Abstract: The inhibitory effects of hydrolyzable tannins, condensed tannins and related polyphenols on the activity of xanthine oxidase (XOD), catalyzing uric acid formation from xanthine, were investigated Marked differences in the strength of the inhibition were observed Some of the differences among the monomeric hydrolyzable tannins were due to their molecular weights, reflecting the number of phenolic hydroxyl groups in the molecule However, the inhibitory activity of several oligomeric hydrolyzable tannins seemed particularly low in spite of their large molecular size It was also observed that differences in location of acyl groups on the carbohydrate cores caused differences in the inhibitory activity among monomeric and oligomeric hydrolyzable tannins A caffeic acid derivative (caffeetannin), 3,5-di-O-caffeoylquinic acid (24), also inhibited this enzyme Galloylation and the degree of polymerization in proanthocyanidins were also shown to affect remarkably the strength of the inhibition Among the compounds tested in the present study, valoneic acid dilactone (29), isolated from Mallotus japonicus, inhibited the enzyme most effectively A kinetic study showed that this dilactone inhibited XOD non-competitively Comparison of the inhibitory effect on XOD, with the binding activity to hemoglobin, for each tannin, suggests that their inhibition of XOD is not based on non-specific binding to the protein Similar comparison of the inhibitory effect on XOD with the inhibitory effect on the generation of superoxide anion radical (O2-) from the hypoxanthine-XOD system revealed that the inhibition of O2- generation by tannins is due to their radical-scavenging activity, and not due to their inhibitory activity upon the enzyme

Abstract: Variation in polyphenot oxidase activity and levels of total polyphenols and catechins with respect to different clones and shoot components, and its effect on quality of black tea (Camellia sinensis (L) 0 Kuntze, were studied. There was a wide variation in polyphenol oxidase activity of the different clones tested. The optimum fermentation time and polyphenol oxidase activity of different clones exhibited a hyperbolic relationship, viz y = 2.36 + 1129/x, where y = optimum fermentation time in minutes and x = polyphenol oxidase activity in μM catechol oxidised g−1 acetone powder min−1, with an r value of −0.98, which is signi Jicant at P ≤ 0.001. A good non-linear relationship was found between polyphenol oxidase activity of ji-esh tea shoots of different clones and the theajavins content of corresponding black teas. Among different shoot components, bud and first leaf had higher levels of polyphenols and catechins than internodes. However, the polyphenol oxidase activity showed a reverse trend: the internodes exhibited a higher enzyme activity compared with other components. Formation of theajavins during fermentation of different shoot components was in good agreement with polyphenol oxidase activity. High performance liquid chromatographic analysis of the theaflavins fraction in tea brew of black teas made from different components of tea shoot showed that buds resulted in black tea with the highest amount of theaflavin gallates, whereas teas produced from internodes had the lowest amount of theaflavin gallates. A new factor, viz theaflavin digallate equivalent, was developed, and the significance of this factor for chemical evaluation of black tea quality is discussed in this paper.

Abstract: Studies of the reversible complexation of a range of phenols and natural polyphenols in aqueous media with caffeine and related heterocycles, and with α- and β-cyclodextrin, using a range of physical methods (1H and 13C NMR spectroscopy, microcalorimetry, and X-ray crystallographic analysis) are reported. Values of the assciation constants (K) for the formation of 1:1 complexes between caffeine and a range of natural polyphenols hav been determined (K 15–138 dm3 mol–1). Amongst galloyl esters there is a dependence for strong binding on molecular size, conformational flexibility, and the ‘free’ galloyl ester group content of the polyphenol. With phenolic flavan-3-ols, association is enhanced by galloylation at C-3. The extent of precipitation of polyphenols by caffeine is related to the assciation constants (K), the molecular size of the polyphenol, and the initial concentration of both substrates. Polysaccharide cavity sequestration of polyphenols has been studied by means of the model substrates α- and β-cyclodextrin. Compared with that of the natural galloyl esters (K 76–340 dm3 mol–1) the binding of phenolic flavan-3-ols to β-cycloextrin is strong (K 210–6232 dm3 mol–1). Models are proposed for encapsulation within the cyclodextrin cavity. The results of these model studies are discussed in terms of the relative significance of hydrophobic effects and hydrogen bonding in polyphenol complexation. They provide a basis for the interpretation of the behaviour of polyphenols in their association with proteins, polysaccharides and other macromolecules.

Abstract: NMR spectroscopic methods, based upon 1H and 13C and two-dimensional long-range heteronuclear shift correlation, have been used accurately to define the positions of esterification to D-glucopyranose of structurally related phenolic acids in natural polyphenols. Quantitative measurements of physical properties i.e. gelling, distribution between octan-1-ol and water, and self-association of natural phenolic esters are described and related in some cases to features of putative biogenetic schemes for these metabolites.

Abstract: A chemical examination of polyphenols in Euphorbia helioscopia L. (Euphorbiaceae) has led to the isolation of four new hydrozable tannins named helioscopinins A (10) and B (9), and helioscopins A (11) and B (12), together with eight known tannins (1-8). On the basis of chemical and spectroscopic evidence, the structures of compounds 9-12 were established as 1, 6-(S)-hexahydroxydiphenoyl-3-O-galloyl-β-D-glucose, 1, 6-(S)-hexahydroxydiphenoyl-2, 4-(S)-dehydrohexahydroxydiphenoyl-3-O-galloyl-β-D-glucose, 1, 6-(S)-hexahydroxydiphenoyl-2, 4-(R)-elaeocarpusionoyl-3-O-galloyl-β-D-glucose and 1, 3, 6-tri-O-galloyl-2, 4-(R)-elaeocarpusinoyl-β-D-glucose, respectively.

Abstract: Centrifugal partition chromatography (CPC) has been applied to the preparative fractionation of pharmacologically active polyphenols contained in the crude extracts from three medicinal plants. 1) (-)-Epigallocatechin gallate, the main component of tea polyphenols, which inhibits tumor promotion, 2) oligomeric hydrolyzable tannins, having host-mediated anti-tumor activity and antiviral activity, contained in Woodfordia fruticosa flower, 3) polyphenolic components of licorice, having anti-HIV activity. The results obtained with cartridges of medium volume and of small volume were compared during the fractionation of tea polyphenols.

Abstract: Tannic acid stimulated the iodination (incorporation of radioactive iodine into an acid-insoluble fraction) of human peripheral blood polymorphonuclear cells (PMN) and human promyelocytic leukemic HL-60 cells, without affecting the iodination of 9 other cultured cell lines The stimulation of both PMN and HL-60 cells depended on incubation time and temperature, and was significantly suppressed by myeloperoxidase inhibitors Among chemically defined natural polyphenols, condensed tannins (epicatechin gallate oligomers) and monomeric and oligomeric hydrolyzable tannins potently stimulated PMN iodination, whereas polyphenols of lower molecular weight (gallic acid, alkyl gallates, epicatechin, epicatechin gallate, epigallocatechin, caffeic acid derivatives and licorice flavonoids) had much less activity Various synthetic polyphenolic compounds structurally unrelated to tannins also stimulated PMN iodination depending upon their molecular weight, but to a slightly lesser extent The results suggest that the stimulation activity of tannins and related polyphenols might depend more on their molecular weights than the number of hydroxyl groups on each benzene ring in the molecule, or the presence of sugars or hexahydroxydiphenoyl groups

Abstract: PURPOSE: To provide the subject gum base composed of a tea polyphenol and a collagen and having an antioxidation effect, a preventive effect for increase in cholesterol concentration in blood, an antineoplastic, antihypertensive, antitoxic, antimicrobial and plaque forming inhibition functions, etc. CONSTITUTION: An objective gum base composed of a tea polyphenol [preferably epigallocatechin gallate, epicatechin gallate, epigallocatechin, epicatechin, (+) catechin, free teafravin, teafravin monogallate A, teafravin monogallate B or teafravin digallate] and a collagen (preferably water soluble collagen). COPYRIGHT: (C)1991,JPO&Japio

Abstract: The effect was investigated of some polyphenol compounds on the growth and intracellular enzyme activity of human-derived cells and Chinese hamster ovary (CHO) cells. Quercetin, a mutagen, inhibited the growth of serum-free cultured human-human hybridomas (SI102 and HB4C5) and a human histiocytic lymphoma cell line (U-937), but did not affect the growth of CHO cells. Glycosides of quercetin such as quercetin-4'-glucoside (Q-4'-G), quercetin-3, 4'-glucoside (Q-3, 4'-G) and rutin, and other polyphenol compounds (catechin and epicatechin) had no significant inhibiting effect on the growth of human-derived cells or CHO cells. These compounds slightly promoted the growth of human-derived cells. Most of the polyphenols used increased the activity of a drug-metabolizing enzyme, NADPH-cytochrome C reductase, in the U-937 cells and CHO cells, this effect being more marked in the CHO cells than in the U-937 cells. Quercetin markedly reduced the activity of catalase in the human-derived cell lines, while it slightly activated catalase in the CHO cells. Rutin, Q-4'-G, Q-3, 4'-G, catechin and epicatechin produced no significant change in catalase activity. Quercetin also reduced the activity of glutamic oxaloacetic transaminase in the U-937 cells.

Abstract: PURPOSE: To remove undesirable tastes such as bitterness and astringency from cocoa and chocolate and to enrich cocoa and chocolate with a good sweetness by immersing cacao nib in a solution of polyphenol oxidase, treating with the enzyme, drying and roasting. CONSTITUTION: Cacao nib is immersed in a solution of polyphenol oxidase, treated with the enzyme, dried and roasted. An enzyme which oxidizes hydroquinone, p-phenylenediamine, ascorbic acid, cyanine dyed, etc., is not interfered with CO and does not act on monophenol is preferable as the polyphenol oxidase used. A polyphenol oxidase-containing plant or fungus tissue or polyphenol oxidase obtained from a culture mixture by culturing a fungus capable of producing polyphenol oxidase can be used for the flavor improving method. COPYRIGHT: (C)1992,JPO&Japio

Abstract: PURPOSE:To obtain a polyphenol with high purity by reacting an arom. aldehyde with an excess amt. of phenol in the presence of an acid catalyst, washing off the acid catalyst with water and distilling off excess phenol. CONSTITUTION:In a method for preparing a polyphenol by reacting a phenol with an arom. aldehyde in the presence of an acid catalyst, the aimed polyphenol is obtd. by performing the reaction using an excess amt. of phenol, removing the acid catalyst in a condensate by washing with water and distilling off excess phenol. Said reaction, namely, dehydration condensation is performed in such a way that the phenol is generally in the range of 2-60mol, pref. 3-32mol based on 1mol of the arom. aldehyde and the acid catalyst is in the range of 0.01-10 pts.wt., pref. 0.2-5 pts.wt., at 60-200 deg.C for 1-10hr. As the acid catalyst used, hydrochloric acid, sulfuric acid, p-toluenesulfonic acid, phosphoric acid, etc., are cited.

Abstract: Phenolic compounds are of outstanding importance for beverage production. Following a survey of the polyphenols occurring in fruit juices and their participation in browning reactions, the microbial polyphenol oxidases («blue copper enzymes») and their action mechanism are discussed. A laccase from Trametes versicolor was applied for the specific phenol oxidation in apple juices. Furthermore, the present paper reports on the purification and biochemical characterization of the enzyme preparation

Abstract: Polyphenols in banana buds were found to consist of flavanan tannin (condensed tannin) as the major component; catechin, its oligomers, dopamine and dopa as minor components. Total phenol and vanillin-positive phenol were higher in the buds of cultivars Bungulan, Lacatan and Latundan and lower in the buds of cv. Saba. Polyphenol oxidase (PPO) in cv. Saba was localized in the male flower; 3 times less in the peduncle and bract; and about 30 and 300 times less in the peel and pulp of the fruit respectively. PPO activity in the male flower, peduncle and bract was inhibited by 0.13M NaCl about 20 to 30%, while that in the peel and pulp was inhibited about 40 to 50%. Buds of the other cultivars had similar levels of PPO which were inhibited about 20% by 0.13M NaCl. The Ki value for NaCl of PPO in the peel was estimated to be 0.28M. The astringency, bitterness and color of banana buds were monitored before and after heating, NaCl treatment and squeezing. These are discussed with reference to the polyphenols and PPO focussing on food quality.

Abstract: The chlorogenic and caffeic acid combined in apple juice cultivars and ciders correlated very well with total phenol content (P 0.001; r = 0.989; n = 22). The same correlation was found when analyzed strictly by cultivar (P 0.001; r = 0.986; n = 10). Analysis used automated Folin Ciocalteu (FC) colorimetry values for total phenols and reversed-phase HPLC (280 nm detection) for chlorogenic and caffeic acid before and after fermentation. Concentrations were between 8 and 1012 mg/L (as chlorogenic acid) in different cultivars. The total chlorogenic acid by HPLC represented only 6.2 to 10.7% of the total polyphenol (calculated as chlorogenic acid) by FC in the apple cultivars for all samples. Total peak areas correlated very well with total phenol content by FC (P 0.001; r = 0.994; n = 22).