Combinatorial Chemistry Review

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Use of a surrogate analyte to define the reaction path to which the solid support was exposed, and hence imply the structure of a member of a combinatorial library or the reaction sequence for its preparation.

A polymer having a regular branched structure. If suitably functionalized (such as the benzyl alcohol-substituted it may be used as a soluble support, in which case the desired, dendrimer-supported, material may be isolated by size-exclusion chromatography. Dendrimers may also be attached to a polymer and used as a solid support, with significantly increased loading over the initial resin.

Numerical representation of a molecular property, including bulk properties (e.g. log P, molecular weight), two-dimensional (2-D) features (atom connectivity’s) or three-dimensional (3-D) features (molecular shape). A complete set of descriptors comprises a fingerprint.

Directed Library
Library which uses a limited number of building blocks chosen on the basis of pre-existing information or hypothesis which defines the type of functionalities deemed important to obtain a particular activity.

Directed Sorting
Technique for organizing a mixture of solid-supported samples by identifying each particle (for instance, on the basis of its shape, marking or by reading a radiofrequency code) and transferring it to an appropriate position in an array.

The "unrelatednes" of a set of, for example, building blocks or members of a combinatorial library, as measured by their properties, such as atom connectivity, physical properties, computational measurements or bioactivity.

Diversity Reagent
One of a set of reagents which introduces diversity into the library products, as opposed to one which results in an identical conversion for each member of the library. Similar to building block but may be useful to distinguish from other (i.e. "non-diversity") reagents.

Any substance presented for treating, curing or preventing disease in human beings or in animals. A drug may also be used for making a medical diagnosis or for restoring, correcting, or modifying physiological functions.

Drug Development Process
•Discovery: Identification of a biological, genetic or protein target linked to a particular disease; subsequent lead identification of a potential drug that interacts with the target to help cure the disease or halt its progression.
•Pre-clinical Phase: Comprehensive in vitro and animal testing of the drug candidate to establish its target specificity, toxicity in various doses and pharmacokinetics.
•Clinical Phase I: Human trials conducted to demonstrate safety and effectiveness (efficacy); tests with paid, healthy volunteers to establish dosage, side effects and pharmacokinetics.
•Clinical Phase II: Trials with small numbers of patients conducted to identify drug performance characteristics (optimal dosing, administration, key indication).
•Clinical Phase III: Pivotal trials conducted with larger patient populations to establish efficacy and provide additional safety information.
•Approval: Data is analyzed and submitted for regulatory review. The U.S. submission to the FDA is called an NDA (New Drug Application) or BLA (Biologic License Application); the European submission to the EMEA (European Medicines Evaluation Agency) is called an MAA (Marketing Authorization Application). After stringent analysis and review of the submission, the regulatory agency provides final approval.

Drug Targeting
A strategy aiming at the delivery of a compound to a particular tissue of the body.

Dynamic Library
Collection of compounds in dynamic equilibrium. If the composition of the library is altered, for instance by the presence of a receptor which selectively binds certain library members, then shifting of the equilibrium will lead to an increase in the amount of those components which bind to the target with relatively high affinity.

Strategy for pool/split synthesis whereby a surrogate analyte is associated with each member of a combinatorial library. This is often achieved by the use of tags attached to the particle of solid support on which the library members are assembled. This allows the determination of the reaction history of an individual particle.

A macromolecule, usually a protein, that functions as a (bio) catalyst by increasing the reaction rate. In general, an enzyme catalyzes only one reaction type (reaction selectivity) and operates on only one type of substrate (substrate selectivity). Substrate molecules are transformed at the same site (regioselectivity) and only one of a chiral substrate or of a racemate is transformed (enantioselectivity).