Total Synthesis of Aaptamine, Demethyloxyaaptamine, and Their 3-Alkylamino Derivatives.

A simple and efficient synthetic route for preparing the benzonaphthyridine framework is reported. Only seven steps are needed for the assembly of 3-alkylamino aaptamine from inexpensive isoquinoline 6 by this route with about 20% overall yield. The two key steps are a novel palladium-catalyzed reductive cyclization with Mo(CO) as reductant to form aaptamine and demethyloxyaaptamine and a hydrogen-bond-mediated oxidative alkylamination to account for the complete regioselectivity.

Imidazole Alkaloids and Their Zinc Complexes from the Calcareous Marine Sponge Leucetta chagosensis.

Five new imidazole derivatives (1-5), together with eight related known alkaloids, were isolated from a calcareous marine sponge, Leucetta chagosensis, collected from the South China Sea. Their structures were fully characterized by spectroscopic methods. Structurally, 1 possesses an unusual skeleton featuring imidazole and oxazolone rings linked via a nitrogen atom, whereas 2 bears an intriguing guanylurea-substituted imidazole ring.

Suppression of bamboo mosaic virus accumulation by a putative methyltransferase in Nicotiana benthamiana.

Bamboo mosaic virus (BaMV) is a 6.4-kb positive-sense RNA virus belonging to the genus Potexvirus of the family Flexiviridae. The 155-kDa viral replicase, the product of ORF1, comprises an N-terminal S-adenosyl-l-methionine (AdoMet)-dependent guanylyltransferase, a nucleoside triphosphatase/RNA 5'-triphosphatase, and a C-terminal RNA-dependent RNA polymerase (RdRp).

Isolation and biochemical characterization of an endo-1,3-beta-glucanase from Streptomyces sioyaensis containing a C-terminal family 6 carbohydrate-binding module that binds to 1,3-beta-glucan.

A gene encoding 1,3-beta-glucanase was isolated from Streptomyces sioyaensis based on an activity plate assay. Analysis of the deduced amino acid sequence of the gene revealed that the matured 1,3-beta-glucanase has two functional domains separated by a stretch of nine glycine residues. The N-terminal domain shares sequence similarity with bacterial endo-1,3-beta-glucanases classified in glycosyl hydrolase family 16 (GHF 16), while the C-terminal domain is a putative carbohydrate-binding module (CBM) grouped into CBM family 6.