RESUMO
We report herein that the oroidin-derived alkaloids palau'amine (1), dibromophakellin (2), and dibromophakellstatin (3) inhibit the proteolytic activity of the human 20S proteasome as well as the (i)20S immunoproteasome catalytic core. Palau'amine is found to prevent the degradation of ubiquitinylated proteins, including IκBα, in cell culture, which may be indicative of the potential mechanism by which these agents exhibit their exciting cytotoxic and immunosuppressive properties.
Assuntos
Alcaloides/farmacologia , Guanidinas/farmacologia , Compostos Heterocíclicos de 4 ou mais Anéis/farmacologia , Imidazóis/farmacologia , Inibidores de Proteassoma , Pirróis/farmacologia , Compostos de Espiro/farmacologia , Alcaloides/química , Guanidinas/química , Células HeLa , Compostos Heterocíclicos de 4 ou mais Anéis/química , Humanos , Imidazóis/química , Microscopia Confocal , NF-kappa B/metabolismo , Complexo de Endopeptidases do Proteassoma/química , Pirróis/química , Compostos de Espiro/química , EstereoisomerismoRESUMO
The sponge-derived alkaloid dibromoagelaspongin was prepared from a dihydrooroidin derivative by exploiting the Pummerer reaction twice in succession. Oxidative cyclization of the substrate's pyrrole-2-carboxamide function into the imidazole moiety was achieved in a regiospecific manner to establish both C-N bonds to C(6) of the target.
Assuntos
Alcaloides/síntese química , Pirróis/síntese química , Alcaloides/química , Ciclização , Imidazolinas/química , Oxirredução , Pirróis/química , Estereoisomerismo , Especificidade por SubstratoRESUMO
The sponge metabolite dibromoagelaspongin was synthesized in 16 steps from imidazole. The route features two successive oxidative cyclizations with complete control of regiochemistry to deliver the unusual triaminomethane core of the target. These oxidative cyclizations likely resulted from Pummerer-like processes on the imidazole-2-sulfoxide (sulfide) precursors.
Assuntos
Pirróis/síntese química , Alcaloides/síntese química , Ciclização , Guanidinas/síntese química , Imidazóis/química , Oxirredução , Estereoisomerismo , Sulfetos/química , Sulfóxidos/químicaRESUMO
The syntheses of (+/-)-dibromophakellstatin and, from this species, (+/-)-dibromophakellin are described. Oxidative cyclization of a phenylthiolated dihydrooroidin derivative triggered by a Pummerer reaction constitutes the key step in this biomimetic approach to this family of marine alkaloids.
Assuntos
Alcaloides/síntese química , Química Orgânica/métodos , Imidazóis/síntese química , Piperazinas/síntese química , Alcaloides/química , Ciclização , Imidazóis/química , Estrutura Molecular , Piperazinas/química , EstereoisomerismoRESUMO
The solution-phase synthesis of a discovery library of 178 tricyclic pyrrole-2-carboxamides was accomplished in nine steps and seven purifications starting with three benzoyl-protected amino acid methyl esters. Further diversity was introduced by two glyoxaldehydes and 41 primary amines. The combination of Pauson-Khand, Stetter, and microwave-assisted Paal-Knorr reactions was applied as a key sequence. The discovery library was designed with the help of QikProp 2.1, and physicochemical data are presented for all pyrroles. Library members were synthesized and purified in parallel and analyzed by LC/MS. Selected compounds were fully characterized.
Assuntos
Amidas/síntese química , Ácidos Carboxílicos/química , Compostos Heterocíclicos com 3 Anéis/síntese química , Pirróis/química , Pirróis/síntese química , Técnicas de Química Combinatória , Biologia Computacional , Simulação por Computador , Cromatografia Gasosa-Espectrometria de Massas , Estrutura Molecular , Preparações Farmacêuticas , EstereoisomerismoRESUMO
Cascade reactions of internal and terminal alkynes, zirconocene hydrochloride, dimethylzinc, and phosphinoyl imines (prepared in one step from aldehydes and diphenylphosphinoyl amide) lead to allylic phosphinoyl amides after aqueous workup. Microwave acceleration allows the completion of this one-pot reaction sequence in 10 min. These allylic amides can be converted into a variety of derivatives, including carbamates and sulfonamides, or reacted prior to workup with diiodomethane to give novel C-cyclopropylalkylamides. A solution-phase "libraries from libraries" approach was used to generate an intermediate 20-member library which was subsequently expanded to a 100-member library by a series of N-functionalizations. The biological activity was evaluated in an assay for competitive binding to the estrogen receptor (ERalpha), revealing three potent lead compounds of a new structural type.
