Pyrrole-derived alkaloids

Tsukamoto S, Tane K, Ohta T, Matsunaga S, Fusetani N, van Soest RWM (2001) Four New Bioactive Pyrrole-Derived Alkaloids from the Marine Sponge Axinella brevistyla. J Nat Prod 64 1576... 

Tsukamoto, S., Tane, K., Ohta, T., Matsunaga, S., Fusetani, N., van Soest, R. W. M., (2001). Four new bioactive pyrrole-derived alkaloids from the marine sponge Axinella brevistyla. J. Nat. Prod. 64, 1576-1578. 

Manzacidins A-C. A trio of novel pyrrole-derived alkaloids containing a tetrahydropyriniidine in their structures, manzacidins A-C, (41) were also... 

On distillation with zinc dust the alkaloid gives an easily hydrogenated pyrrole base, and on dehydrogenation by platinised asbestos at 260-290 it yields (1) an amorphous dehydro-base, which forms an oxime and a methiodide, C17H23O4N. Mel, decomp. 227-8 , and contains a lactone and a methoxyl group, (2) a neutral pyrrole derivative, and (3) an acid giving a dark green colour with ferric chloride (1939). 

Pyridoxal 157,158,253 Pyridoxamine 253 Pyridoxine 253 Pyrimidines 266,438, 439 Pyrocatechol see 1,2-Dihydroxybenzene I ocatecholsulfophthalein 398 I ocatechol violet reagent 398 Pyrolysis of organic compounds 92, 96 a,y-Pyrone derivatives 288 Pyrrole alkaloids 66 Pyrrole derivatives 266, 269, 270 Pyruvic acid 426... 

Monocrotaline (170) has been the subject of extensive metabolic study with mammalian and microbiological systems. Pyrrolizidine alkaloids such as monocrotaline require metabolic activation to the corresponding pyrrole derivatives or dehydro alkaloids before they are capable of forming covalent bonds with critical macromolecules within the cell. The X-ray structure of dehydromonocrotaline has recently been determined (226), and the ability of dihydroretronicine derived from monocrotaline to react with deoxyguanosine has been demonstrated in vitro (225). 

Butler, W. H., Mattoeks, A. R. and Barnes, J. M. 1970. Lesions in the liver and lungs of rats given pyrrole derivatives of pyrrolizidine alkaloids. Journal of Pathology, 100 169-175. 

White, I. N. H., Mattocks, A. R. and Butler, W. H. 1973. The conversion of the pyrrolizidine alkaloid retrorsine to pyrrolic derivatives in vivo and in vitro and its acute toxicity to various animal species. Chemistry-Biology Interaction, 6 207-218. 

Lindel T, Hoffmann H, Hochgiirtel M, Pawlik JR (2000) Structure-Activity Relationship of Inhibition of Fish Feeding by Sponge-Derived and Synthetic Pyrrole-Imidazole Alkaloids. J Chem Ecol 26 1477... 

Crude alkaloid Rat liver microsomes (Pyrrolic derivatives) (-) 171, 172... 

The crude alkaloid preparation from Senecio jacobaea (tangsy ragwort) is converted to pyrrolic derivatives by mammalian liver microsomes. Highest yields were obtained with microsomes from the hamster liver (171, 172). 

Pyrrole (1) and indole (2) moieties occur widely in synthetic and natural products, either as a simple structural unit or as part of more complex an-nulated systems [1-9]. The pyrrole derivatives 3 and 4 display antibacterial activity [1-3]. Marine alkaloids ( )-B-norrhazinal (5) and (-)-rhazinilam... 

Although the annelated octahydropyrrolo[2,3-6 ]pyrrole unit occurs in the physostigmine-type alkaloids, simple systems were reported only in 1978. DIBAL reduction of the pyrrolidones (348) furnished the octahydropyrrolo[2,3-6]pyrrole derivatives (349 Scheme 120). It is interesting to note that LAH failed to bring about ring closure (78JOC4276). 

Separation of mono- and di-ester pyrrolizidine alkaloids has been achieved by ion-pair adsorption t.l.c., using chloride (or iodide) as the counter-ion.48 Chloranil has been used to oxidize pyrrolizidine alkaloids on t.l.c. The pyrrole derivatives that were formed were then detected with Ehrlich s reagent49 or sulphuric acid.50 Mixtures of pyrrolizidine alkaloids have been separated by h.p.l.c. on a reversed-phase styrene-divinylbenzene resin.51 In a sensitive method for the detection of pyrrolizidine alkaloids, the protonated alkaloids were complexed with aqueous methyl orange. The dye was then released from the complex and estimated spectrophotometrically.52... 

Many pyrrolizidine alkaloids are metabolized to toxic pyrrole metabolites in the liver by mixed-function oxidases. The structural and chemical features necessary for the formation of these metabolites have been discussed.77 The most important features, in addition to the 3-hydroxymethyl-3-pyrroline system, are steric hindrance to hydrolysis of the ester, lipophilic character (favouring attack by the hepatic microsomal enzymes), and the presence of a conformation that allows preferential oxidation of the pyrroline ring rather than 7V-oxidation. The alkylating activities of a series of these pyrrole derivatives have been examined.78... 

The first examples of tetrameric pyrrole imidazole alkaloids, stylissadine A (100) and B, were isolated from the Caribbean sponge Stylissa carihica in 2006 [128]. They possess a symmetric dimeric stmcture derived from condensation of two massadine units, and differ in the configuration at the center C-2. Stylissadines represent the largest pyrrole-imidazole alkaloids isolated so far, and, with their 16 stereogenic centers, they are the most complex stmctures known within the oroidin alkaloid family. 

Assmann et al. described, in addition to known alkaloids, the isolation of the first pyrrole-imidazole alkaloid with a guanidine function instead of the aminoimidazole (127) [152] from the sponge Agdas wiedenmayeri, while its decarboxylated derivate laughine (128) was isolated from the sponge Eurypon laughlini [153],... 

Different molecular mechanisms have been separately postulated for dibromo-phakellin [74], dibromoagelaspongin [91], agelastatin [92], mauritiamine [88], and palau amine [78]. A1 Mourabit and Potier proposed a universal chemical pathway, starting from the simple precursors 101 and 140 and leading to over 60 pyrrole-imidazole alkaloids [80]. A new biomimetic spontaneous conversion of proline to 2-aminoimidazolinone derivatives using a self-catalyzed intramolecular transamination reaction together with peroxide dismutation as key step has been described [166]. This work has pointed to dispacamide A as the forerunner of oroidin and compounds 101 and 140 as probable hydrolysis products of oroidin and not the precursors. In this... 

Sml2-induced cyclizations with participation of indole and pyrrole derivatives in stereoselective syntheses of alkaloids 04SL422. 

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