Gallic acid oxidation by turnip peroxidase

Kamel, Mamdouh Y.; Saleh, Nabil; Ghazy, Abdel-Hady M.

doi:10.1016/0031-9422(77)80006-x

Cited by 24 publications

(11 citation statements)

References 22 publications

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“…Interestingly, the maximum concentrations of EA increased with the amount of galloyl groups, but not with the amount of HHDP groups (Table ), although ellagic acid is considered to be the hydrolysis product of ETs. The formation of EA from gallic acid, pentaGG or similar compounds without the HHDP groups has been encountered occasionally in alkaline conditions (Yoshida et al ., ) or with the strong oxidant peroxidase (Kamel et al ., ; Fig. ).…”

Section: Resultsmentioning

confidence: 99%

Stability and Oxidation Products of Hydrolysable Tannins in Basic Conditions Detected by HPLC/DAD–ESI/QTOF/MS

Tuominen

Sundman

2013

Phytochemical Analysis

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Section: Resultsmentioning

confidence: 99%

Stability and Oxidation Products of Hydrolysable Tannins in Basic Conditions Detected by HPLC/DAD–ESI/QTOF/MS

Tuominen

Sundman

2013

Phytochemical Analysis

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“…Results from 2 experiments. et al, 1977;Kahn, 1985b;Takahama, 1989), residual PPO and POX activities were determined under conditions allowing discrimination between their activities. POX was assayed in the presence of added H,O, and guaiacol (not a substrate for PPO due to its ether functional group) or tropolone (an inhibitor of PPO).…”

Section: Results and Discussion General Conditions For Discolorationmentioning

confidence: 99%

Endogenous Polyphenoloxidase Activity Associated with the “Black Ring” Defect in Canned Beet (Beta vulgaris L.) Root Slices

Im¹,

Parkin²,

Elbe³

1990

Journal of Food Science

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Discoloration of canned beet root slices resulted after 5-10 min exposure of beet roots to live steam, and subsequent incubation of slices in air at least 20 min. The "black ring" of discoloration moved radially toward the center of the slice as time of steam-peeling was increased. Dipping slices (prepared after steam-peeling) in solutions of inhibitors of PPO before incubation in air inhibited or prevented discoloration. Based on these data, thermal stability of PPO and POX, heat penetration profiles, and location of the discoloration zone, a model to explain discoloration was developed.

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“…Gallic acid and ellagic acid concentrations were determined using a previously published procedure using thin-layer chromatography (TLC) (Kamel et al ., 1977; Wagh, 2010). Standards of gallic acid and ellagic acid of varying concentrations (0 - 10 mM) were used to calculate both concentrations in triplicates of non-anthesis and anthesis nectar samples.…”

Section: Methodsmentioning

confidence: 99%

“…Intriguingly, the total phenolic content (ellagic + gallic acid) is roughly the same between the light and dark colored nectars, but anthesis nectar has significantly lower gallic acid and higher ellagic acid. This finding is particularly important since gallic acid is a precursor of 395 ellagic acid (Kamel et al, 1977). 396…”

Section: Iron and Ellagic Acid Are Required For Black Pigment Formationmentioning

confidence: 99%

Post-secretory synthesis of a natural analog of iron-gall ink in the black nectar ofMelianthusspp.

Magner

Roy

Saxhaug

et al. 2022

Preprint

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The black nectar ofMelianthusflowers is thought to serve as a visual attractant to pollinators, but the chemical identity and biosynthesis of the black pigment are unknown. Here we report that the black nectar contains a natural analog of iron-gall ink, which humans have used since medieval times. Specifically, dark black nectar at anthesis contains high levels of ellagic acid and iron; synthetic solutions of ellagic acid and iron(III) recapitulate the black color of the nectar. Conversely, lightly colored nectars before and after anthesis contain significantly lower levels of ellagic acid and iron, but higher levels of gallic acid. We then explored the possibility of post-secretory synthesis of ellagic acid from gallic acid. Indeed,Melianthusnectar contains a peroxidase that oxidizes gallic acid to form ellagic acid. Reactions containing the nectar peroxidase, gallic acid, hydrogen peroxide, and iron can fully recreate the black color of the nectar. Visual modeling indicates that the black color is both visible and conspicuous to birds within the context of the flower. In summary, the black nectar ofMelianthusis derived from an ellagic acid-Fe complex analogous to iron-gall ink and is likely involved in the attraction of passerine bird pollinators.

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Gallic acid oxidation by turnip peroxidase

Cited by 24 publications

References 22 publications

Stability and Oxidation Products of Hydrolysable Tannins in Basic Conditions Detected by HPLC/DAD–ESI/QTOF/MS

Stability and Oxidation Products of Hydrolysable Tannins in Basic Conditions Detected by HPLC/DAD–ESI/QTOF/MS

Endogenous Polyphenoloxidase Activity Associated with the “Black Ring” Defect in Canned Beet (Beta vulgaris L.) Root Slices

Post-secretory synthesis of a natural analog of iron-gall ink in the black nectar ofMelianthusspp.

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