Absorption Spectra of Metal Complexes of Flavonoid Compounds

Jurd, L.; Geissman, T. A.

doi:10.1021/jo01118a018

Cited by 131 publications

(72 citation statements)

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“…The formation of Fe3 +-phenol complexes that yield absorption spectra in the visible region is well documented (Wesp and Brode 1934;Jurd and Geissman 1956;Brune et al 1991) and the complex is more stable as the polyphenols are oxidised (DaDamio and Thompson 1992). The cation may also bind to other organic compounds in the fruits such as the cell wall polymers (Platt and Clydesdale 1987).…”

Section: Introductionmentioning

confidence: 95%

Effect of pH on the colour formed by Fe‐phenolic complexes in ripe olives

et al. 1995

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The effects of the pH in the flesh of ripe olives processed for table olive production, the type of acid used to correct it, the heating process used and the iron content of the flesh on the colour of the final product were studied. The best colour was obtained by bottling the fruits at pH 7. Additions of acids, especially citric acid, always caused discoloration when olives were bottled at a pH of around 7. On the other hand, when the fruits were packed at a pH higher than 7 the addition of certain amounts of acids produced darker olives. Darker colours are related to higher iron contents in the flesh, but treatment of olives with ferrous gluconate before neutralising the pH of the flesh yielded better colours than those treated after neutralising for the same iron concentration in the olives. Results obtained after adding iron to the oxidation solutions did not show the same pattern as those obtained using fruits. These results suggest that the fixation of the colour formed is not only due to the phenol-iron complexes.

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Section: Introductionmentioning

confidence: 95%

Effect of pH on the colour formed by Fe‐phenolic complexes in ripe olives

et al. 1995

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“…Because of interference by other, nonflavonoid compounds in this spectral region, these compounds could not be quantitated directly in plant extracts. The visible absorption maximum of flavonol glycosides in alcoholic solutions is known to undergo a bathochromic shift in the presence of AlCl3 (13). This property of the compounds has been used in the past as one of the criteria in their structural identification.…”

Section: Discussionmentioning

confidence: 99%

Induction of Flavonoid Synthesizing Enzymes by Light in Etiolated Pea (Pisum sativum cv. Midfreezer) Seedlings

Hrazdina¹,

Parsons²

1982

Plant Physiol.

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Etiolated pea (Pisum sativum cv. Midfreezer) seedlings respond to illumination with white light by changes in the activity of phenylpropanoid and flavonoid synthesizing enzymes. Unlike in cell cultures, changes in enzyme activity in pea seedlings are not concerted. Phenylalanine ammonia-lyase (EC 4.3.1.5) activity peaked approximately 18 hours after onset of illumination. The phenylacetate path did not interfere with the measurement of phenylalanine ammonia-lyase activity. Activity of cinnamic acid 4-hydroxylase (EC 1.14.13.11) showed an early peak after 8 hours illumination, declined thereafter sharply, then gradually increased during the remainder of the experiment. Activities of chalcone synthase and UDP glucose:flavonol 3-O-glucosyltransferase (EC 2.4.1.91) increased steadily and reached a plateau after approximately 70 hours illumination time. Activity of 4-hydroxycinnamate:coenzyme A ligase (EC 6.2.1.12) remained relatively unchanged, whereas that of chalcone isomerase (EC 5.5.1.6) declined steadily during the course of the experiment. The relative in vitro enzyme activities suggest that the rate-limiting step for the phenylpropanoid path is the cinnamic acid 4-hydroxylase, that of the flavonoid pathway is the chalcone synthase. Integration of enzyme activity curves, however, show that only the curve deriving from phenylanine ammonia-lyase activity matches closely the production of the flavonol glycosides.Detailed investigations on the effect of light on dark-grown parsley cell suspension cultures resulted in recognition of coordinated induction in phenylpropanoid-and flavonoid-metabolizing enzyme activities (6). This coordinated induction of enzyme activity is due to de novo synthesis of the subunits and assembly of the enzymes (20) and not to activation of preformed inactive components.There are indications that in intact plants the change in enzyme activities upon illumination are not so straight forward (3, 15). Etiolated pea seedlings respond to exposure of light with complex pattern of transitory changes in the concentration of their flavonoid components (22). These flavonoids are the 3-triglucosides and 3-p-coumaryl triglucosides of kaempferol and quercetin, and the 3-sophoroside 5-glucosides and 3-sambubioside 5-glucosides of cyanidin and delphinidin (4, 25). Correlation between changes in PAL' activity and flavonoid glycoside production suggested the involvement of two different systems in flavonoid synthesis: a lowmagnitude, phytochrome-mediated response, and a long-term response of greater magnitude dependent on continuous illumination (21).In this paper we report the changes in flavonoid glycoside production and in the activity of phenylpropanoid and flavonoid Moustafa and Wong (17); quercetin 3-glucoside was synthesized as previously described (2).Buffers. The buffers used are as follows: A, 0.2 M K2HPO4/ KH2PO4 (pH 8.0); B, 0.2 M K2HPO4/ KH2PO4 (pH 7.5); C, 0.1 M Tris-HCl (pH 7.6). All buffers contained 4 mM 2-mercaptoethanol.Determination of the Flavonol Glycoside Content. Approxima...

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“…The quantification of flavonoids was determined as previously described (Jurd & Geissman, 1956).The values were expressed as mg of quercetin equivalent per gram of freeze-dried peel. The determination of ascorbic acid was performed as described (Benassi & Antunes, 1988).…”

Section: Determination Of Flavonoids and Ascorbic Acidmentioning

confidence: 99%

Enrichment of Commercially-Prepared Juice With Pomegranate (Punica granatum L.) Peel Extract as a Source of Antioxidants

Barros¹,

Salgado²,

Melo³

et al. 2014

JFR

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Ready-to eat foods meet the demands of a modern lifestyle and the number of people seeking food that is convenient and safe is increasing. The extracts of peels from four different fruits were tested as potential value-added foods to offer to consumers. Physical and chemical analyses of the peel extracts were conducted to measure total phenolic compounds, tannins, phytic acid and antioxidant activity using the 1'-1'Diphenyl-2'picrylhydrazyl, and 2,2'-azino-bis-3-ethylbenzothiazoline-6-sulphonic acid methods. The result of screening the antioxidant activity showed that the pomegranate peel had higher activity than the other peels (p<0.05). In addition, flavonoids and vitamin C were measured in the pomegranate peel, and low amounts of these components were found. The pomegranate peel had a high amount of phenolic compounds and high levels of antioxidants, and this peel was used to enrich a commercially-available juice. Furthermore, the sensory evaluation showed no difference between the control and enriched juice. The product was well accepted and feasible from a technological standpoint. Because the waste is rich in bioactive compounds, value is added to the final product, as these antioxidant compounds are known to protect health and improve the quality of life of the consumers.

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Absorption Spectra of Metal Complexes of Flavonoid Compounds

Cited by 131 publications

References 0 publications

Effect of pH on the colour formed by Fe‐phenolic complexes in ripe olives

Effect of pH on the colour formed by Fe‐phenolic complexes in ripe olives

Induction of Flavonoid Synthesizing Enzymes by Light in Etiolated Pea (Pisum sativum cv. Midfreezer) Seedlings

Enrichment of Commercially-Prepared Juice With Pomegranate (Punica granatum L.) Peel Extract as a Source of Antioxidants

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