Preface

Volume 9 of the eBook series “Frontiers in Medicinal Chemistry” is a compilation of six superbly written reviews on various aspects of medicinal chemistry, including critical analysis of various drug targets, and understanding of the manifestations of various types of ligand-receptor interactions. These reviews provide valuable insights of the chemical, and pharmacological importance of various classes of chemical compounds for drug discovery against diseases.

In chapter 1 Burnstock covers the involvement of purinergic receptors and signaling in pain, and other essential cellular functions. Purinergic signaling is an extracellular signaling process, mediated by purine nucleotides, and nucleosides. It involves the activation of purinergic receptors in the cell and/or in nearby cells, thereby regulating diverse cellular functions. There are many different types of purinergic receptors which mediate in various biological functions. The chapter highlights the current classification of receptor sub-types for purines and pyrimidines and recent developments of various classes of compounds as potential inhibitors of purinergic receptors for the treatment of both visceral and neuropathic pain have been reviewed.

Santucci et al review the consequence of mitochondrial damage in various diseases in chapter 2, Mitochondria play an important role in programmed cell death process (apoptosis). Any mitochondrial malfunction provokes the unregulated release of cytochrome c and pro-apoptotic factors, which through a complex cascade, lead to cell death. This review provides an excellent overview of the key role that mitochondria play in the apoptotic process and ramifications of mitochondrial damage on this process.

Dipeptidyl peptidase-4 (DPP4) is expressed on the surface of many cell type, and catalyses the cleavage of X-proline from the N-terminus of polypeptides. Its role in various physiological functions, such as regulation of the biological activity of hormones and chemokines, including glucagon-like peptide-1, and glucosedependent insulinotropic polypeptide has been widely studied in recent years. The enzyme has also been identified as a valid target for inhibition for the discovery of drugs against many diseases including diabetes mellitus II. Matteucci and Giampietro in chapter 3 have contributed a comprehensive review on physiological roles, and pathological functions of DPP4. Development of various classes of new inhibitors of DPP4 as potential drugs along with their specificity, risk-benefits of the currently available DPP4 inhibitors and future prospects in this key field have been discussed.

D’Andrea et al have compiled a systematic review in chapter 4 on the modulation of angiogenesis by using various classes of small molecules, including peptides. Angiogenesis has been implicated in many diseases, including cancer. Modulation of angiogenesis is highly desirable for the treatment of these diseases. The authors have explained at length the molecular mechanism of the angiogenic cascade, which involves a balance in pro- and anti-angiogenic factors, selective binding of these growth factors to cell surface receptors, the resulting signaling to initiate biochemical pathways, and the corresponding angiogenic response. Many classes of peptides have been developed with the capacity to target the growth factorreceptor interface which lead to inhibition of angiogenesis. Pharmacological and diagnostic applications of these peptides are extensively reviewed with reference to their possible applications for the treatment of angiogenic related diseases, including cancers.

Obesity is a major, yet preventable, cause of mortality and morbidity. Unfortunately the effective treatment for obesity and associated disorders is yet to be developed. Many of the blockbuster drugs against obesity have been either withdrawn or find only restricted use due to unwarranted side effects. A considerable success has be achieved in identifying the molecular mechanisms involved in energy imbalance leading to obesity. This has opened new vistas for the development of innovative therapies for the obesity disorders. Chapter 5 contributed by Hruby and Cai is focused on scientific evidences on the involvement of melanocortins 3 (MC3R) and 4 (MC4R) receptors in energy balance, feeding behaviors, and many other physiological functions. Their selective agonists and antagonists, including melanotropin ligands, can modulate MC3R and MC4R activity, and can thus serve as drugs for the treatment of feeding disorders. The review discusses various aspects of the topic, including new directions.

Recent developments in nanotechnology have revolutionized various fields, including drug delivery. Debbage et al. in chapter 6 have contributed an excellent review on the discovery and development of diverse array of nanoparticles for targeted transport of drugs. In recent years, several classes of nanomaterials, made up of liposomes, synthetic polymers, proteins, dendrimers, fullerenes, etc., have been developed. Many of them are similar to proteins and other macromolecules which are found inside the living cells, and thus can take advantage of existing cellular machinery to facilitate the delivery of drugs at the target. Nanoparticles have the capacity to encapsulate, disperse, absorb, and conjugate drugs that can lead to enhanced performance in a variety of dosage forms, and improved pharmacokinetics and pharmcodynamic properties. Based on specific architecture and basic material, nanoparticle based drugs (“nanomedicines”) can overcome cellular resistance, rapidly cross cellular barriers, provide enhanced adhesion to biological surfaces, and transport large payloads of drugs, thereby providing rapid therapeutic results, and improved bioavailability. The review provides an excellent overview of the entire field of nanomediciens, including challenges and opportunities for the future.

At the end we are profoundly grateful to all the contributors for timely completion of their writing assignments. The present 9^th volume of the eBook series is the result of the efficient management of the entire team of Bentham Science Publishers, particularly Mr. Omer Shafi (Assistant Manager Publications), Mr. Shehzad Naqvi (Senior Manager Publications) and the team leader Mr. Mahmood Alam (Director Publications) who deserve our deepest appreciation for putting together an excellent treatise of well written articles in an efficient manner. We are confident that this volume of eBook series will receive wide appreciation from students, researchers and established scientists.