Natural polyphenols

Biological activity (BA) was chosen as such parameter. The BA determined using a system and a technique for a class of natural polyphenolic bonds nicotinamide adenine dinucleotide restored (NAD H ) - ferricyanide (KjFe(CN)g) in a phosphates buffer solution. 

MEDINA I, SATUE-GRACIA M T, GERMAN J B and FRANKEL E N (1999) Comparison of natural polyphenol antioxidants from extra virgin olive oil with synthetic antioxidants in tuna lipids during thermal oxidation, JAgric Food Chem, 47, 4873-9. 

Recent scientific investigations of natural polyphenols have demonstrated their powerful antioxidant property (Niki et al, 1995). Several classes of polyphenols have been chemically identified. Some of these are grape polyphenols, tea polyphenols, soy polyphenols, oligomeric proanthocyanidines (OPA) and other natural polyphenols of the flavone class. Rice bran polyphenols are different from the above in that they are p-hydroxy cinnamic acid derivatives such as p-coumaric acid, ferulic acid and p-sinapic acid. Tricin, a flavone derivative, has also been isolated from rice bran. 

The effects of catechin, epicatechin, procyanidin B2, caffeic acid, / -coumaric acid, myricetrin, and quercetrin on the color intensity and stability of malvidin 3-glucoside at a molar ratio of 1 1 under conditions similar to red wine were evaluated. " Flavan 3-ols appeared to have the lowest protective effects and flavonols the highest strong color changes were visually perceptible. " In the complexation of malvin chloride and natural polyphenols, flavonol glycosides by far exerted the best protector effect. ... 

Instant tea produced as described above will dissolve completely in hot water but not in cold water, as the caffeine-polyphenol complexes are insoluble under those conditions. Since virtually all instant tea manufacture in the U.S. is for iced tea preparation, process modification is required. This initial extract may be cooled to 5 to 10°C and the cold water insoluble material or cream be allowed to precipitate. Under these conditions, 20 to 35% of the extract solids may be separated by centrifugation. The supernatant solids will reconstitute in cold water after concentration and drying.105 It is also possible to process the cream to make a portion of it compatible with the product and thereby retain the caffeine and some polyphenolic components that are present in this fraction.106 Commercial use of the enzyme Tannase, which removes gallic acid from gallated tea polyphenols107 and reduces cream formation108 can be used to reduce cream losses and manufacture instant teas retaining more of the natural polyphenol content. 

This method is relatively easy to use for anhydrous systems, but not for emulsions, foods, or biological media where the presence of water is detrimental. The method has been applied for determining antioxidant activity of both individual natural polyphenols and vegetable extracts. Methods based on this one have been used to evaluate the peroxide value in walnuts (Wilson-Kakashita and others 1995), mango seeds (Joseph 1995), almonds (Uthman and others 1998), and coconut cream powder (Yusof and others 2007). 

Cervellati R, Renzulli C, Guerra MC and Speroni E. 2002. Evaluation of antioxidant activity of some natural polyphenolic compounds using the Briggs-Rauscher reaction method. J Agric Food Chem 50(26) 7504-7509. 

In addition to their possible prooxidant activity (see above) polyphenols and flavonoids may influence cancer cells via their antioxidant properties. Recently, Jang et al. [219] studied cancer chemopreventive activity of resveratrol, a natural polyphenolic compound derived from grapes (Chapter 29). These authors showed that resveratrol inhibited the development of preneoplastic lesions in carcinogen-treated mouse mammary glands in culture and inhibited tumorigenesis in a mouse skin cancer model. Flavonoids silymarin and silibinin also exhibited antitumor-promoting effects at the stage I tumor promotion in mouse skin [220] and manifested antiproliferative effects in rat prostate cancer cells [221]. 

Phase 1 clinical trials of the natural polyphenol quercetin (33) against several types of cancer have shown that this compound is well tolerated when administered at a dose of 70 mg/kg by i.v. bolus [63,64]. Further studies revealed that 33 inhibits GST Pl-1 completely after 2 h at a concentration of 25 pM however, addition of GSH partially restores activity. HPLC and LC-MS studies indicate that 33 inhibits GST Pl-1 through the formation of a covalent yet reversible bond with GST Pl-1 cysteine residue at position 47. 

Haslam, E., Natural polyphenols (vegetable tannins) as drugs possible modes of action, J. Nat. Prod., 59, 205, 1996. 

Salvi, A. et al., Protein protection by antioxidants development of a convenient assay and structure-activity relationships of natural polyphenols, Helv. Chim. Acta, 85, 867, 2002. 

Wu SN, Chiang HT, Shen AY, Lo YK. 2003. Differential effects of quercetin, a natural polyphenolic flavonoid, on L-type calcium current in pituitary tumor (GH3) cells and neuronal NG108-15 cells. J Cell Physiol 195 298-308. 

McCarty MF. 2005. Potential utility of natural polyphenols for reversing fat-induced insulin resistance. Med Hypotheses 64 628-635. 

Rotondo S, Rajtar G, Manarini S, Celardo A, Rotillo D, de Gaetano G, Evangelista V, Cerletti C. 1998. Effect of trans-resveratrol, a natural polyphenolic compound, on human polymorphonuclear leukocyte function. Br J Pharmacol 123 1691-1699. 

Martinez J, Moreno JJ. 2000. Effect of resveratrol, a natural polyphenolic compound, on reactive oxygen species and prostaglandin production. Biochem Pharmacol 59 865-870. 

Neves MA, Dinis TC, Colombo G, Sa e Melo ML (2007). Combining computational and biochemical studies for a rationale on the anti-aromatase activity of natural polyphenols, chem med chem 2 1750-1762. 

Tannic acid has been reported to inhibit the formation of hydroxyl radical by chelation of Fe2+ [16], Because tannic acid is a plant-derived material, it and other natural polyphenols may be important for subsurface applications of Fenton chemistry. A study of 50 different iron chelators assessed the affect of each chelator on the Fenton process initiated with Fe3+ and hydrogen peroxide [17]. Among the nine classes of chelators tested, results indicated that the chelators ranged from inactive to highly active in terms of hydroxyl radical formation. 

Born, M., Carrupt, P. A., Zini, R., Bree, T., Tillement, J. R, Hostettmann, K., and Testa, B. (1996), Electrochemical behaviour and antioxidant activity of some natural polyphenols, Helv. Chim. Acta, 79,1147. 

So, as we are the first to show, humic acids, being natural polyphenols, actively dissolve the biogenic silica of siliceous rocks, and we used the scheme of obtaining the ammonium salt of the tricatechol ether of monosilicic acid in order to understand the methods of synthesis of biogeochemically active SOC, formed from natural amorphous silica and polyphenols in natural systems. 

Flavonoids are natural polyphenolic substances widely distributed in the different parts of plants such as fruits, bark, stems, roots, leaves and flowers. Structurally they are characterized by a pyran ring or a similar structure of three carbons. These polyphenolic compounds are well known for displaying a remarkable spectrum of biological activities, including antibacterial and antifungal properties. In the Anthemideae tribe, some of these compounds were isolated by bioassay-guided fractionation, after previously detecting antimicrobial activity on the part of the plant. 

CAS 303-45-7. C30I I t0O8. A natural polyphenol. Properties Yellow, crystalline pigment having three modifications. Insoluble in water soluble in alcohol. 

Various natural polyphenols in soils, including those in humic acids, can reduce Fe to Fe, for example ... 

Microbial metabolites have proved to be more amenable to biosynthetic studies than the natural products obtained from higher plants partly because there are not the seasonal problems of production and also because the incorporation of labelled preeursors is higher. In 1907 Collie had proposed that natural polyphenols might be biosynthesized from polyearbonyl compounds (polyketides)... 

In summary, the natural polyphenols TE3, EGCG, and 5GG exhibit their inhibitory effects on androgen action in prostate cancer cells by two mechanisms, including the inhibition of 5a-reductase activity (figures 12.1 and 12.2) and the suppression of AR protein levels. Therefore, tea polyphenols and 5GG may have the potential to become chemopreventive and chemotherapeutic agents for prostate tumors. 

Numerous natural polyphenols such as moracins [41-43] or norlignans [44], Fig. (14) contain a 2-phenylbenzofuran unit that has stimulated numerous studies [45] on the synthesis of this skeleton. 

---