Tuesday, 24 May 2005 - 9:40 AM

This presentation is part of: Physical Organic

Polysulfane Natural Products as Evolved Chemical Warfare Agents

Edyta M. Brzostowska and Alexander Greer. The City University of New York (CUNY), Brooklyn College, Brooklyn, NY

Ascidians (tunicates) contain compounds with a large range of pharmacological activities. With the most common of chemical ingredients, elemental sulfur and dopamine, we hypothesize that an ascidian has developed a means to protect itself from predators using in essence chemical warfare. A novel aspect of this work is the idea that tunicates can filter elemental sulfur, transform solid insoluble Sx, and transfer sulfur atoms chemically into a phenolic molecule for use as a protecting agent. Our work focused on a biomimetic HSx- reaction with o-quinone as a biosynthetic generator of antimicrobial (anticancer) o-benzopolysulfanes. Experiments using HPLC and SIM GC/MS revealed the presence of benzotrithiole, pentathia-benzocycloheptene, and heptathia-benzocyclononane compounds. The benzo-S3, -S5, and -S7 products co-exist in equilibrium, where their relative concentrations are influenced by solvent. Detection of heptathia-benzocyclononane is an exciting new result that had been predicted by our density functional theory (DFT) computation. This suggests that natural product o-benzopolysulfanes exist as a mixture of the S3-, S5-, and S7-homologs. Factors controlling the formation and interconversion of the S3-, S5-, and S7-polysulfanes and possible biological implications will be discussed.

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