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June 01, 2010 (Vol. 30, No. 11)

Use of Secondary Recovery in Screening

Ultrasonic Fluid Processor Re-Solubilizes Fragment Precipitates and Can Increase Yields

  • Click Image To Enlarge +
    Figure 2. By virtually eliminating precipitates from fragment libraries, the Hendrix SM100 allows researchers to screen a significantly higher proportion of their compounds than they would be able to otherwise. This process is called secondary recovery.

    LUT technology allows for a very dynamic range of power control and, unlike other ultrasonic methods, does not cause cavitation. At high power, LUT technology can be used for solubilization and for thawing applications; at low power, the same technology can be used for assay mixing or for bead suspension.

    The lack of cavitation helps preserve the integrity of samples when the higher power settings are utilized. By adding the Hendrix SM100 to the FBDD process, researchers are able to re-solubilize precipitated fragment libraries and consequently recover samples that are often unavailable using conventional methods. This secondary recovery process both increases sample concentrations and improves the accuracy of screening results. See Figure 2 for secndary recovery process map.

  • Primary Screening Activity

    Click Image To Enlarge +
    Figure 3. When comparing the control group (left) to the secondary recovery group (right), fragments put through the Hendrix SM100 for secondary recovery showed higher activities with more samples distributed into the higher % inhibition groups. Higher activity in primary screening also generated more leads at a higher quality for secondary screening; for example, the >80% inhibition group expanded from 29% to 38% of the screened fragments.

    With the assistance of Michael Jobling, head of compound management at Elan Pharmaceuticals, we conducted experiments to analyze how secondary recovery could positively impact drug screening results. We re-solubilized precipitated fragment samples back into solution in DMSO, and then sent 24 samples to primary screening.

    The percent inhibition results were compared to the control group, which had visible precipitates at the bottom of the tubes and did not go through the ultrasonic secondary recovery process.

    In the control experiment, 29% of the screened fragments showed less than 20% inhibition, 17% of the group showed 20–40% inhibition, 21% of the group showed 40–60% inhibition, 4% showed 60-80% inhibition, and 29% showed high activity with greater than 80% inhibition.

    In the secondary recovery experiment, with precipitated samples recovered back into solution, the primary screening accuracy increased: 38% of the screened fragments showed high activity with greater than 80% inhibition, 12% showed 60–80% inhibition, and 17% showed 40–60% inhibition. The differences between the control and the secondary recovery experiments are summarized in Figure 3.

    Fragments put through the Hendrix SM100 for secondary recovery increased activity by an average of 68% with a maximum increase in inhibition of 384%.

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