Groups of Alkaloids

There are only two groups of alkaloids that appear to be derived from tyrosine (25, R = OH) utilized as a Cg—C2 fragment and a Cg—Cj unit which comes from phenylalanine (25, R = H). The first is that small group found only in the Orchidaceae, exemplified by cryptostyline I [22324-79-4] (67, from Cryptostylisfulva Schltri) C29H22NO4. 

The presence of alkaloids in Lobelia injlata, Linn., was first recorded by Proctor. Lobeline was prepared by Lewis as a basic oil from which Siebert made and analysed a series of salts and proposed the formula, CigHjsOjN. In 1921 Bohringer and Sohne protected a process for the isolation and separation of three alkaloids, a-, 3 and y-lobelines. In the same year Wieland published the first of a series of papers in which is described the isolation of several groups of alkaloids, to most of which constitutional formulae have been assigned and, in some cases, confirmed... 

The following are the names and formulas of this group of alkaloids —... 

Craig, Michaelis, Graniek and Jacobs have reeently studied the ultra-violet absorption speetra of a series of items in this group of alkaloids. 

This group of alkaloids is obtained from three Liliaceous plants, sabadilla or cevadilla seeds (Schoenocavlon officinale, A. Gray) and the rhizomes of... 

This association of sempervirine with yohimbine is of biological interest since the former alkaloid is derived from a plant of the Loganiaceas in which alkaloids of the strychnos group seemed to be characteristic, whereas the yohimbine group of alkaloids have so far only been found in the Apocynaceae and Rubiace c. 

Ill spite of their importance, basicity constants rarely figure in descriptions of alkaloids. Figures for a series of alkaloids and related substances were published by Kolthoff in 1925 and have been extensively used. Recently a few more have been added by Schoorl, and Adams and Mahan have provided figures for the whole group of necines, the amino-alcohols resulting from the hydrolysis of the pyrrolizidine group of alkaloids. ... 

The isoquinoline alkaloids (1-4) along with the indole alkaloids are the most abundant groups of alkaloids. Their chemistry and synthesis have been extensively studied. In recent years one of the most interesting features of the chemistry of these alkaloids is the transformation among the different types. 

Secoquettamine (234) and dihydrosecoquettamine (235) together with their probable biogenetic precursor quettamine (236) form a small group of alkaloids. They were isolated by Shamma et at. (179) from Berberis baluchista-nica in yields of 0.00036,0.00017, and 0.0012%, respectively. These alkaloids incorporate either a benzofuran or a dihydrobenzofuran ring within the molecular framework, and the seco ones possess the /V,W-dimethylaminoethyl substituent. The structures of these bases were determined on the grounds of spectral data as well as by total synthesis. There is one chiral center at C in dihydrosecoquettamine (235) however, the base was isolated in the form of a racemic mixture (179). 

The pyrrolizidines and indolizidines are a group of alkaloids that are characterized by the presence of the basic azabicyclo[3.3.0]octane and azabicyclo[4.3.0]nonane frameworks, respectively. These alkaloids exhibit remarkably diverse types of biological activity and have been reported to act as antitumor, hypotensive, anti-inflammatory, carcinogenic, or hepatoxic agents. Various pyrrolizidines and indolizidines have been prepared by 1,3-dipolar cycloaddition.115 Synthesis of these is described in the section 8.2 discussing cycloaddition. 

Gunn, J. A. (1935) Relations between chemical composition, pharmacologic actions, and therapeutic uses, in the harmine group of alkaloids. Arch. Int. Pharmacodyn. Then, 50 379-396. 

Nearly all of the microbial and mammalian transformation studies with this group of alkaloids have been focused on nicotine. Microorganisms have been used to resolve racemic nicotine to make available unnatural (/ )-(+)-nicotine for biological evaluation. Highly significant work has detailed the mechanism of nicotine oxidation in mammals, and has resulted in the identification of reactive intermediates formed as the alkaloid is transformed by hepatic monooxygenases. The chemistry and pharmacology of the pyridine alkaloids is discussed by Strunz and Findlay in Volume 26 of this treatise. 

The 2-azaspiro[5.5]undecane group of alkaloids occur in certain plants of the genus Nitraria. There has been some interest in the biological activity of these alkaloids because their structures are similar to the histrionicotoxins, a group of... 

The synthesis of some alcaloids has been achieved by means of the amide version of PFR [201]. Another application is the recent synthesis of diazonamides, an unusual group of alkaloids [202]. In this case, a macrolactam was irradiated. 

This is the latest volume in the series "The Alkaloids Chemistry and Biology and covers a group of alkaloids comprising the carbazole nucleus. Single-topic volumes in this series have been rare, and the last one discussed antitumor alkaloids and was published as Volume 25 in 1985. This is the first volume dedicated to a single alkaloid structure type since Volume 8, which dealt with the monoterpene indole alkaloids over 40 years ago. 

Alkaloids as non-final products of the secondary metabolism are very different in their structure and life functions in organisms. Many different groups of alkaloids are known. As mentioned, they have different precursors and rings. They also have different sub-pathways and intermedia. 

Piperidine alkaloids contain the piperidine nucleus. The structural development of this group of alkaloids in synthesis is presented in Figure 52. Here a is L-lysine and /3 is cadaverine. The basic ring of j3 is the same as in a, although the activity of PLP reduces carbon dioxide. The j3 is biogenic amine, neither a stable nor a poisonous compound... 

The third structural group of alkaloids, from the same a, are quinolizidine alkaloids (QAs). It is a large group of compounds with very different... 

This group of alkaloids has a pyridone nucleus and generally takes the tetracyclic or tricyclic form. The a for pyridone alkaloids is L-lysine, while the j8, q> and X the same as for other quinolizidine alkaloids. Quinolizidine alkaloids containing the pyridone nucleus are the P from the (—/-sparteine by cleavage of the C4 unit. The first quinolizidine alkaloid with the pyridone nucleus is tricyclic cytisine, which converts to four cyclic alkaloids. In this synthesis the anagyrine, the most poisonous quinolizidine alkaloid with a pyridone nucleus, has its own synthesis pathway. 

The pyrrolizidine nucleus is characteristic of this group of alkaloids. The a is either L-ornithine or L-arginine, and the /3 is a biogenic amine, the putrescine. Oxidative deamination by enzyme NAD+ converts two molecules of putrescine... 

This group of alkaloids is an exception in the transformation process of structures, because the imidazole nucleus is already made at the stage of the precursor. The a of these alkaloids is L-histidine, and the first A is developed in a decarboxylation process by histidine decarboxylase (HDC). The histamine is a product of... 

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