Crinipellin B

Four fungal metabolites, chaetoglobosin A (CGA), crinipellin B (CPB), geodin (GE) and triticone B (TTB), were found to enhance fibrinolytic activity of bovine aortic endothelial cells. Plasmin generation on the cells was elevated 2- to 4-fold when treated with these agents at a concentration of 3 approximately 100 microM. These effects were dependent on plasminogen and inhibited by anti-urokinase antibody. The effect of CGA, but not of CPB, GE and TTB, was abolished by cycloheximide. In a cell-free system, plasmin and urokinase activities as well as urokinase-catalyzed plasminogen activation were not enhanced by these agents. CGA, but not others, induced the production of urokinase in endothelial cells. CPB and GE accelerated plasminogen activator inhibitor- 1 (PAI-1) inactivation, and TTB caused direct, reversible inhibition of PAI-1. Thus, induction of urokinase by CGA and inhibition of PAI-1 by CPB, GE and TTB may, at least partly, account for the elevation of fibrinolytic activity of endothelial cells.

Wender and Howbert's remarkable synthesis of alpha-cedrene in 1981 brought the attention of the synthetic community to the alkene-arene meta-photocycloaddition reaction. Here we review the natural product syntheses that have been achieved, over the last 25 years, utilising this strategic level reaction.

Efficient total syntheses of the naturally occurring, potent antibiotic compounds (-)-crinipellin A and (-)-crinipellin B are described. The key advanced intermediate, a fully functionalized tetraquinane core, was constructed by a novel thiourea/palladium-catalyzed Pauson-Khand reaction. This intermediate can serve as a common intermediate for the collective total synthesis of other members of the crinipellin family.