TORONTO—Advanced Chemistry Development Inc., (ACD/Labs) recently announced that it has been collaborating with leading Alzheimer's research scientist Dr. Gilbert Rishton, founder and director of the Channel Islands Alzheimer's Institute at California State University, to evaluate central nervous system drugs and gain a deeper understanding of the parameters that effect blood-brain barrier permeability. The result has been a refinement of in-silico techniques for the prediction of blood-brain barrier permeability and thus an advancement in the predictive software functionality that ACD/Labs can offer its customers.
"Many times you'll have something that looks like a fantastic drug when you test it on an assay but when you get in cell-based assays or animals, the drug fails because it doesn't get to right places or not enough gets to the right places," notes Karim Kassam, senior applications scientist, team leader for ACD/Labs. "We built some scripts in the software and integrated data that [Dr. Rishton] was able to extract from analyses using our software, so that we could create a tool to give a quick answer about which compounds might be worth considering for Alzheimer's and which are not."
What was key in the collaboration with Rishton, Kassam says, was bringing to light that while researchers are making strides in discovering new targets for Alzheimer's, they need to identify the physiochemical properties desirable for compounds designed to reach those targets, particularly with the blood-brain barrier being such a formidable wall.
As Kassam notes, the company—which employs a number of Ph.D. chemists experienced in drug discovery—has worked to keep open collaborations with researchers in the chemical and pharmaceutical industries, as well as non-profit organizations and academic institutions. Other notable collaborators include Chemical Abstract Service—which provides ACD/Labs' physicochemical property values to subscribers of their online research discovery tool, SciFinder—and GlaxoSmithKline, with whom pKa predictors were refined with in-house experimental data.
These collaborations, Kassam says, help solve very complex chemical issues, in part by continually refining ACD/Labs software. Alzheimer's disease has turned out to be particularly challenging in term of unraveling the chemistry, hence the work with Rishton.
In the collaboration, Rishton used ACD/Labs' physiochemical software tools to predict logP, logD, pKa, solubility and other molecular physical properties thought to influence blood-brain barrier permeability and conducted a comparative study of several known central nervous system drugs versus new secretase inhibitors.
Among the major findings were the importance of the logP of a compound, the polar surface area and the number of freely rotatable bonds. As the software offerings continue to improve and relevant properties for therapeutics continue to be explored, so too will researchers' preclinical and clinical success improve, Rishton notes.
"Alzheimer's disease and neurodegeneration in general remains one of the most urgent unmet medical needs of our time," Rishton says. "The ACD/Labs blood-brain barrier tool provides medicinal chemists with the ability to rapidly assess the potential of small-molecule CNS drug leads to reach their molecular targets in the brain. It is an easy, rapid, and predictive tool for any discovery program where brain exposure is a requirement or, in some cases, a liability."