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DRUGS companies have led the way in fast, high-volume testing of experimental
compounds. Now a pesticides manufacturer is making the process even faster.

Zeneca Agrochemicals in Bracknell has developed what it calls 鈥渉igh
throughput鈥� screening methods that test compounds on entire organisms.

Since the early 1990s, the pharmaceuticals industry has pioneered the use of
鈥渃ombinatorial chemistry鈥� for making and screening huge numbers of compounds.
Companies regularly produce many slightly varying compounds then screen them, 96
at a time, to see which ones bind to an enzyme important in disease. The ones
that pass this preliminary test go on to be tested in cells, tissues and,
ultimately, in whole organisms.

Now the pesticide industry is developing preliminary tests for herbicides,
fungicides and insecticides that bypass all these stages, and use entire
organisms at the first go. If the technique suits the tiny insects, plants and
fungi, which can fit in the centimetre-sized wells, they only require testing
with small amounts of chemicals to show which are effective.

John Ormrod, the biologist leading the project at Zeneca, says that testing
on whole organisms mimics real-life use of the compounds much more closely and
makes it more accurate. Cutting out the enzyme screening also saves time: a
compound that affects an enzyme may fail in the organism, where it may be broken
down.

Ormrod says high throughput screening could be used for the other tests that
pesticides must go through before they are marketed. Apart from killing the
pest, a desirable pesticide should not be toxic to other organisms and should
not linger in the soil. 鈥淚n all these areas of testing, we will inevitably get
into miniaturisation. It鈥檚 an ambition for the future,鈥� he says.