Types of Alkaloids

Bisindole Alkaloids from Tryptophan. There are two widely different types of alkaloids derived from two tryptophan (26) units. The first is a rather small group of compounds based simply on the dimers of tryptophan which includes compounds such as calycanthine (113) (Table 10),... 

The names, formulae and structures of these alkaloids are given in the following table. The esters of tropine or -tropine are known as tropeines or -tropeines respectively. The first eleven items in the table are sometimes called the solanaceous alkaloids, but they are not the only alkaloids, or even the only type of alkaloid, found in the botanical family Solanaceas. They are also sometimes referred to as the mydriatic alkaloids though other alkaloids also exert this action. 

It has become customary to call the principal members of this group the lupin alkaloids, but in view of their wide distribution in the Papilionaceae, a better title is that suggested above, since they appear to be the characteristic alkaloids of this leguminous sub-family. This is not the only type of alkaloid found in the Leguminosae other types occur, e.g., in Acacia (p. 631), Crotalaria (p. 601), Erythrina (p. 386), Mimosa (p. 4) and Pentaclethra (p. 776). 

Ammodendrine, C jH oONj, HjO (No. 1, table, p. 116). The base has m.p. 73 °, becomes anhydrous at 70-80°, and then melts at 50-60°, Wd i 0°. The salts are amorphous and deliquescent except the hydriodide B. HI, which forms a crystalline precipitate, m.p. 218-20°, from alcohol, and the perchlorate, m.p. 199-200°. An amorphous A-benzoyl derivative was obtained. With methyl iodide ammodendrine behaves as a secondary base, yielding first A-methylammodendrine hydriodide (a crystalline precipitate, m.p. 183-5°, from a mixture of alcohol and acetone), and at the second stage iV-methylammodendrine methiodide, m.p. 163-5°. On hydrogenation ammodendrine furnishes a dihydro-base, which is hydrolysed into acetic acid and 2 3 -dipiperidyl, C oHjoNj, and must be dZ-A-acetyl-3-a-piperidylpiperidine. Ammodendrine should therefore be acetyltetrahydroanabasine and is of biological interest as the first recorded occurrence of this type of alkaloid in the Leguminoss. ... 

The following list is not exhaustive, but it records the reasonably authenticated occurrences of the berberine type of alkaloid and its associates. Brief descriptions are included in the list, of alkaloids not of Sufficient importance to be described fully in the later text. 

It should, however, be noted that though Spath and Kruta were unable to condense tetrahydropapaverines with formaldehyde to the berberine type of alkaloid, they found that tetrahydropapaverolines condensed with formaldehyde in both ways, and examples will be found under corydaline (p. 289) and the constitution of palmatine and the related bases (p. 343). 

Coclaurine is of special interest since worcoclaurine (I MeO HO) can be regarded as the parent substance from which by ether formation the series of bisbenzylisoquinoline alkaloids can arise. Thus, the dauricine type of alkaloid may be formed by a single ether linkage between the 4 -hydroxyl of one woreoclaurine molecule and a hydrogen atom ortho to the 4 -hydroxyl of a second molecule. 

HgO), but which regenerates the N-benzoyl derivative on recovery of the base with sodium hydroxide solution.. Similar migrations of the acyl group in this type of alkaloid have been recorded by Nagai and Kanao. ... 

If the union occurs in a position already bearing a substituent, loss of hydrogen is impossible except by migration and a morphine type of alkaloid is formed. 

Although C—O bond cleavage is of little importance for transformations of protoberberines to other types of alkaloids, the selective C—O bond cleavage reaction provides access to naturally unabundant or nonnatural protoberberines from naturally abundant protoberberines such as berberine. 

NPR191>. Periodical reports on other types of alkaloids from the same sources also contain information on certain arenoquinolizine alkaloids like the berberin and emetan derivatives that are normally classified as isoquinoline alkaloids. For surveys of the literature published prior to 1996, perusal of the corresponding chapters in previous editions of this work <1984CHEC(2)525, 1996CHEC-II(8)507> is recommended. 

The first example of this type of alkaloid, compound 535, known hitherto merely as 205B, has recently been isolated from the skin of the Panamanian frog Dendrobates pumilio. The absolute stereochemistry of the natural (—)-alkaloid was first established by the total synthesis of its (+)-enantiomer by a multistage route from the fused piperidine 536... 

Deplancheine (7) was isolated first from the stem and bark of Alstonia deplanchei van Heurck and Muell. Arg. by Husson et al. (14). The structure of this novel type of alkaloid has been established from spectral evidence the trans annellation of rings C and D is supported by the presence of characteristic Bohlmann bands in the IR spectrum and also by the chemical shift of the C-3 proton below 3.7 ppm. The ethylidene side chain was also indicated by the H-NMR spectrum [8 1.52 (3H, d, J =6 Hz), 5.30 (1H, q, J = 6 Hz)] and its E configuration was confirmed by regio- and stereospecific total synthesis (14). 10-Methoxydeplancheine (8) has been found in the leaves of Alstonia lanceolifera... 

Dihydrocorynantheol (21), first isolated from Aspidosperma marcgravianum (147), is the simplest corynanthe alkaloid. The members of this type of alkaloid have three stereo centers in the D ring of the indolo[2,3-a]quinolizine skeleton. This substitution pattern allows four possible relative arrangements for the C-3, C-15, and C-20 stereo centers, the names of which are normal, pseudo, alio, and epiallo, respectively. 

The alkaloid aspidodasycarpine (28), known since the 1960s (64TL3899), has been isolated from other plants in succeeding years (68P2045, 83JNP708). The nitrogen atom in its azocane fragment is not substituted, a phenomenon quite unique for this type of alkaloid. 

In 1976, 1-deoxynojirimycin (2) was discovered as a natural product in a Moms species and coined moranoline.26 Incidentally, in the same year, a novel type of alkaloid was found in the liana plant, Derris elliptica, a native of Borneo but widespread in the tropics, and it was identified as 2,5-dideoxy-2,5-imino-D-mannitol (7, Scheme 3), also known as DMDP (2,5-dihydroxymethyl-3,4-dihy droxypyrrolidine).27... 

Alkaloids are generally classified by their common molecular precursors, based on the biological pathway used to construct the molecule. From a structural point of view, alkaloids are divided according to their shapes and origins. There are three main types of alkaloids (1) true alkaloids, (2) protoalkaloids and (3) pseudoalkaloids. True alkaloids and protoalkaloids are derived from amino acids, whereas pseudoalkaloids are not derived from these compounds (Table 1). 

Definition, Typology and Occurrence of Alkaloids Table 1 Main types of alkaloids and their chemical groups... 

This pathway clearly proves that the first quinolizidine alkaloid to be synthesized is (—) lupinine (two cycling alkaloids) and subsequently both (+)-lupanine and (-)-sparteine. This is a new approach to the synthesis of this type of alkaloids because in the older literature just four cycling alkaloids (lupanine and sparteine) were mentioned as the first synthesized molecules . In the cadaverine conversion, the participation of diamine oxidase is more reliable than the oxosparteine synthase mentioned by some older studies °. 

Although L-phenylalanine is a protein amino acid, and is known as a protein acid type of alkaloid precursor, its real role in biosynthesis (providing C and N atoms) only relates to carbon atoms. L-phenylalanine is a part of magic 20 (a term deployed by Crick in his discussion of the genetic code) and just for this reason should also be listed as a protein amino acid type of alkaloid precursor, although its duty in alkaloid synthesis is not the same as other protein amino acids. However, in relation to magic 20 it is necessary to observe that only part of these amino acids are well-known alkaloid precursors. They are formed from only two amino acid families Histidine and Aromatic and the Aspartate family . 

Tetracyclic quinolizidine alkaloids can be divided into two types, both according to chemical structure and, especially, biological activity. These are tetracychc alkaloids, which contain a quinohzidine nucleus, and others with a pyridone nucleus. Here, the first type of alkaloids (with a quinohzidine nucleus) will be discussed. The second type will be considered in the next sub-chapter as pyridone alkaloids. 

Although Schumanniophyton is the only genus of the Rubiaceae in which this type of alkaloid has been found it should be noted that related genera have shown... 

Tables I through VIII summarize the occurrences of alkaloids from ants and other insects. Each table presents chemical structures as well as specific sources of particular types of alkaloids e.g.. Table I covers piperidines and pyridines. Table II, pyrrolidines, pyrroles, and indolizidines.

The opium is obtained from the opium poppy Papaver somniferum. It contains two type of alkaloids e.g. phenanthrene derivatives (morphine, codeine thebaine) and benzyl isoquinoline derivatives (papaverine and noscapine). 

Figure 3.10. An example of a common feature of some types of alkaloid biosynthesis, the linking of a substance with an amino group (such as the amino acid shown here) and a substance with an aldehyde group (in this case, comprising the first stages of the route to the benzylisoquinoline alkaloids).

As representative of the derivatives of pyridoacridine, eilatin, a marine alkaloid inhibits in vitro cell proliferation in chronic myeloid leukemia patients [244], Other members of the pyridoacridines, such as alkaloids isolated from a Cystodytes sp. ascidian, inhibit topoisomerase II [245], Additionally, analogues derivatives of these type of alkaloids showed interesting anti-HIV activity [246],... 

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