Isonitriles from marine sources

Formerly, isonitriles were perhaps best known to many chemists through the indescribably vile odor of volatile members of the series encountered during the Hofmann carbylamine test for primary amines. Over recent years, however, isonitriles have come into their own as versatile synthetic reagents. Several reliable preparative methods now allow ready access to this family of substances and their remarkable chemistry. Biological pathways to isonitriles are also known, the first such substance isolated being the antibiotic xanthocillin (141), isolated from Penicillium notatumP Isonitrile compounds are also isolated fairly frequently from marine sources. ... 

Several carbonimidic dichlorides, such as 144, have been isolated from marine sources h252 xhese compounds unlike their corresponding isonitriles were not biologically active, and the latter may be chlorinated in vivo to give protected compounds that could be readily unmasked to give the active species when needed. 

The structural diversity of natural products with antimalarial activity from marine and freshwater sources are stunning, ranging from isonitrile-containing derivatives to depsipeptides through peroxides and alkaloids. 

ABSTRACT A series of about 70 secondary metabolites produced by marine organisms have been grouped into three structural types and discussed in terms of their reported antimalarial activities. The major groups of metabolites include isonitrile derivatives, alkaloids and cycloperoxide derivatives. Structure-activity relationships and, when applicable, mechanisms of action of the isolated molecules, have been discussed. The following discussion evidences that antimalarial marine molecules can efficiently integrate the panel of lead compounds isolated from terrestrial sources with new chemical backbones and, sometimes, with typically marine functional groups (as isonitriles). 

As frequently happened in the rising field of marine natural product chemistry, at the time of the isolation of isonitrile terpenoids and analogues from Axinella cannabina, and from other marine sources [31], Authors were intrigued by their unprecedented chemical structures and by their possible biogenetic origin, but they did not realize the pharmacological potential of the molecules in their hands. 

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