Brian L. Márquez

Three new gradient-selected NMR experiments for the analysis of long-range heteronuclear coupling constants are presented. They are demonstrated on a series of compounds including sucrose, strychnine and a complex macrolide, phormidolide, isolated from a marine cyanobacterium. These 1D and 2D heteronuclear single quantum multiple bond correlation (HSQMBC) experiments provide pure absorption, antiphase lineshapes for precise, direct measurement of nJ(C,H) coupling constants. The example compounds were chosen to demonstrate the high sensitivity and ease of spectral interpretation provided by these HSQMBC experiments. In addition, suppression of one-bond CH correlations has been introduced into the HSQMBC pulse sequence. Copyright © 2000 John Wiley & Sons, Ltd.

Hectochlorin (1) was isolated from marine isolates of Lyngbya majuscula collected from Hector Bay, Jamaica, and Boca del Drago Beach, Bocas del Toro, Panama. The planar structure was deduced by one- and two-dimensional NMR spectroscopy. X-ray crystallography was used to determine the absolute stereochemistry of hectochlorin as 2S,3S,14S,22S. Hectochlorin is equipotent to jasplakinolide (5) in its ability to promote actin polymerization, but unlike jasplakinolide, is unable to displace a fluorescent phalloidin analogue from polymerized actin. In addition, hectochlorin shows both a unique profile of cytotoxicity by the COMPARE algorithm and potent inhibitory activity toward the fungus Candida albicans. Structurally, hectochlorin resembles dolabellin and the recently reported lyngbyabellin class of compounds.