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A Reappraisal of the Relationship Between Free and Bound Coumarin in Melilotus 1
Author(s) -
Haskins F. A.,
Gorz H. J.
Publication year - 1961
Publication title -
crop science
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.76
H-Index - 147
eISSN - 1435-0653
pISSN - 0011-183X
DOI - 10.2135/cropsci1961.0011183x000100050006x
Subject(s) - geneticist , library science , biology , computer science , genetics
DUNCAN and Dustman (3, 4), Clayton and Larmour (1), and Stevenson and Clayton (13) were among the first investigators to attempt the assay of coumarin in sweetclover (Melilotus spp.). All of these workers apparently believed that the coumarin measured by their assay methods existed in the free form in the plant. Roberts and Link (8, 9) recognized the presence of bound coumarin in sweetclover seeds and green tissues and indicated that provision must be made for the hydrolysis of this form if reliable values for total coumarin content were to be obtained. However, they stated that in succulent, green tissues the free form usually predominated over the bound form (9). Slatensek and Washburn (12) observed that Pioneer sweetclover, a variety described by Stevenson and White (14) as being low in coumarin on the basis of colorimetric analysis of alcoholic extracts, appeared to be high in coumarin when assayed by a fluorometric method which involved heating the plant tissue in alkali. The difference in values obtained by the two methods was attributed to the presence of bound coumarin which was hydrolyzed in the fluorometric procedure but not in the colorimetric assay. Although the fluorometric assay described by Slatensek and Washburn (12) did not permit distinction between free and bound coumarin, it is apparent that these investigators considered coumarin to be in the free form in all coumarincontaining varieties other than Pioneer. In recent years, Goplen et al. (5) have reported on the influence of two pairs of alleles, Cu/cu and B/b, upon the level and form of coumarin in sweetclover. A qualitative colorimetric method was used for the detection of free coumarin in alcoholic extracts; and, for quantitative measurements of total coumarin, a fluorometric assay similar to that described by Slatensek and Washburn (12) was used. The authors concluded that the Cu/cu allelic pair governed presence or absence of coumarin and that the B/b alleles determined the type of coumarin (free or bound) present in Cu individuals. The assay methods did not permit deter-