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The chemist warily unpacks a container of innocuous-looking white powder sent to him by a colleague at a big pharmaceutical company. Clouds of packaging are pulled out of the large box, revealing the tiny vial within.
“I’m not going to open it,” he tells us. “If I did, none of my male colleagues will want to come in to my office. I might not want to go into it myself.”
That’s because the white powder is Sildenafil citrate, the chemical compound which forms the active ingredient of Viagra. Martyn Poliakoff — Research Professor of Chemistry at The University of Nottingham and international star of the Periodic Table of Videos web project — has been sent 17.98 grams of the stuff by process chemist Peter Dunn. That’s enough to make more than 300 of those famous little blue pills that are the scourge of internet firewalls across the globe.
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Professor Poliakoff examines the compound for the latest of The Molecular Videos, an offshoot of the Periodic Table of Videos project. As well as looking at how and why the compound has the effects that it does, he also talks about its links with the field of green chemistry.
Sildenafil citrate is a very potent drug that causes blood vessels to expand, enabling blood to flow around the body much more easily. The drug was originally tested to treat pulmonary hypertension — a condition where blood does not flow properly into the lungs.
It was found that the compound made it easier for the heart to pump blood through the blood vessels, but tests found that it affected other parts of the body.
“When the drug was first discovered and developed people didn’t realise all of the things it could do,” said Professor Poliakoff. “Only when the researchers were testing it and they saw the effect the compound had on male rats did they realise they were on to something quite exciting.
“The molecule is designed to inhibit the enzyme PDE 5, which causes blood vessels to contract. Obviously it’s quite embarrassing when your blood vessels contract at the wrong moment, when you’d really like them to relax…”
A little known fact about Viagra is that Peter Dunn, who worked on the compound, is a green chemist. When the drug was originally developed it required 13.5 litres of solvent for every ten grams of compound. Applying the principles of green chemistry he managed to get this down to just 60ml — using solvents that were far less harmful to the environment.
“You have to generate some waste when you are doing chemistry, but I don’t want to use large amounts of chemicals that need incinerating or dumping,” said Professor Poliakoff. “We want to minimise it to make sure the waste we do produce is as environmentally harmless as possible.”
To watch the video visit
www.youtube.com/watch?v=78jg5DUbNZ0 or
www.periodicvideos.com
— Ends —
Notes to editors: The University of Nottingham is ranked in the UK's Top 10 and the World's Top 100 universities by the Shanghai Jiao Tong (SJTU) and Times Higher (THE) World University Rankings.
More than 90 per cent of research at The University of Nottingham is of international quality, according to RAE 2008, with almost 60 per cent of all research defined as ‘world-leading’ or ‘internationally excellent’. Research Fortnight analysis of RAE 2008 ranks the University 7th in the UK by research power. In 27 subject areas, the University features in the UK Top Ten, with 14 of those in the Top Five.
The University provides innovative and top quality teaching, undertakes world-changing research, and attracts talented staff and students from 150 nations. Described by The Times as Britain's "only truly global university", it has invested continuously in award-winning campuses in the United Kingdom, China and Malaysia. Twice since 2003 its research and teaching academics have won Nobel Prizes. The University has won the Queen's Award for Enterprise in both 2006 (International Trade) and 2007 (Innovation — School of Pharmacy), and was named ‘Entrepreneurial University of the Year’ at the Times Higher Education Awards 2008.
Nottingham was designated as a Science City in 2005 in recognition of its rich scientific heritage, industrial base and role as a leading research centre. Nottingham has since embarked on a wide range of business, property, knowledge transfer and educational initiatives (www.science-city.co.uk) in order to build on its growing reputation as an international centre of scientific excellence. The University of Nottingham is a partner in Nottingham: the Science City.