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The alkaloids of Lobelia yuccoides Hillebr
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|Title:||The alkaloids of Lobelia yuccoides Hillebr|
|Authors:||Goldberg, Arthur Samuel|
|Abstract:||The Lobelieae constitute a tribe of the plant family Campanulaceae and comprise some 22 genera. Six of these are endemic to the Hawaiian Islands. In addition, the cosmopolitan genus Lobelia is represented in Hawaii by five endemic species, one of which is Lobelia yuccoides Hillebr. Of some 200 species of the genus Lobelia, only 21 have been examined chemically through 1964. As a result of these investigations 43 different alkaloids have been described, 37 of which have been characterized. No Hawaiian species have, however, been investigated chemically. An investigation of an alkaloidal extract of the root and stem bark of Lobelia yuccoides Hillebr. using two-dimensional thin-layer chromatography indicated the presence of 10-14 alkaloids. One of these tentatively referred to as A-l, was isolated in a yield corresponding to 0.0006% of dry bark through the use of column chromatography. Alkaloid A-l was shown to be identical with 8-phenylnorlobelol (I), an alkaloid previously isolated from Lobelia inflata. The second alkaloid was isolated in yields of 0.003- 0.004% of dry bark, m.p. 208-210° (dec.), [α]D^22 0.00 (water), pKa 7.2, and is referred to as A-2. Alkaloid A-2 was isolated by extraction of an aqueous solution of the alkaloid hydrochlorides with chloroform, evaporation of the chloroform extract to dryness followed by trituration with chloroform, and then by cooling the resulting solution. This resulted in the selective precipitation of alkaloid A-2. Elemental analyses, mass spectrum, and potentiometric titration of A-2 led to a molecular formula of C19H25N2O2Cl. Chemical degradation and spectral evidence pointed to a postulated structure (II) for A-2. This structure is different from previously characterized Lobelia alkaloids and constitutes, therefore, a new structural type.|
Thesis (Ph. D.)--University of Hawaii, 1966.
Bibliography: leaves -88.
x, 88 l illus., tables
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|Appears in Collections:||Ph.D. - Chemistry|
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