Humble spud sprouts surprise

UK scientists have identified bioactive plant chemicals in the most practical of staple foods, the potato. These natural chemicals have been associated with reduced blood pressure and they selectively affect a chemotherapeutic target for trypanosome diseases such as sleeping sickness.

“Potatoes have been cultivated for thousands of years, and we thought traditional crops were pretty well understood”, says food scientist Dr Fred Mellon from the Institute of Food Research (IFR). “But this surprise finding shows that even the most familiar of foods might conceal a hoard of health-promoting chemicals”.

Kukoamines and related compounds were found at higher levels than some other compounds in potatoes that have a long history of scientific investigation. However, kukoamines are little studied, as they have only previously been found in an exotic plant whose bark is used to make an infusion in Chinese herbal medicine.

Dr Mellon and his team stumbled across the compounds while doing an analysis funded by the Food Standards Agency. “No-one had expected to find them in one of the staple food crops of the Western world”, he says.

Scientists used to have to know what they were looking for when analysing composition. They might look for 30 or so known compounds. With new “metabolomic” techniques, they can find the unexpected by analysing the 100s or even 1000s of small molecules produced by an organism. IFR has just taken delivery of a new instrument to be used for metabolomics studies in diet and health, and food safety research.

“Only a small proportion of plants have been subjected to serious phytochemical analysis”, said Dr Mellon. “Until now none of the new metabolites we found in this study had ever been identified from any of the species we examined, and only one had ever been described from another plant source. Modern profiling techniques should enable major breakthroughs to be made in understanding how genes interact with environment to determine the complex position of a plant or animal in life”.

The scientists have yet to determine the stability of compounds during cooking and to conduct detailed dose-response studies to determine their impact on health.

The findings were published in the Journal of Agricultural and Food Chemistry yesterday and available online through the journal’s ASAP advance access: http://pubs.acs.org/cgi-bin/asap.cgi/jafcau/asap/pdf/jf050298i.pdf

Notes to Editors

Please contact Zoe Dunford for more information, images of some of the potato varieties studied and an interview with Dr Fred Mellon or Dr Adrian Parr: 01603 255111 / 07768 164185 zoe.dunford@bbsrc.ac.uk
The mission of the Institute of Food Research (www.ifr.ac.uk) is to carry out independent basic, and strategic research on food safety, quality, nutrition and health. It is a company limited by guarantee, with charitable status, grant aided by the Biotechnology and Biological Sciences Research Council (BBSRC).
Metabolomics is the science of analysing the diversity of small molecules produced by an organism in relation to genome function and to other properties of interest, such as nutritional status and disease.
IFR has taken delivery of the first part of a leading-edge spectrometer to be used for metabolomics. It will enable complex mixtures of small molecules to be analysed at high resolution and the chemical structures of unknown compounds to be determined. The new instrument will make a major contribution to a wide range of research projects in the fields of diet and health, food-safety microbiology and plant and microbial science. It is worth in excess of £600k, is shared with the John Innes Centre and has been funded under a grant from the BBSRC Research Equipment Initiative, with contributions from IFR, JIC and Bruker Biospin. It is a Bruker LC/SPE/NMR/MS instrument that combines the separate techniques of liquid chromatography, nuclear magnetic resonance and mass spectrometry.
The original study for the Food Standards Agency (www.food.gov.uk), initiated and coordinated by Prof Howard Davies at the Scottish Crop Research Institute (www.scri.ac.uk), was aimed at exploring the use of modern gene, protein, and metabolite profiling approaches to assess the potential for unintended effects in genetically modified potatoes. The results were published in September last year and are available online, reference: J. Agric. Food Chem.; 2004; 52(20) pp 6075 – 6085.
The Scottish Crop Research Institute (SCRI) increases knowledge in plant and environmental sciences. It is grant-aided by the Scottish Executive Environment and Rural Affairs Department (SEERAD) and has charitable status.

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