Pyridine based dual binding site aromatase (CYP19A1) inhibitors.

Aromatase (CYP19A1) inhibitors are the mainstay therapeutics for the treatment of hormone dependant breast cancer, which accounts for approximately 70% of all breast cancer cases. However, increased resistance to the clinically used aromatase inhibitors, including letrozole and anastrazole, and off target effects, necessitates the development of aromatase inhibitors with improved drug profiles. The development of extended 4th generation pyridine based aromatase inhibitors with dual binding (haem and access channel) is therefore of interest and here we describe the design, synthesis and computational studies. Cytotoxicity and selectivity studies identified the pyridine derivative (4-bromophenyl)(6-(but-2-yn-1-yloxy)benzofuran-2-yl)(pyridin-3-yl)methanol (10c) as optimal with CYP19A1 IC50 0.83 nM (c.f. letrozole IC50 0.70 nM), and an excellent cytotoxicity and selectivity profile. Interestingly, computational studies for the 6-O-butynyloxy (10) and 6-O-pentynyloxy (11) derivatives identified an alternative access channel lined by Phe221, Trp224, Gln225 and Leu477, providing further insight into the potential binding mode and interactions of the non-steroidal aromatase inhibitors.

4th generation nonsteroidal aromatase inhibitors: An iterative SAR-guided design, synthesis, and biological evaluation towards picomolar dual binding inhibitors.

One in every eight women will be diagnosed with breast cancer during their lifetime and approximately 70% of all patients are oestrogen receptor (ER) positive depending upon oestrogen for their growth accounting for third generation aromatase (CYP19A1) inhibitors being the mainstay in the treatment of ER-positive breast cancer. Despite the success of current aromatase inhibitors, acquired resistance occurs after prolonged therapy. Although the precise mechanisms of resistance are not known, lack of cross resistance among aromatase inhibitors drives the need for a newer generation of inhibitors to overcome this resistance alongside minimising toxicity and adverse effects. Novel triazole-based inhibitors were designed based on previously published parent compound 5a, making use of the now available crystal structure of CYP19A1 (PDB 3S79), to make modifications at specific sites to explore the potential of dual binding at both the active site and the access channel. Modifications included adding long chain substituents e.g. but-2-ynyloxy and pent-2-ynyloxy at different positions including the most active compound 13h with IC50 value in the low picomolar range (0.09 nM). Aromatase inhibition results paired with molecular dynamics studies provided a clear structure activity relationship and favourable dual binding mode was verified. Toxicity assays and CYP selectivity profile studies for some example compounds were performed to assess the safety profile of the prepared inhibitors providing the basis for the 4th generation nonsteroidal aromatase inhibitors.

Cost-effectiveness analysis of KTE-X19 CAR T therapy versus real-world standard of care in patients with relapsed/refractory mantle cell lymphoma post BTKi in England.

AIMS: The objective of this study is to estimate the cost-effectiveness of KTE-X19 versus standard of care (SoC) in the treatment of patients with relapsed/refractory (R/R) mantle cell lymphoma (MCL) post-Bruton tyrosine kinase inhibitor (BTKi) treatment from a UK healthcare perspective. MATERIALS AND METHODS: A three-state partitioned survival model (pre-progression, post-progression and death) with a cycle length of one month was used to extrapolate progression-free and overall survival over a lifetime horizon. Population inputs along with KTE-X19 (brexucabtagene autoleucel) efficacy and safety data were derived from the single-arm trial ZUMA-2 (NCT02601313). The composition of SoC was informed by a literature-based meta-analysis, SoC efficacy data were obtained from the SCHOLAR-2 real-world study. Survival was modelled using standard parametric curves for SoC and a mixture-cure methodology for KTE-X19. It was assumed that patients whose disease had not progressed after five years experienced long-term remission. Costs, resource use and utility, and adverse event disutility inputs were obtained from published literature and publicly available data sources. An annual discount rate of 3.5% was applied to costs and health outcomes. Modelled outcomes for KTE-X19 and SoC included expected life years (LY), quality-adjusted life years (QALY) and total costs. Deterministic and probabilistic sensitivity analyses and scenario analyses were performed. RESULTS: Estimated median survival was 5.96 years for KTE-X19 and 1.38 for SoC. Discounted LYs, QALYs and lifetime costs were 8.27, 5.99 and £385,765 for KTE-X19 versus 1.98, 1.48 and £79,742 for SoC, respectively. The KTE-X19 versus SoC cost per QALY was £67,713 and the cost per LY was £48,645. Influential scenario analyses use alternative KTE-X19 survival curves and discount rates, and shorter time horizons. CONCLUSION: Considering the survival and quality of life benefits compared to SoC, KTE-X19 for R/R MCL appears as a cost-effective treatment in the real-world UK setting.

Phenylalanyl tRNA synthetase (PheRS) substrate mimics: design, synthesis, molecular dynamics and antimicrobial evaluation.

Antimicrobial resistance is a very challenging medical issue and identifying novel antimicrobial targets is one of the means to overcome this challenge. Phenylalanyl tRNA synthetase (PheRS) is a promising antimicrobial target owing to its unique structure and the possibility of selectivity in the design of inhibitors. Sixteen novel benzimidazole based compounds (5a-b), (6a-e), (7a-d), (9a-e) and three N,N-dimethyl-7-deazapurine based compounds (16a-c) were designed to mimic the natural substrate of PheRS, phenylalanyl adenylate (Phe-AMP), that was examined through flexible alignment. The compounds were successfully synthesised chemically in two schemes using 4 to 6-steps synthetic pathways, and evaluated against a panel of five microorganisms with the best activity observed against Enterococcus faecalis. To further investigate the designed compounds, a homology model of E. faecalis PheRS was generated, and PheRS-ligand complexes obtained through computational docking. The PheRS-ligand complexes were subjected to molecular dynamics simulations and computational binding affinity studies. As a conclusion, and using data from the computational studies compound 9e, containing the (2-naphthyl)-l-alanine and benzimidazole moieties, was identified as optimal with respect to occupancy of the active site and binding interactions within the phenylalanine and adenosine binding pockets.

Synthesis, computational study and biological evaluation of 9-acridinyl and 1-coumarinyl-1,2,3-triazole-4-yl derivatives as topoisomerase II inhibitors.

Topoisomerase (IIB) inhibitors have been involved in the therapies of tumour progression and have become a major focus for the development of anticancer agents. New three-component hybridised ligands, 1,4-disubstituted-1,2,3-triazoles (8-17), were synthesised via a 1,3-dipolar cycloaddition reaction of 9-azidoacridine/3-azidocoumarin with N/O-propargyl small molecules under click reaction conditions. Cancer cell growth inhibition of the synthesised triazoles was tested against human cell-lines in the NCI-60-cell-panel, and the most active compounds tested against topoisomerase (IIB)-enzymes. The acridinyl ligands (8-10) revealed 60-97% cell growth inhibition in six cancer cell-panels. Cell-cycle analysis of MCF7 and DU-145 cells treated with the active acridinyl ligands exhibited cell-cycle arrest at G2/M phase and proapoptotic activity. In addition, compound 8 displayed greater inhibitory activity against topoisomerase (IIB) (IC50 0.52 µM) compared with doxorubicin (IC50 0.83 µM). Molecular dynamics simulation studies showed the acridine-triazole-pyrimidine hybrid pharmacophore was optimal with respect to protein-ligand interaction and fit within the binding site, with optimal orientation to allow for intercalation with the DNA bases (DG13, DC14, and DT9).

Cost-effectiveness for KTE-X19 CAR T therapy for adult patients with relapsed/refractory mantle cell lymphoma in the United States.

AIMS: The objective of this study is to estimate the cost-effectiveness of KTE-X19 versus standard of care (SoC) in the treatment of relapsed/refractory (R/R) mantle cell lymphoma (MCL) patients from a US healthcare perspective. MATERIALS AND METHODS: A three-state partitioned-survival model (pre-progression, post-progression, and death) with a cycle length of 1 month was used to extrapolate progression-free and overall survival (OS) over a lifetime horizon. Due to the long tail of the OS curve, OS was modeled applying a mixture-cure methodology, using the assumption that patients whose disease had not progressed after 5 years experienced long-term remission. Population inputs were derived from the ZUMA-2 trial. This was also the source of KTE-X19 efficacy and safety data, while this data was obtained from the literature for SoC. Costs and resource use inputs were derived from the published literature and publicly available data sources. Health state utilities were derived from the ZUMA-2 trial (NCT02601313), applying the US tariff. Adverse event disutilities were derived from the published literature. Costs and health outcomes were discounted at 3% per year. The model estimated expected life years (LY), quality-adjusted life years (QALY), and total costs for KTE-X19 vs SoC. Deterministic and probabilistic sensitivity analyses were performed. RESULTS: Median survival was 9.71 years for KTE-X19 and 2.13 for SoC. Discounted LYs, QALYs, and lifetime costs were 8.99, 7.39, and $693,832 for KTE-X19 vs 4.47, 3.65, and $574,263 for SoC, respectively. The KTE-X19 vs SoC cost per QALY was $31,985. The most influential model parameter was the utility for patients with long-term remission. At a willingness-to-pay threshold of $150,000 per QALY, the probability that KTE-X19 was cost-effective was 99%. CONCLUSION: The treatment of R/R MCL with KTE-X19 presents a potentially cost-effective alternative to the current SoC, deriving its value from incremental survival and health-related quality-of-life benefits.

Liposomal delivery of hydrophobic RAMBAs provides good bioavailability and significant enhancement of retinoic acid signalling in neuroblastoma tumour cells.

Retinoid treatment is employed during residual disease treatment in neuroblastoma, where the aim is to induce neural differentiation or death in tumour cells. However, although therapeutically effective, retinoids have only modest benefits and suffer from poor pharmacokinetic properties. In vivo, retinoids induce CYP26 enzyme production in the liver, enhancing their own rapid metabolic clearance, while retinoid resistance in tumour cells themselves is considered to be due in part to increased CYP26 production. Retinoic acid metabolism blocking agents (RAMBAs), which inhibit CYP26 enzymes, can improve retinoic acid (RA) pharmacokinetics in pre-clinical neuroblastoma models. Here, we demonstrate that in cultured neuroblastoma tumour cells, RAMBAs enhance RA action as seen by morphological differentiation, AKT signalling and suppression of MYCN protein. Although active as retinoid enhancers, these RAMBAs are highly hydrophobic and their effective delivery in humans will be very challenging. Here, we demonstrate that such RAMBAs can be loaded efficiently into cationic liposomal particles, where the RAMBAs achieve good bioavailability and activity in cultured tumour cells. This demonstrates the efficacy of RAMBAs in enhancing retinoid signalling in neuroblastoma cells and shows for the first time that liposomal delivery of hydrophobic RAMBAs is a viable approach, providing novel opportunities for their delivery and application in humans.

Statistical models for the deterioration of kidney function in a primary care population: A retrospective database analysis.

Background: Evidence for kidney function monitoring intervals in primary care is weak, and based mainly on expert opinion. In the absence of trials of monitoring strategies, an approach combining a model for the natural history of kidney function over time combined with a cost-effectiveness analysis offers the most feasible approach for comparing the effects of monitoring under a variety of policies. This study aimed to create a model for kidney disease progression using routinely collected measures of kidney function. Methods: This is an open cohort study of patients aged ≥18 years, registered at 643 UK general practices contributing to the Clinical Practice Research Datalink between 1 April 2005 and 31 March 2014. At study entry, no patients were kidney transplant donors or recipients, pregnant or on dialysis. Hidden Markov models for estimated glomerular filtration rate (eGFR) stage progression were fitted to four patient cohorts defined by baseline albuminuria stage; adjusted for sex, history of heart failure, cancer, hypertension and diabetes, annually updated for age. Results: Of 1,973,068 patients, 1,921,949 had no recorded urine albumin at baseline, 37,947 had normoalbuminuria (<3mg/mmol), 10,248 had microalbuminuria (3-30mg/mmol), and 2,924 had macroalbuminuria (>30mg/mmol). Estimated annual transition probabilities were 0.75-1.3%, 1.5-2.5%, 3.4-5.4% and 3.1-11.9% for each cohort, respectively. Misclassification of eGFR stage was estimated to occur in 12.1% (95%CI: 11.9-12.2%) to 14.7% (95%CI: 14.1-15.3%) of tests. Male gender, cancer, heart failure and age were independently associated with declining renal function, whereas the impact of raised blood pressure and glucose on renal function was entirely predicted by albuminuria. Conclusions: True kidney function deteriorates slowly over time, declining more sharply with elevated urine albumin, increasing age, heart failure, cancer and male gender. Consecutive eGFR measurements should be interpreted with caution as observed improvement or deterioration may be due to misclassification.

Synthesis, molecular modelling and CYP24A1 inhibitory activity of novel of (E)-N-(2-(1H-imidazol-1-yl)-2-(phenylethyl)-3/4-styrylbenzamides.

CYP24A1 (25-hydroxyvitamin D-24-hydroxylase) is a useful enzyme target for a range of medical conditions including cancer, cardiovascular and autoimmune disease, which show elevated CYP24A1 levels and corresponding reduction of calcitriol (the biologically active form of vitamin D). A series of (E)-N-(2-(1H-imidazol-1-yl)-2-(phenylethyl)-3/4-styrylbenzamides have been synthesised using an efficient synthetic route and shown to be potent inhibitors of CYP24A1 (IC50 0.11-0.35µM) compared with the standard ketoconazole. Molecular modelling using our CYP24A1 homology model showed the inhibitors to fill the hydrophobic binding site, forming key transition metal interaction between the imidazole nitrogen and the haem Fe3+ and multiple interactions with the active site amino acid residues.

Expression of the retinoic acid catabolic enzyme CYP26B1 in the human brain to maintain signaling homeostasis.

Retinoic acid (RA) is a potent regulator of gene transcription via its activation of a set of nuclear receptors controlling transcriptional activation. Precise maintenance of where and when RA is generated is essential and achieved by local expression of synthetic and catabolic enzymes. The catabolic enzymes Cyp26a1 and Cyp26b1 have been studied in detail in the embryo, where they limit gradients of RA that form patterns of gene expression, crucial for morphogenesis. This paracrine role of RA has been assumed to occur in most tissues and that the RA synthetic enzymes release RA at a site distant from the catabolic enzymes. In contrast to the embryonic CNS, relatively little is known about RA metabolism in the adult brain. This study investigated the distribution of Cyp26a1 and Cyp26b1 transcripts in the rat brain, identifying several novel regions of expression, including the cerebral cortex for both enzymes and striatum for Cyp26b1. In vivo use of a new and potent inhibitor of the Cyp26 enzymes, ser 2-7, demonstrated a function for endogenous Cyp26 in the brain and that hippocampal RA levels can be raised by ser 2-7, altering the effect of RA on differential patterning of cell proliferation in the hippocampal region of neurogenesis, the subgranular zone. The expression of CYP26A1 and CYP26B1 was also investigated in the adult human brain and colocalization of CYP26A1 and the RA synthetic enzyme RALDH2 indicated a different, autocrine role for RA in human hippocampal neurons. Studies with the SH-SY5Y human neuroblastoma cell line implied that the co-expression of RA synthetic and catabolic enzymes maintains retinoid homeostasis within neurons. This presents a novel view of RA in human neurons as part of an autocrine, intracellular signaling system.

Small-molecule inhibitors of 25-hydroxyvitamin D-24-hydroxylase (CYP24A1): synthesis and biological evaluation.

The synthesis of imidazole styrylbenzamide, tert-butyl styrylimidazole, and tert-butyl styrylsulfonate derivatives is described. Evaluation of binding affinity and inhibitory activity against CYP24A1 identified the imidazole styrylbenzamides as potent inhibitors of CYP24A1, having selectivity with respect to CYP27B1 comparable with or greater than that of the standard ketoconazole. Further evaluation of the 3,5-dimethoxy and 3,4,5-trimethoxy derivatives in chronic lymphocytic leukemia cells revealed that co-treatment of 1α,25-dihydroxyvitamin D3 plus inhibitor coordinately upregulated GADD45α and CDKN1A. Docking experiments on the inhibitors in the CYP24A1 enzyme active site suggest the compounds reach the active site through the vitamin D access tunnel and are exposed to multiple hydrophobic residues. The imidazole styrylbenzamides are optimally positioned to allow interaction of the imidazole with the heme, and, in the case of the methoxy derivatives, a hydrogen bond between the 3-methoxy group and Gln82 stabilizes the molecule in a favorable active conformation.

Synthesis and CYP26A1 inhibitory activity of novel methyl 3-[4-(arylamino)phenyl]-3-(azole)-2,2-dimethylpropanoates.

The role of all-trans-retinoic acid (ATRA) in the development and maintenance of many epithelial and neural tissues has raised great interest in the potential of ATRA and related compounds (retinoids) as pharmacological agents, particularly for the treatment of cancer, skin, neurodegenerative and autoimmune diseases. The use of ATRA or prodrugs as pharmacological agents is limited by a short half-life in vivo resulting from the activity of specific ATRA hydroxylases, CYP26 enzymes, induced by ATRA in liver and target tissues. For this reason retinoic acid metabolism blocking agents (RAMBAs) have been developed for treating cancer and a wide range of other diseases. The synthesis, CYP26A1 inhibitory activity and molecular modeling studies of novel methyl 3-[4-(arylamino)phenyl]-3-(azole)-2,2-dimethylpropanoates are presented. From this series of compounds clear SAR can be derived for 4-substitution of the phenyl ring with electron-donating groups more favourable for inhibitory activity. Both the methylenedioxyphenyl imidazole (17, IC(50) = 8 nM) and triazole (18, IC(50) = 6.7 nM) derivatives were potent inhibitors with additional binding interactions between the methylenedioxy moiety and the CYP26 active site likely to be the main factor. The 6-bromo-3-pyridine imidazole 15 (IC(50) = 5.7 nM) was the most active from this series compared with the standards liarozole (IC(50) = 540 nM) and R116010 (IC(50) = 10 nM).

Novel retinoic acid 4-hydroxylase (CYP26) inhibitors based on a 3-(1H-imidazol- and triazol-1-yl)-2,2-dimethyl-3-(4-(phenylamino)phenyl)propyl scaffold.

Retinoic acid (RA), the biologically active metabolite of vitamin A, is used medicinally for the treatment of hyperproliferative diseases including dermatological conditions and cancer. The antiproliferative effects of RA have been well documented as well as the limitations owing to toxicity and the development of resistance to RA therapy. RA metabolism inhibitors (RAMBAs or CYP26 inhibitors) are attracting increasing interest as an alternative method for enhancing endogenous levels of retinoic acid in the treatment of hyperproliferative disease. Here the synthesis and inhibitory activity of novel 3-(1H-imidazol- and triazol-1-yl)-2,2-dimethyl-3-(4-(phenylamino)phenyl)propyl derivatives in a MCF-7 CYP26A1 microsomal assay are described. The most promising inhibitor methyl 2,2-dimethyl-3-(4-(phenylamino)phenyl)-3-(1H-1,2,4-triazol-1-yl)propanoate (6) exhibited an IC(50) of 13 nM (compared with standards Liarozole IC(50) 540 nM and R116010 IC(50) 10 nM) and was further evaluated for CYP selectivity using a panel of CYP with >100-fold selectivity for CYP26 compared with CYP1A2, 2C9 and 2D6 observed and 15-fold selectivity compared with CYP3A4. The results demonstrate the potential for further development of these potent inhibitors.

Synthesis and biological evaluation of 3-(1H-imidazol- and triazol-1-yl)-2,2-dimethyl-3-[4-(naphthalen-2-ylamino)phenyl]propyl derivatives as small molecule inhibitors of retinoic acid 4-hydroxylase (CYP26).

The synthesis and potent inhibitory activity of novel 3-(1H-imidazol- and triazol-1-yl)-2,2-dimethyl-3-(4-(naphthalen-2-ylamino)phenyl)propyl derivatives vs a MCF-7 CYP26A1 microsomal assay is described. This study focused on the effect of modifying the heme binding azole group and the flexible C3 chain on inhibitory activity and selectivity. The most promising inhibitor 2,2-dimethyl-3-[4-(naphthalen-2-ylamino)-phenyl]-3-[1,2,4]triazol-1-yl-propionic acid methyl ester (17) (IC(50) = 0.35 nM as compared with liarozole IC(50) = 540 nM and R116010 IC(50) = 10 nM) was evaluated for CYP selectivity and hepatic stability. Compounds with CYP26 inhibitory IC(50) values ≤50 nM enhanced the biological activity of exogenous ATRA, as evidenced by a 3.7-5.8-fold increase in CYP26A1 mRNA in SH-SY5Y neuroblastoma cells as compared with ATRA alone. All compounds demonstrated an activity comparable with or better than R116010, and the induction correlated well with CYP26 inhibition data. These studies highlight the promising activity profile of this novel CYP26 inhibitor and suggest it as an appropriate candidate for future development.

Small molecule inhibitors of retinoic acid 4-hydroxylase (CYP26): synthesis and biological evaluation of imidazole methyl 3-(4-(aryl-2-ylamino)phenyl)propanoates.

The synthesis and potent inhibitory activity of novel imidazole methyl 3-(4-(aryl-2-ylamino)phenyl)propanoates in a MCF-7 CYP26A1 microsomal assay is described. The induction of CYP26A1 mRNA was used to evaluate the ability of the compounds to enhance the biological effects of all-trans retinoic acid (ATRA) in a retinoid-responsive neuroblastoma cell line. The most promising inhibitor, 3-imidazol-1-yl-2-methyl-3-[4-(naphthalen-2-ylamino)-phenyl]-propionic acid methyl ester (20), with an IC(50) of 3 nM (compared with liarozole IC(50) of 540 nM and R116010 IC(50) of 10 nM) was further evaluated for CYP selectivity using a panel of CYP enzymes, mutagenicity (Ames screen), and hepatic stability.

Mode of action of hydrogen peroxide and other oxidizing agents: differences between liquid and gas forms.

OBJECTIVES: Antimicrobials such as chlorine dioxide, peracetic acid and hydrogen peroxide (H(2)O(2)) share a basic mechanism of action (chemical oxidation of cellular components), but profound differences arise in their efficacy against microorganisms. Optimization of activity requires an understanding of their interaction with microbial targets and a clear differentiation between the chemical efficacies of each oxidative biocide. This study aimed to elucidate the biochemical mechanisms of action of oxidizing biocides at a macromolecular level, using amino acids, protein and an enzyme as model substrates for the action of each biocide. METHODS: The interactions of a number of oxidising agents (liquid and gaseous H(2)O(2), ClO(2), peracetic acid formulations) with amino acids, proteins (bovine serum albumin and aldolase) and enzymes were investigated by spectrophotometry, SDS-PAGE and alkaline phosphatase activity measurements. RESULTS: Biocide reactions yielded different types of oxidative structural change and different degrees of oxidation to amino acids and proteins, and differences in activity against a microbial enzyme. In particular there was a marked difference in the interactions of liquid H(2)O(2) and gaseous H(2)O(2) with the macromolecules, the latter causing greater oxidation; these results explain the dramatic differences in antimicrobial efficacy between liquid and gas peroxide. CONCLUSIONS: These results provide a comprehensive understanding of the differences in interactions between a number of oxidizing agents and macromolecules commonly found in microbial cells. Biochemical mechanistic differences between these oxidative biocides do exist and lead to differential effects on macromolecules. This in turn could provide an explanation as to their differences in biocidal activity, particularly between liquid and gas peroxide.

Design and synthesis of substituted imidazole and triazole N-phenylbenzo[d]oxazolamine inhibitors of retinoic acid metabolizing enzyme CYP26.

The design of N-phenylbenzo[d]oxazolamines as CYP26A1 inhibitors involved ligand docking experiments using molecular modeling (FlexX) and analysis of ligand interactions at the binding domain. The synthesis of the benzooxazol-2-yl-[phenyl-imidazol-1-yl-methyl)phenyl]amines was achieved by cyclisation of the corresponding isothiocyanates with subsequent introduction of the haem-binding heterocycle. Triazole and tetrazole derivatives were also prepared for comparison with the lead imidazole derivative. The benzooxazol-2-yl-[phenyl-imidazol-1-yl-methyl)phenyl]amines with small substituents in the phenyl ring were moderately potent CYP26A1 inhibitors (IC(50) 8 and 12 microM) and comparable with liarozole (IC(50) 7 microM).

Novel azolyl-(phenylmethyl)]aryl/heteroarylamines: potent CYP26 inhibitors and enhancers of all-trans retinoic acid activity in neuroblastoma cells.

The synthesis and potent inhibitory activity of novel 4-[(imidazol-1-yl and triazol-1-yl)(phenyl)methyl]aryl-and heteroaryl amines versus a MCF-7 CYP26A1 cell assay is described. Biaryl imidazole ([4-(imidazol-1-yl-phenyl-methyl)-phenyl]-naphthalen-2-yl-amine (8), IC(50)=0.5 microM; [4-(imidazol-1-yl-phenyl-methyl)-phenyl]-indan-5-yl-amine (9), IC(50)=1.0 microM) and heteroaryl imidazole derivatives ((1H-benzoimidazol-2-yl)-{4-[(5H-imidazol-1-yl)-phenyl-methyl]-phenyl}-amine (15), IC(50)=2.5 microM; benzooxazol-2-yl-{4-[(5H-imidazol-1-yl)-phenyl-methyl]-phenyl}-amine (16), IC(50)=0.9 microM; benzothiazol-2-yl-{4-[(5H-imidazol-1-yl)-phenyl-methyl]-phenyl}-amine (17), IC(50)=1.5 microM) were the most potent CYP26 inhibitors. Using a CYP26A1 homology model differences in activity were investigated. Incubation of SH-SY5Y human neuroblastoma cells with the imidazole aryl derivative 8, and the imidazole heteroaryl derivatives 16 and 17 potentiated the atRA-induced expression of CYP26B1. These data suggest that further structure-function studies leading to clinical development are warranted.

Homology model of 1alpha,25-dihydroxyvitamin D3 24-hydroxylase cytochrome P450 24A1 (CYP24A1): active site architecture and ligand binding.

Homology models of cytochrome P450 24A1 (CYP24A1) were constructed using three human P450 structures, CYP2C8, CYP2C9 and CYP3A4 as templates for the model building. Using molecular operating environment (MOE) software the lowest energy CYP24A1 model was then assessed for stereochemical quality and side chain environment. Further active site optimisation of the CYP24A1 model built using the CYP3A4 template was performed by molecular dynamics to generate a final CYP24A1 model. The natural substrate, 1,25-dihydroxyvitamin D(3) (calcitriol) and the CYP24 inhibitor (R)-N-(2-(1H-imidazol-1-yl)-2-phenylethyl)-4'-chlorobiphenyl-4-carboxamide ((R)-VID-400) were docked into the model allowing further validation of the active site architecture. Using the docking studies structurally and functionally important residues were identified with subsequent characterisation of secondary structure.

Synthesis and CYP26A1 inhibitory activity of 1-[benzofuran-2-yl-(4-alkyl/aryl-phenyl)-methyl]-1H-triazoles.

Methodology previously described by our group was applied to the preparation of a series of 4-alkyl/aryl-substituted 1-[benzofuran-2-yl-phenylmethyl]-1H-triazoles. The [1,2,4]-triazole derivatives were prepared for a range of alkyl and aryl substituents, and for the 4-methyl, 4-ethyl, 4-(i)propyl, 4-(t)butyl, 4-phenyl and 4-chlorophenyl derivatives, the minor [1,3,4]-triazole isomer also isolated. All the triazole derivatives were evaluated for CYP26A1 inhibitory activity using a MCF-7 cell-based assay. The 4-ethyl and 4-phenyl-1,2,4-triazole derivatives displayed inhibitory activity (IC(50) 4.5 and 7 microM, respectively) comparable with that of the CYP26 inhibitor liarozole (IC(50) 7 microM). Using a CYP26A1 homology model (based on CYP3A4) template, docking experiments were performed with MOE with multiple hydrophobic interactions observed in addition to coordination between the triazole nitrogen and the haem transition metal.