The first enzyme involved is phenylalanine ammonia-lyase (PAL) that converts L-phenylalanine to trans-cinnamic acid and ammonia.

In the pharmaceutical industry, shikimic acid from the Chinese star anise (Illicium verum) is used as a base material for production of oseltamivir (Tamiflu).

Although shikimic acid is present in most autotrophic organisms, it is a biosynthetic intermediate and in general found in very low concentrations.

The low isolation yield of shikimic acid from the Chinese star anise is blamed for the 2005 shortage of oseltamivir.

Shikimic acid can also be extracted from the seeds of the sweetgum (Liquidambar styraciflua) fruit,[2] which is abundant in North America, in yields of around 1.5%.

[4][5][6] A 2010 study released by the University of Maine showed that shikimic acid can also be readily harvested from the needles of several species of pine tree.

However, the availability of a cheap chiral building block can overcome these additional costs, for example, shikimic acid for oseltamivir.