Secrets of poppy compound unlocked       

Scientists at the University of York and GlaxoSmithKline (GSK) Australia have discovered a complex cluster of ten genes encoding five different enzyme classes is responsible for the synthesis of the medicinal compound noscapine.

The breakthrough came when the scientists discovered that poppy varieties that produce noscapine express a number of genes that are absent in varieties that are noscapine free. They then analysed the inheritance pattern of these genes in hundreds of offspring from crosses between noscapine and no-noscapine varieties. When they saw that all of these genes are inherited together, they realised they could be looking at an incredibly complex gene cluster. The identity and arrangement of genes in the cluster was determined by cloning and DNA sequencing.

Professor Ian Graham, Director of the Centre for Novel Agricultural Products at the University of York, said: “We were amazed to find that this gene cluster encodes for almost the entire biosynthetic pathway for noscapine. With this one discovery we have been able to produce an outline of the pathway and define a number of the steps involved - something that normally takes years.”

Noscapine has been used as a suppressant in cough mixtures for decades. More recently, it has been reported to have anti-cancer activity and is currently in early stage clinical trials. Tim Bowser, Head of R&D for GSK Australia’s Opiates Division, said: “The fact that the genes are grouped in a cluster means that plant breeding becomes faster and easier. GSK are using this discovery to develop high yielding commercial noscapine poppies in order to establish a reliable route of supply.”