Crystal structure, docking study and structure–activity relationship of carborane-containing androgen receptor antagonist 3-(12-hydroxymethyl-1,12-dicarba-closo-dodecaboran-1-yl)benzonitrile

Artepillin C overcomes apalutamide resistance through blocking androgen signaling in prostate cancer cells

Prostate cancer has a relatively good prognosis, but most cases develop resistance to hormone therapy, leading to castration-resistant prostate cancer (CRPC). Androgen receptor (AR) antagonists and a cytochrome P450 17A1 inhibitor have been used to treat CRPC, but cancer cells readily develop resistance to these drugs. In this study, to improve the therapy of CRPC, we searched for natural compounds which block androgen signaling. Among cinnamic acid derivatives contained in Brazilian green propolis, artepillin C (ArtC) suppressed expressions of androgen-induced prostate-specific antigen and transmembrane protease serine 2 in a dose-dependent manner. Reporter assays revealed that ArtC displayed AR antagonist activity, albeit weaker than an AR antagonist flutamide. In general, aberrant activation of the androgen signaling is involved in the resistance of prostate cancer cells to hormone therapy. Recently, apalutamide, a novel AR antagonist, has been in clinical use, but its drug-resistant cases have been already reported. To search for compounds which overcome the resistance to apalutamide, we established apalutamide-resistant prostate cancer 22Rv1 cells (22Rv1/APA). The 22Rv1/APA cells showed higher AR expression and androgen sensitivity than parental 22Rv1 cells. ArtC inhibited androgen-induced proliferation of 22Rv1/APA cells by suppressing the enhanced androgen signaling through blocking the nuclear translocation of AR. In addition, ArtC potently sensitized the resistant cells to apalutamide by inducing apoptotic cell death due to mitochondrial dysfunction. These results suggest that the intake of Brazilian green propolis containing ArtC improves prostate cancer therapy.

Carboranes in drug discovery, chemical biology and molecular imaging

There exists a paucity of structural innovation and limited molecular diversity associated with molecular frameworks in drug discovery and biomolecular imaging/chemical probe design. The discovery and exploitation of new molecular entities for medical and biological applications will necessarily involve voyaging into previously unexplored regions of chemical space. Boron clusters, notably the carboranes, offer an alternative to conventional (poly)cyclic organic frameworks that may address some of the limitations associated with the use of novel molecular frameworks in chemical biology or medicine. The high thermal stability, unique 3D structure and aromaticity, kinetic inertness to metabolism and ability to engage in unusual types of intermolecular interactions, such as dihydrogen bonds, with biological receptors make carboranes exquisite frameworks in the design of probes for chemical biology, novel drug candidates and biomolecular imaging agents. This Review highlights the key developments of carborane derivatives made over the last decade as new design tools in medicinal chemistry and chemical biology, showcasing the versatility of this unique family of boron compounds.

Quantification of solid-phase chemical reactions using the temperature-dependent terahertz pulsed spectroscopy, sum rule, and Arrhenius theory: thermal decomposition of α-lactose monohydrate

Transformations of the low-energy vibrational spectra are associated with structural changes in an analyte and closely related to the instability of weak chemical bounds. Terahertz (THz)/far-infrared optical spectroscopy is commonly used to probe such transformation, aimed at characterization of the underlying solid-phase chemical reactions in organic compounds. However, such studies usually provide quite qualitative information about the temperature- and time-dependent parameters of absorption peaks in dielectric spectra of an analyte. In this paper, an approach for quantitative analyses of the solid-phased chemical reactions based on the THz pulsed spectroscopy was developed. It involves studying an evolution of the sample optical properties, as a function of the analyte temperature and reaction time, and relies on the classical oscillator model, the sum rule, and the Arrhenius theory. The method allows one to determine the temperature-dependent reaction rate V₁(T) and activation energy E_a. To demonstrate the practical utility of this method, it was applied to study α-lactose monohydrate during its temperature-induced molecular decomposition. Analysis of the measured THz spectra revealed the increase of the reaction rate in the range of V₁ ≃ ~9 × 10^-4-10^-2 min^-1, when the analyte temperature rises from 313 to 393 K, while the Arrhenius activation energy is E_a ≃ ~45.4 kJ/mol. Thanks to a large number of obtained physical and chemical parameters, the developed approach expands capabilities of THz spectroscopy in chemical physics, analytical chemistry, and pharmaceutical industry.

Structure-property and structure-activity relationships of phenylferrocene derivatives as androgen receptor antagonists

Ferrocene is a representative organometallic compound having a sandwich structure with high stability and hydrophobicity. In this study, we determined the physicochemical properties of a series of nitro- and cyanophenylferrocenes, and evaluated their biological activity as androgen receptor (AR) antagonists. Ferrocene derivatives exhibited hydrophobicity parameter π values in the range between 2.54 and 3.23, depending on the substituents, indicating that the hydrophobicity of ferrocene is suitable for its application as a hydrophobic core structure of nuclear receptor ligands. The synthesized ferrocene derivatives showed AR-antagonistic activity, and among them, 3-nitrophenylferrocene 14 exhibited the most potent activity with an IC₅₀ value of 0.28 μM. The developed compounds may be candidates for further structural development as AR antagonists. These findings also support the utility of organometallic species as structural options for drug discovery.

Structure-Activity Relationship of para-Carborane Selective Estrogen Receptor β Agonists

Selective agonism of the estrogen receptor (ER) subtypes, ERα and ERβ, has historically been difficult to achieve due to the high degree of ligand-binding domain structural similarity. Multiple efforts have focused on the use of classical organic scaffolds to model 17β-estradiol geometry in the design of ERβ selective agonists, with several proceeding to various stages of clinical development. Carborane scaffolds offer many unique advantages including the potential for novel ligand/receptor interactions but remain relatively unexplored. We synthesized a series of para-carborane estrogen receptor agonists revealing an ERβ selective structure-activity relationship. We report ERβ agonists with low nanomolar potency, greater than 200-fold selectivity for ERβ over ERα, limited off-target activity against other nuclear receptors, and only sparse CYP450 inhibition at very high micromolar concentrations. The pharmacological properties of our para-carborane ERβ selective agonists measure favorably against clinically developed ERβ agonists and support further evaluation of carborane-based selective estrogen receptor modulators.

Development of Force Field Parameters for p-Carborane to Investigate the Structural Influence of Carborane Derivatives on Drug Targets by Complex Formation

Androgen receptor (AR) has a key role in the development and progression of prostate cancer, and AR antagonists are used for its remedy. Recently, carborane derivatives, which are carbon-containing boron clusters have attracted attention as new AR ligands. Here we determined the force field parameters of 10-vertex and 12-vertex p-carborane to facilitate in silico drug design of boron clusters. Then, molecular dynamics (MD) simulations of complexes of AR-carborane derivatives were performed to evaluate the parameters and investigate the influences of carborane derivatives on the three-dimensional structure of AR. Energy profiles were obtained using quantum chemical calculations, and the force-field parameters were determined by curve fitting of the energy profiles. The results of MD simulations indicated that binding of the antagonist-BA341 changed some hydrogen-bond formations involved in the structure and location of helix 12. Those results were consistent with previously reported data. The determined parameters are also useful for refining the structure of the carborane-receptor complex obtained by docking simulations and development of new ligands with carborane cages not only for AR but also for various receptors.

Boron's journey: advances in the study and application of pharmacokinetics

Boron-containing compounds (BCCs) are attractive chemical entities in drug development. Some of these compounds have been used in the treatment of human disease, and studies on their pharmacodynamics suggest that they employ multiple forms of activity. However, less is known about the pharmacokinetic profile of these molecules. Areas covered: The herein compiled reported data is presented in accordance with the classical 'ADME' system for identifying the scope of BCCs in the respective fields. Our analysis suggests that these compounds have several distinct ways to move within the human body, and that the specific structural features of each molecule account for its distinct pharmacokinetic profile. These insights should be useful for designing BCCs with a desired effect. Expert opinion: Increasing knowledge about the pharmacokinetics of BCCs is providing a broader understanding about the design of new release systems and potential drugs, as well as probable protein transporters that could be related to key roles in physiological processes. These transporters may be involved in sodium transport, hormone release and regulation of the cell cycle. The shared features among groups of BCCs are being identified in order to apply these insights to the design of advantageous compounds.

Transformation and dehydration kinetics of methylene blue hydrates detected by terahertz time-domain spectroscopy

Three methylene blue crystalline hydrates were identified by terahertz spectroscopy according to their different THz absorption features.

Boron-containing compounds: chemico-biological properties and expanding medicinal potential in prevention, diagnosis and therapy

INTRODUCTION

Although the medicinal use of boron-containing compounds (BCCs) had long been limited to antiseptics, in the last few decades, these compounds have been used as antibiotics or chemotherapeutic agents. In the last few years, boron has been included in the moieties of many known drugs to improve their capacity in binding to their respective target receptors.

AREAS COVERED

The current review focuses on research and patent literature of the last decade related to the development of BCCs as preventive, diagnostic and therapeutic tools. It explores the possible mechanisms of action of these compounds as well as the advantageous features of their structure and chemico-pharmacological properties.

EXPERT OPINION

Although uncertainties exist about the mechanism of action of BCCs, increasing evidence about their toxicological profile strongly suggests that many can be safely administered to humans. Even stronger evidence exists regarding the capacity of BCCs to reach multiple targets that are involved in the treatment of common diseases. It seems fair to say that some BCCs will reach the market for medicinal use in the near future, not only for targeting microbial or neoplastic systems but also for acting on cell-signaling processes involved in many other disorders.