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Title: Studies on naturally occurring plant phenols
Author: Macleod, Norma June
Awarding Body: University of London
Current Institution: Royal Holloway, University of London
Date of Award: 1962
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Various monocotyledenous and dicotyledonous plants have been examined and found to possess an enzyme capable of deaminating 3,4-dihydroxypheny (DOPA) with the formation of transcaffeic acid. The activity of this enzyme in barley, dandelion and wheat is relatively high, whereas in broad-bean leaves it is low and in potato tubers tissues, negligible. It is possible that in the broad-bean, this low activity may be, at least in part, responsible for the high concentration of DOPA in the tissues. Broad-bean leaves also contain a tyrosine deaminase. It has been shown that "foreign" phenols can move rapidly up and down the stems of broad-bean plants and that glucosylation of many of these compounds readily occurs. Phenols fed into the cut ends of the main veins of leaves quickly appear in the sieve tubes of the stem. This has been proved by the use of the aphid, Macrosiphium pisi. Aphid techniques have also strongly suggested that the sieve tubes of broad-bean and willow normally contain phenolic compounds. The reaction of boron trichloride and methanol on cinnamic acid derivatives has been Investigated in detail and a procedure has been devised which aids the identification of these acids in plant tissues. Using this method all glycosidie, esterified and methoxylated derivatives are converted to the corresponding mono-, di-, or tri-hydroxyxy-methyl cinnamates which can be identified on paper chromatograms or electrophoretograms. Thus the cinnamic acids present can be classified into one or more of these families. The paper electrophoretic examination of high molecular weight phenols as azo dye derivatives has also been investigated. These phenols have been coupled with dizaotised p-aminobenzoic or diazotised sulphanilic acids. The resulting dyes possess strongly dissociated acidic groupings and therefore exhibit relatively high electrophoretic mobilities in comparison with the unsubstituted phenols.
Supervisor: Not available Sponsor: Not available
Qualification Name: Thesis (Ph.D.) Qualification Level: Doctoral
EThOS ID:  DOI: Not available
Keywords: Organic Chemistry