APR-246 overcomes resistance to cisplatin and doxorubicin in ovarian cancer cells.

Two main causes of platinum resistance are mutation in the tumor suppressor gene TP53 and drug-induced increase in intracellular glutathione concentration. Mutations in TP53 occur in about 50% of human tumors. APR-246 (PRIMA-1(MET)) is the first clinical-stage compound that reactivates mutant p53 and induces apoptosis. APR-246 is a prodrug that is converted to the active compound methylene quinuclidinone (MQ), a Michael acceptor that binds to cysteine residues in mutant p53 and restores its wild-type conformation. Here, we show that MQ also binds to cysteine in glutathione, thus decreasing intracellular free glutathione concentration. We also show that treatment with APR-246 completely restores the cisplatin and doxorubicin sensitivity to p53-mutant drug-resistant ovarian cancer cells. We propose that this unique ability of APR-246/MQ to bind to cysteines in both mutant p53 and glutathione has a key role in the resensitization as well as in the outstanding synergistic effects observed with APR-246 in combination with platinum compounds in ovarian cancer cell lines and primary cancer cells. However, MQ binding to cysteines in other targets, for example, thioredoxin reductase, may contribute as well. Strong synergy was also observed with the DNA-damaging drugs doxorubicin and gemcitabine, while additive effects were found with the taxane docetaxel. Our results provide a strong rationale for the ongoing clinical study with APR-246 in combination with platinum-based therapy in patients with p53-mutant recurrent high-grade serous (HGS) ovarian cancer. More than 96% of these patients carry TP53 mutations. Combined treatment with APR-246 and platinum or other DNA-damaging drugs could allow dramatically improved therapy of a wide range of therapy refractory p53 mutant tumors.

Stimulation of angiotensin AT2 receptors by the non-peptide agonist, Compound 21, evokes vasodepressor effects in conscious spontaneously hypertensive rats.

BACKGROUND AND PURPOSE: Angiotensin type 2 receptor (AT(2) receptor) stimulation evokes vasodilator effects in vitro and in vivo that oppose the vasoconstrictor effects of angiotensin type 1 receptors (AT(1) receptors). Recently, a novel non-peptide AT(2) receptor agonist, Compound 21, was described, which exhibited high AT(2) receptor selectivity. EXPERIMENTAL APPROACH: Functional cardiovascular effects of the drug candidate Compound 21 were assessed, using mouse isolated aorta and rat mesenteric arteries in vitro and in conscious spontaneously hypertensive rats (SHR). KEY RESULTS: Compound 21 evoked dose-dependent vasorelaxations in aortic and mesenteric vessels, abolished by the AT(2) receptor antagonist, PD123319. In vivo, Compound 21 administered alone, at doses ranging from 50 to 1000 ng.kg(-1).min(-1) over 4 h did not decrease blood pressure in conscious normotensive Wistar-Kyoto rats or SHR. However, when given in combination with the AT(1) receptor antagonist, candesartan, Compound 21 (300 ng.kg(-1).min(-1)) lowered blood pressure in SHR only. Further analysis in separate groups of conscious SHR revealed that, at a sixfold lower dose, Compound 21 (50 ng.kg(-1).min(-1)) still evoked a significant depressor response in adult SHR ( approximately 30 mmHg) when combined with different doses of candesartan (0.01 or 0.1 mg.kg(-1)). Moreover, the Compound 21-evoked depressor effect was abolished when co-infused (50 microg.kg(-1).min(-1) for 2 h) with the AT(2) receptor antagonist PD123319. CONCLUSION AND IMPLICATIONS: Collectively, our results indicate that acute administration of Compound 21 evoked blood pressure reductions via AT(2) receptor stimulation. Thus Compound 21 can be considered an excellent drug candidate for further study of AT(2) receptor function in cardiovascular disease.

Fathers and their children's health: a telephone interview study.

OBJECTIVE: To study fathers' perception of, and involvement in, their children's health. DESIGN: Telephone interviews according to a structured guide. SETTING: County of Skåne, Sweden. MAIN OUTCOME MEASURES: Answers regarding care and upbringing of child, child's health and ill health, and role of father. SUBJECTS: 237 fathers of small children. RESULTS: Fathers seem to be involved in their children to a large extent, both in caring and playing activities with their children. Most of them (82%) think that the child's health is good, and half of them (55%) have, at some time, contacted a doctor. The fathers mention security, love and commitment as important factors for being a good father, and almost all (97%) think that they are good fathers. Yet, only slightly more than half of them (54%) state that they have sufficient time for the child. CONCLUSIONS: Today, fathers are subject to quite different expectations to participate actively in their children's everyday life than was the case for previous generations. Therefore, more studies of fathers' involvement in their children are needed, as well as a new approach within the health care system to fathers' participation.

Computational inhibitor design against malaria plasmepsins.

Plasmepsins are aspartic proteases involved in the degradation of the host cell hemoglobin that is used as a food source by the malaria parasite. Plasmepsins are highly promising as drug targets, especially when combined with the inhibition of falcipains that are also involved in hemoglobin catabolism. In this review, we discuss the mechanism of plasmepsins I-IV in view of the interest in transition state mimetics as potential compounds for lead development. Inhibitor development against plasmepsin II as well as relevant crystal structures are summarized in order to give an overview of the field. Application of computational techniques, especially binding affinity prediction by the linear interaction energy method, in the development of malarial plasmepsin inhibitors has been highly successful and is discussed in detail. Homology modeling and molecular docking have been useful in the current inhibitor design project, and the combination of such methods with binding free energy calculations is analyzed.

Synthesis and AT2 receptor-binding properties of angiotensin II analogues.

The present study investigates the importance of the amino acid side chains in the octapeptide angiotensin II (Ang II) for binding to the AT2 receptor. A Gly scan was performed where each amino acid in Ang II was substituted one-by-one with glycine. The resulting set of peptides was tested for affinity to the AT2 receptor (porcine myometrial membranes). For a comparison, the peptides were also tested for affinity to the AT1 receptor (rat liver membranes). Only the substitution of Arg2 reduced affinity to the AT2 receptor considerably (92-fold when compared with Ang II). For the other Gly-substituted analogues the affinity to the AT2 receptor was only moderately affected. To further investigate the role of the Arg2 side chain for receptor binding, we synthesized some N-terminally modified Ang II analogues. According to these studies a positive charge in the N-terminal end of angiotensin III [Ang II (2-8)] is not required for high AT2 receptor affinity but seems to be more important in Ang II. With respect to the AT1 receptor, [Gly2]Ang II and [Gly8]Ang II lacked binding affinity (Ki > 10 microM). Replacement of the Val3 or Ile5 residues with Gly produced only a slight decrease in affinity. Interestingly, substitution of Tyr4 or His6, which are known to be very important for AT1 receptor binding, resulted in only 48 and 14 times reduction in affinity, respectively.

Resistance profiles of cyclic and linear inhibitors of HIV-1 protease.

Resistance to anti-HIV protease drugs is a major problem in the design of AIDS drugs with long-term efficacy. To identify structural features associated with a certain resistance profile, the inhibitory properties of a series of symmetric and asymmetric cyclic sulfamide, cyclic urea and linear transition-state analogue inhibitors of HIV-1 protease were investigated using wild-type and mutant enzyme. To allow a detailed structure-inhibition analysis, enzyme with single, double, triple and quadruple combinations of G48V, V82A, 184V and L90M substitutions was used. Kinetic analysis of the mutants revealed that catalytic efficiency was 1-30% of that for the wild-type enzyme, a consequence of reduced kcat in all cases and an increased KM for all mutants except for the G48V enzyme. The overall structure-inhibitory profiles of the cyclic compounds were similar, and the inhibition of the V82A, 184V and G48V/L90M mutants were less efficient than of the wild-type enzyme. The greatest increase in Ki was generally observed for the 184V mutant and least for the G48V/L90M mutant, and additional combinations of mutations did not result in improved inhibition profiles for the cyclic compounds. An extended analysis of additional mutants, and including a set of linear compounds, showed that the profile was unique for each compound, and did not reveal any general structural features associated with a certain inhibition profile. The effects of structural modifications in the inhibitors, or of mutations, were not additive and they differed depending on their context. The results demonstrate the difficulties in predicting resistance, even for closely related compounds, and designing compounds with improved resistance profiles.

Synthesis of potent C(2)-symmetric, diol-based hiv-1 protease inhibitors. Investigation of thioalkyl and thioaryl P1/P1' substituents.

The synthesis of novel, potent diol-based HIV-1 protease inhibitors, having either -SAr, -SCH(2)Ar, or -SCH(2)R groups as P1/P1' substituents is described. They can be prepared using a straightforward synthesis involving a thiol nucleophilic ring opening of a diepoxide. Inhibitor 13 was found to be a potent inhibitor of HIV-1 PR, showing good antiviral activity in a cell-based assay.

Synthesis of novel, potent, diol-based HIV-1 protease inhibitors via intermolecular pinacol homocoupling of (2S)-2-benzyloxymethyl-4-phenylbutanal.

The synthesis of novel, potent, diol-based HIV-1 protease inhibitors, having phenethyl groups (-CH(2)CH(2)Ph) in P1/P1' position is described. An intermolecular pinacol homocoupling of (2S)-2-benzyloxymethyl-4-phenylbutanal 16 was the key step in the synthesis. From this reaction sequence four carba analogues, compounds 8a, 8b, 9a, and 9b, were prepared, having the inverted configuration of one or both of the stereogenic centers carrying the diol hydroxyls as compared to the parent series represented by inhibitors 6 and 7. Inhibitor 8b was found to be a potent inhibitor of HIV-1 protease (PR), showing excellent antiviral activity in the cell-based assay and in the presence of 40% human serum. The absolute stereochemistry of the central diol of the potent inhibitor (8b) was determined from the X-ray crystallographic structure of its complex with HIV-1 PR.

Design and synthesis of potent C(2)-symmetric diol-based HIV-1 protease inhibitors: effects of fluoro substitution.

Implementation of derivatized carbohydrates as C(2)-symmetric HIV-1 protease inhibitors has previously been reported. With the objective of improving the anti-HIV activity of such compounds, we synthesized a series of fluoro substituted P1/P1' analogues. These compounds were evaluated for antiviral activity toward both wild type and mutant virus. The potency of the analogues in blocking HIV-1 protease was moderate, with K(i) values ranging from 1 to 7 nM. Nonetheless, compared to the parent nonfluorous inhibitors, a majority of the compounds exhibited improved antiviral activity, for example the 3-fluorobenzyl derivative 9b, which had a K(i) value of 7.13 nM and displayed one of the most powerful antiviral activities in the cellular assay of the series. Our results strongly suggest that fluoro substitution can substantially improve antiviral activity. The X-ray crystal structures of two of the fluoro substituted inhibitors (9a and 9f) cocrystallized with HIV-1 protease are discussed.

Highly regioselective, sequential, and multiple palladium-catalyzed arylations of vinyl ethers carrying a coordinating auxiliary: an example of a Heck triarylation process.

This article describes the development of new auxiliary-accelerated Heck multiarylations by intramolecular presentation of the oxidative addition complex. The introduction of a specific, palladium-coordinating dimethylamino group allows for the desired chelation-accelerated and chelation-controlled tri- and diarylation reactions. We report (a) the first example of a Heck triarylation process, (b) highly selective palladium-catalyzed diarylations of alkyl vinyl ethers, and (c) a very rapid two-phase protocol for the microwave-assisted hydrolysis of amino-substituted, arylated vinyl ethers constituting an entry to diarylated ethanals and substituted desoxybenzoins. X-ray structures and product patterns support the suggested substrate-controlled Heck reaction pathway. The catalyst-directing alkyl dimethylamino functionality was rapidly (1-2 min) and efficiently released by microwave hydrolysis after Heck multiarylation reactions. The liberated aromatic carbonyl compounds were thereafter isolated and fully characterized.

Parents: the best experts in child health care? Viewpoints from parents and staff concerning child health services.

The aim was to describe what parents and staff think about child health care, to identify agreements and disagreements. A qualitative study was made with semi-structured interviews based on a phenomenographic approach. Sixty parents, 14 nurses and six doctors from southern Sweden were interviewed. Parents and staff emphasized two tasks as being of particular importance: support and check-ups. There was a conflict between parents' need for security versus integrity. Individual nurses experienced a conflict between what they wanted to do and what they felt that they had to do. The parents viewed parental education as a chance to exchange experiences with other parents and receive support from other adults, while the staff mainly saw it as an opportunity to inform parents and strengthen them in their parental role. The study gives grounds for reflection about how the work of child health care can be changed in the future.

Design, synthesis, computational prediction, and biological evaluation of ester soft drugs as inhibitors of dihydrofolate reductase from Pneumocystis carinii.

A series of lipophilic soft drugs structurally related to the nonclassical dihydrofolate reductase (DHFR) inhibitors trimetrexate and piritrexim have been designed, synthesized, and evaluated in DHFR assays, with special emphasis on the inhibition of P. carinii DHFR. The best inhibitors, encompassing an ester bond in the bridge connecting the two aromatic systems, were approximately 10 times less potent than trimetrexate and piritrexim. The metabolites were designed to be poor inhibitors. Furthermore, molecular dynamics simulations of three ligands in complex with DHFR from Pneumocystis carinii and from the human enzyme were conducted in order to better understand the factors determining the selectivity. A correct ranking of the relative inhibition of DHFR was achieved utilizing the linear interaction energy method. The soft drugs are intended for local administration. One representative ester was selected for a pharmacokinetic study in rats where it was found to undergo fast metabolic degradation to the predicted inactive metabolites.

Regioselective palladium-catalyzed synthesis of beta-arylated primary allylamine equivalents by an efficient Pd-N coordination.

A highly regioselective Heck arylation, utilizing aryl triflates and a palladium/dppf catalytic system, can be performed at the internal, beta-carbon of Boc- and phthalimido-protected allylamines, yielding arylated primary allylamine equivalents. The very high regioselectivity obtained with secondary Boc-protected allylamides is suggested to be caused by an efficient coordination between an anionic nitrogen and palladium. Single-mode microwave irradiation has been utilized to shorten the reaction times and, in the case of Boc-protected allylamides, to improve the yields of two electron-poor aryl triflates.

Aqueous DMF-potassium carbonate as a substitute for thallium and silver additives in the palladium-catalyzed conversion of aryl bromides to acetyl arenes.

Highly selective palladium-catalyzed internal alpha-arylations of alkyl vinyl ethers with aryl and heteroaryl bromides were conveniently conducted in aqueous DMF with potassium carbonate as base and with DPPP as bidentate ligand. The corresponding acetyl arene products were, after hydrolysis, isolated in good to excellent yields. This Heck reaction procedure does not require toxic thallium or expensive silver salt additives, is promoted by water, and is suggested to proceed via charged organopalladium intermediates. Single-mode microwave irradiation was utilized in one example to shorten the reaction time.

Synthesis, receptor binding affinities and conformational properties of cyclic methylenedithioether analogues of angiotensin II.

Cyclic 12-, 13- and 14-membered ring angiotensin II analogues related to disulfides but encompassing methylene-dithioether bridges have been prepared. The affinity data from these derivatives were compared to those from the disulfides. The methylenedithioether analogues displayed good binding affinities to rat liver AT1 receptors although in most cases somewhat lower than their disulfide counterparts. One of the methylenedithioethers with a 13-membered ring system demonstrated the highest binding affinity among the thioethers. Theoretical conformational analysis of model compounds of the two series were performed suggesting a similarity between the disulfide and the corresponding methylenedithioether analogues and also between the ring size homologues. This analysis also suggested that some of the model compounds were prone to adopt inverse gamma-turn conformations, which was further supported by use of NMR spectroscopy of the 12-membered ring analogue in the series. The easily executed methylenedithioether cyclization should constitute a valuable complement to the common disulfide methodology for fine-tuning and for probing the bioactive conformation of peptides.

P1/P1' modified HIV protease inhibitors as tools in two new sensitive surface plasmon resonance biosensor screening assays.

The commonly used HIV-1 protease assays rely on measurements of the effect of inhibitions on the hydrolysis rate of synthetic peptides. Recently an assay based on surface plasmon resonance (SPR) was introduced. We have taken advantage of the fact that the SPR signal is proportional to the mass of the analyte interacting with the immobilised molecule and developed two new improved efficient competition assay methods. Thus, high molecular weight binders were used as amplifiers of the surface plasmon resonance signal. Linkers were attached by a Heck reaction to the para-positions of the P1/P1' benzyloxy groups of a linear C2-symmetric C-terminal duplicated inhibitor to enable (a) biotin labelling or (b) direct immobilisation of the inhibitor to the biosensor surface matrix. The interaction properties of a series of 17 structurally diverse inhibitors was assessed and compared to previously reported data. The most sensitive assay was obtained by immobilising the enzyme and amplifying the signal with an antibody, giving a detection range between 0.1 nM and 10 microM. Immobilisation of the inhibitor resulted in a stable and durable surface but a narrower detection range (1-100 nM). The two competition assays are anticipated to be very suitable for fast screening of potential HIV inhibitors.

Microwave-assisted high-speed chemistry: a new technique in drug discovery.

In both lead identification and lead optimization processes there is an acute need for new organic small molecules. Traditional methods of organic synthesis are orders of magnitude too slow to satisfy the demand for these compounds. The fields of combinatorial and automated medicinal chemistry have been developed to meet the increasing requirement of new compounds for drug discovery; within these fields, speed is of the essence. The efficiency of microwave flash-heating chemistry in dramatically reducing reaction times (reduced from days and hours to minutes and seconds) has recently been proven in several different fields of organic chemistry. We believe that the time saved by using focused microwaves is potentially important in traditional organic synthesis but could be of even greater importance in high-speed combinatorial and medicinal chemistry.

Inhibition of hepatitis C virus NS3 protease activity by product-based peptides is dependent on helicase domain.

Structure activity relationships (SARs) of product-based inhibitors of hepatitis C virus NS3 protease were evaluated using an in vitro assay system comprising the native bifunctional full-length NS3 (protease-helicase/NTPase). The results were compared to previously reported data derived from the corresponding NS3 protease domain assay. Shortening the length of the protease inhibitors from hexapeptides to tripeptides revealed that the decrease in potency was much less when determined in the assay system with the full-length NS3 protein. Disagreements in SARs at different positions (P5 P2) were also discovered. Taken together, the results suggest that the impact of the helicase domain upon protease inhibitor binding is substantial.

Synthesis and comparative molecular field analysis (CoMFA) of symmetric and nonsymmetric cyclic sulfamide HIV-1 protease inhibitors.

We have previously reported on the unexpected flipped conformation in the cyclic sulfamide class of inhibitors. An attempt to induce a symmetric binding conformation by introducing P2/P2' substituents foreseen to bind preferentially in the S2/S2' subsite was unsuccessful. On the basis of the flipped conformation we anticipated that nonsymmetric sulfamide inhibitors, with P2/P2' side chains modified individually for the S1' and S2 subsites, should be more potent than the corresponding symmetric analogues. To test this hypothesis, a set of 18 cyclic sulfamide inhibitors (11 nonsymmetric and 7 symmetric) with different P2/P2' substituents was prepared and evaluated in an enzyme assay. To rationalize the structure-activity relationship (SAR) and enable the alignment of the nonsymmetric inhibitors, i.e., which of the P2/P2' substituents of the nonsymmetric inhibitors interact with which subsite, a CoMFA study was performed. The CoMFA model, constructed from the 18 inhibitors in this study along with seven inhibitors from previous work by our group, has successfully been used to rationalize the SAR of the cyclic sulfamide inhibitors. Furthermore, from the information presented herein, the SAR of the cyclic sulfamide class of inhibitors seems to differ from the SAR of the related cyclic urea inhibitors reported by DuPont and DuPont-Merck.

Fast microwave-assisted preparation of aryl and vinyl nitriles and the corresponding tetrazoles from organo-halides

Aryl and vinyl nitriles have been prepared in very high yields from the corresponding bromides using palladium-catalyzed reactions with microwave irradiation employed as the energy source. Furthermore, flash heating was used successfully for the conversion of these nitriles into aryl and vinyl tetrazoles by cycloaddition reactions. One-pot transformation of aryl halides directly to the aryl tetrazoles could be accomplished both in solution and on solid support. All reactions were completed in minutes rather than in hours or days as previously reported with the standard thermal heating technique. A very potent HIV-1 protease inhibitor (K(i) = 0. 56 nM), comprising two tetrazole heterocycles as carboxyl group bioisosteres, was prepared in one pot by microwave-promoted cyanation of a bromo precursor and a subsequent cycloaddition reaction. The temperature-time profiles at 13, 20, and 60 W magnetron input power in DMF are presented.