Alkaloids, definition

In addition to the foregoing five phthalideisoquinoline alkaloids obtained from opium, Manske has isolated from genera of the Rhceadales six more alkaloids definitely assigned to, and three, including base F38 (p. 173), which he considers may belong to this group. Hydrastine, already dealt with (p. 162), is also a phthalidcMoquinoline derivative. 

Furoquinoline Alkaloids.—Definitive studies on the biosynthesis of furoquinoline alkaloids which had been reported in preliminary form have now appeared as... 

In spite of differences between the research fields of biology, medicine, and chemistry and the fact that there remain some differences of accentuation in alkaloid definitions, such definitions are very similar, indeed almost identical. Scientists are recognizing the vital importance of these products for biology, medicine, and chemistry. 

Therefore the basic task of scientific work is development of sensitive, selective and simple methods of quantitative definition of the total contents of the alkaloids in the expert-criminal objects with the help of electrochemical methods of the analysis. 

Coniine, CgH jN. The alkaloid was first isolated by Giesecke. but the formula was suggested by Blyth and definitely established by Hofmann. 

The three hydrocarbons were synthesised, but their physical constants proved to be so similar and so like those of the pentadecane obtained from sparteine that no definite information as to the constitution of the alkaloid could be obtained from them. 

Para, Tube or Bamboo Curare. This variety was packed in sections of bamboo, but this almost traditional information needs modification since tube curare became a commercial article. It is now a viscous, solid or even powdered extract, exported in sealed tins. In view of the relationship established between bebeerine, curine, and tubocurarhie, the active alkaloid of this variety of curare, the suggestion was made, first by Spath, Leithe and Ladeck, and more definitely by King that its botanical source should be sought among the Brazilian Menispermaceae, and as shown later the search for the source of the d-tubocurarine found in this variety of curare has been narrowed down to Chondrodendron tomentosum, or possibly a closely related species liable to be confused with it. 

In future a third new group will be required, according to another preliminary statement published quite recently by a team of Australian chemists, Messrs. Hughes, Lahey, Price and Webb. They have isolated six alkaloids from three rutaceous species of that country, five of which have been definitely shown to be acridine derivatives. This appears to be the fiipst-fruits of a survey of the type referred to above, which is being carried out on the Australian flora under the auspices of the Council for Scientific and Industrial Research and several of the Australian Universities. ... 

Under the heading Alkaloids of Undetermined Constitution, have been included bases about which a good deal of information is available, though they cannot yet be allocated to sturctural groups, either because sufficient, definite information is not available, or because such data are available only about one or two members of an extensive series found in one plant or one genus. The Diehroa bases are probably quinazolines. Of the Erythrophloeum alkaloids some might be placed in the group of... 

The known changes in polyphenolic material have already been noted. Fermentation also results in slight loss of extractable caffeine. Decreases of 5 to 7% have been observed.31 Higher-than-normal fermentation times and temperatures accelerate this effect. The fate of caffeine made unavailable during fermentation is not definitely known. It has been demonstrated that caffeine interacts with polyphenols,80-81 so it is likely that the alkaloid becomes complexed with the most insoluble thearubigen fractions that do not become part of the beverage.31... 

Sodium borohydride reduction of aknadinine gave a pair of epimeric alcohols, one of which was found to be identical to natural epihernandolinol and the other identical to the known alkaloid hemandolinol (10) (28). As the structure of hemandolinol (10) had been proposed without resolution of the stereochemistry (28), the stereochemistry of epihernandolinol (9) was not definitely established (27). 

Since Huisgen s definition of the general concepts of 1,3-dipolar cycloaddition, this class of reaction has been used extensively in organic synthesis. Nitro compounds can participate in 1,3-dipolar cycloaddition as sources of 1,3-dipoles such as nitronates or nitroxides. Because the reaction of nitrones can be compared with that of nitronates, recent development of nitrones in organic synthesis is briefly summarized. 1,3-Dipolar cycloadditions to a double bond or a triple bond lead to five-membered heterocyclic compounds (Scheme 8.12). There are many excellent reviews on 1,3-dipolar cycloaddition, in particular, the monograph by Torssell covers this topic comprehensively. This chapter describes only recent progress in this field. Many papers have appeared after the comprehensive monograph by Torssell. Here, the natural product synthesis and asymmetric 1,3-dipolar cycloaddition are emphasized.630 Synthesis of pyrrolidine and -izidine alkaloids based on cycloaddition reactions are also discussed in this chapter. 

CDC Case Definition A clinically compatible case with (1) detection of urinary ricinine, an alkaloid in the castor bean plant or (2) detection of ricin in environmental samples. The case can be confirmed if laboratory testing is not performed because either a predominant amount of clinical and nonspecific laboratory evidence is present or an absolute certainty of the etiology of the agent is known. 

Chemical degradations have allowed the identification of both extremities of peripentadenine, hexanoic acid (present as an amide) and 2-hydroxy-6-meth-ylacetophenone. 13C NMR showed that the rest of the molecule included two nitrogen atoms, six methylenes, and one methine arranged in a (3-propylami-no)-l-pyrrolidine unit substituted at C-2. This formula was definitively proved by chemical degradations as well as by two total syntheses. As noted before in the cases of hygrine and of the ruspolinone alkaloids, peripentadenine is optically inactive. 

Many pharmacologically active organic chemicals fonnd in natnre are alkaloids. In general, these componnds contain one or more nitrogen atoms, which in turn impart some basicity to the molecnle. Well-known alkaloid examples are caffeine, cocaine, codeine, ephedrine, morphine, nicotine, qninine, and scopolamine. Heroin is derived from morphine by a chemical modification that increases lipophilicity, making the heroin molecnle inherently more pharmacologically potent than morphine. The exhibition of its basic properties by an alkaloid (Aik) involves (by definition) the acceptance of a proton H+ according to ... 

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