Vital ingredient for bird flu drug found in India

By Sakshi Aiyyer

Shikimic Acid Used For Making ‘Tamiflu’ Has Been Discovered In 7 Plants Species Of Western Ghats

Shikimic acid, the most vital ingredient used to make Oseltamivir, (Tamiflu) the only known drug to combat the deadly bird flu, has been found in trees in the Western Ghats.

Scientists from Bangalore have found at least seven plant species that yielded shikimic acid from the Western Ghat forests, known as one of the world’s 10 hottest biodiversity hotspots.

The team from University of Agricultural Sciences, Bangalore, said it scanned through 210 plant species to shortlist “a few promising species whose leaves yielded shikimic acid level higher than 1%”.

Presently, the majority of the acid’s global availability is met by China because it is extracted from the fruits of the Chinese star anise tree, that contains up to 5% of the acid. But the 10-metre tree attains its seed-bearing stage after six years of growth, making it unlikely that the growing market demand of the acid would be met by the single source alone.

The fruits of this tree are traditionally used in China for culinary and medicinal purposes as they contain 2%-7% of shikimic acid, the highest reported estimate from plants.

Interestingly, the trees discovered by Indian scientists have yielded 1%-5.02% of the acid, with a plant species called Araucaria Excelsa yielding almost 5.02% of shikimic acid. The most significant advantages of the newly identified Indian sources is that the estimates are from leaves and not fruits as is the case with star anise.

Reporting their finding in the latest issue of the medical journal ‘Current Science’, the scientists said a total of 193 angiosperms (flowering plants) belonging to 59 families and 17 gymnosperms (plants in which the seeds are not enclosed in an ovary) belonging to five families were collected for the study. “Only 7 of the 193 angiosperm species yielded shikimic acid in excess of 1% while the rest yielded no or low shikimic acid. The most promising species were Calophyllum Apetalum (4.10% shikimic acid). All the 17 gymnosperms had detectable levels of shikimic acid with six species accumulating greater than 1%. Among these, Araucaria Excelsa yielding almost 5.02% of shikimic acid,” the scientists said.

They said that since so much of the acid is being used for industrial and pharmaceutical uses, it is imperative that newer sources of this chemical are identified. It is estimated that nearly two-thirds of the requirement of shikimic acid is being sourced from plants while the remaining one-third is obtained from genetically engineered E Coli.

The team added, “The leads presented here appear more promising than most others. In few of these species, the estimates are comparable to those reported from star anise. Because the estimates are from leaves, the sheer volume of the biomass offered by the leaves would render it economically feasible.

This finding of the new source of shikimic acid can potentially be used to meet the emerging needs of both the domestic and international markets.”

Union health ministry sources said, “Getting the raw material to make Tamiflu in India has been our biggest hurdle. At present, it is found only in China and Germany.” Tamiflu, the drug which blocks the replication of the flu virus, is presently being stockpiled by most countries as a precautionary measure in case of an outbreak of the bird flu among humans.

The price of shikimic acid has, therefore, skyrocketed. Pharma companies in India say the acid, which used to cost $40 a kg earlier, now costs around $1,000 per kg.