Marine organisms continued

Terpenoid constituents of marine organisms continue to attract considerable attention (c/. pp. 85, 86, 96, 101, 108, 116, 136, 156). Red algae of the genus Laurencia are recognized as common sources of these compounds. Recent independent reports have described X-ray crystallographic evidence for the structure and absolute configuration of l-bromo-4-hydroxy-7-chloroselinane (402) and heterocladol (403). These compounds are constituents of... 

Most of the water on Earth s surfece is in the ocean relatively little is present in the atmosphere or on land. Because of its chemical and physical properties, this water has had a great influence on the continuing biogeochemical evolution of our planet. Most notably, water is an excellent solvent. As such, the oceans contain at least a little bit of almost every substance present on this planet. Reaction probability is enhanced if the reactants are in dissolved fitrm as compared with their gaseous or solid phases. Many of the chemical changes that occur in seawater and the sediments are mediated by marine organisms. In some cases, marine organisms have developed unique biosynthetic pathways to help them survive the environmental conditions fitimd only in the oceans. Some of their metabolic products have proven useful to humans as pharmaceuticals, nutraceuticals, food additives, and cosmeceuticals. 

At the same time, researchers remain interested in learning more about the mechanisms by which some natural products exert their effects on the human body and chemical changes that can be made to produce more effective drugs. They also continue their search in the natural world for plants, marine organisms, and other materials that hold promise for possible medicinal uses in the treatment of a wide range of diseases and disorders. 

Marine organisms have also been intensively examined for their sesquiterpene content. Dysidea herbacea is a sponge species which has yielded new metabolites for more than 20 years, and no doubt further collections from different locations will continue to reveal new chemistry. 

Novel indole derivatives continue to be found in marine organisms those reported recently include dendrodoine (3), a cytotoxic thiadiazole derivative, which occurs in the tunicate Dendrodoa grossularia, from Brittany,4 and the keto-lactam (4), one of two lactams isolated from the Caribbean sponge Hali-chondria melanodocia.5... 

Interest continues in the isolation and structural elucidation of halogenated sesquiterpenoids produced by marine organisms (e.g. algae). Many of these compounds are chamigrane derivatives and new members of this group include prepacifenol epoxide (89)46 from Aplysia californica, elatol (90)47 from Laurencia elata, nidifidienol (91)48 from Laurencia nidifica, and the compounds (92) and (93)49 from... 

Marine organisms have continued to provide unusual diterpenoid skeleta. 14-Bromo-obtus-l-ene-13,ll-diol (144) has been obtained from the sea hare Aplysia dactylomola. The irieols A—G (145)—(151) are a group of dibromo-diterpenoids which have been obtained from the marine red alga Laurencia irieii. Their structures were established by n.m.r. spectroscopy and by degradation to a bicyclic aldehyde. 

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