Concept: Polyphenol antioxidant
Numerous studies have demonstrated the importance of naturally occurring dietary polyphenols in promoting cardiovascular health and emphasized the significant role these compounds play in limiting the effects of cellular aging. Polyphenols such as resveratrol, epigallocatechin gallate (EGCG), and curcumin have been acknowledged for having beneficial effects on cardiovascular health, while some have also been shown to be protective in aging. This review highlights the literature surrounding this topic on the prominently studied and documented polyphenols as pertaining to cardiovascular health and aging.
Resveratrol (3,5,4'-trihydroxy-trans-stilbene) is a polyphenol found in various plants, especially in the skin of red grapes. The effect of resveratrol on human health is the topic of numerous studies. In fact this molecule has shown anti-cancer, anti-inflammatory, blood-sugar-lowering ability and beneficial cardiovascular effects. However, for many polyphenol compounds of natural origin bioavailability is limited by low solubility in biological fluids, as well as by rapid metabolization in vivo. Therefore, appropriate carriers are required to obtain efficient therapeutics along with low administration doses.Liposomes are excellent candidates for drug delivery purposes, due to their biocompatibility, wide choice of physico-chemical properties and easy preparation.In this paper liposome formulations made by a saturated phosphatidyl-choline (DPPC) and cholesterol (or its positively charged derivative DC-CHOL) were chosen to optimize the loading of a rigid hydrophobic molecule such as resveratrol.Plain and resveratrol loaded liposomes were characterized for size, surface charge and structural details by complementary techniques, i.e. Dynamic Light Scattering (DLS), Zeta potential and Small Angle X-ray Scattering (SAXS). Nuclear and Electron Spin magnetic resonances (NMR and ESR, respectively) were also used to gain information at the molecular scale.The obtained results allowed to give an account of loaded liposomes in which resveratrol interacted with the bilayer, being more deeply inserted in cationic liposomes than in zwitterionic liposomes. Relevant properties such as the mean size and the presence of oligolamellar structures were influenced by the loading of RESV guest molecules.The toxicity of all these systems was tested on stabilized cell lines (mouse fibroblast NIH-3T3 and human astrocytes U373-MG), showing that cell viability was not affected by the administration of liposomial resveratrol.
The traditional Mediterranean diet (MD) is associated with long life and lower prevalence of cardiovascular disease and cancers. The main components of this diet include high intake of fruit, vegetables, red wine, extra virgin olive oil (EVOO) and fish, low intake of dairy and red meat. Olive oil has gained support as a key effector of health benefits and there is evidence that this relates to the polyphenol content. Olive leaf extract (OLE) contains a higher quantity and variety of polyphenols than those found in EVOO. There are also important structural differences between polyphenols from olive leaf and those from olive fruit that may improve the capacity of OLE to enhance health outcomes. Olive polyphenols have been claimed to play an important protective role in cancer and other inflammation-related diseases. Both inflammatory and cancer cell models have shown that olive leaf polyphenols are anti-inflammatory and protect against DNA damage initiated by free radicals. The various bioactive properties of olive leaf polyphenols are a plausible explanation for the inhibition of progression and development of cancers. The pathways and signaling cascades manipulated include the NF-κB inflammatory response and the oxidative stress response, but the effects of these bioactive components may also result from their action as a phytoestrogen. Due to the similar structure of the olive polyphenols to oestrogens, these have been hypothesized to interact with oestrogen receptors, thereby reducing the prevalence and progression of hormone related cancers. Evidence for the protective effect of olive polyphenols for cancer in humans remains anecdotal and clinical trials are required to substantiate these claims idea. This review aims to amalgamate the current literature regarding bioavailability and mechanisms involved in the potential anti-cancer action of olive leaf polyphenols.
Phenolic compounds, which are secondary plant metabolites, are considered an integral part of the human diet. Physiological properties of dietary polyphenols have come to the attention in recent years. Especially, proanthocyanidins (ranging from dimers to decamers) have demonstrated potential interactions with biological systems, such as antiviral, antibacterial, molluscicidal, enzyme-inhibiting, antioxidant, and radical-scavenging properties. Agroindustry produces a considerable amount of phenolic-rich sources, and the ability of polyphenolic structures to interacts with other molecules in living organisms confers their beneficial properties. Cocoa wastes and grape seeds and skin byproducts are a source of several phenolic compounds, particularly mono-, oligo-, and polymeric proanthocyanidins. The aim of this work is to compare the phenolic composition of Theobroma cacao and Vitis vinifera grape seed extracts by high pressure liquid chromatography coupled to a quadrupole time-of-flight mass spectrometer and equipped with an electrospray ionization interface (HPLC-ESI-QTOF-MS) and its phenolic quantitation in order to evaluate the proanthocyanidin profile. The antioxidant capacity was measured by different methods, including electron transfer and hydrogen atom transfer-based mechanisms, and total phenolic and flavan-3-ol contents were carried out by Folin-Ciocalteu and Vanillin assays. In addition, to assess the anti-inflammatory capacity, the expression of MCP-1 in human umbilical vein endothelial cells was measured.
The baobab fruit (Adansonia digitata L.) is found throughout regions of Africa and is becoming increasingly recognized for its high nutrient and polyphenol content. Polyphenols have been beneficial for their effects on reducing the glycemic response (GR) and for improving various other metabolic parameters. Based on previous research, it was hypothesized that the baobab fruit extract would reduce starch digestion in vitro and would show potential for reducing the GR and for increasing satiety and diet-induced thermogenesis in humans. Six extracts of baobab from 6 different locations in Africa were measured for their antioxidant and polyphenol content using the ferric ion-reducing antioxidant power and the Folin-Ciocalteu methods, respectively. Baobab extract was baked into white bread at different doses to determine the optimal dose for reducing starch breakdown and sugar release from white bread after an in vitro digestion procedure. In vivo, baobab extract was consumed in solution at both a low-dose (18.5 g) and a high-dose (37 g) aqueous drink in 250 mL of water along with white bread, and resulting GR, satiety, and postprandial energy expenditure were measured. All extracts in this study were shown to be good sources of polyphenols. Baobab fruit extract added to white bread at 1.88 % significantly (P < .05) reduced rapidly digestible starch from white bread samples. In vivo, the baobab fruit extract at both low and high doses significantly (P < .05) reduced GR, although there was no significant effect on satiety or on energy expenditure.
The antioxidant properties of extracts of Sybaris liquorice roots have been assessed using 2,2'-diphenyl-1-picrylhydrazyl (DPPH) radical scavenging activity assay. The extracts, obtained by Soxhlet extraction (Et(2)O, AcOEt, MeOH and BuOH) of the yellow (inner part) and brown (cortex) root powders ensuing from decortication of the raw dry roots, followed by separation and powderisation, were analysed for their scavenging activity by evaluating the colourimetric decrease in the absorbance of DPPH. The highest antioxidant activity (98.39 ± 0.56%) was observed in the case of the Et(2)O extract of the brown powder, at a concentration of 3.33 mg mL(-1). Moreover, the total phenolic content of the extracts was determined using the Folin-Ciocalteu reagent and expressed as milligram gallic acid equivalent per gram of dry extract. Our results show that the Et(2)O extract of the liquorice root cortex could be used as an attractive natural source of antioxidant additives for food, cosmetic or pharmaceutical applications.
The binding sites of antioxidant polyphenols resveratrol, genistein and curcumin are located with milk α- and β-caseins in aqueous solution. FTIR, CD and fluorescence spectroscopic methods and molecular modeling were used to analyse polyphenol binding sites, the binding constant and the effects of complexation on casein stability and conformation. Structural analysis showed that polyphenols bind casein via hydrophilic and hydrophobic interactions with the number of bound polyphenol molecules (n) 1.20 for resveratrol, 1.4 for genistein and 1.4 for curcumin with α-casein and 1.2 for resveratrol, 1.3 for genistein and 1.3 for curcumin with β-casein. The overall binding constants of the complexes formed are Kres-α-casein = 1.9 (± 0.6) x 104 M-1, Kgen-α-casein = 1.8 (± 0.4) x 104 M-1 , Kcur-α-casein = 2.8 (± 0.8) x 104 M-1 with α-casein and Kres-β-casein = 2.3 (± 0.3) x 104 M-1, Kgen-β-casein = 3.0 (± 0.5) x 104 M-1 and Kcur-β-casein = 3.1 (± 0.5) x 104 M-1 for β-casein. Molecular modeling showed the participation of several amino acids in polyphenol-protein complexes, which were stabilized by hydrogen bonding network with the free binding energy of -11.56 (resveratrol-α-casein), -12.35 (resveratrol-β-casein), -9.68 (genistein-α-casein, -9.97 (genistein-β-casein), -8.89 (curcumin-α-casein) and -10.70 kcal/mol (curcumin-β-casein). The binding sites of polyphenols are different with α- and β-caseins. Polyphenol binding altered casein conformation with reduction of α-helix indicating a partial protein destabilization. Caseins might act as carriers to transport polyphenol in vitro.
A variety of polyphenol antioxidant compounds derived from natural products have demonstrated neuroprotective activity against neuronal cell death. The objective of this study was to investigate the effect of resveratrol (RESV) and bioflavonoids in attenuating hydrogen peroxide (H2O2)-induced oxidative stress in neuronal cells. H2O2 levels were increased by the addition of L-3,4-dihydroxyphenylalanine (L-DOPA) to cultured dopaminergic SKNSH cells. H2O2 was monitored by peroxyfluor-1, a selective H2O2 optical probe. To examine the neuroprotective effects of RESV and bioflavonoids against L-DOPA, we cotreated RESV, quercetin, or (-) epigallocatechin gallate with L-DOPA and monitored for H2O2 levels. The combination of RESV and L-DOPA was 50% more effective at reducing H2O2 levels than the combination of quercetin or epigallocatechin gallate with L-DOPA. However, the combination of each antioxidant with L-DOPA was effective at preserving cell viability.
Abstract Context: The search for new sources of natural antioxidants from plant material may have beneficial therapeutic potential for those diseases associated with oxidative stress. The medicinal plant Haplophyllum tuberculatum (Forsskal) A. Juss. (Rutaceae) contains phenolic compounds as main phytochemicals; however, there are no reports on its antioxidant properties. Objective: To evaluate antioxidant and cytoprotective potential of ethanol extract of Haplophyllum tuberculatum aerial parts. Materials and methods: Total phenol content was determined using Folin-Ciocalteu reagent; antiradical activity was measured using ORAC assay and the analysis of the major polyphenols was carried out using a HPLC-MS method. The antioxidant and cytoprotective effect were also investigated by the MTT assay and DCFH-DA method. The human astrocytoma U373-MG cell line was pretreated with ethanol extract (from 0.025 to 250 µg/mL) for 24 h, prior to 1 mM H2O2 exposure (30 min). Results and conclusion: Total phenol content was 46.2 mg gallic acid/g sample and ORAC value was 1.283 µmol TE/mg sample. Chemical constituents were methoxyflavones, flavonols (mainly quercetin derivatives), cinnamic acids and benzoic acids. In cell system model of oxidative stress, pretreatments with ethanol extract at the concentrations of 2.5, 0.25 and 0.025 µg/mL significantly attenuated H2O2-induced loss in viability by 13.5, 17 and 20.5%, respectively. Furthermore, these ethanol extract concentrations markedly inhibited intracellular ROS production with IC50 0.026 µg/mL. These findings demonstrate the beneficial properties of ethanol extract of Haplophyllum tuberculatum aerial parts, rich in phenolic compounds, as antioxidant and radical scavenger ameliorating ROS-related processes and diseases such as several neurodegenerative disorders.
Phytochemical profiles (phenolic compounds, l-ascorbic acid, antioxidant and PPO activities) of 13 different quince varieties and 5 genotypes were studied. Polyphenols were identified by LC-PDA-QTof/MS and quantified by UPLC-PDA and UPLC-FL. A total of 26 polyphenolic compounds found in quince tissues were identified and presented: 9 flavan-3-ols ((-)-epicatechin, procyanidin B2, 3 procyanidin dimers and trimers, and 1 tetramer); 8 hydroxycinnamates, derivatives of caffeoylquinic and coumaroylquinic acid; and 9 kaempferol and quercetin derivatives. The content of total polyphenols was between 1709.43 (genotype ‘S1’) and 3436.56 mg/100 g dry weight (‘Leskovač’). Flavan-3-ols, which are the major class of quince polyphenols, represented between 78 and 94% of the total polyphenolic compounds. The activity of PPO enzyme ranged from 709.85 to 1284.59 ΔU/min, and that of l-ascorbic acid ranged from 5.86 to 26.42 mg/100 g. Some quince varieties and their products characterized by a higher content of phenolic compounds may be selected to promote their positive effect on health.