Alkaloids carboline

1 B-Carboline Alkaloids.— Preliminary results (c. Vol. 12, p.l4) which show that the amino-acid (51) is an efficient 

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In the course of structural investigations of a number of jS-carboline alkaloids, reactions leading to ring cleavage have been encountered. Oxidation of harmine (271) and of harmaline... 

Cleavage of the hetero ring in a number of extended tetrahydro-j8-carboline systems was observed in the course of structural elucidation of tetrahydro-jS-carboline alkaloids. A few examples only will be given. The indole derivative 287 was isolated as one of the products of the selenium dehydrogenation of yohimbine (358 R = and... 

The inverse electron demand Diels-Alder reaction has also been used to provide expedient access to unnatural 6-carboline alkaloids from 1,2,4-triazines, prepared by microwave-assisted MCR [92]. One-pot reaction of an acyl hydrazide-tethered indole 73, 1,2-diketone and ammonium acetate in acetic acid provided triazines 74 (see Sect. 3.2, Scheme 22), bearing an electron-rich dienophilic indole moiety (Scheme 31). By carrying out the... 

Carboline alkaloids Hedy Otis capitellata SiOj Cx + CHCI3 + EtjNH - Identification 20... 

Note that the plant elaborates a series of carboline alkaloids including 1-carbobutoxy-(3-carboline, N9-formylharman, 1 -carboethoxy- (3-carboline, 1-carbomethoxy- fl-carboline, perlolyrine, harman, and norharman (23). An interesting development would be to assess these alkaloids for central nervous activity. 

Tetracyclic /3-carboline alkaloids, known as canthines, have a peri-fused indolo[3,2,Tnaphthyridine structure. Over 40 members of this class of compound have been isolated, and they are of interest on account of their broad range of pharmacological effects (antimicrobial, cytotoxic, antibacterial, anticancer). 

Recently the continuous-addition-of-reagent (CAR) technique [182] was applied for the determination of fluorophores by POCL chemistry [95-99], The applicability of this technique was demonstrated by the determination of natively fluorescent acepromazine in horse plasma [95], the alkaloid harmaline in plasma [96], and other dansylated alkaloids [97], A separation step has also been included and applied to postcolumn detection of PAHs [98] and dansylated P-carboline alkaloids [99],... 

Table 4 illustrates the use of the CAR technique to develop CL kinetic-based determinations for various analytes in different fields. As can be seen, the dynamic range, limit of detection, precision, and throughput (—80-100 samples/ h) are all quite good. All determinations are based on the use of the TCPO/ hydrogen peroxide system by exception, that for p-carboline alkaloids uses TCPO and DNPO. A comparison of the analytical figures of merit for these alkaloids reveals that DNPO results in better sensitivity and lower detection limits. However, it also leads to poorer precision as a result of its extremely fast reactions with the analytes. Finally, psychotropic indole derivatives with a chemical structure derived from tryptamines have also been determined, at very low concentrations, by CAR-CLS albeit following derivatization with dansyl chloride. 

P-Carboline alkaloids (harmaline, har-malol, harmane, harmol, harmine) 0.3-150 0.25-90 2.9-3.1 Harmaline was determined in plasma samples DNPO was used as aryl oxalate 45... 

Tse SY, Mak IT, Dickens BF. (1991). Antioxidative properties of harmane and beta-carboline alkaloids. Biochem Pharmacol. 42(3) 459-64. 

Dennis J. McKenna and G. H. N. Towers. "Ultra-violet mediated cytotoxic activity of B-carboline alkaloids." Phytochemistry 20 (1981) 1001-1004. 

A method was developed for preparation of the tetracyclic carboline alkaloids iso-canthine, isocanthin-6-one and l-methylisocanthin-3-one by an intramolecular hetero-Diels-Alder reaction. For example, oxime 317 in sulfolane at 285 °C afforded isocanthine 318 in 8% yield (equation 137) . 

L-tyrosine Tyrosine-derived alkaloids Indole alkaloids Quinoline alkaloids /3-carboline alkaloids Pyrroloindole alkaloids Ergot alkaloids Iboga alkaloids Corynanthe alkaloids Aspidosperma alkaloids Protoalkaloids Terpenoid indole alkaloids True alkaloids... 

This structural group of indole alkaloids covers simple indole alkaloids (e.g., tryptamine, serotonin, psilocin and psilocybin), /3-carboline alkaloids (e.g., harmine), terpenoid indole (e.g., ajmalicine, catharanthine and tabersonine), quinoline alkaloids (e.g., quinine, quinidine and cinchonidine), pyrroloindole... 

The a of carboline alkaloids is l -tryptophan and the is tryptamine, wWle the

[Pg.112]

Carboline alkaloids, and especially /3-carbolines, are common in mammals . 

Chloro-P-carboline (25) has served as a common intermediate in palladium-catalyzed cross-coupling reactions, offering easy access to several pyridine alkaloids. In Bracher s total synthesis of perlolyrine (27), a P-carboline alkaloid, the Suzuki reaction of 25 with 5-formylfuranyl-2-boronic acid (26) formed the C-C bond between the pyridine and the furan rings <92LA1315>. Reduction of the resulting Suzuki adduct with NaBIL subsequently... 

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