Osmium tetroxide as a reagent for the estimation of tannins and their derivatives

Mitchell, C. Ainsworth

doi:10.1039/an9244900162

Cited by 13 publications

(3 citation statements)

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“…noted that in this work the colorimetric method of Mitchell (1924) was used, whereas Shearer employed the gravimetric hide-powder method as described by Rosenthaler (1930), a method which it is known may give rather high and sometimes variable results. Ash and silica.…”

Section: Chemical Compositionmentioning

confidence: 99%

The composition and nutritive value of bracken

Moon¹,

Pal²

1949

J. Agric. Sci.

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Samples of bracken were taken at regular intervals between June and October from a hill grazing where losses of cattle from ‘bracken poisoning’ had occurred in previous years. These were separated into leaf and stem for analysis. Dry, mature bracken cut in October was examined for digestibility and nutritive value, and in the following season the digestibility of fresh, green bracken was determined for both cattle and sheep.Chemical composition. Analyses of the fresh bracken fed in the digestibility trials were in line with those of the samples collected in the previous year. Crudeprotein content was high in June and July, but fell markedly in August and September, whilst the crude fibre varied in the opposite direction, increasing markedly in August. An increase in the tannin content was observed in September but this was not comparable with the increases reported by Shearer. An attempt to elucidate the significance of tannin in the in vitro digestion of bracken-leaf protein was unsuccessful. The potassium content was found to be rather lower than in good pasture grass, confirming the findings of Ferguson & Armitage. The potassium was highly soluble in water but the soluble part was not entirely in the form of chloride.

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Section: Chemical Compositionmentioning

confidence: 99%

The composition and nutritive value of bracken

Moon¹,

Pal²

1949

J. Agric. Sci.

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“…No chloride was released from any of the substrates, in the absence of extract, by the addition of tungstic acid. Metabolism of phenol or catechol was assessed by measuring the extent of disappearance of the substrates (Lacoste et al, 1959;Mitchell, 1924). In the catechol assay, 0.05% osmic acid was added to a solution buffered at pH 7.8.…”

Section: Methodsmentioning

confidence: 99%

Phenoxyacetate herbicide detoxication by bacterial enzymes

Loos¹,

Bollag²,

Alexander³

1967

J. Agric. Food Chem.

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Extracts of an Arthrobacter sp. contained enzymes dehalogenating 2,4-dichloro-, 2-methyl-4-chloro-, and 2and 4-chlorophenoxyacetates. From the phenoxyacetates, these enzyme preparations produced compounds with the chromatographic charac-teristics of the corresponding phenols. The bacterial extracts further metabolized the phenols as well as several chloroand methylcatechols. The enzyme acting on the phenoxy compounds was separated from the enzyme metabolizing the chlorophenols.The phenoxyacetates are one of the major groups of herbicides used for selective control of weeks, and the vast amounts that are used annually are degraded ultimately to yield nontoxic products. Despite the

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“…2,4-DCP was determined by the method of Lacoste et al (1959), and 3,5-DCC by the procedure of Mitchell (1924). Protein was determined by biuret assay.…”

Section: Batch Culturementioning

confidence: 99%

Induction of enzymes of 2,4-dichlorophenoxyacetate degradation in Burkholderia cepacia 2a and toxicity of metabolic intermediates

Smith

Beadle

2008

Biodegradation

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Burkholderia cepacia 2a inducibly degraded 2,4-dichlorophenoxyacetate (2,4-D) sequentially via 2,4-dichlorophenol, 3,5-dichlorocatechol, 2,4-dichloromuconate, 2-chloromuconolactone and 2-chloromaleylacetate. Cells grown on nutrient agar or broth grew on 2,4-D-salts only if first passaged on 4-hydroxybenzoate- or succinate-salts agar. Buffered suspensions of 4-hydroxybenzoate-grown cells did not adapt to 2,4-D or 3,5-dichlorocatechol, but responded to 2,4-dichlorophenol at concentrations <0.4 mM. Uptake of 2,4-dichlorophenol by non-induced cells displayed a type S (cooperative uptake) uptake isotherm in which the accelerated uptake of the phenol began before the equivalent of a surface monolayer had been adsorbed, and growth inhibition corresponded with the acquisition of 2.2-fold excess of phenol required for the establishment of the monolayer. No evidence of saturation was seen even at 2 mM 2,4-dichlorophenol, possibly due to absorption by intracellular poly-beta-hydroxybutyrate inclusions. With increasing concentration, 2,4-dichlorophenol caused progressive cell membrane damage and, sequentially, leakage of intracellular K(+), P(i), ribose and material absorbing light at 260 nm (presumed nucleotide cofactors), until at 0.4 mM, protein synthesis and enzyme induction were forestalled. Growth of non-adapted cells was inhibited by 0.35 mM 2,4-dichlorophenol and 0.25 mM 3,5-dichlorocatechol; the corresponding minimum bacteriocidal concentrations were 0.45 and 0.35 mM. Strain 2a grew in chemostat culture on carbon-limited media containing 2,4-D, with an apparent growth yield coefficient of 0.23, and on 2,4-dichlorophenol. Growth on 3,5-dichlorocatechol did not occur without a supplement of succinate, probably due to accumulation of toxic quantities of quinonoid and polymerisation products. Cells grown on these compounds were active towards all three, but not when grown on other substrates. The enzymes of the pathway therefore appeared to be induced by 3,5-dichlorocatechol or some later metabolite. A possible reason is offered for the environmental persistence of 2,4,5-trichlorophenoxyacetic acid (2,4,5-T).

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Osmium tetroxide as a reagent for the estimation of tannins and their derivatives

Cited by 13 publications

References 0 publications

The composition and nutritive value of bracken

The composition and nutritive value of bracken

Phenoxyacetate herbicide detoxication by bacterial enzymes

Induction of enzymes of 2,4-dichlorophenoxyacetate degradation in Burkholderia cepacia 2a and toxicity of metabolic intermediates

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