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Molecular structure of apigenin, a polyphenol antioxidant
A polyphenol antioxidant is a type of antioxidant containing a polyphenolic substructure. In human health these compounds, numbering over 4,000 distinct species, are thought to be instrumental in combating oxidative stress, a process associated with some neurodegenerative diseases and some cardiovascular diseases.
Sources of polyphenol antioxidants
The main source of polyphenol antioxidants is nutritional, since they are found in a wide array of phytonutrient-bearing foods. For example, most legumes; fruits such as apples, blackberries, blueberries, cantaloupe, cherries, cranberries, grapes, pears, plums, raspberries, and strawberries; and vegetables such as broccoli, cabbage, celery, onion and parsley are rich in polyphenol antioxidants. Red wine, chocolate, green tea, coffee, olive oil, bee pollen (honey) and many grains are alternative sources. The principal benefit of ingestion of antioxidants seems to stem from the consumption of a wide array of phytonutrients; correspondingly, the role of dietary supplements as a method of realizing these health benefits is the subject of considerable discussion.
Blackberries are a source of polyphenol antioxidants
Biochemical regulationThe regulation chemistry consists of a polyphenol antioxidant’s ability to scavenge free radicals and up-regulate certain metal chelation reactions. That is to say various reactive oxygen species must be continually removed from cells to maintain healthy metabolic function. Some specific free radicals affected are the reactive oxygen species singlet oxygen, peroxynitrite and hydrogen peroxide. Diminishing the concentrations of reactive oxygen species can have several benefits. Since reactive oxygen species are linked to mobilization of ion transport systems, they are known to have roles in redox signaling. In particular, platelets involved in wound repair and blood homeostasis can release reactive oxygen species to recruit platelets to sites of injury. These also provide a link to the adaptive immune system via the recruitment of leukocytes. When polyphenols down-regulate reactive oxygen species formation, they also contribute to improved endothelial health through anti-inflammatory action.
Biological consequences
A macrophage stretching its arms to engulf two particles. Reactive oxygen species promote oxidized LDL and polyphenol antioxidants combat this inflammatory response.
Occurrence of an abundance of polyphenol antioxidants is associated with several salutary effects in higher animal species
Reduction in inflammatory effects such as coronary artery disease including specific medical research into the pathways of improved endothelial health via downregulation of oxidative LDL.
More generally the tea polyphenol (medically known as TP) antioxidant epigallocatechin gallate (EGCG), has been shown to reduce reactive oxygen species levels in vivo. Reactive oxygen species are important markers for inflammatory diseases.
Some polyphenol antioxidants, such as resveratrol, inhibit occurrence and/or growth of mammalian tumors.
A variety of other beneficial health effects have been attributed to consumption of foods rich in polyphenolic antioxidants. Among these salutary effects discussed are anti-aging consequences such as slowing the process of skin wrinkling.For some of the side-benefits (such as prevention of peripheral artery disease), further research is continuing to clarify the role polyphenol antioxidants may have.
Difficulty in analyzing effects of specific chemicals
Grapes contain certain polyphenol antioxidant compounds.
It is difficult to evaluate the medical effects of specific polyphenolic antioxidants, since such a large number of individual compounds may occur even in a single food. For example, over sixty different chemically distinct flavonoids are known to occur in a given red wine. Numerous scientific studies have been conducted to attempt to arrive at one consistent index for food antioxidant power. Since it has been proved that the dietary intake of compounds having antioxidant activity is medically important, various chemical, biological, and electrochemical methods have been proposed to evaluate the antioxidant power of compounds such as polyphenols. Wine, although nonessential, has a high polyphenol content up to two to three grams per liter in red wines obtained by traditional maceration. The polyphenol content of wines is usually evaluated by the Folin-Ciocalteu reagent, which provides an appropriate response to the requirements of wine manufacturers. Statistical least squares analysis has been conducted to demonstrate the Folin method correlates well with alternative chemical and biological procedures for determining antioxidant potential.Therefore, there is some reason to believe more universally accepted protocols may be forthcoming to permit quantitative evaluation of antioxidant strength of polyphenol antioxidant compounds.
Other more detailed chemical research has been conducted elucidating the difficulty of isolating individual polyphenolic antioxidants. Fajardo-Lirai et al. have demonstrated that significant variation in polyphenol content among various brands of tea can explain the inconsistency in previous epidemiological studies that have tried to correlate beneficial health effects of polyphenol antioxidants using specific green tea blends. The Oxygen Radical Absorbance Capacity (ORAC) test is a possible emerging standard by which science measures antioxidant power in foods and dietary supplements
Practical aspects of dietary polyphenol antioxidants
Cocoa is the prime ingredient of chocolate, a source of polyphenol antioxidants.
There is debate regarding the total body absorption of dietary intake of polyphenolic compounds. While individual studies seem to demonstrate the favourable health effects of certain specific polyphenols, more research is needed to understand the interactions between a variety of these chemicals acting in concert within the human body. In particular there is evidence that some combinations of foods may inhibit efficient intestinal transfer of certain polyphenol antioxidants; refined sugars, for example, have been shown to impede this uptake under certain circumstances. Furthermore caution should be exercised in attempting diets depending largely on dietary supplements as opposed to a broad array of food sources, since the quality and concentrations of beneficial chemicals in some commercial products is subject to question.
Topical application of polyphenol antioxidants
There is some data that reactive oxygen species play a role in the process of aging. The skin is exposed to various exogenous sources of oxidative stress, including ultraviolet radiation. These spectral components are generally viewed as responsible for the extrinsic type of skin aging, sometimes termed photo-aging. It has been shown not only that increased levels of protective low molecular weight antioxidants through a diet rich in phytochemicals, but also by direct topical dermal application have proved that a few low molecular weight antioxidants, notably vitamins C and E, as well as lipoic acid, exert protective effects against oxidative stress. However, controlled long-term studies on the efficacy of low molecular weight antioxidants in the prevention or treatment of skin aging in humans are lacking.
Labdanum resin.
Infections with influenza A viruses still pose a major threat to humans and several animal species. The occurrence of highly pathogenic avian influenza viruses of the H5N1 subtype capable to infect and kill humans highlights the urgent need for new and efficient countermeasures against this viral disease. Here we demonstrate that a polyphenol rich extract (CYSTUS052) from the Mediterranean plant Cistus incanus exerts a potent anti-influenza virus activity in A549 or MDCK cell cultures infected with prototype avian and human influenza strains of different subtypes. CYSTUS052 treatment resulted in a reduction of progeny virus titers of up to two logs. At the effective dose of 50 microg/ml the extract did not exhibit apparent harming effects on cell viability, metabolism or proliferation, which is consistent with the fact that these plant extracts are already used in traditional medicine in southern Europe for centuries without any reported complications. Viruses did not develop resistance to CYSTUS052 when compared to amantadine that resulted in the generation of resistant variants after only a few passages. On a molecular basis the protective effect of CYSTUS052 appears to be mainly due to binding of the polymeric polyphenol components of the extract to the virus surface, thereby inhibiting binding of the hemagglutinin to cellular receptors. Thus, a local application of CYSTUS052 at the viral entry routes may be a promising approach that may help to protect from influenza virus infections.
of medicinal herbs that have been perpetuated along several generations based simply on a folk tradition are Cistus and green tea. The principal active constituents of the genus Cistus and green tea are polyphenolic compounds. Polyphenols exhibit a wide range of antibacterial, antifungal and antiinflammatory effects.
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tal of 300 patients (277 completers) treated with CYSTUS052 given in lozenges compared with treatment with an extract of green tea. The patients scored the subjective severity of target symptoms using a predefined scale.
e urgent need for new and efficient countermeasures against this disease. Several antiviral compounds have been developed against influenza virus; their long-term efficacy is often limited, because of their toxicity or the emergence of drug-resistant virus mutants. Moreover, neuraminidase inhibitors the most common anti-influenza agents are less effective against new H5N1 isolates. In this regard, we were able to show that a polyphenol rich plant extract from a special variety of Cistus incanus named Cystus052 exhibits antiviral activity against influenza viruses in vitro, in a mouse model and a randomized, placebo controlled clinical study. The recovery from clinical symptoms was 2.5 days faster in the Cystus052 group compared to patients taken the placebo. The protective effect of Cystus052 appears to be mainly due to binding of the polymeric polyphenol components of the extract to the virus surface, thereby inhibiting binding of the hemagglutinin to cellular receptors. The antiviral 
potential of Cystus052 against seven H5N1 viruses by IC50, EC50, Km, Vmax and Ki values indicated that Cystus052 was much more potent than oseltamivir. In addition, using an in vitro infectivity inhibition assay we found that a single treatment of Cystus052 was up to 100-fold more effective against these H5N1 viruses compared to oseltamivir (Tamiflu), during the first 24 hours after infection. We conclude that Cystus052 given prior to infection might be an effective antiviral with prophylactic potential against influenza viruses including A/H5N1.
