Tuesday, November 08, 2005

Shikimic acid and the synthesis of Tamiflu. Frost's US 6,613,552

The New York Times quoted Ernie Prisbe, vice president for chemical development at Gilead Sciences (which holds the patent for Tamiflu): Whether for Gilead or for others, when it comes to making Tamiflu "on a scale of 1 to 10 in difficulty, this is maybe a 7 or so. There's nothing that overwhelming in this kind of synthesis, or that formidable, that someone couldn't do it."

The synthesis of Tamiflu can start with shikimic acid (although it does not have to). Shikimic acid can be extracted from star anise.

Of the allegations that limited supplies of star anise are a bottleneck to making Tamiflu, Professor John W. Frost of Michigan State University states: "I'm just completely astonished about the gnashing of teeth and the wringing of hands about the shikimic acid. The bottleneck should not be shikimic acid availability."

Frost developed, and patented, and method for making the starting material, shikimic acid, without utilizing star anise. Roche has used Professor Frost's method in recent years, but Frost says he heard the company had cut back. In the fiscal year that ended in June, 2005, Michigan State received $113,000 in royalties from Roche, according to Paul Hunt, the university's associate vice president for research and graduate studies. Roche pays $1.85 for each kilogram of shikimic acid it makes using the process, indicating it made about 60 metric tons in that year.

Frost's patent, titled Biocatalytic synthesis of shikimic acid, is US 6,613,552, issued September 2, 2003. The patent notes: Work on this invention was sponsored in part by the United States Department
Of Agriculture Grant No. 95-37500-1930 and the National Science
Foundation Grant No. CHE963368 amendment 002. The Government may have certain rights in the invention.


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