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Introduction Presently a wide range of approaches are available for the high throughput screening of compound libraries. Broadly the screening may be target oriented or diversity oriented screening. The high cost of screening whit lesser chances of successful hits is the main bottleneck in exponential rate of screening. Target focused approach eases this bottleneck to a greater extent. Target focused compound libraries are based on the designing of inhibitors against a particular protein target, or related family of targets for example kinases, ligand gated channels, proteases etc. The screening against therapeutic targets helps in rapid developments to be made in the process of drug discovery. The designing of a targeted library needs the specification of target first. Once the required target is figured out, the next step is to find out a suitable scaffold, to which recognition elements (also called substituents /side chains) to which recognition elements can bind. This scaffold-substituent complex should be designed in such a way that it can successfully interact with the target of interest. In addition to proper interaction, chemistry of this complex should be such that it is easy to synthesize and purify for commercial scale replica production. Various useful softwares may be used to choose the appropriate scaffold for various substituents. Easy to use and beneficial software in this regard is SAR: Scaffold Matching software. This software uses the substrate scaffold matching algorithm to predict the best scaffold for the substituents which can then accurately bind their targets like kinase inhibitors, parp inhibitors, egfr inhibitors etc. Example In order to find appropriate scaffold, the structure of the substituent compound has to be known. Structure of the compound is aligned with scaffolds to find the best possible match. For example, following figure shows the molecule and the possible scaffold generated by the SAR software. The software contains those scaffolds which are known to interact with therapeutic targets in human beings. Hence the scaffold predicted for this molecule is confirmed to bind the required target. By overlying the core scaffold onto the molecule, the unmatched points can be pointed out. Proper substituent placeholders R1 and R2 are invented to attach the substituents onto the scaffold. This is how scaffold-substituent complex is generated. In 2006, list of 268 molecular targets was approved for drug development and are available in Therapeutic Targets Database [1]. The analysis of US FDA Orange Book and the Centre for Biologics Evaluation and Research showed that 21000 drugs have been discovered so far out of which 1204 are small molecules. Some of these drugs target only one target while others have the ability to inhibit many potential targets. Imatinib, for example, is one of polypharmacological drug which was formerly known to inhibit only c-ABL but later on it was discovered that imatinib inhibits many other kinases like c-KIT etc. which increases its clinical significance. Systematic study of targets is crucial to design target-oriented compound libraries. More than 50% of the drugs target four key gene families: • Class I GPCRs • Nuclear Receptors • Ligand Gated Ion Channels • Voltage Gated Ion Channels Following figure [2] shows the share of different families of drug targets. The list shows the top ten most drugged targets. The reason for excessive drugging of these targets is their role in clinical pathologies especially cancer. Design of target oriented compound libraries against these targets has helped a lot in the combating these ailments. Conclusion Taken together, target-oriented compound libraries are highly helpful in designing required successful hits. Many computational softwares aid in comparing the new inhibitors to the already established scaffolds, which help to improve the chemistries of new models in order to make them clinically administrable drugs. It is interesting to notice that target oriented drug design not only helps to develop drugs for already established targets but also opens doors for the new researchers to explore and unveil newer targets by designing their compound libraries. References 1. Zheng, C. J. et al. Therapeutic targets: progress of their explorations and investigation of their characteristics. Pharma. Rev. 2006; 58: 259–279. 2. Overington JP, Lazikani BA et al. How many drug targets are there? Nature Reviews Drug Discovery 2006Dec; 5: 993-996. Related Posts An Introduction to Compound Libraries We has established long-term and stable relationships with more than 10,000 customers from pharmaceutical and biotech companies, universities and research institutions. We have high quality inhibitors like Celecoxib, Gemcitabine, Docetaxel& more. We have headquarters in both United States and Europe, and also has 38 distributors worldwide. We provide overnight delivery in North America and Europe.
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