Fluorescent kapakahines serve as non-toxic probes for live cell Golgi imaging.

AIMS: There is an ongoing need for fluorescent probes that specifically-target select organelles within mammalian cells. This study describes the development of probes for the selective labeling of the Golgi apparatus and offers applications for live cell and fixed cell imaging. MAIN METHODS: The kapakahines, characterized by a common C(3)-N(1') dimeric tryptophan linkage, comprise a unique family of bioactive marine depsipeptide natural products. We describe the uptake and subcellular localization of fluorescently-labeled analogs of kapakahine E. Using confocal microscopy, we identify a rapid and selective localization within the Golgi apparatus. Comparison with commercial Golgi stains indicates a unique localization pattern, which differs from currently available materials, therein offering a new tool to monitor the Golgi in live cells without toxic side effects. KEY FINDINGS: This study identifies a fluorescent analog of kapakahine E that is rapidly uptaken in cells and localizes within the Golgi apparatus. SIGNIFICANCE: The advance of microscopic methods is reliant on the parallel discovery of next generation molecular probes. This study describes the advance of stable and viable probe for staining the Golgi apparatus.

Cyclopropylazetoindolines as precursors to C(3)-quaternary-substituted indolines.

This manuscript describes the generation and use of a cyclopropylazetoindoline, a novel fused heterocycle, in coupling reactions with hetero- and carbon nucleophiles to give C(3)-quaternary-substituted pyrroloindolines.

Total synthesis of kapakahine E and F.

The total synthesis of the cyclic peptides kapakahine E and F using bromopyrroloindoline heterodimerization reactions, indoline to alpha-carboline rearrangements, and Negishi coupling reactions is described.

Benzothiazines in synthesis. Further studies of the intramolecular, stereoselective addition of sulfonimidoyl carbanions to alpha,beta-unsaturated functional groups.

A variety of alkenes substituted by electron-withdrawing groups serve as competent electrophiles for the stereoselective, intramolecular nucleophilic addition of sulfonimidoyl carbanions to form benzothiazines. This reaction generally proceeds with complete stereoselectivity within the limits of our detection. In some cases, benzothiazine formation occurs in a single pot at relatively high temperatures during N-arylation of the simple sulfoximine used in this study. Yet, the process occurs with the same direction and extent of stereoselectivity as that seen when the Michael addition is performed at very low temperatures.

An expeditious synthesis of C(3)-N(1') heterodimeric indolines.

This paper describes the efficient and relatively simple synthesis of C(3)-N(1') heterodimeric indolines from the addition of indole nucleophiles to readily available bromopyrroloindolines.