Base-Catalyzed Reactions of (−)-Epicatechin: Formation of Enantiomers of Base-Catalyzed Reaction Products from (+)-Catechin

Hashida, Koh; Ohara, Seiji; Makino, Rei

doi:10.1081/wct-120026930

Cited by 9 publications

(26 citation statements)

References 5 publications

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Section: Introductionmentioning

confidence: 99%

“…Analysis was performed by methylation followed by NMR and mass spectrometry [12,13]. Characterization of condensed tannins in plant sources is mainly by NMR [12][13][14][15] but a relatively pure isolate is needed which is a disadvantage for mixtures. Among chromatographic techniques, normal or reversed phase liquid chromatography mass spectrometry (LC-MS) equipped with ESI and APCI ion sources [16,17] and size-exclusion chromatography [18] are the principle methods of the analysis of catechins and condensed tannins.…”

Section: Introductionmentioning

confidence: 99%

See 1 more Smart Citation

Analysis of catechins and condensed tannins by thermally assisted hydrolysis/methylation-GC/MS and by a novel two step methylation

Shadkami

Estévez

Helleur

2009

Journal of Analytical and Applied Pyrolysis

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Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Analysis of catechins and condensed tannins by thermally assisted hydrolysis/methylation-GC/MS and by a novel two step methylation

Shadkami

Estévez

Helleur

2009

Journal of Analytical and Applied Pyrolysis

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“…In these, the catechin dimer is linked covalently to either a catechin monomer or another catechin dimer, such as those shown by the peaks for the oligomers at 1169 Da = 1145 + 1 × Na + (Figure 2 Higher oligomers in which catechin has dimerised also occurs, this being a fairly common reaction [16,17]. In these, the catechin dimer is linked covalently to either a catechin monomer or another catechin dimer, such as those shown by the peaks for the oligomers at 1169 Da = 1145 + 1 × Na + (Figure 2 Higher oligomers in which catechin has dimerised also occurs, this being a fairly common reaction [16,17]. In these, the catechin dimer is linked covalently to either a catechin monomer or another catechin dimer, such as those shown by the peaks for the oligomers at 1169 Da = 1145 + 1 × Na + ( Figure 2) and at 1404 and 1459 Da, deprotonated.…”

Section: Maldi-tofmentioning

confidence: 99%

“…In these, the catechin dimer is linked covalently to either a catechin monomer or another catechin dimer, such as those shown by the peaks for the oligomers at 1169 Da = 1145 + 1 × Na + (Figure 2 Higher oligomers in which catechin has dimerised also occurs, this being a fairly common reaction [16,17]. In these, the catechin dimer is linked covalently to either a catechin monomer or another catechin dimer, such as those shown by the peaks for the oligomers at 1169 Da = 1145 + 1 × Na + (Figure 2 It must be made clear that the structures above are not the only possible isomers deduced from the peaks of the MALDI-ToF spectra, but that other isomer possibilities do exist for them.…”

Section: Maldi-tofmentioning

confidence: 99%

“…Dimers of two catechin monomers linked covalently through an hexamethylenediamine occurs, such as the peak occurring at 664 Da ( Higher oligomers in which catechin has dimerised also occurs, this being a fairly common reaction [16,17]. In these, the catechin dimer is linked covalently to either a catechin monomer or another catechin dimer, such as those shown by the peaks for the oligomers at 1169 Da = 1145 + 1 × Na + (Figure 2 Higher oligomers in which catechin has dimerised also occurs, this being a fairly common reaction [16,17].…”

Section: Maldi-tofmentioning

confidence: 99%

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Polycondensation Resins by Flavonoid Tannins Reaction with Amines

et al. 2017

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Reaction of a condensed flavonoid tannin, namely mimosa tannin extract with a hexamethylene diamine, has been investigated. For that purpose, catechin was also used as a flavonoid model compound and treated in similar conditions. Solid-state cross-polarisation/ magic-angle spinning (CP-MAS) carbon 13 nuclear magnetic resonance ( 13 C NMR) and matrix assisted laser desorption ionisation time of flight (MALDI-ToF) mass spectroscopy studies revealed that polycondensation compounds leading to resins were obtained by the reaction of the amines with the phenolic hydroxy groups of the tannin. Simultaneously, a second reaction leading to the formation of ionic bonds between the two groups occurred. These new reactions have been shown to clearly lead to the reaction of several phenolic hydroxyl groups, and flavonoid unit oligomerisation, to form hardened resins.

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Is (−)-Catechin a Novel Weapon of Spotted Knapweed (Centaurea stoebe)?

et al. 2009

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The novel weapons hypothesis states that some invasive weed species owe part of their success as invaders to allelopathy mediated by allelochemicals that are new to the native species. Presumably, no resistance has evolved among the native species to this new allelochemical (i.e., the novel weapon). In their native habitat, however, the plants that co-evolved with these invasive species have theoretically evolved defenses that obviate the allelochemical advantage. Previous studies have claimed that catechin is such a novel weapon of spotted knapweed (Centaurea stoebe = C. maculosa), an invasive species in the non-native habitat of North America. These studies indicated that (-)-catechin is more phytotoxic than (+)-catechin. Other studies have not found sufficient catechin in field soils to support this theory. We report that (-)-catechin and (+)-catechin are essentially equal, but poorly phytotoxic to a variety of plant species in bioassays without soil. In a dose/response experiment with Montana soils, we found the lowest dose for a growth reduction of two native Montana grasses (Koeleria macrantha and Festuca idahoensis) by a racemic mixture of (+/-)-catechin that ranged from about 25 to 50 mM, concentrations, orders of magnitude higher than expected in nature. Autoclaving the soil before adding the catechin did not affect the activity of catechin. We found (-)-catechin to be a potent antioxidant, in contrast to a previous claim that it acts as an allelochemical by causing oxidative stress. Our findings suggest that catechin is not a novel weapon of spotted knapweed and that other allelochemical(s) or alternative mechanisms must be found to explain the success of this species as an invader in North America.

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Base-Catalyzed Reactions of (−)-Epicatechin: Formation of Enantiomers of Base-Catalyzed Reaction Products from (+)-Catechin

Cited by 9 publications

References 5 publications

Analysis of catechins and condensed tannins by thermally assisted hydrolysis/methylation-GC/MS and by a novel two step methylation

Analysis of catechins and condensed tannins by thermally assisted hydrolysis/methylation-GC/MS and by a novel two step methylation

Polycondensation Resins by Flavonoid Tannins Reaction with Amines

Is (−)-Catechin a Novel Weapon of Spotted Knapweed (Centaurea stoebe)?

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