Highly potent and selective alphaVbeta3-receptor antagonists: solid-phase synthesis and SAR of 1-substituted 4-amino-1H-pyrimidin-2-ones

Small molecules for bone diseases

IMPORTANCE OF THE FIELD

Bones play many roles in the body, providing structure, protecting organs, anchoring muscles and storing calcium. Over 100 million people worldwide suffer from bone diseases, mainly osteoporosis, cancer-related bone loss, osteoarthritis and inflammatory arthritis. Osteoporosis itself has no specific symptoms, and the main consequence is the increased risk of bone fractures. Therefore, the prevention of bone diseases is important to maintain the quality of life in the human society. However, treatment options are still insufficient.

AREAS COVERED IN THIS REVIEW

This review article gives a summary of the low molecular mass modulators of bone diseases targets disclosed in patent applications and articles, mainly during the last 5 years.

WHAT THE READER WILL GAIN

Readers will rapidly gain an overview of these modulators not only for historical targets, but also of emerging and re-visited targets. Readers will also be able to see the current research trend and the main players in this field.

TAKE HOME MESSAGE

Drug discovery for bone diseases has made progress in the last years. The research area has dynamically shifted from historical targets (bisphosphonate, parathyroid hormone and calcitonin) to newly confirmed targets or targets re-visited which were biologically validated in the past. Cathepsin K inhibitors should be very close to launching in the market.

Design and synthesis of novel potent and selective integrin alphanubeta3 antagonists--novel synthetic routes to isoquinolinone, benzoxazinone, and quinazolinone acetates

An unexpected ring contraction of benzazepinone based alpha(nu)beta(3) antagonists led to the design of quinolinone-type derivatives. Novel and efficient synthetic routes to isoquinolinone, benzoxazinone, and quinazolinone acetates were established. Nanomolar alpha(nu)beta(3) antagonists based on these new scaffolds were prepared. Moreover, benzoxazinones 15a and 15b exhibited high microsomal stability and good permeability.

Novel potent and selective αvβ3/αvβ5 integrin dual antagonists with reduced binding affinity for human serum albumin

The binding of lead compounds and drugs to human serum albumin (HSA) is a ubiquitous problem in drug discovery since it modulates the availability of the leads and drugs to their intended target, which is linked to biological efficacy. In our continuing efforts to identify small molecule alpha(V)beta(3) and alpha(V)beta(5) dual antagonists, we recently reported indoles 2-4 as potent and selective alpha(V)beta(3)/alpha(V)beta(5) antagonists with good oral bioavailability profile. In spite of subnanomolar binding affinity of these compounds to human alpha(V)beta(3) and alpha(V)beta(5) integrins, high HSA binding (96.5-97.3%) emerged as a limiting feature for these leads. Structure-activity HSA binding data of organic acids reported in the literature have demonstrated that the incorporation of polar groups into a given molecule can dramatically decrease the affinity toward HSA. We sought to apply this strategy by examining the effects of such modifications in both the central core constrain and the substituent beta to the carboxylate. Most of these derivatives were prepared in good yields through a cesium fluoride-catalyzed coupling reaction. This reaction was successful with a variety of nitrogen-containing scaffolds (20, 33, and 43) and selected acetylenic derivatives (16, 19, and 34). Among the compounds synthesized, the 3-[5-[2-(5,6,7,8-tetrahydro [1,8]naphthyridin-2-yl)ethoxy]indol-1-yl]-3-[5-(N,N-dimethylaminomethyl)-3-pyridyl]propionic acid (25) was found to be the most promising derivative within this novel series with a subnanomolar affinity for both alpha(v)beta(3) and alpha(v)beta(5) (IC(50) = 0.29 and 0.16 nM, respectively), similar to our initial lead receptor antagonists 2-4, and exhibiting a low HSA protein binding (40% bound, K(d) = 1.1+/-0.4 x 10(3) microM) and an improved in vitro stability profile toward human and mouse microsomes (99.9% and 98.7% remaining after 10 min). Moreover, the selectivity of 25 toward alpha(5)beta(1) and IIbIIIa integrins was perfectly maintained when compared to the parent leads 2-4. Thus, compound 25 was selected as a new lead with improved drug-like properties for further evaluations in the field of oncology and osteoporosis.

Design, synthesis, and biochemical evaluation of novel αvβ3 integrin ligands

Studies on integrin alphaVbeta3 have implicated this receptor in a number of pathologies. In this article we describe some of our initial efforts to design small molecules alphaVbeta3 ligands incorporating an indole core template and an oxyguanidine as basic ending. Synthesis, biochemical activity and pharmacological properties are analyzed.