Impact of Minor Structural Modifications on Properties of a Series of mTOR Inhibitors.

Minor structural modifications-sometimes single atom changes-can have a dramatic impact on the properties of compounds. This is illustrated here on structures related to known mTOR inhibitor Sapanisertib. Subtle changes in the hinge binder lead to strikingly different overall profiles with changes in physical properties, metabolism, and kinase selectivity.

Measurement of Nocturnal Scratching in Patients with Pruritus Using a Smartwatch: Initial Clinical Studies with the Itch Tracker App.

Three clinical studies were conducted to test a newly-developed app for smartwatches, which included an algorithm to measure nocturnal scratching using acceleration data. The first study in 5 patients with atopic dermatitis demonstrated high reliability of the app for measurement of scratching compared with video monitoring (positive predictive value 90.2 ± 6.6%, sensitivity 84.6 ± 10.2%, correlation of scratching duration per h r = 0.851-0.901, p < 0.001). The second study in 20 patients with atopic dermatitis and 10 healthy volunteers showed that total scratching duration in patients was significantly longer than in healthy volunteers and correlated positively with Eczema Area and Severity Index (EASI) scores. In the third study, conducted in an open-entry manner in which 201 evaluable participants measured nocturnal scratching, those who self-reported itch or pruritic diseases had a significantly longer duration of scratching than those who did not. In conclusion, this app has a high reliability and potential clinical usefulness for measurement of nocturnal scratching.

Squaramides as novel class I and IIB histone deacetylase inhibitors for topical treatment of cutaneous t-cell lymphoma.

A series of squaramide-based hydroxamic acids were designed, synthesized and evaluated against human HDAC enzyme. Squaramides were found to be potent in the Hut78 cell line, but initially suffered from low solubility. Leads with improved solubility and metabolic profiles were shown to be class I, IIB and IV selective.

Structure-based design of Trifarotene (CD5789), a potent and selective RARγ agonist for the treatment of acne.

Retinoids have a dominant role in topical acne therapy and to date, only RARß and RARγ dual agonists have reached the market. Given the tissue distribution of RAR isoforms, it was hypothesized that developing RARγ -selective agonists could yield a new generation of topical acne treatments that would increase safety margins while maintaining the robust efficacy of previous drugs. Structural knowledge derived from the X-ray structure of known γ-selective CD437, suggested the design of a novel triaryl series of agonists which was optimized and ultimately led to the discovery of Trifarotene/CD5789.

Rational Drug Design of Topically Administered Caspase 1 Inhibitors for the Treatment of Inflammatory Acne.

The use of an interleukin ß antibody is currently being investigated in the clinic for the treatment of acne, a dermatological disorder affecting 650M persons globally. Inhibiting the protease responsible for the cleavage of inactive pro-IL1ß into active IL-1ß, caspase-1, could be an alternative small molecule approach. This report describes the discovery of uracil 20, a potent (38 nM in THP1 cells assay) caspase-1 inhibitor for the topical treatment of inflammatory acne. The uracil series was designed according to a published caspase-1 pharmacophore model involving a reactive warhead in P1 for covalent reversible inhibition and an aryl moiety in P4 for selectivity against the apoptotic caspases. Reversibility was assessed in an enzymatic dilution assay or by using different substrate concentrations. In addition to classical structure-activity-relationship exploration, topical administration challenges such as phototoxicity, organic and aqueous solubility, chemical stability in solution, and skin metabolic stability are discussed and successfully resolved.

New Caspase-1 inhibitor by scaffold hopping into bio-inspired 3D-fragment space.

Virtual fragmentation of a library of 12,000 compounds inspired by natural products led to a dataset of 153,000 fragments that was used as a source to identify effective P2-P3 scaffold replacement solutions for peptidic Caspase-1 inhibitors. Our strategy led to the identification of an original 2-azabicyclo-octane scaffold (2-ABO) that was further elaborated into the potent Caspase-1 inhibitor CD10847 (IC50 = 17 nM). The crystal structure of Caspase-1 in complex with CD10847 was obtained, and its binding mode was shown to be similar to the one predicted by docking and in good agreement with other known inhibitors.

Discovery of phenoxyindazoles and phenylthioindazoles as RORγ inverse agonists.

Targeting the IL17 pathway and more specifically the nuclear receptor RORγ is thought to be beneficial in multiple skin disorders. The Letter describes the discovery of phenoxyindazoles and thiophenoxy indazoles as potent RORγ inverse agonists. Optimization of the potency and efforts to mitigate the phototoxic liability of the series are presented. Finally, crystallization of the lead compound revealed that the series bound to an allosteric site of the nuclear receptor. Such compounds could be useful as tool compounds for understanding the impact of topical treatment on skin disease models.

Exploratory clinical trial to evaluate the efficacy of a topical traditional chinese herbal medicine in psoriasis vulgaris.

Objective. To evaluate the efficacy and safety of herbal ointment, Shi Du Ruan Gao, in patients with plaque-type psoriasis. Design. Single-center, randomized, investigator-blinded, parallel group, placebo-controlled study. Participants. One hundred outpatients with mild to moderate chronic plaque-type psoriasis were enrolled. Intervention. The patients applied either Shi Du Ruan Gao ointment or vehicle ointment topically to for 8 weeks. Main Outcome Measures. The outcomes were assessed using the following criteria: Total Severity Score (TSS, sum of erythema, scaling, and plaque elevation/induration, on a 0 to 4 scale), Investigator Global Assessment (IGA) evaluated on a 0 (Clear) to 4 (s to very severe) scale, and Global Subjects' Assessment of treatment response on a 7-point scale from -1 (worse) to 5 (Cleared). Results. Significant reductions in the Total Severity Score (P < 0.001) (mean score: 2.7 after Shi Du Ruan Gao treatment versus 5.1 in control subjects). Both Investigator Global Assessment (IGA) and Global Subjects' Assessment of treatment are better in the Shi Du Ruan Gao group than the control group (P < 0.001). Conclusion. Shi Du Ruan Gao ointment was a safe, and effective therapy for plaque-type psoriasis.

High-resolution structure of the native histone octamer.

Crystals of native histone octamers (H2A-H2B)-(H4-H3)-(H3'-H4')-(H2B'-H2A') from chick erythrocytes in 2 M KCl, 1.35 M potassium phosphate pH 6.9 diffract X-rays to 1.90 A resolution, yielding a structure with an R(work) value of 18.7% and an Rfree of 22.2%. The crystal space group is P6(5), the asymmetric unit of which contains one complete octamer. This high-resolution model of the histone-core octamer allows further insight into intermolecular interactions, including water molecules, that dock the histone dimers to the tetramer in the nucleosome-core particle and have relevance to nucleosome remodelling. The three key areas analysed are the H2A'-H3-H4 molecular cluster (also H2A-H3'-H4'), the H4-H2B' interaction (also H4'-H2B) and the H2A'-H4 beta-sheet interaction (also H2A-H4'). The latter of these three regions is important to nucleosome remodelling by RNA polymerase II, as it is shown to be a likely core-histone binding site, and its disruption creates an instability in the nucleosome-core particle. A majority of the water molecules in the high-resolution octamer have positions that correlate to similar positions in the high-resolution nucleosome-core particle structure, suggesting that the high-resolution octamer model can be used for comparative studies with the high-resolution nucleosome-core particle.

Histone structures: targets for modifications by molecular assemblies.

The core histone proteins contain modification sites that are key elements in the regulation of the cell cycle, DNA replication and repair with histone assembly, control of gene expression, and transcriptional elongation. Much work has been done on the various molecular assemblies that remodel nucleosomes, methylate, ubiquitinate, and cause ADP-ribosylation of histones, and acetylate and phosphorylate core histone tails. The core histones are the final targets of the enzymes in the molecular assemblies. What structural changes in the histones are correlated with these modifications? This paper considers the high-resolution structure of the histone octamer and stresses the importance of histone docking sequences in the binding of the two (H2A-H2B) dimers to the (H3-H4)(2) tetramer. There is an extensive acid-base area of interaction between histone octamers in crystals at high salt, which may have implications for nucleosome remodeling. We show that there are regions of high alpha-helix probability in all core histone N-terminal tails in regions where lysine acetylation occurs. There are also consensus sequences spanning up to eight amino acid residues between some histone tail regions. Circular dichroism studies using synchrotron radiation at wavelengths as low as 130 nm are promising for the accurate measurement of changes of histone secondary structure related to function.

Crystal structure of human L-isoaspartyl-O-methyl-transferase with S-adenosyl homocysteine at 1.6-A resolution and modeling of an isoaspartyl-containing peptide at the active site.

Spontaneous formation of isoaspartyl residues (isoAsp) disrupts the structure and function of many normal proteins. Protein isoaspartyl methyltransferase (PIMT) reverts many isoAsp residues to aspartate as a protein repair process. We have determined the crystal structure of human protein isoaspartyl methyltransferase (HPIMT) complexed with adenosyl homocysteine (AdoHcy) to 1.6-A resolution. The core structure has a nucleotide binding domain motif, which is structurally homologous with the N-terminal domain of the bacterial Thermotoga maritima PIMT. Highly conserved residues in PIMTs among different phyla are placed at positions critical to AdoHcy binding and orienting the isoAsp residue substrate for methylation. The AdoHcy is completely enclosed within the HPIMT and a conformational change must occur to allow exchange with adenosyl methionine (AdoMet). An ordered sequential enzyme mechanism is supported because C-terminal residues involved with AdoHcy binding also form the isoAsp peptide binding site, and a change of conformation to allow AdoHcy to escape would preclude peptide binding. Modeling experiments indicated isoAsp groups observed in some known protein crystal structures could bind to the HPIMT active site.

Gd-HPDO3A, a complex to obtain high-phasing-power heavy-atom derivatives for SAD and MAD experiments: results with tetragonal hen egg-white lysozyme.

A neutral gadolinium complex, Gd-HPDO3A, is shown to be a good candidate to use to obtain heavy-atom derivatives and solve macromolecular structures using anomalous dispersion. Tetragonal crystals of a gadolinium derivative of hen egg-white lysozyme were obtained by co-crystallization using different concentrations of the complex. Diffraction data from three derivative crystals (100, 50 and 10 mM) were collected to a resolution of 1.7 A using Cu Kalpha radiation from a rotating anode. Two strong binding sites of the gadolinium complex to the protein were located from the gadolinium anomalous signal in both the 100 and 50 mM derivatives. A single site is occupied in the 10 mM derivative. Phasing using the anomalous signal at a single wavelength (SAD method) leads to an electron-density map of high quality. The structure of the 100 mM derivative has been refined. Two molecules of the gadolinium complex are close together. Both molecules are located close to tryptophan residues. Four chloride ions were found. The exceptional quality of the SAD electron-density map, only enhanced by solvent flattening, suggests that single-wavelength anomalous scattering with the Gd-HPDO3A complex may be sufficient to solve protein structures of high molecular weight by synchrotron-radiation experiments, if not by laboratory experiments.