Benzo-fused lactams from a diversity-oriented synthesis (DOS) library as inhibitors of scavenger receptor BI (SR-BI)-mediated lipid uptake

Halolactonization of N-Acyl-N-(2-cyclohex-1-en-1-yl-6-methylphenyl)glycines: Towards Production of 4,1-Benzoxazoheterocycles

A significant influence of the nature of the acyl substituent at the nitrogen atom on the direction of the reaction in the interaction of N-acyl-N-(2-cyclohex-1-en-1-yl-6-methylphenyl)glycines with bromine was found. In the case of the N-benzoyl derivative, along with benzoxazocinone, which is formed through the stages of pseudoallyl halogenation and subsequent lactonization due to the replacement of the bromine atom by the oxygen atom of the carboxyl group, a mixture of axially chiral isomers of spiro-fused 2′-bromocyclohexane-benzoxazepin-3-ones was also obtained. The aR*,R*,R*-isomer of benzoxazepinone, which initially is four times predominant in the reaction mixture, upon dissolution in deuterochloroform, slowly transforms into aS*-conformer until a ratio of 2:1 is established. In the case of the N-acetyl analogue of this glycine, the only heterocycle is the product of 7-exo-halogenlactonization, the benzoxazepinone spiro-fused with 2′-bromocyclohexane and an undetermined configuration of the axial chirality.

Inhibition of Scavenger Receptor Class B Type 1 (SR-B1) Expression and Activity as a Potential Novel Target to Disrupt Cholesterol Availability in Castration-Resistant Prostate Cancer

There have been several studies that have linked elevated scavenger receptor class b type 1 (SR-B1) expression and activity to the development and progression of castration-resistant prostate cancer (CRPC). SR-B1 facilitates the influx of cholesterol to the cell from lipoproteins in systemic circulation. This influx of cholesterol may be important for many cellular functions, including the synthesis of androgens. Castration-resistant prostate cancer tumors can synthesize androgens de novo to supplement the loss of exogenous sources often induced by androgen deprivation therapy. Silencing of SR-B1 may impact the ability of prostate cancer cells, particularly those of the castration-resistant state, to maintain the intracellular supply of androgens by removing a supply of cholesterol. SR-B1 expression is elevated in CRPC models and has been linked to poor survival of patients. The overarching belief has been that cholesterol modulation, through either synthesis or uptake inhibition, will impact essential signaling processes, impeding the proliferation of prostate cancer. The reduction in cellular cholesterol availability can impede prostate cancer proliferation through both decreased steroid synthesis and steroid-independent mechanisms, providing a potential therapeutic target for the treatment of prostate cancer. In this article, we discuss and highlight the work on SR-B1 as a potential novel drug target for CRPC management.

Multiple Chemical Features Impact Biological Performance Diversity of a Highly Active Natural Product-Inspired Library

A systematic, diversity-oriented synthesis approach was employed to access a natural product-inspired flavonoid library with diverse chemical features, including chemical properties, scaffold, stereochemistry, and appendages. Using Cell Painting, the effects of these diversity elements were evaluated, and multiple chemical features that predict biological performance diversity were identified. Scaffold identity appears to be the dominant predictor of performance diversity, but stereochemistry and appendages also contribute to a lesser degree. In addition, the diversity of chemical properties contributed to performance diversity, and the driving chemical property was dependent on the scaffold. These results highlight the importance of key chemical features that may inform the creation of small-molecule, performance-diverse libraries to improve the efficiency and success of high-throughput screening campaigns.

Computational-aided design of a library of lactams through a diversity-oriented synthesis strategy

Small molecule libraries for virtual screening are becoming a well-established tool for the identification of new hit compounds. As for experimental assays, the library quality, defined in terms of structural complexity and diversity, is crucial to increase the chance of a successful outcome in the screening campaign. In this context, Diversity-Oriented Synthesis has proven to be very effective, as the compounds generated are structurally complex and differ not only for the appendages, but also for the molecular scaffold. In this work, we automated the design of a library of lactams by applying a Diversity-Oriented Synthesis strategy called Build/Couple/Pair. We evaluated the novelty and diversity of these compounds by comparing them with lactam moieties contained in approved drugs, natural products, and bioactive compounds from ChEMBL. Finally, depending on their scaffold we classified them into β-, γ-, δ-, ε-, and isolated, fused, bridged and spirolactam groups and we assessed their drug-like and lead-like properties, thus providing the value of this novel in silico designed library for medicinal chemistry applications.

Chemical probes and drug leads from advances in synthetic planning and methodology

Screening of small-molecule libraries is a productive method for identifying both chemical probes of disease-related targets and potential starting points for drug discovery. In this article, we focus on strategies such as diversity-oriented synthesis that aim to explore novel areas of chemical space efficiently by populating small-molecule libraries with compounds containing structural features that are typically under-represented in commercially available screening collections. Drawing from more than a decade's worth of examples, we highlight how the design and synthesis of such libraries have been enabled by modern synthetic chemistry, and we illustrate the impact of the resultant chemical probes and drug leads in a wide range of diseases.

Rediscovering scavenger receptor type BI: surprising new roles for the HDL receptor

PURPOSE OF REVIEW

Scavenger receptor BI (SR-BI) is classically known for its role in antiatherogenic reverse cholesterol transport as it selectively takes up cholesterol esters from HDL. Here, we have highlighted recent literature that describes novel functions for SR-BI in physiology and disease.

RECENT FINDINGS

A large population-based study has revealed that patients heterozygous for the P376L mutant form of SR-BI showed significantly increased levels of plasma HDL-cholesterol and had increased risk of cardiovascular disease, demonstrating that SR-BI in humans is a significant determinant of cardiovascular disease. Furthermore, SR-BI has been shown to modulate the susceptibility to LPS-induced tissue injury and the ability of sphingosine 1 phosphate to interact with its receptor, linking SR-BI to the regulation of inflammation. In addition, important domains within the molecule (Trp-415) as well as novel regulators (procollagen C-endopeptidase enhancer protein 2) of SR-BI's selective uptake function have recently been identified. Moreover, relatively high expression levels of the SR-BI protein have been observed in a variety of cancer tissues, which is associated with a reduced overall survival rate.

SUMMARY

The HDL receptor SR-BI is a potential therapeutic target not only in the cardiovascular disease setting, but also in inflammatory conditions as well as in cancer.

Discovery of bisamide-heterocycles as inhibitors of scavenger receptor BI (SR-BI)-mediated lipid uptake

A new series of potent inhibitors of cellular lipid uptake from HDL particles mediated by scavenger receptor, class B, type I (SR-BI) was identified. The series was identified via a high-throughput screen of the National Institutes of Health Molecular Libraries Small Molecule Repository (NIH MLSMR) that measured the transfer of the fluorescent lipid DiI from HDL particles to CHO cells overexpressing SR-BI. The series is characterized by a linear peptidomimetic scaffold with two adjacent amide groups, as well as an aryl-substituted heterocycle. Analogs of the initial hit were rapidly prepared via Ugi 4-component reaction, and select enantiopure compounds were prepared via a stepwise sequence. Structure-activity relationship (SAR) studies suggest an oxygenated arene is preferred at the western end of the molecule, as well as highly lipophilic substituents on the central and eastern nitrogens. Compound 5e, with (R)-stereochemistry at the central carbon, was designated as probe ML279. Mechanistic studies indicate that ML279 stabilizes the interaction of HDL particles with SR-BI, and its effect is reversible. It shows good potency (IC50=17 nM), is non-toxic, plasma stable, and has improved solubility over our alternative probe ML278.