[Basic Organic and Inorganic Chemistry of Boron Clusters and Its Application to Drug Discovery].

In the past, drug discovery using low-molecular-weight compounds was dominated by structural design based on combinations of non-metallic elements such as carbon, nitrogen, oxygen, and halogens. Recent drug discovery efforts have shown extraordinary progress, an example of which is the adoption of non-universal elements. The approval of boron neutron capture therapy (BNCT) using a neutron accelerator in Japan ahead of other countries is still fresh in our memory.

Challenging Approach to the Development of Novel Estrogen Receptor Modulators Based on the Chemical Properties of Guaiazulene.

Tamoxifen, a therapeutic agent for breast cancer, has been associated with genetic polymorphisms in the metabolism of ,-dialkylaminoethyl substituent, which plays an important role in the expression of selective estrogen receptor modulator (SERM) activity. To solve this problem, we developed a novel estrogen receptor (ER) modulator, Az-01, on the basis of the aromaticity, dipole moment, and isopropyl group of guaiazulene. Az-01 showed four-fold lower binding affinity for ER than E2 but had similar ER-binding affinity to that of 4-hydroxytamoxifen (4-HOtam).

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.

Antidepressant effect of BE360, a new selective estrogen receptor modulator, activated via CREB/BDNF, Bcl-2 signaling pathways in ovariectomized mice.

We have previously reported that the carborane compound BE360, a novel selective estrogen receptor modulator, has a therapeutic potential against dementia. This study aimed to explore the effects and underlying mechanisms of BE360 on depression-like behaviors in ovariectomized (OVX) mice subjected to subchronic stress, which are postmenopausal depression models. BE360 was subcutaneously administrated using a mini-osmotic pump, for 2 weeks.

Design and Synthesis of Novel Breast Cancer Therapeutic Drug Candidates Based upon the Hydrophobic Feedback Approach of Antiestrogens.

Based upon hydrophobic feedback approaches, we designed and synthesized novel sulfur-containing ERα modulators ( and ) as breast cancer therapeutic drug candidates. The tetrahydrothiepine derivative showed the highest binding affinity toward ERα because of its high hydrophobicity, and it acted as an agonist toward MCF-7 cell proliferation. The corresponding alkylamino derivative maintained high binding affinity to ERα and potently inhibited MCF-7 cell proliferation (IC: 0.

ER subtype selectivity of m-carborane-containing phenols: C-alkyl groups on the m-carborane cage enhance ERα selectivity.

Estrogen receptor (ER) exhibits two subtypes, ERα and ERβ, whose biological functions are quite different despite expression in the same tissues. We developed diiodo-m-carborane derivative 3a, which showed 14-fold selectivity for ERβ with high binding affinity toward ERβ. Interestingly, introduction of an alkyl group into the carbon atom of the m-carborane cage of 3a markedly enhanced the binding affinity toward ERα and decreased affinity toward ERβ.

An automated microliter-scale high-throughput screening system (MSHTS) for real-time monitoring of protein aggregation using quantum-dot nanoprobes.

Protein aggregation is the principal component of numerous protein misfolding pathologies termed proteinopathies, such as Alzheimer's disease, Parkinson's disease, prion disease, and AA amyloidosis with unmet treatment needs. Protein aggregation inhibitors have great potential for the prevention and treatment of proteinopathies. Here we report the development of an automated real-time microliter-scale high throughput screening (MSHTS) system for amyloid aggregation inhibitors using quantum-dot nanoprobes.

Anti-cancer activity of m-carborane-containing trimethoxyphenyl derivatives through tubulin polymerization inhibition.

m-Carborane-containing compound 1a was identified as a cell growth inhibitor from a random screening of a boron compound library. As 1a is a mixture of diastereomers due to the presence of two chiral carbons, we designed achiral derivatives 2-4 and studied the structure-activity relationships of the methoxy groups on the benzene ring. 3,4,5-Trimethoxybenzyl derivative 2a and 3,4,5-trimethoxybenzoyl derivative 3a showed more potent anti-cancer activity against the human breast cancer cell line MDA-MB-453 than lead compound 1a.

Novel androgen receptor full antagonists: Design, synthesis, and a docking study of glycerol and aminoglycerol derivatives that contain p-carborane cages.

Based on the co-crystal structure of bicalutamide with a T877A-mutated androgen receptor (AR), glycerol and aminoglycerol derivatives were designed and synthesized as a novel type of carborane-containing AR modulators. The (R)-isomer of 6c, whose chirality is derived from the glycerol group, showed 20 times more potent cell inhibitory activity against LNCaP cell lines expressing T877A-mutated AR than the corresponding (S)-isomer. Docking studies of both isomers with AR suggested that (R)-6c is in closer spatial proximity to helix-12 of the AR than (S)-6c, which is the most important common motif in the secondary structure of AR for the expression of antagonistic activity.

Synthesis, structure-activity relationships, and mechanistic studies of 5-arylazo-tropolone derivatives as novel xanthine oxidase (XO) inhibitors.

Xanthine oxidase (XO) is an enzyme that contains molybdenum at the active site and catalyzes the oxidation of purine bases to uric acid. Even though XO inhibitors are widely used for the treatment of hyperuricemia and gout, only very few such compounds are clinically used as drugs for the treatment of these diseases. Given the unique physicochemical properties of tropolone, i.

Design and synthesis of p-carborane-containing sulfamates as multitarget anti-breast cancer agents.

The development of multitarget anticancer agents is of high interest to medicinal chemists in terms of overcoming drug resistance and preventing cancer-cell migration. Based on the structure of the potent carborane-containing estrogen BE120, non-steroidal multitarget anti-breast cancer agent candidates 1a-1j were designed and synthesized. Compound 1f shows potent STS-inhibitory activity (IC = 1.

Novel p-carborane-containing multitarget anticancer agents inspired by the metabolism of 17β-estradiol.

The female hormone 17 β-estradiol (E2) is synthesized from estrone by steroid sulfatase (STS), and metabolized into 2-methoxyestradiol (2-ME), whereby the biological activity of the latter is substantially different from that of E2. Based on the metabolic pathways of E2, a carborane-containing 2-ME mimic (1c) and its derivatives (1 and 2) were designed and synthesized as novel multitarget anticancer agents. Bissulfamate 1f exhibited potent STS-inhibitory activity and tubulin-polymerization-inhibitory activity.

Design and synthesis of iodocarborane-containing ligands with high affinity and selectivity toward ERβ.

The selectivity and the binding affinity of previously reported carborane-containing ligands 2 and 3 toward ERβ remains to be optimized. To improve their biological profiles, a series of iodinated carboranyl phenol derivatives (4-6) were designed and synthesized as prospective ERβ-selective ligands with high affinity. Several iodinated carboranyl phenols showed high relative binding affinity (RBA) values for both ERs, and especially for ERβ, due to suitable hydrophobic interactions of the iodine atoms with the hydrophobic amino acid residues of the ERβ ligand-binding domains.

Structure-activity relations of rosmarinic acid derivatives for the amyloid β aggregation inhibition and antioxidant properties.

Amyloid-β aggregation inhibitors are expected to be therapeutic or prophylactic agents for Alzheimer's disease. Rosmarinic acid, which is one of the main aggregation inhibitors derived from Lamiaceae, was employed as a lead compound and its 25 derivatives were synthesized. In this study, the structure-activity relations of rosmarinic acid derivatives for the amyloid-β aggregation inhibitory effect (MSHTS assay), antioxidant properties, and xanthine oxidase inhibition were evaluated.

Targeting Cancer with PCPA-Drug Conjugates: LSD1 Inhibition-Triggered Release of 4-Hydroxytamoxifen.

Targeting cancer with small molecule prodrugs should help overcome problems associated with conventional cancer-targeting methods. Herein, we focused on lysine-specific demethylase 1 (LSD1) to trigger the controlled release of anticancer drugs in cancer cells, where LSD1 is highly expressed. Conjugates of the LSD1 inhibitor trans-2-phenylcyclopropylamine (PCPA) were used as novel prodrugs to selectively release anticancer drugs by LSD1 inhibition.

Design, synthesis, and anti-proliferative activity of 1-(4-methoxyphenyl)-12-hydroxymethyl-p-carborane derivatives.

1-(4-Methoxyphenyl)-12-hydroxymethyl-p-carborane (2a), which is a precursor to the previously developed potent carborane-containing ER agonist BE120, exhibited weak cell growth inhibitory activity against four human cancer cell lines (MCF-7, MDA-MB-453, LNCaP, and PC-3). The biological evaluation of a series of derivatives of 2a revealed that an increased number of methoxy groups on the benzene ring of 2a enhanced the cell growth inhibitory activity. Trimethoxyphenyl derivative 2g afforded the most potent cell growth inhibitory activity (mean GI50 value: 5.

Symmetric 4,4'-(piperidin-4-ylidenemethylene)bisphenol derivatives as novel tunable estrogen receptor (ER) modulators.

We designed and synthesized 4,4'-(piperidin-4-ylidenemethylene)bisphenol derivatives as novel tunable estrogen receptor (ER) modulators. The introduction of hydrophobic substituents on the nitrogen atom of the piperidine ring enhanced ERα binding affinity. In addition, the introduction of four methyl groups adjacent to the piperidine ring nitrogen atom remarkably enhanced ERα binding affinity.

Activation of RXR/PPARγ underlies neuroprotection by bexarotene in ischemic stroke.

The identification of novel drug targets for the treatment of ischemic stroke is currently an urgent challenge. Recent experimental findings have highlighted the neuroprotective potential of immunomodulatory strategies, based on polarization of myeloid cells toward non-inflammatory, beneficial phenotypes. Given the role of retinoid X receptors (RXR) in myeloid cells differentiation and polarization, here we have explored the neuroprotective potential of the RXR agonist bexarotene in mice subjected to focal cerebral ischemia.

BE360, a new selective estrogen receptor modulator, produces antidepressant and antidementia effects through the enhancement of hippocampal cell proliferation in olfactory bulbectomized mice.

We have reported that the carborane compound BE360 is a novel selective estrogen receptor modulator and new therapy option for osteoporosis. The aim of this study was to explore the effects and underlying mechanisms of BE360 on depressive-like behavior and memory impairment in the olfactory bulbectomized (OBX) mice, an experimental animal model of depression and dementia. BE360 was administered subcutaneously to mice using a mini-osmotic pump for 2 weeks.

Estrogenic activity of bis(4-hydroxyphenyl)methanes with cyclic hydrophobic structure.

Monoalkylated bis(4-hydroxyphenyl)methanes (e.g., 1) are reported to show weak binding affinity for estrogen receptor (ER).

Design and synthesis of carborane-containing estrogen receptor-beta (ERβ)-selective ligands.

Candidates for highly selective estrogen receptor-beta (ERβ) ligands (6a-c, 7a-c, 8a and 8b) were designed and synthesized based on carborane-containing ER ligands 1 and 2 as lead compounds. Among them, p-carboranylcyclohexanol derivatives 8a and 8b exhibited high ERβ selectivity in competitive binding assay: for example, 8a showed 56-fold selectivity for ERβ over ERα. Docking studies of 8a and 8b with the ERα and ERβ ligand-binding domains (LBDs) suggested that the p-carborane cage of the ligands is located close to key amino acid residues that influence ER-subtype selectivity, that is, Leu384 in the ERα LBD and Met336 in the ERβ LBD.

Synthesis and biological evaluation of novel m-carborane-containing estrogen receptor partial agonists as SERM candidates.

We designed and synthesized novel m-carborane-containing selective estrogen receptor modulator (SERM) candidates using previously reported m-carborane-containing ER partial agonist 1 as the lead compound. Biological activities were evaluated by means of ERα competitive binding assay and MCF-7 cell proliferation assay. Re-positioning the N,N-dimethylaminoethyloxy group at the para position of 1 to the meta position enhanced the ERα-binding affinity, and 4c showed the highest relative binding affinity (RBA: 83 vs 17β-estradiol = 100) among the tested compounds.

Structure-activity relationship study of diphenylamine-based estrogen receptor (ER) antagonists.

We have reported the design and synthesis of novel estrogen receptor (ER) agonists with a diphenylamine skeleton, which has several advantages over the formerly used diphenylmethane skeleton for drug development. Here, we confirmed the versatility of the diphenylamine skeleton by designing and synthesizing ER antagonist candidates bearing a basic alkylamino side chain on one of the two phenol groups of the diphenylamine agonist core structure. Among the tested compounds, cyclic alkylamine-containing derivatives showed more potent ER-antagonistic activity than the corresponding acyclic derivatives in cell proliferation assay using the MCF-7 cell line.