes in gut microbiota composition, primarily in the jejunum and colon, respectively. Notably, PAC consumption substantially increased the abundance of Limosilactobacillus reuteri. In vitro experiments with porcine macrophages and intestinal epithelial cells supported a role for both PAC polymers and PAC-derived microbial metabolites in regulating oxidative stress responses in host tissues. Thus, dietary PAC may have distinct beneficial effects on intestinal health during infection with mucosal pathogens, while having a limited activity to modulate naturally-induced type-2 pulmonary inflammation. Our results shed further light on the mechanisms underlying the health-promoting properties of PAC-rich foods, and may aid in the design of novel dietary supplements to regulate mucosal inflammatory responses in the gastrointestinal tract.

Paralog- and ortholog-specificity of inhibitors of human and mouse lipoxygenase-isoforms

Lipoxygenases (ALOX-isoforms) are lipid peroxidizing enzymes, which have been implicated in cell differentiation and maturation but also in the biosynthesis of lipid mediators playing important roles in the pathogenesis of inflammatory, hyperproliferative and neurological diseases. In mammals these enzymes are widely distributed and the human genome involves six functional genes encoding for six distinct human ALOX paralogs. In mice, there is an orthologous enzyme for each human ALOX paralog but the catalytic properties of human and mouse ALOX orthologs show remarkable differences. ALOX inhibitors are frequently employed for deciphering the biological role of these enzymes in mouse models of human diseases but owing to the functional differences between mouse and human ALOX orthologs the uncritical use of such inhibitors is sometimes misleading. In this study we evaluated the paralog- and ortholog-specificity of 13 frequently employed ALOX-inhibitors against four recombinant human and mouse ALOX paralogs (ALOX15, ALOX15B, ALOX12, ALOX5) under different experimental conditions. Our results indicated that except for zileuton, which exhibits a remarkable paralog-specificity for mouse and human ALOX5, no other inhibitor was strictly paralog specific but some compounds exhibit an interesting ortholog-specificity. Because of the variable isoform specificities of the currently available ALOX inhibitors care must be taken when the biological effects of these compounds observed in complex in vitro and in vivo systems are interpreted.

Docking Characterization and in vitro Inhibitory Activity of Flavan-3-ols and Dimeric Proanthocyanidins Against the Main Protease Activity of SARS-Cov-2

We report to use the main protease (M^pro) of SARS-Cov-2 to screen plant flavan-3-ols and proanthocyanidins. Twelve compounds, (-)-afzelechin (AF), (-)-epiafzelechin (EAF), (+)-catechin (CA), (-)-epicatechin (EC), (+)-gallocatechin (GC), (-)-epigallocatechin (EGC), (+)-catechin-3-O-gallate (CAG), (-)-epicatechin-3-O-gallate (ECG), (-)-gallocatechin-3-O-gallate (GCG), (-)-epigallocatechin-3-O-gallate (EGCG), procyanidin A2 (PA2), and procyanidin B2 (PB2), were selected for docking simulation. The resulting data predicted that all 12 metabolites could bind to M^pro. The affinity scores of PA2 and PB2 were predicted to be -9.2, followed by ECG, GCG, EGCG, and CAG, -8.3 to -8.7, and then six flavan-3-ol aglycones, -7.0 to -7.7. Docking characterization predicted that these compounds bound to three or four subsites (S1, S1', S2, and S4) in the binding pocket of M^pro via different spatial ways and various formation of one to four hydrogen bonds. In vitro analysis with 10 available compounds showed that CAG, ECG, GCG, EGCG, and PB2 inhibited the M^pro activity with an IC₅₀ value, 2.98 ± 0.21, 5.21 ± 0.5, 6.38 ± 0.5, 7.51 ± 0.21, and 75.3 ± 1.29 μM, respectively, while CA, EC, EGC, GC, and PA2 did not have inhibitory activities. To further substantiate the inhibitory activities, extracts prepared from green tea (GT), two muscadine grapes (MG), cacao, and dark chocolate (DC), which are rich in CAG, ECG, GAG, EGCG, or/and PB2, were used for inhibitory assay. The resulting data showed that GT, two MG, cacao, and DC extracts inhibited the M^pro activity with an IC₅₀ value, 2.84 ± 0.25, 29.54 ± 0.41, 29.93 ± 0.83, 153.3 ± 47.3, and 256.39 ± 66.3 μg/ml, respectively. These findings indicate that on the one hand, the structural features of flavan-3-ols are closely associated with the affinity scores; on the other hand, the galloylation and oligomeric types of flavan-3-ols are critical in creating the inhibitory activity against the M^pro activity.

The Effects of Flavonoids in Cardiovascular Diseases

Flavonoids are metabolites of plants and fungus. Flavonoid research has been paid special attention to in recent times after the observation of their beneficial effects on the cardiovascular system. These favorable effects are exerted by flavonoids mainly due to their antioxidant properties, which result from the ability to decrease the oxidation of low-density lipoproteins, thus improving the lipid profiles. The other positive effect exerted on the cardiovascular system is the ability of flavonoids to produce vasodilation and regulate the apoptotic processes in the endothelium. Researchers suggested that these effects, including their anti-inflammatory function, are consequences of flavonoids' potent antioxidant properties, but recent studies have shown multiple signaling pathways linked to them, thus suggesting that there are more mechanisms involved in the beneficial effect of the flavonoids on the human body. This review aims to present the latest data on the classification of these substances, their main mechanisms of action in the human body, and the beneficial effects on the physiological and pathological status of the cardiovascular system.

Impact of food polyphenols on oxylipin biosynthesis in human neutrophils

The intake of food polyphenols is associated with beneficial impacts on health. Besides anti-oxidative effects, anti-inflammatory properties have been suggested as molecular modes of action, which may result from modulations of the arachidonic acid (AA) cascade. Here, we investigated the effects of a library of food polyphenols on 5-lipoxygenase (5-LOX) activity in a cell-free assay, and in human neutrophils. Resveratrol, its dimer (ε-viniferin), and its imine analogue (IRA) potently blocked the 5-LOX-mediated LT formation in neutrophils with IC₅₀ values in low μM-range. Among the tested flavonoids only the isoflavone genistein showed potent 5-LOX inhibition in neutrophils (IC₅₀ = 0.4 ± 0.1 μM), however was ineffective on isolated 5-LOX. We exclude an interference with the 5-LOX-activating protein (FLAP) in HEK_5-LOX/±FLAP cells and suggest global effects on intact immune cells. Using LC-MS based targeted oxylipin metabolomics, we analyzed the effects of 5-LOX-inhibiting polyphenols on all branches of the AA cascade in Ca²⁺-ionophore-challenged neutrophils. While ε-viniferin causes a clear substrate shunt towards the remaining AA cascade enzymes (15-LOX, cyclooxygenase - COX-1/2, cytochrome P450), resveratrol inhibited the COX-1/2 pathway and showed a weak attenuation of 12/15-LOX activity. IRA had no impact on 15-LOX activity, but elevated the formation of COX-derived prostaglandins, having no inhibitory effects on COX-1/2. Overall, we show that food polyphenols have the ability to block 5-LOX activity and the oxylipin pattern is modulated with a remarkable compound/structural specificity. Taken the importance of polyphenols for a healthy diet and their concentration in food supplements into account, this finding justifies further investigation.

Cardioprotective Mechanisms of Cocoa

Cardiovascular diseases are the main cause of deaths in highly developed countries. Dietetic interventions that involve recommendations for consumption of products with a confirmed health-improving action are an important aspect of prevention of cardiovascular diseases. Cocoa is an alimentary product with significant cardioprotective potential due to its high content of bioactive compounds. The aim of the present study was to review the most recent literature concerning the effectiveness and mechanisms of action of compounds contained in cocoa with regard to selected cardiovascular risk factors and cardiometabolic markers. Study results indicate that cocoa consumption, especially in the form of dark chocolate with high flavonoid content, may be a good strategy to diminish cardiovascular risk due to its beneficial effect on platelet aggregation, decreasing blood pressure, diminishing dyslipidemia, and decreasing blood plasma glucose concentration. Many studies have shown that cocoa-derived flavonoids have antioxidant and anti-inflammatory activity and also play a significant role in preventing insulin resistance. However, in order to completely confirm the potential cardiovascular benefits, it is necessary to conduct larger and longer studies, also with regard to potential dangers associated with long-term consumption of large amounts of flavonoids and determination of a safe and effective dose. Key teaching points Cocoa consumption may be a good strategy in diminishing cardiovascular risk. Beneficial effects on platelet aggregation, blood pressure, dyslipidemia, glycemia, as well as antioxidant and anti-inflammatory activity are observed. There is a need to conduct larger and longer studies to determine a safe and effective dose of cocoa flavonoids.

Cardioprotection by Cocoa Polyphenols and ω-3 Fatty Acids: A Disease-Prevention Perspective on Aging-Associated Cardiovascular Risk

Cardiovascular disease (CVD) remains the leading cause of death today. Many of the biochemical alterations associated with the pathophysiology of CVD can be modified by adequate intakes of bioactive nutrients through a correct diet or supplementation. Recently, there has been growing public and clinical interest in cocoa polyphenols (CPs) and omega-3 (ω-3) fatty acids. A plethora of nutritional intervention trials and experimental studies demonstrates that consumption of these bioactive food compounds is beneficial to promote cardiovascular health. The purpose of this review is to summarize the major cardioprotective effects of CPs and ω-3 fatty acids, providing a scientific rationale for incorporating the combination of these molecules as a nutritional intervention in the prevention of CVD. Although several studies have shown the individual cardioprotective nature of these compounds, a combination treatment with CPs and ω-3 fatty acids may be a promising approach to enhance the preventive value of these molecules and reduce cardiovascular risk factors associated with aging. Therefore, this article also reviews some of the key studies on the interaction between CPs and the metabolism of ω-3 fatty acids.

Effects of the supplementation with an high-polyphenols extra-virgin olive oil on kinetic sperm features and seminal plasma oxidative status in healthy dogs

The aim of this work was to evaluate the effects of the supplementation of two extra-virgin olive oils (EVOO) having different polyphenols content, on canine spermatozoa kinetic parameters and seminal plasma oxidative status. The study was conducted on 12 clinically healthy dogs of different breeds (2-7 years, 5-48 kg of body weight) divided into two groups: an experimental group supplemented with EVOO (Coratina cultivar) high in polyphenols (H-P) and a control group fed EVOO (Cima di Bitonto cultivar) low in polyphenols (L-P). The oil was daily administered per os (1 ml/3 kg BW) before meal. Semen collection was made twice at 15 days distance (D0₁ and D0₂ ) and then at 30 (D30), 60 (D60) and 90 (D90) days. Semen concentration and kinetic parameters were measured using computer-assisted sperm analysis (CASA) system to evaluate: sperm total count, sperm motile (MOT%), progressive motility (PROGR%) and its fractions, straight-line velocity (VSL, μm/s), curvilinear velocity (VCL, μm/s), average path velocity (VAP, μm/s), amplitude of lateral head displacement (ALH, μm), beat cross frequency (BCF, Hz), straightness (STR%) and linearity (LIN%). On seminal plasma, reactive oxygen species (ROS) and biological antioxidant potential (BAP) were tested. From findings, no differences were found for sperm MOT, VSL, VCL, VAP, ALH, BCF, STR, LIN and BAP. A gradual enhancement of PROGR% was observed in H-P group (p < .01). The ROS levels were higher in dogs H-P compared to the other group (p < .05). In conclusion, our results highlight the positive effects of EVOO polyphenols on sperm PROGR% in healthy dogs.

Mast cells and pro-inflammatory cytokines roles in assessment of grape seeds extract anti-inflammatory activity in rat model of carrageenan-induced paw edema

OBJECTIVES

Reactive oxygen species (ROS)-produced oxidative disorders were involved at the pathophysiology of many inflammatory processes via the generation of pro-inflammatory cytokines and antioxidant defense system suppression. Although herbal antioxidants as mono-therapy relief many inflammatory diseases including, autoimmunity rheumatoid arthritis, but as combination therapy with other proven anti-inflammatory drugs in order to decreasing their toxic impacts has not yet been studied clearly, especially against chemical substances that's induced local inflammation with characteristic edema.

MATERIALS AND METHODS

Grape seeds extract (GSE) at a concentration of 40 mg/kg B. wt alone or in combination with indomethacin (Indo.) at a dose of 5 mg/Kg B. wt orally given for 10 days prior (gps VI, VII, VIII) or as a single dose after edema induction (gps IX, X, XI) in rat's left hind paw by sub-planter single injection of 0.1 carrageenan: saline solution (1%) (gp. V) to assess the prophylactic and therapeutic anti-inflammatory activities of both through the estimation of selective inflammatory mediators and oxidative damage-related biomarkers as well as tissue mast cell scoring. Furthermore, both substances were given alone (gps II, III, IV) for their blood, liver and kidney safety evaluation comparing with negative control rats (gp. I) which kept without medication.

RESULTS

A marked reduction on the inflammatory mediators, edema volume and oxidative byproducts in edema bearing rats' prophylactic and treated with grape seeds extract and indomethacin was observed. Indomethacin found to induce some toxicological impacts which minimized when administered together with GSE.

CONCLUSION

GSE is a safe antioxidant agent with anti-inflammatory property.

Do flavanols-rich natural products relieve obesity-related insulin resistance?

Growing evidence support that insulin resistance may occur as a severe problem due to chronic energetic overfeeding and subsequent obesity. When an abundance of glucose and saturated fat enter the cell, impaired blood flow, hypoxia, inflammation and macrophage infiltration in obese adipose tissue may induce oxidative stress and insulin resistance. Excessive circulating saturated fatty acids ectopically accumulate in insulin-sensitive tissues and impair insulin action. In this context, excessive hepatic lipid accumulation may play a central, pathogenic role in insulin resistance. It is thought that dietary polyphenols may ameliorate obesity-related insulin resistance by attenuating inflammatory responses and oxidative stress. The most often occurring natural polyphenolic compounds are flavonoids. In this review, the possible mechanistic effect of flavonoid-rich natural products on insulin resistance-related metabolic pathways is discussed. Polyphenol intake can prevent high-fat-diet-induced insulin resistance via cell surface G protein-coupled estrogen receptors by upregulating the expression of related genes, and their pathways, which are responsible for the insulin sensitivity.

Nutritional constituents, phytochemical profiles, in vitro antioxidant and antimicrobial properties, and gas chromatography-mass spectrometry analysis of various solvent extracts from grape seeds (Vitis vinifera L.)

The present study revealed that the nutritive value of grape seeds (Vitis vinifera L.) was 383.55±0.13 Kcal/100 g, with magnesium as the most abundant mineral element (70.44±0.88 mg/L). The maximum phenolic (392.58±1.70mg of GAE/g), flavonoid (256.16±1.60 mg of QE/g), and tannin (30.95±0.17mg of CE/g) contents were also found in the ethanol, dichloromethane, and hexane extracts, respectively. The major phytochemical compounds in the ethyl acetate extract were identified via gas chromatography-mass spectrometry (GC-MS) analysis. The ethanol extract has the highest antioxidant activity (IC50=140±1.20 μg/mL for DPPH, 145.28±0.45mg α-tocopherol/g for total antioxidant capacity, and EC50=80±1.41 μg/mL for ferric-reducing power assays). For β-carotene test, the highest antioxidant activity was obtained in the hexane extract. A satisfactory antimicrobial activity was found against a panel of microorganisms with the ethyl acetate extract as the best antimicrobial agent. Additionally, it was found that the bactericidal concentration required for the grape seed extract to kill Listeria monocytogenes should be less than 12.50 mg/mL (minimum inhibitory concentration=4).

Pentameric Procyanidins Isolated from Theobroma cacao Seeds Selectively Downregulate ErbB2 in Human Aortic Endothelial Cells

Flavonoids isolated from cocoa have biological activities relevant to oxidant defenses, vascular health, tumor suppression, and immune function. The intake of certain dietary flavonoids, along with other dietary substances such as tocopherols, ascorbate, and carotenoids, is epidemiologically associated with a reduced risk of cardiovascular disease. Flavonoids have also been shown to modulate tumor pathology in vitro and in animal models. We took advantage of the conserved sequences found in tyrosine kinases to study the influence of cocoa fractions and controls on gene expression. We report that the pentameric procyanidin (molecular weight of 1442 daltons) fraction isolated from cocoa was a potent inhibitor of tyrosine kinase ErbB2 expression, a receptor important in angiogenesis regulation. Consistent with this primary observation, the cocoa flavonoid fraction also suppressed human aortic endothelial cell (HAEC) growth and decreased expression of two tyrosine kinases responsive to ErbB2 modulation, namely VEGFR-2/KDR and MapK 11/p38β2. These inhibitory effects were observed when HAECs were treated with the flavonol fraction (molecular weight 280 daltons) isolated from cocoa, which comprise the structural subunits from which the procyanidin flavonoid subclass is biosynthetically constructed. Down-regulation of ErbB2 and inhibition of HAEC growth by cocoa procyanidins may have several downstream implications, including reduced vascular endothelial growth factor (VEGF) activity and angiogenic activity associated with tumor pathology. These results suggest specific dietary flavonoids are capable of selectively inhibiting ErbB2 and therefore may offer important insight into the design of therapeutic agents that target tumors overexpressing ErbB2.

Review: Health Effects of Cocoa Flavonoids

Flavonoids are phenolic substances widely found in fruits and vegetables. Many epidemiological studies associate the ingestion of flavonoids with a reduced risk of cardiovascular disease and certain types of cancer. These effects are due to the physiological activity of flavonoids in the reduction of oxidative stress, inhibiting low-density lipoproteins (LDL) oxidation and platelet aggregation, acting as vasodilators in blood vessels, inhibiting the adherence of monocytes to the vascular endothelium, promoting fibrinolysis, acting as immunomodulators and anti-inflammatory agents and as inhibitors in the different phases of tumour process. Cocoa is an important source of polyphenols, which comprise 12-18% of its total weight on dry basis; the major phenolic compounds are epicatechin, proanthocyanidins and cate-chin. The levels of flavonoids contained are higher than the ones founds in apples, onions or wine, foods known for their high amount of phenolic compounds. Cocoa and cocoa products are important sources of flavonoids in our diet. In the Dutch population chocolate contributes up to 20% of the total flavonoid intake in adults, and in children the percentage is even higher. The bioavailability of these compounds depends on other food constituents, and their interaction with the food matrix. This article reviews current evidence on the health effects of cocoa flavonoids in our diet. The compiled data supports the premise that the consumption of cocoa flavonoids is beneficial to human health.

A randomized controlled trial of green tea catechins in protection against ultraviolet radiation-induced cutaneous inflammation

BACKGROUND

Safe systemic protection from the health hazards of ultraviolet radiation (UVR) in sunlight is desirable. Green tea is consumed globally and is reported to have anti-inflammatory properties, which may be mediated through the impact on cyclooxygenase and lipoxygenase pathways. Recent data suggest that green tea catechins (GTCs) reduce acute UVR effects, but human trials examining their photoprotective potential are scarce.

OBJECTIVE

We performed a double-blind, randomized, placebo-controlled trial to examine whether GTCs protect against clinical, histologic, and biochemical indicators of UVR-induced inflammation.

DESIGN

Healthy adults (aged 18-65 y, phototypes I-II) were randomly allocated to 1350 mg encapsulated green tea extract (540 mg GTC) with 50 mg vitamin C or placebo twice daily for 3 mo. Impact on skin erythema, dermal leukocytic infiltration, and concentrations of proinflammatory eicosanoids was assessed after solar-simulated UVR challenge, and subject compliance was determined through assay of urinary GTC metabolite epigallocatechin glucuronide.

RESULTS

Volunteers were assigned to the active (n = 25) or the placebo (n = 25) group. After supplementation, median (IQR) sunburn threshold (minimal erythema dose) was 28 (20-28) and 20 (20-28) mJ/cm(2) in the active and placebo groups, respectively (nonsignificant), with no difference in AUC analysis for measured erythema index after a geometric series of 10 UVR doses. Skin immunohistochemistry showed increased neutrophil and CD3(+) T-lymphocyte numbers post-UVR in both groups (P < 0.01) with no statistically significant differences between groups after supplementation. Cyclooxygenase and lipoxygenase metabolites prostaglandin E2 (vasodilator) and 12-hydroxyeicosatetraenoicacid (chemoattractant), respectively, increased after UVR (P < 0.05), with no differences between supplementation groups.

CONCLUSION

Oral GTC (1080 mg/d) with vitamin C over 3 mo did not significantly reduce skin erythema, leukocyte infiltration, or eicosanoid response to UVR inflammatory challenge. This trial was registered at clinicaltrials.gov as NCT01032031.

Redox pioneer: professor Helmut Sies

Dr. Helmut Sies (MD, 1967) is recognized as a Redox Pioneer, because he authored five articles on oxidative stress, lycopene, and glutathione, each of which has been cited more than 1000 times, and coauthored an article on hydroperoxide metabolism in mammalian systems cited more than 5000 times (Google Scholar). He obtained preclinical education at the University of Tübingen and the University of Munich, clinical training at Munich (MD, 1967) and Paris, and completed Habilitation at Munich (Physiological Chemistry and Physical Biochemistry, 1972). In early research, he first identified hydrogen peroxide (H2O2) as a normal aerobic metabolite and devised a method to quantify H2O2 concentration and turnover in cells. He quantified central redox systems for energy metabolism (NAD, NADP systems) and antioxidant GSH in subcellular compartments. He first described ebselen, a selenoorganic compound, as a glutathione peroxidase mimic. He contributed a fundamental discovery to the physiology of GSH, selenium nutrition, singlet oxygen biochemistry, and health benefits of dietary lycopene and cocoa flavonoids. He has published more than 600 articles, 134 of which are cited at least 100 times, and edited 28 books. His h-index is 115. During the last quarter of the 20th century and well into the 21st, he has served as a scout, trailblazer, and pioneer in redox biology. His formulation of the concept of oxidative stress stimulated and guided research in oxidants and antioxidants; his pioneering research on carotenoids and flavonoids informed nutritional strategies against cancer, cardiovascular disease, and aging; and his quantitative approach to redox biochemistry provides a foundation for modern redox systems biology. Helmut Sies is a true Redox Pioneer.

Antioxidant/Prooxidant and antibacterial/probacterial effects of a grape seed extract in complex with lipoxygenase

In an attempt to determine the antioxidant/prooxidant, antibacterial/probacterial action of flavan-3-ols and procyanidins from grape seeds, pure catechin (CS), and an aqueous grape seed extract (PE), were applied in the absence and presence of pure lipoxygenase (LS) or in extract (LE) to leucocyte culture, Escherichia coli B 41 and Brevibacterium linens, and observed whether there was any effect on lipid peroxidation, cytotoxicity, or growth rate. Short time periods of coincubation of cells with the polyphenols, followed by the exposure to LS and LE, revealed a high level of lipid peroxidation and a prooxidative effect. Longer coincubation and addition of LS and LE resulted in the reversal of the prooxidant action either to antioxidant activity for CS + LS and PE + LS or to the control level for CS + LE and PE + LE. Lipid peroxidation was significantly reduced when cells were exposed to polyphenols over a longer period. Longer exposure of E. coli to CS or PE followed by addition of LS for 3 h resulted in bactericidal activity. Significant stimulatory effect on microbial growth was observed for PE + LS and PE + LE treatments in B. linens, illustrating the potential probacterial activity in B. linens cultures. Lipoxygenase-polyphenols complex formation was found to be responsible for the observed effects.

Cuminaldehyde as a lipoxygenase inhibitor: in vitro and in silico validation

The search for lipoxygenase (LOX) inhibitors has been carried out for decades due to its importance in inflammatory diseases. In the present study, it was observed that the methanolic extract of Cuminum cyminum L. inhibited LOX activity. Activity-guided screening of the C. cyminum crude extracts helped the identification and isolation of cuminaldehyde as a 15-LOX inhibitor. The enzyme kinetics analysis suggested cuminaldehyde to be a competitive inhibitor and the IC 50 value derived from LB plots is 1,370 μM. Binding constants of cuminaldehyde on LOX was deduced by isothermal titration calorimetry. The combined thermodynamics and molecular modeling analyses suggested cuminaldehyde as a competitive LOX inhibitor. It is proposed from the present study that the coordinate bond between the Fe(2+) atom in the active site of the enzyme and the cuminaldehyde may be responsible for the enzyme inhibition. The study suggests that cuminaldehyde may be acting as an anti-inflammatory compound and may be therefore included in the category of leads for developing dual COX-LOX inhibitors as non-steroidal anti-inflammatory drugs (NSAIDs).

Consumption of both low and high (-)-epicatechin apple puree attenuates platelet reactivity and increases plasma concentrations of nitric oxide metabolites: a randomized controlled trial

We hypothesised that consumption of flavanol-containing apple puree would modulate platelet activity and increase nitric oxide metabolite status, and that high flavanol apple puree would exert a greater effect than low flavanol apple puree. 25 subjects consumed 230 g of apple puree containing 25 and 100mg epicatechin (low and high flavanol apple puree, respectively) and aspirin (75 mg) in random order. Measurements were made at baseline, acutely after treatment (2, 6 and 24 h), and after 14 d of treatment. Low flavanol apple puree significantly attenuated ADP and epinephrine-induced integrin-β3 expression 2 h and 6 h after consumption and ADP and epinephrine-induced P-selectin expression within 2h of consumption. High flavanol apple puree attenuated epinephrine and ADP-induced integrin-β3 expression after 2 and 6h. ADP and epinephrine-induced integrin-β3 expression was significantly attenuated 2, 6 and 24 h after consumption of aspirin, whilst 14 d aspirin consumption attenuated collagen-induced P-selectin expression only. The plasma total nitric oxide metabolite conc. was significantly increased 6h after consumption of both low and high flavanol apple purees. In conclusion, consumption of apple purees containing ⩾25 or 100 mg flavanols transiently attenuated ex vivo integrin-β3 and P-selectin expression and increased plasma nitric oxide metabolite conc. in healthy subjects, but the effect was not enhanced for the high flavanol apple puree.

Cocoa polyphenols and inflammatory markers of cardiovascular disease

Epidemiological studies have demonstrated the beneficial effect of plant-derived food intake in reducing the risk of cardiovascular disease (CVD). The potential bioactivity of cocoa and its polyphenolic components in modulating cardiovascular health is now being studied worldwide and continues to grow at a rapid pace. In fact, the high polyphenol content of cocoa is of particular interest from the nutritional and pharmacological viewpoints. Cocoa polyphenols are shown to possess a range of cardiovascular-protective properties, and can play a meaningful role through modulating different inflammatory markers involved in atherosclerosis. Accumulated evidence on related anti-inflammatory effects of cocoa polyphenols is summarized in the present review.

A review on the role of nutraceuticals as simple as se(2+) to complex organic molecules such as glycyrrhizin that prevent as well as cure diseases

Nutraceuticals are nutritional medicines which are present in edible food items. Most of them are antioxidants with various other biological properties viz, anti inflammatory, anti atherogenic, anticancer, anti viral, anti aging properties etc. They are as simple as minerals like Se(2+) to complex organic molecules such as glycyrrhizin (Ca(2+), K(+) salts of glycyrrhizic acid). They can prevent as well as cure various diseases. Most of the medical people are not aware of the importance of the nutraceuticals as such matters are not part of their text books. Many still think that vitamins are the major nutritional medicines. Actually other dietary principles like terpenes, carotenes, phytosterols, polyphenols, flavanoids, di and poly sulphides, their sulfoxides and their precursor amino acids are necessary to scavenge free radicals in the body which are reactive oxygen species to protect and maintain the vitamin levels in the body. They down regulate the activities of those enzymes which are increased in diseases and they increase those that remove oxidants and detoxify carcinogens. They are immune boosters too. Recently glucosinolates, non toxic alkaloids, certain proteins and even fiber are included in the list of nutraceuticals.

Bioguidage search of active compounds from Waltheria indica L. (Malvaceae) used for asthma and inflammation treatment in Burkina Faso

Waltheria indica is used in traditional pharmacopeia in Burkina Faso for the treatment of asthma and conditions of inflammation. To evaluate its pharmacological properties and isolate the active compounds, a study through a bioguided phytochemical approach was conducted. This search was guided by a two-level investigation. First, we evaluated the impact of various fractions on the activity of enzymes involved in smooth muscle contraction (PDE4A1α) and inflammatory processes (PLA2 , 5-LOX). Second, we investigated the inhibitory effect of fractions on isolated rat trachea. The initial hydroalcoholic extract from roots of W. indica (HA), n-hexane fraction (F1 ), dichloromethane fraction (F2 ), ethyl acetate fraction (F3 ), residuary fraction (F4 ) reduced enzyme activity of PDE4A1α (inhibition of 22-42% at 50 μg/mL), 5-LOX (60-80% at 10 μg/mL), and PLA2 (42-94% at 100 μg/mL). On isolated rat trachea, only HA, F3 , and fractions obtained from F3 by chromatography on silica gel column, using dichloromethane/methanol, dose dependently inhibited contraction induced by acetylcholine. IC50 was 1051 μg/mL for HA and comprised between 181 and 477 μg/mL for F3 and its fractions. The most active fractions were purified and led to the identification of (-)-epicatechin. (-)-epicatechin from W. indica dose dependently inhibited PLA2 (IC50 = 154.7 μm) and 5-LOX (IC50 = 15.8 μm). In conclusion, both inhibition of PDE4A1α, 5-LOX, and PLA2 activities and rat trachea relaxation by W. indica validate its use in traditional management of asthma and other conditions of inflammation. These effects should be, at least in part, attributed to the presence of (-)-epicatechin in roots of W. indica.

Dietary flavonol epicatechin prevents the onset of type 1 diabetes in nonobese diabetic mice

Type 1 diabetes (T1D) is an autoimmune disease characterized by the selective destruction of pancreatic β-cells. Although successful islet transplantation provides a promising treatment, high cost, lack of donor organs, immune-mediated destruction of transplanted islets, and side effects from immunosuppressive drugs greatly limit its uses. Therefore, the search for novel and cost-effective agents that can prevent or ameliorate T1D is extremely important to decrease the burden of T1D. In this study, we discovered that epicatechin (EC, 0.5% in drinking water), a flavonol primarily in cocoa, effectively prevented T1D in nonobese diabetic (NOD) mice. At 32 weeks of age, 66.7% of control mice had overt diabetes, whereas only 16.6% of EC-treated mice became diabetic. Consistently, EC mice had significantly higher plasma insulin levels but lower glycosylated hemoglobin concentrations compared to control mice. EC had no significant effects on food or water intake and body weight gain in NOD mice, suggesting that EC's effect was not due to alterations in these variables. Treatment with EC elevates circulating anti-inflammatory cytokine interleukin-10 levels, ameliorates pancreatic insulitis, and improves pancreatic islet mass. These findings demonstrate that EC may be a novel, plant-derived compound capable of preventing T1D by modulating immune function and thereby preserving islet mass.

Modulation of metabolic syndrome-related inflammation by cocoa

Cocoa (Theobroma cacao L., Sterculiaceae) is a widely consumed food ingredient. Although typically found in high-fat, high-sugar foods such as chocolate, cocoa is rich in polyphenols, methylxanthines, and monounsaturated fatty acids. There is increasing evidence that moderate consumption of cocoa and cocoa-containing foods may have beneficial effects on the health including vasodilatory, antioxidant, and anti-inflammatory effects. Polyphenols in cocoa, including monomeric flavanols, as well as polymeric proanthocyanidins, may play a role in these observed beneficial effects. Chronic inflammation represents a potential mechanistic link between obesity and its related pathologies: insulin resistance, dyslipidemia, and hypertension, which comprise the metabolic syndrome. In the present review, we discuss the available data regarding the modulation of metabolic syndrome-related inflammation by cocoa and cocoa-derived compounds. We emphasize studies using laboratory animals or human subjects since such studies often represent the strongest available evidence for biological effects. In vitro studies are included to provide some mechanistic context, but are critically interpreted. Although the available data seem to support the anti-inflammatory effects of cocoa, further studies are needed with regard to the dose-response relationship as well as the underlying mechanisms of action. We hope this review will stimulate further research on cocoa and its anti-inflammatory activities.

Oral green tea catechin metabolites are incorporated into human skin and protect against UV radiation-induced cutaneous inflammation in association with reduced production of pro-inflammatory eicosanoid 12-hydroxyeicosatetraenoic acid

Green tea catechins (GTC) reduce UV radiation (UVR)-induced inflammation in experimental models, but human studies are scarce and their cutaneous bioavailability and mechanism of photoprotection are unknown. We aimed to examine oral GTC cutaneous uptake, ability to protect human skin against erythema induced by a UVR dose range and impact on potent cyclo-oxygenase- and lipoxygenase-produced mediators of UVR inflammation, PGE2 and 12-hydroxyeicosatetraenoic acid (12-HETE), respectively. In an open oral intervention study, sixteen healthy human subjects (phototype I/II) were given low-dose GTC (540 mg) with vitamin C (50 mg) daily for 12 weeks. Pre- and post-supplementation, the buttock skin was exposed to UVR and the resultant erythema quantified. Skin blister fluid and biopsies were taken from the unexposed and the UVR-exposed skin 24 h after a pro-inflammatory UVR challenge (three minimal erythema doses). Urine, skin tissue and fluid were analysed for catechin content and skin fluid for PGE2 and 12-HETE by liquid chromatography coupled to tandem MS. A total of fourteen completing subjects were supplement compliant (twelve female, median 42·5 years, range 29–59 years). Benzoic acid levels were increased in skin fluid post-supplementation (P= 0·03), and methylated gallic acid and several intact catechins and hydroxyphenyl-valerolactones were detected in the skin tissue and fluid. AUC analysis for UVR erythema revealed reduced response post-GTC (P= 0·037). Pre-supplementation, PGE2 and 12-HETE were UVR induced (P= 0·003, 0·0001). After GTC, UVR-induced 12-HETE reduced from mean 64 (sd 42) to 41 (sd 32) pg/μl (P= 0·01), while PGE2 was unaltered. Thus, GTC intake results in the incorporation of catechin metabolites into human skin associated with abrogated UVR-induced 12-HETE; this may contribute to protection against sunburn inflammation and potentially longer-term UVR-mediated damage.

Molecular mechanism underlying anti-inflammatory and anti-allergic activities of phytochemicals: an update

The resort worldwide to edible medicinal plants for medical care has increased significantly during the last few years. Currently, there is a renewed interest in the search for new phytochemicals that could be developed as useful anti-inflammatory and anti-allergic agents to reduce the risk of many diseases. The activation of nuclear transcription factor-kappa B (NF-κB) has now been linked to a variety of inflammatory diseases, while data from numerous studies underline the importance of phytochemicals in inhibiting the pathway that activates this transcription factor. Moreover, the incidence of type I allergic disorders has been increasing worldwide, particularly, the hypersensitivity to food. Thus, a good number of plant products with anti-inflammatory and anti-allergic activity have been documented, but very few of these compounds have reached clinical use and there is scant scientific evidence that could explain their mode of action. Therefore, this paper intends to review the most salient recent reports on the anti-inflammatory and anti-allergic properties of phytochemicals and the molecular mechanisms underlying these properties.

Beneficial effects of polyphenols on cardiovascular disease

In recent years, numerous studies have demonstrated the health benefits of polyphenols, and special attention has been paid to their beneficial effects against cardiovascular disease, the leading cause of death in the world today. Polyphenols present vasodilator effects and are able to improve lipid profiles and attenuate the oxidation of low density lipoproteins. In addition, they present clear anti-inflammatory effects and can modulate apoptotic processes in the vascular endothelium. It has been suggested that most of these effects are a consequence of the antioxidant properties of polyphenols, but this idea is not completely accepted, and many other mechanisms have been proposed recently to explain the health effects of these compounds. In fact, different signaling pathways have been linked to polyphenols. This review brings together some recent studies which establish the beneficial properties of polyphenols for cardiovascular disease and analyzes the mechanisms involved in these properties.

Inhibitory effects of balsamic vinegar on LDL oxidation and lipid accumulation in THP-1 macrophages

Oxidized low-density lipoprotein (LDL) is believed to contribute to atherosclerosis in part by being taken up into macrophages via scavenger receptors, thus accounting for foam cells. Balsamic vinegar is made from grapes and generally consumed in the Mediterranean region. In this study, we investigated the preventive effects of balsamic vinegar on LDL oxidation and foam cell formation. Balsamic vinegar had stronger 1,1-diphenyl-2-picrylhydrazyl (DPPH) radical scavenging abilities and higher polyphenol concentrations than rice vinegar. Balsamic vinegar dramatically inhibited LDL oxidation by azoradicals and endothelial cell-mediated oxidation in vitro. Further, we assessed the anti-oxidative effect against LDL after balsamic vinegar consumption in human subjects. Balsamic vinegar prolonged the LDL oxidation lag time and decreased lipid peroxide (LPO) and lyso-phosphatidylcholine (LPC) in LDL particles. We next examined the effect of balsamic vinegar on foam cell formation. Oil red O staining showed that balsamic vinegar inhibited oxidized LDL-induced foam cell formation in THP-1 macrophages. The concentrations of intracellular triglycerides and total cholesterols were reduced in the presence of balsamic vinegar. In addition, balsamic vinegar decreased the mRNA and protein expression level of scavenger receptors in THP-1 macrophages. These results showed that balsamic vinegar contained abundant polyphenols and inhibited LDL oxidation and oxidized LDL-induced foam cell formation by decreasing the expression of scavenger receptors.

Polyphenols as antimicrobial agents

Polyphenols are secondary metabolites produced by higher plants, which play multiple essential roles in plant physiology and have potential healthy properties on human organism, mainly as antioxidants, anti-allergic, anti-inflammatory, anticancer, antihypertensive, and antimicrobial agents. In the present review the antibacterial, antiviral, and antifungal activities of the most active polyphenol classes are reported, highlighting, where investigated, the mechanisms of action and the structure-activity relationship. Moreover, considering that the microbial resistance has become an increasing global problem, and there is a compulsory need to find out new potent antimicrobial agents as accessories to antibiotic therapy, the synergistic effect of polyphenols in combination with conventional antimicrobial agents against clinical multidrug-resistant microorganisms is discussed.

Sweet potato (Ipomoea batatas L.) leaves suppressed oxidation of low density lipoprotein (LDL) in vitro and in human subjects

Sweet potato (Ipomoea batatas L.) leaves are consumed as vegetables around the world, especially in Southeast Asia. The aim of this study was to investigate the inhibitory effect of sweet potato leaves on low-density lipoprotein oxidation in vitro and in human subjects. We compared the antioxidant activity of 8 kinds of sweet potato leaves. Every sweet potato leaf had high radical scavenging activity and prolonged a lag time for starting low-density lipoprotein oxidation in vitro. We found that sweet potato leaves contained abundant polyphenol compounds and the radical scavenging activity and prolongation rate of lag time were highly correlated with total polyphenol content. We also confirmed that thiobarbituric acid reactive substances production was increased in endothelial cell-mediated low-density lipoprotein oxidation, which was decreased by treatment with sweet potato leaves. We further measured the low-density lipoprotein oxidizability in 13 healthy volunteers after their intake of 18 g of “Suioh”, raw sweet potato leaves. “Suioh” prolonged a lag time for starting low-density lipoprotein oxidation and decreased low-density lipoprotein mobility. These results suggest that sweet potato leaves have antioxidant activity leading to the suppression of low-density lipoprotein oxidation.

Development of a fluorescent intensity assay amenable for high-throughput screening for determining 15-lipoxygenase activity

15-Lipoxygenase-1 catalyzes the introduction of molecular oxygen into polyunsaturated fatty acids to form a lipid hydroperoxide. The authors have developed an assay for the detection of lipid hydroperoxides formed by human 15-lipoxygenase (15-LO) in enzyme or cellular assays using either a 96-well or a 384-well format. The assays described take advantage of the ability of lipid hydroperoxides to oxidize nonfluorescent diphenyl-1-pyrenylphosphine (DPPP) to a fluorescent phosphine oxide. Oxidation of DPPP yields a fluorescent compound, which is not sensitive to temperature and is stable for more than 2 h. The assay is sensitive toward inhibition and robust with a Z' value of 0.79 and 0.4 in a 96- and 384-well format, respectively, and thus amenable for high-throughput screening. The utility of DPPP as a marker for 15-lipoxygenase activity was demonstrated with both enzyme- and cell-based assays for the identification of hits and to determine potency by IC(50) determinations.

Cocoa, chocolate, and cardiovascular disease

A significant body of evidence demonstrates that diets rich in fruits and vegetables promote health and attenuate, or delay, the onset of various diseases, including cardiovascular disease, diabetes, certain cancers, and several other age-related degenerative disorders. The concept that moderate chocolate consumption could be part of a healthy diet has gained acceptance in past years based on the health benefits ascribed to selected cocoa components. Specifically, cocoa as a plant and chocolate as food contain a series of chemicals that can interact with cell and tissue components, providing protection against the development and amelioration of pathological conditions. The most relevant effects of cocoa and chocolate have been related to cardiovascular disease. The mechanisms behind these effects are still under investigation. However, the maintenance or restoration of vascular NO production and bioavailability and the antioxidant effects are the mechanisms most consistently supported by experimental data. This review will summarize the most recent research on the cardiovascular effects of cocoa flavanols and related compounds.

Bioavailability of the polyphenols: status and controversies

The current interest in polyphenols has been driven primarily by epidemiological studies. However, to establish conclusive evidence for the effectiveness of dietary polyphenols in disease prevention, it is useful to better define the bioavailability of the polyphenols, so that their biological activity can be evaluated. The bioavailability appears to differ greatly among the various phenolic compounds, and the most abundant ones in our diet are not necessarily those that have the best bioavailability profile. In the present review, we focus on the factors influencing the bioavailability of the polyphenols. Moreover, a critical overview on the difficulties and the controversies of the studies on the bioavailability is discussed.

Polyphenols from cocoa and vascular health-a critical review

Cocoa is a rich source of dietary polyphenols. In vitro as well as cell culture data indicate that cocoa polyphenols may exhibit antioxidant and anti-inflammatory, as well as anti-atherogenic activity. Several molecular targets (e.g., nuclear factor kappa B, endothelial nitric oxide synthase, angiotensin converting enzyme) have been recently identified which may partly explain potential beneficial cardiovascular effects of cocoa polyphenols. However cocoa polyphenol concentrations, as used in many cell culture studies, are not physiologically achievable. Bioavailability studies indicate that plasma concentrations of cocoa polyphenols following dietary intake are low and in the nanomolar range. Human studies regarding the effect of cocoa polyphenols on vascular health are often underpowered and lack a rigorous study design. If dietary cocoa polyphenol intake is due to chocolate its high energy content needs to be taken into account. In order to determine potential health benefits of cocoa polyphenols large scale, long term, randomized, placebo controlled studies, (ideally with a cross-over design) as well as prospective studies are warranted.

Mechanisms of flavonoid protection against myocardial ischemia-reperfusion injury

Flavonoids have long been acknowledged for their unique antioxidant properties, and possess other activities that may be relevant to heart ischemia-reperfusion. They may prevent production of oxidants (e.g. by inhibition of xanthine oxidase and chelation of transition metals), inhibit oxidants from attacking cellular targets (e.g. by electron donation and scavenging activities), block propagation of oxidative reactions (by chain-breaking antioxidant activity), and reinforce cellular antioxidant capacity (through sparing effects on other antioxidants and inducing expression of endogenous antioxidants). Flavonoids also possess anti-inflammatory and anti-platelet aggregation effects through inhibiting relevant enzymes and signaling pathways, resulting ultimately in lower oxidant production and better re-establishment of blood in the ischemic zone. Finally, flavonoids are vasodilatory through a variety of mechanisms, one of which is likely interaction with ion channels. These multifaceted activities of flavonoids raise their utility as possible therapeutic interventions to ameliorate ischemia-reperfusion injury.