Isocoumarins have been isolated from a wide variety of microbial, plant and insect sources and have been shown to possess an impressive array of biological activities. Since the review by BARRY in 1963 (24), the number of known naturally occurring isocoumarins has increased dramatically. This increase is largely due to improvements in isolation procedures and structural analysis. Previous reviews have concentrated on fungal isocoumarins (293,294) and mycotoxic isocoumarins (301). This review lists over 160 naturally occurring isocoumarins. Leading references on isolation, structure elucidation, biosynthesis and synthesis are given in the accompanying Tables. The known natural isocoumarins are listed in the Tables according to the number and orientation of oxygen atoms on the benzenoid ring and by carbon substituents. For completeness, those isocoumarins bearing additional fused carbocyclic rings and those containing nitro gen substituents are included in separate Tables. It is hoped that by using these Tables in conjunction with the Formula Index, the Trivial Name Index and the Source Index the reader will be able to locate key references in the literature and gain an understanding of the fascin ating chemistry and action of naturally occurring isocoumarins.

Despite the long association of organohalogen compounds with human activities, nature is the producer of nearly 5,000 halogen-containing chemicals. Once dismissed as accidents of nature or isolation artifacts, organohalogen compounds represent an important and ever growing class of natural products, in many cases exhibiting exceptional biological activity. Since the last comprehensive review in 1996 (Vol. 68, this series), there have been discovered an additional 2,500 organochlorine, organobromine, and other organohalogen compounds. These natural organohalogens are biosynthesized by bacteria, fungi, lichen, plants, marine organisms of all types, insects, and higher animals including humans. These compounds are also formed abiogenically, as in volcanoes, forest fires, and other geothermal events.In some instances, natural organohalogens are precisely the same chemicals that man synthesizes for industrial use, and some of the quantities of these natural chemicals far exceed the quantities emitted by man.

The volumes of this classic series, now referred to simply as "Zechmeister" after its founder, L. Zechmeister, have appeared under the Springer imprint ever since the series was founded in 1938. The volumes contain contributions on various topics related to the origin, distribution, chemistry, synthesis, biochemistry, function or use of various classes of naturally occurring substances ranging from small molecules to biopolymers. Each contribution is written by a recognized authority in his field and provides a comprehensive and up-to-date review of the topic in question. Addressed to biologists, technologists and chemists alike, the series can be used by the expert as a source of information and literature citations and by the non-expert as a means of orientation in a rapidly developing discipline.

The volumes contain contributions on various topics related to the origin, distribution, chemistry, synthesis, biochemistry, function or use of various classes of naturally occurring substances ranging from small molecules to biopolymers. Each contribution is written by a recognized authority in his field and provides a comprehensive and up-to-date review of the topic in question.