Molecular similarity searching is fast becoming a key tool in organic chemistry. In this book, the editor has brought together an international team of authors, each working at the forefront of this technology, providing a timely and concise overview of current research. The chapters focus principally on those methods which have reached sufficient maturity to be of immediate practical use in molecular design.

The authors introduce the concept of Molecular Quantum Similarity, developed in their laboratory, in a didactic form. The basis of the concept combines quantum theoretical calculations with molecular structure and properties even for large molecules. They give definitions and procedures to compute similarities molecules and provide graphical tools for visualization of sets of molecules as n-dimensional point charts.

Molecular similarity is the foundational principle for drug design, wherein new molecules are designed that are “similar enough” to known compounds to have a good chance at being active but “different enough” to have a chance at being superior. Quantifying the level of similarity or dissimilarity between two molecules has been a long-standing area of investigation, and decades of research have yielded an impressive array of tools and techniques for measuring and calculating these relationships. Molecular Similarity: Concepts and Applications for Pharmaceutical Research provides a comprehensive review of “best practices” within the field of molecular similarity as it applies to drug design, covering fundamentals and concepts, case studies, and strategies for integration. Topics covered include: • theory and concepts in molecular similarity • 1-D, 2-D and 3-D methods for chemical similarity • biochemical similarity • target similarity – pockets and docking • integrating multiple approaches to chemical similarity • case studies in lead discovery, optimization and target discovery; kinome/GPCR profiling; polypharmacology; and off-target discovery Molecular Similarity: Concepts and Applications for Pharmaceutical Research will appeal to both the newcomer and the expert, providing a foundational text upon which to gain familiarity with the field, develop localized strategies, and conduct further research.

The aim of this text is to provide reviews and monographs on topics involving molecular similarity, ranging from the fundamental physical properties underlying molecular behaviour to applications in industrially important fields such as pharmaceutical drug design and molecular engineering. The editors hope that this series will encourage new ideas and approaches, help to systematize the rapidly accumulating new chemical information, and make chemistry better understood and better applied.

Volumes 2 and 3 of the 3D QSAR in Drug Design series aim to review the progress being made in CoMFA and other 3D QSAR approaches since the publication of the highly successful first volume about four years ago. Volume 2 (Ligand-Protein Interactions and Molecular Similarity) divides into three sections dealing with Ligand-Protein Interactions, Quantum Chemical Models and Molecular Dynamics Simulations, and Pharmacophore Modelling and Molecular Similarity, respectively. Volume 3 (Recent Advances) is also divided into three sections, namely 3D QSAR Methodology: CoMFA and Related Approaches, Receptor Models and Other 3D QSAR Approaches, and 3D QSAR Applications. More than seventy distinguished scientists have contributed nearly forty reviews of their work and related research to these two volumes which are of outstanding quality and timeliness. These works present an up-to-date coverage of the latest developments in all fields of 3D QSAR.

The molecular modeling perspective in drug design. (N. Calude Cohen). Molecular graphics and modeling: tools of the trade. (Roderick E. Hubbard). Molecular modeling of small molecules. (Tamara Gund). Computer assisted new lead design. (Akiko Itai, Miho Yamada Mizutani, Yoshihiko Nishibata, and Nubuo Tomioka). Experimental techniques and data banks. (John P. Priestle and C. Gregory Paris). Computer-assisted drug discovery. (Peter Gund, Gerald Maggiora, and James P. Snyder). Modeling drug-receptor interactions. (Konrad F. Koehler, Shashidhar N. Rao, and James P. Snyder). Glossary of terminology. (J. P. Tollenaere).

In recent years the fundamental concepts and applied methodologies of molecular similarity analysis have experienced a revolutionary development. Motivated by the increased degree of understanding of elementary molecular properties on the levels ranging from fundamental quantum chemistry to the complex interactions of biomolecules, and aided by the spectacular progress in computer technology and access to computer power, the area has opened up to many new ideas and new approaches. This book covers topics in quantum similarity approaches, electron density shape analysis methods, and it provides better theoretical understanding of molecular similarity. Additionally, quantitative shape analysis, especially activity relations (QShAR) and the prediction of the pharmacological or toxicological effects of molecules in the related context of quantum QSAR (QQSAR). This volume written by the experts in the various subfields of molecular similarity, provides a collection of the most recent ideas, advances, and methodologies. It is the hope of the Editors that by representing these topics within a single volume, the readers will find a balanced overview of the status of the field. We also hope that the book will serve as a tool for selecting and assessing the best approach for various new types of problems of molecular similarity that may arise and it will provide a set of easy references for further studies and applications.

High-throughput screening and combinatorial chemistry are two of the most potent weapons ever to have been used in the discovery of new drugs. At a stroke, it seems to be possible to synthesise more molecules in a month than have previously been made in the whole of the distinguished history of organic chemistry, Furthermore, all the molecules can be screened in the same short period. However, like any weapons of immense power, these techniques must be used with care, to achieve maximum impact. The costs of implementing and running high-throughput screening and combinatorial chemistry are high, as large dedicated facilities must be built and staffed. In addition, the sheer number of chemical leads generated may overwhelm the lead optimisation teams in a hail of friendly fire. Mother nature has not entirely surrendered, as the number of building blocks that could be used to build libraries would require more atoms than there are in the universe. In addition, the progress made by the Human Genome Project has uncovered many proteins with different functions but related binding sites, creating issues of selectivity. Advances in the new field of pharmacogenomics will produce more of these challenges. There is a real need to make hi- throughput screening and combinatorial chemistry into 'smart' weapons, so that their power is not dissipated. That is the challenge for modellers, computational chemists, cheminformaticians and IT experts. In this book, we have broken down this grand challenge into key tasks.

Similarities in chemical reactivity depend on molecular properties, and are ultimately dependent on the similarities of electronic structures. Fundamentally, quantum chemical similarities are manifested in similarities of molecular behaviour. This book covers both the quantum chemical origins and the methods of phenomenological descriptions of molecular similarity. The emphasis on reactivity is a unique feature. The exposition of computational methods and the prediction of reactivities, as well as the description of actual computer programs constitute important aspects of the book. Specific applications in drug design and techniques for the interpretation of the roles of functional groups in reactivity are of interest in molecular engineering. The selection of topics provides a detailed and balanced introduction to the field of similarity-based assessment of chemical reactivity. For researchers and graduate students in both fundamental chemistry and applied fields, such as biochemistry, pharmacology and drug design.

This book provides a myriad of fresh ideas and energetic approaches to the newer aspects of everyday drug modelling. With contributions from some of the best young talents of today, Molecular Modelling and Drug Design encourages a break from old traditions and probes the unexplored avenues of the modelling tool. The contributors' views act as a gauge to future trends in computer-aided drug design-an area that continues to expand and play an ever more significant role in drug discovery.