Deoxypseudophrynaminol: a novel antibacterial alkaloid

Formation of Pyrroloindolines via the Alkylation of Tryptamines with Trichloroacetimidates

Pyrroloindolines and related systems are present in a large number of complex natural products. These core structures have generated considerable synthetic interest, as many of the compounds possess challenging, elaborate structures and interesting biological properties. Recently we have focused on using trichloroacetimidates for the synthesis of these fascinating molecules. Trichloroacetimidates can be used as an electrophilic source of an alkyl group to form the pyrroloindoline directly from tryptamine derivatives. In this manner trichloroacetimidates provide a flexible solution to forming highly functionalized pyrroloindoline core structures, needing only a catalytic amount of a Lewis acid to effect the requisite transformations.

Bromotryptamine and Imidazole Alkaloids with Anti-inflammatory Activity from the Bryozoan Flustra foliacea

Chemical investigation of the marine bryozoan Flustra foliacea collected in Iceland resulted in isolation of 13 new bromotryptamine alkaloids, flustramines Q-W (1-7) and flustraminols C-H (8-13), and two new imidazole alkaloids, flustrimidazoles A and B (14 and 15), together with 12 previously described compounds (16-27). Their structures were established by detailed spectroscopic analysis using 1D and 2D NMR and HRESIMS. Structure 2 was verified by calculations of the 13C and 1H NMR chemical shifts using density functional theory. The relative and absolute configurations of the new compounds were elucidated on the basis of coupling constant analysis, NOESY, [α]D, and ECD spectroscopic data, in addition to chemical derivatization. The compounds were tested for in vitro anti-inflammatory activity using a dendritic cell model. Eight compounds (1, 3, 5, 13, 16, 18, 26, and 27) decreased dendritic cell secretion of the pro-inflammatory cytokine IL-12p40, and two compounds (4 and 14) increased secretion of the anti-inflammatory cytokine IL-10. Deformylflustrabromine B (27) showed the most potent anti-inflammatory effect (IC50 2.9 μM). These results demonstrate that F. foliacea from Iceland expresses a broad range of brominated alkaloids, many without structural precedents. The potent anti-inflammatory activity in vitro of metabolite 27 warrants further investigations into its potential as a lead for inflammation-related diseases.

Antibacterial activity of (−)-deoxypseudophrynaminol versus its racemate and derivatives

(-)-Deoxypseudophrynaminol 1 possesses 43-fold greater antibacterial potency than the racemate toward Staphylococcus aureus, indicating that the (-)-enantiomer is the biologically active isomer in this assay. Comparison of the percent growth inhibition by derivatives of 1 indicates that prenylation of N8 and replacement of N1-methyl by methyl carbamate are detrimental to antibacterial potency. (-)-1 is a promising lead structure for the development of the novel hexahydropyrrolo[2,3-b]indole class of antibacterial agents.