Not many people know that when they are given the drug, Tamiflu (oseltamivir) for swine flu, bird flu or seasonal influenza they are taking a product derived from the particularly tasty, decorative spice, star anise.
Star anise (Illicium verum) is a universally used spice grown primarily in China, India and the Philippines. It is included in a wide array of ethnic dishes and is a component of Chinese cooking’s five spice powder and Indian cuisine’s garam masala. It has a similar taste to ordinary anise and is often used as a substitute for that spice. However it is the star-shaped pericarps (seed-pods), rather than the seeds themselves, that gives it both its flavor and provides the shikimic acid – the chemical compound used in the production of Tamiflu.
Shikimic acid itself does not have any known antiviral activity. However it does have a distinctive chemical structure that is used as the starting point for a complex, multistage process that culminates in the production of Tamiflu.
Oseltamivir is known as a neuraminidase inhibitor that does not actually kill swine flu or other influenza viruses directly. Instead it inhibits the internal spread of these viruses by blocking a protein that facilitates the escape of replicating viral particles from body cells. Although some virus strains have developed resistance to this drug it is still very effective in most cases – especially if it is taken early on in the infective process.
As a result of the growing swine flu pandemic there is now a global shortage of star anise. However this is likely to be a temporary problem as shikimic acid can now be produced by the fermentation of specific E. coli bacteria. Another less important plant source of shikimic acid is the fruit of the liquidambar (sweetgum) tree. However the sweetgum fruit does not have very high concentrations of this compound. Other spices that contain shikimic acid, but are not used as commercial sources for the compound, are ginger and fennel.
Other health benefits of star anise
Although shikimic acid does not have any direct antiviral effects, star anise contains a compound called linalool that does indeed have antiviral activity. Like all spices, star it also has strong antioxidant activity. In particular it protects against the oxidation of fatty acids thereby helping to contain the deposition of cholesterol deposits in the arterial walls. Limonene is another important phytonutrient found in star anise that demonstrates strong anticancer activity.
In star anise we have yet another spice that, in addition to its enhancement of our gustatory experiences, is making a massive contribution to the containment of one more life-threatening disease.