Three dilignol rhamnosides were isolated in 0.15 to 0.40% yield from the ethyl acetate solubles of a methyl alcohol extract of western red cedar (Thuja plicata Donn) leaves using silicic acid and Sephadex LH-20 pressure column chromatography.
One of the three dilignol rhamnosides was characterized as l-(3'-methoxy-4'-hydroxyphenyl)-2-0-l"-[2"-hydroxy-4"-(propane-3"'-α-L-rhamnoside)phenyl]-propane-l,3 diol, using NMR and chemical
degradation in conjunction with mass spectral techniques on the compound and its derivatives. The other dilignol rhamnosides were not completely characterized, but were shown to be chemically related to the dilignol identified. Based upon NMR, chemical and mass spectral data, the uncharacterized dilignol rhamnosides are speculated to contain phenylcoumaran and guaiacyl benzdioxane structures.
The characterized dilignol rhamnoside represents the first reported occurrence of a free dilignol glycoside in plant tissues. The unusual α-L-rhamnose moiety of the dilignol occurs in a previously unreported linkage to the n-propyl hydroxyl group uncommon in lignin. The rhamnoside also displays the previously unreported guaiacylglycerol-catechol-β-aryl ether structure rather than the commonly observed guaiacylglycerol-guaiacyl-β-aryl ether structure. A new combustion-absorption technique was developed and validated which allows high efficiency evaluation of low activity
radioactive products separated on thin layer cellulose chromatography plates. The technique was applied to an analysis of the anabolic products of an infusion feeding of U- (14)C--L-phenylalanine to western red cedar leaves. Facile imbibition of U-(14)
C-L-phenylalanine occurs within ten hours. Maximum incorporation
of 0.30%. and 0.40% of the available radioactivity occurs in the characterized dilignol rhamnoside, and its suspected phenylcoumaran homolog respectively, at the three to five hour period of the infusion feeding. The incorporation results indicate the participation of the dilignol rhamnosides in aromatic metabolism in the leaves of western red cedar. This feeding experiment is preliminary to future detailed biosynthetic studies in the leaf tissue.
The combustion-absorption technique is limited to combustible sample weights of 7 mg. / Forestry, Faculty of / Graduate
| Identifer | oai:union.ndltd.org:UBC/oai:circle.library.ubc.ca:2429/34264 |
| Date | January 1970 |
| Creators | Manners, Gary Duane |
| Publisher | University of British Columbia |
| Source Sets | University of British Columbia |
| Language | English |
| Detected Language | English |
| Type | Text, Thesis/Dissertation |
| Rights | For non-commercial purposes only, such as research, private study and education. Additional conditions apply, see Terms of Use https://open.library.ubc.ca/terms_of_use. |
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