Léo Marion

The biogenesis of stachydrine

Abstract The amino-acids omithine and proime have been shown to serve as precursors of the alkaloid stachydrine in the mature 5 1 2 -6 month old alfalfa plant. Degradation of the alkaloid obtained from experiments with dl -ornithine-2-14C has shown that no randomization occurs and that the label is entirely located on carbon atom 2.

A suggested structure for delsoline

The alkaloid delsoline (C25H41O7N) was oxidized by acid permanganate mostly to dehydrooxodelsoline, and by neutral permanganate to anhydrohydroxydelsoline. Oxidation of the alkaloid with mercuric acetate produced anhydrohydroxy-N-de-ethyldelsoline which could be re-ethylated with ethyl iodide, thus showing the presence of an N-ethyl group in delsoline. Anhydrohydroxydelsoline was also obtained from O-acetyldelsoline perchlorate by oxidation to an anhydronium salt followed by hydrolysis with sodium hydroxide, and this method of preparation provides evidence of its carbinolamine structure. O-Acetyloxodelsoline, obtained from acetyldelsoline, is cleaved by lead tetra-acetate to a secodiketone that loses the elements of methanol on recrystallization. Hence the base contains two vicinal tertiary hydroxyls, one of which is β to a methoxyl group. Dehydrooxodelsoline is also cleaved by lead tetra-acetate and the product undergoes an internal aldol rearrangement. These results are interpreted in the light of a structure that is tentatively suggested for delsoline.

The biogenesis of ricinine

Abstract It has been postulated that in some bacteria and some higher plants the pyridine ring of such compounds as nicotinic acid ( Ortega and Brown, 1960 ), nicotine ( Griffith, Hellman, and Byerrum, 1960 ), and the α-pyridone ring of ricinine (Waller and Henderson, 1960) may be synthesized from simple metabolic intermediates related to acetate, succinate, glycerol, or propionate. On the other hand, Tamir and Ginsberg (1959) claimed the specific incorporation of DL-lysine-2-C14 into ricinine. The present study confirms the incorporation of several simple precursors into ricinine (Fig. 1) by Ricinus communis L. It is suggested that the results obtained, as well as the results of other workers, can best be explained by adopting the idea that succinic acid or a closely related 4-carbon dicarboxylic acid found in the Krebs tricarboxylic acid cycle is a direct precursor of ricinine.

Chapter 2 The Pyrrolidine Alkaloids

Publisher Summary This chapter discusses the pyrrolidine alkaloids. The recent investigations to be described relate to hygrine, hygroline, cuscohygrine, stachydrine, betonicine, and turicine. The structure of carpaine has also been fully elucidated, and this alkaloid has been shown to be a piperidine and not a pyrrolidine alkaloid and hence will be described under the heading “The Pyridine Alkaloids.” It is reported that the catalytic reduction of the product of the reaction of N-methylpyrrole and diazoacetone gave dl -hygrine. Hygroline has been synthesized by the catalytic reduction of l -hygrine. Cuscohygrine has been detected in the fresh roots of Atropa belladonna. The stereochemistry of the hydroxyproline betaines, betonicine and turicine, has now been done by the use of nonepimerizing methylating conditions on hydroxyprolines of known stereochemistry.

Chapter XIII The Indole Alkaloids

Publisher Summary This chapter presents information on indole alkaloids. The chapter presents a classification of various groups of alkaloids, according to the position of the substituents and the degree of substitution in the pyrrole part of the indole nucleus. The groups are extended to accommodate alkaloids, carrying substituents in the benzene ring, as well as those already specified for each group. The chapter discusses the following: (1) abrine, (2) hypaphorine, (3) gramine, (4) the ergot alkaloids, (5) the alkaloids of Peganum harmala , (6) those of Evodia rutaecarpa , (7) the yohimbe alkaloids, (8) the quebracho alkaloids, (9) the alkaloids of Rauwolfia species, (10) the alkaloids of Gelsemium species, (11) the alkaloids of Calycanthareae , (12) those of the calabar bean, (13) the iboga alkaloids, (14) the Alstonia alkaloids, (15) those of Geissospermum vellosii , (16) quinamine and cinchonamine, and (17) C-dihydrotoxiferine-I. The action of amyl alcoholic potassium hydroxide on quinamine causes rapid epimerization and three products are obtained—namely, epiquinamine, isoquinamine, and epi-isoquinamine. The chapter presents a table on the alkaloids and their transformation products.

Chapter XIV The Erythrina Alkaloids

Publisher Summary This chapter describes erythrina alkaloids. The alkaloids found in numerous species of the genus Erythrina are, with the exception of hypaphorine, of wide interest, because of their remarkable physiological action. The occurrence of hypaphorine in Erythrina subumbrans has long been known. In a systematic investigation, it has been shown that out of 105 known species of Erythrina , the 50 that have been tested contain alkaloids of paralyzing activity. Besides hypaphorine that occurs in a number of species, the bases found in these plants fall into two groups. The free alkaloids isolated so far are erythramine, erythraline, erythratine, and erythroidine that occur in two isomeric forms, α - and β -erythroidine. Only two “combined” alkaloids, erysothiovine and erysothiopine, have been characterized, while the following “liberated” alkaloids have been described in the chapter: erysopine, erysovine, erysodine, and erysonine. The chapter discusses the method of extracting alkaloids from the seeds of Erythrina species. Free alkaloids are isolated directly from the extracts of the plant without the necessity of previous hydrolysis and are purified by fractional crystallization of their salts. Erysopine, on hydrogenation, gives rise to tetrahydroerysopine that still contains a tertiary nitrogen atom. The chapter also presents a table on the physical constants of the erythrina alkaloids and their products of transformation and degradation.

Chapter 4 The Pyridine Alkaloids

Publisher Summary Two facts concerning tobacco are significant. Although growing tobacco was restricted in Europe and Asia by the need for food crops, the world production for the season 1945-46 was estimated at 6,654,000,000 lbs. One of the factors forcing the economics of Britain into an unfavorable position is the import of tobacco into that country from the dollar areas. These two facts clearly illustrate that at least one of the pryidine alkaloids occupies a unique position of economic and industrial importance, commensurate with its theoretical interest. There are isolated instances where the parent bases, pyridine and piperidine, have been found to occur in nature. However, it is the more complex members of this series of bases that have attracted the attention of alkaloid chemists. The distribution of the more complex pyridine alkaloids in the plant kingdom is more widespread. In this chapter, the various groups of alkaloids are classified according to the position of the substituents and the degree of substitution in the pyridine nucleus (the term “pyridine” is used loosely in this classification scheme to include also those alkaloids with a piperidine nucleus) of the index compound or main member of each group of alkaloids.

Chapter III The Pyrrolidine Alkaloids

Publisher Summary Comparatively few pyrrolidine alkaloids have been found to occur naturally. The parent substance is a constituent of Daucus carota L. and is one of the minor alkaloids of tobacco. Another minor alkaloid from tobacco and Atropa belladonna L., proved to be N-methylpyrroline, identical with that obtained from the reduction Of N-methylpyrrole with zinc and hydrochloric acid. A hygroscopic hydrochloride has been prepared but its conversion to a nitrosamine could not be realized. Tobacco and Atropa belladonna have yielded a third member of this group. It is a component of the volatile tobacco alkaloids and was recovered from this fraction after the trimethylamine had been removed. Preparation of a number of its crystalline salts and comparison of their melting points by admixture with those from synthetic N-methylpyrrolidine completed the identification of this volatile amine. The volatile bases occurring in Peruvian Cusco leaves and those of the Coca plant contain hygrine, a fourth member of this series. An oily base first designated as hygrine by Wohler and Lossen proved to be inhomogeneous for it was later separated by Liebermann into lower- and higher-boiling fractions. However, the name hygrine was retained for the oily base with the lower boiling point (b.p. 193-195o). Hesse, another early worker, claimed to have isolated hygrine but the empirical formula, which he assigned to his product leads one to doubt the homogeneity of this preparation.