New Delhi, March 24: Indian scientists have identified trees in the Western Ghats that might serve as an alternative source of raw material for the standard drug against bird flu currently supplied to the world mainly by China.

Researchers from Bangalore exploring the Western Ghats forests have found several trees whose leaves hold exploitable levels of shikimic acid — the raw material used to produce oseltamivir, the standard drug against the avian influenza virus.

The global supply of shikimic acid is met primarily through the fruits of the Chinese star anise tree that contains up to five per cent of the acid. But the tree yields seeds only after six years of growth and scientists have been searching for new sources of the compound.

Now, plant biologist Ramanan Uma Shaankar from the University of Agricultural Sciences, Bangalore, and his colleagues have shown that the leaves of two trees, Calophyllum apetalum and Araucaria excelsa, may contain four to five per cent of shikimic acid.

Their findings will appear in the journal Current Science tomorrow.

Both trees are found scattered along an 800km stretch of the Western Ghats in Karnataka.

The researchers have held back the botanical names of two other species found to contain six per cent of the acid in their leaves after consultation with the Department of Biotechnology that supported the field studies.

“These species may provide an opportunity for India to break China’s monopoly on shikimic acid,” Shaankar said. “But we thought it would be best to keep the identity (of the trees) secret to avoid unplanned exploitation,” Shaankar said.

“We need well-planned and sustainable use of such resources,” he said. The presence of shikimic acid in the leaves is a major advantage that the Indian trees will have over the Chinese star anise, he added.

The seeds from the Chinese star anise can be harvested once a year. Researchers believe the leaves could be harvested through the year and the volume of leaf biomass could make extraction of the acid from these trees economically attractive.

Studies by organic chemist A. Srikrishna at the Indian Institute of Science, Bangalore, have shown that the chemical structure of the shikimic acid from the Western Ghats trees is equivalent to that of the commercial product.

Oseltamivir has been used during outbreaks of bird flu to protect people who may come in contact with infected birds.

Central government health authorities have stockpiled oseltamivir and sent doses of the drug to areas where the H5N1 avian influenza virus has surfaced.

Forestry scientists said whether the trees in the Western Ghats were indeed viable for shikimic acid would depend on their count and distribution within the forests. Their abundance would determine their viability.