Nicos Petasis: Arthur C. Cope Scholar Awardee

Nicos A. Petasis decided to become a chemist rather than a medical doctor because he thought he could help more people by making discoveries that lead to treatments for diseases. His findings have helped develop a drug that alleviates side effects of cancer therapy and other compounds currently in clinical trials.

Petasis, 54, is the Harold E. & Lillian M. Moulton Professor of Chemistry at the University of Southern California. Colleagues praise him for his discovery and development of new organic reactions, particularly involving titanium and boron compounds, and for advancing the chemistry and biology of molecules that shut down inflammation and promote healing.

"His work is often characterized not only by originality, but also by an underlying simplicity, practicality, and usefulness," says G. K. Surya Prakash, a chemistry professor at USC. Petasis has introduced three unique chemical reactions that bear his name and are highly effective under mild conditions, Prakash adds.

The Petasis olefination uses dialkyl titanocenes to convert carbonyl compounds to their corresponding olefins. Dimethyl titanocene is now referred to as the Petasis reagent. Merck licensed the process for the initial multi-hundred-kilogram scale-up of a drug candidate that became the recently marketed Emend, a drug that can help prevent nausea and vomiting caused by chemotherapy. Petasis' group later extended the olefination chemistry to include the synthesis of substituted olefins, allenes, and many carbocyclic and heterocyclic molecules.

The Petasis-Ferrier rearrangement, an aluminum-mediated reaction, allows stereochemically controlled synthesis of cyclic ethers. Colleagues say that the rearrangement has been helpful in synthesizing complex natural products.

Drug companies also took a shine to the Petasis reaction, a boron-based multicomponent reaction that can be used to prepare in one step a wide range of molecules with potential therapeutic value. Amines and carbonyls are treated with a "matchmaker" boronic acid derivative to directly generate highly functionalized nitrogen-containing products. "Without all three being present, there is little or no reaction," Petasis says. Pharmaceutical companies licensed this method to synthesize substituted amino acids and other molecules.

Prakash explains that Petasis' long-term collaboration with biomedical researchers has led to a stream of breakthroughs in understanding lipid mediators, molecules that control physiological processes such as inflammation. He adds that these breakthroughs resulted in a paradigm shift on how to control inflammation.

Two compounds that Petasis initially synthesized have led to new anti-inflammatory drug candidates now in clinical trials. The work has triggered new collaborations to investigate treatments for several diseases, including periodontitis and cystic fibrosis. Recently, the work of Petasis and his collaborators established the first potential mechanisms for the health benefits of omega-3 fatty acids, which led to new therapeutic agents now in development for treating inflammation.

"As indicated by his success in several diverse areas, ranging from new synthetic methodology to synthesizing bioactive materials, Petasis has demonstrated an uncommon versatility and breadth," says K. C. Nicolaou, a chemistry professor at Scripps Research Institute who was Petasis' Ph.D. adviser.

Born in Cyprus, Petasis completed a B.Sc. in chemistry at Aristotle University of Thessaloniki, in Greece, where, as a college junior he penned a 500-page organic chemistry textbook in Greek. At the University of Pennsylvania, he completed a Ph.D. in organic chemistry and was an adjunct faculty member for two years before joining the faculty at the Department of Chemistry of USC, where he is also a member of the Loker Hydrocarbon Research Institute.