TheDMACA-HCl Protocol and the Threshold Proanthocyanidin Content for Bloat Safety in Forage Legumes

Li, Yuguang; Tanner, Gregory J.; Larkin, P. J.

doi:10.1002/(sici)1097-0010(199601)70:1<89::aid-jsfa470>3.0.co;2-n

Cited by 393 publications

(310 citation statements)

References 17 publications

(39 reference statements)

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“…The results were expressed as rutin equivalents. The total flavanol and flavans content (TFAC) was detected with p-DMACA (Li et al, 1996). The results were expressed as (+)-catechin equivalents.…”

Section: Determination Of Total Phenolicssupporting

confidence: 77%

Melatonin treatment of pre-veraison grape berries modifies phenolic components and antioxidant activity of grapes and wine

et al. 2019

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A comprehensive investigation was conducted to determine the effects of exogenous melatonin treatment of pre-veraison grapes on phenolic components and antioxidants of grape berries and wine. The results showed an increase in the concentration of cyanin-3-O-glucoside, peonidin derivatives, and two flavanols [namely (+)-catechins and (−)-epicatechins] of grapes, as well as flavonols in both grapes and wine due to the application of melatonin. These compounds are derivatives of the catalysate of flavonoid 3'-hydroxylase (F3'H) in the flavonoid synthesis pathway of plants. Ot can be inferred that melatonin increased the activity of F3'H or expression of VvF3'H during grape berry maturation. On addition, two melatonin treatments of pre-veraison grape berries reduced the DPPH radical-scavenging ability and copper ion-reducing power of grapes and wine, whereas one melatonin treatment just reduced those in wine. This study will provide a practical strategy to change the phenolic composition of grapes and wine.Keywords: melatonin; grape; wine; phenolics; antioxidant activity.Practical Application: This study will facilitate the production of quality wine using melatonin.

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Section: Determination Of Total Phenolicssupporting

confidence: 77%

Melatonin treatment of pre-veraison grape berries modifies phenolic components and antioxidant activity of grapes and wine

et al. 2019

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“…The sensitivity of the DMACA stain (another aromatic aldehyde) is some 4-fold greater than vanillin, and has been used to detect PA in plant species previously thought to lack PA when tested using vanillin stain (Li et al, 1996). Another advantage of DMACA over vanillin is that DMACA stains PA blue-purple, whereas vanillinstained PA is pink and can be confused with pink anthocyanin pigments in tissues containing both compounds.…”

Section: Discussionmentioning

confidence: 99%

Identification and Biochemical Characterization of Mutants in the Proanthocyanidin Pathway in Arabidopsis

et al. 2002

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Proanthocyanidin (PA), or condensed tannin, is a polymeric flavanol that accumulates in a number of tissues in a wide variety of plants. In Arabidopsis, we found that PA precursors (detected histochemically using OsO 4 ) accumulate in the endothelial cell layer of the seed coat from the two-terminal cell stage of embryo development onwards. To understand how PA is made, we screened mature seed pools of T-DNA-tagged Arabidopsis lines to identify mutants defective in the synthesis of PA and found six tds (tannin-deficient seed) complementation groups defective in PA synthesis. Mutations in these loci disrupt the amount (tds1, tds2, tds3, tds5, and tds6) or location and amount of PA (tds4) in the endothelial cell layer. The PA intermediate epicatechin has been identified in wild type and mutants tds1, tds2, tds3, and tds5 (which do not produce PA) and tds6 (6% of wild-type PA), whereas tds4 (2% of wild-type PA) produces an unidentified dimethylaminocinnamaldehyde-reacting compound, indicating that the mutations may be acting on genes beyond leucoanthocyanidin reductase, the first enzymatic reduction step dedicated to PA synthesis. Two other mutants were identified, an allele of tt7, which has a spotted pattern of PA deposition and produces only 8% of the wild-type level of type PA as propelargonidin, and an allele of tt8 producing no PA. Spotted patterns of PA deposition observed in seed of mutants tds4 and tt7-3 result from altered PA composition and distribution in the cell. Our mutant screen, which was not exhaustive, suggests that the cooperation of many genes is required for successful PA accumulation.Flavonoids are a diverse group of plant secondary metabolites that accumulate in a wide variety of plant tissues and include anthocyanins, flavonols, and the polymeric flavanols known as proanthocyanidins (PAs; Fig. 1). Like their flavanol constituents, PAs are rich in hydrophobic aromatic rings and hydroxyl groups that can interact with biological molecules, particularly proteins, by hydrogen bonds and hydrophobic interactions. Because PAs are polymeric, their interaction with proteins is much stronger than that of monomeric flavanols, presumably because of a "chelate" effect where polymeric PAs can interact with large proteins at multiple sites, increasing the strength of overall molecular interaction as well as minimizing dissociation of the complex once it is formed (Fersht, 1985). This strong interaction of PAs with proteins is probably the basis of their main role in plants and their uses by man.Because PA content of dietary plants can have both positive and negative effects on animal nutrition (Waghorn and Jones, 1989), an important agricultural objective is to manipulate the level of PA in pasture legumes (Morris and Robbins, 1997). When present in bloat-safe forage legumes, PA can bind to and cause the precipitation of dietary proteins, inhibiting the formation of stable proteinaceous foams, thereby preventing bloat (Tanner et al., 1995). Increasing the PA content of pastures such as alfalfa (Medicago s...

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“…Thus, in this investigation, all of the tannin extracts were analysed by HPLC-phloroglucinolysis without further purification to maintain a consistent approach. Another approach would have been to use solid phase extraction, but dimethylcinnamaldehyde staining (Li et al, 1996) indicated that some tannin material was usually retained on these columns and this was not pursued further.…”

Section: Tannin Polymer Lengthmentioning

confidence: 99%

Comparison of Ethanol and Acetone Mixtures for Extraction of Condensed Tannin from Grape Skin

Downey¹,

Hanlin²

2016

SAJEV

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Discrepancies in condensed tannin concentrations in grape skin determined by different analytical methods prompted the closer examination of aspects of the methodologies. One of these was the choice of extraction solvent. Condensed tannins were extracted from Shiraz grape skins using a range of aqueous solvent mixtures ranging from zero to 100% acetone and ethanol to examine the relative effectiveness of each solvent mixture and to determine whether different solvent mixtures extracted similar condensed tannin components. Acetone extracted more condensed tannin than ethanol. Mixtures of 50 to 70% acetone were equally effective. The most effective ethanol concentration was 50%. Epicatechin-gallate terminal subunits were not detected by HPLC following acid-catalysed cleavage in any of the extraction solvents. Extension subunit composition was similar between solvents across most mixtures. Polymers were generally shorter in the ethanol extracts than in the acetone extracts. Despite differences in tannin concentration and polymer length, the subunit composition was similar in 50% ethanol and 70% acetone. More tannin and tannins with longer polymer lengths were extracted with 70% acetone than with 50% ethanol. This suggests that all grape skin tannins are similar in composition, varying only in length. Thus, 50% ethanol and 70% acetone would give a fair indication of the grape skin tannin composition extracted into wine. However, both 50% ethanol and 70% acetone may overestimate the amount of tannin that is extracted into wine, as wine typically has a much lower solvent concentration, ranging between 10 and 15% ethanol.

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TheDMACA-HCl Protocol and the Threshold Proanthocyanidin Content for Bloat Safety in Forage Legumes

Cited by 393 publications

References 17 publications

Melatonin treatment of pre-veraison grape berries modifies phenolic components and antioxidant activity of grapes and wine

Melatonin treatment of pre-veraison grape berries modifies phenolic components and antioxidant activity of grapes and wine

Identification and Biochemical Characterization of Mutants in the Proanthocyanidin Pathway in Arabidopsis

Comparison of Ethanol and Acetone Mixtures for Extraction of Condensed Tannin from Grape Skin

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