Thomas C. Baddeley

Complex Disposition of Methylthioninium Redox Forms Determines Efficacy in Tau Aggregation Inhibitor Therapy for Alzheimer’s Disease

Methylthioninium (MT) is a tau aggregation inhibitor with therapeutic potential in Alzheimer’s disease (AD). MT exists in equilibrium between reduced [leucomethylthioninium (LMT)] and oxidized (MT+) forms; as a chloride salt [methylthioninium chloride (MTC), “methylene blue”], it is stabilized in its MT+ form. Although the results of a phase 2 study of MTC in 321 mild/moderate AD subjects identified a 138-mg MT/day dose as the minimum effective dose on cognitive and imaging end points, further clinical development of MT was delayed pending resolution of the unexpected lack of efficacy of the 228-mg MT/day dose. We hypothesized that the failure of dose response may depend on differences known at the time in dissolution in simulated gastric and intestinal fluids of the 100-mg MTC capsules used to deliver the 228-mg dose and reflect previously unsuspected differences in redox processing of MT at different levels in the gut. The synthesis of a novel chemical entity, LMTX (providing LMT in a stable anhydrous crystalline form), has enabled a systematic comparison of the pharmacokinetic properties of MTC and LMTX in preclinical and clinical studies. The quantity of MT released in water or gastric fluid within 60 minutes proved in retrospect to be an important determinant of clinical efficacy. A further factor was a dose-dependent limitation in the ability to absorb MT in the presence of food when delivered in the MT+ form as MTC. A model is presented to account for the complexity of MT absorption, which may have relevance for other similar redox molecules.

(Pyrazinecarbonyl)hydrazone halobenzaldehydes: supramolecular arrays generated by face to face stacking of ribbons, formed from C–H–O interactions

Abstract The crystal structures of seven (pyrazinecarbonyl)hydrazone mono-halo-benzaldehyde derivatives, N2C4H3CONHN=CHC6H4X (X = F, Cl or Br) are reported. In all cases, hydrogen-bonds link the planar molecules edge to edge to form ribbons which are themselves essentially planar. These ribbons are then packed face to face in a variety of ways dependent upon the position and nature of the halogen substituent. In all of the structures the molecules are found in layers one molecule thick. For the chloro- and bromo-substituted compounds three distinct forms of two-dimensional connectivity in the layers is achieved by combination of π · · · π interactions with the ribbon hydrogen-bonds. For the fluoro- derivatives the ribbon hydrogen-bonds connect layers in which the two-dimensional connectivity is provided by the π · · · π interactions, in one case augmented by C–H · · · F and C–H · · · π bonds, resulting in complete three-dimensional connectivity.

2-Hydroxyacetophenone arylhydrazones. Supramolecular arrangements based on C–H · · · O(H), CH · · · O(NO), N–H · · · O(H), N–H · · · O(NO), C–H · · · π or π · · · π interactions

Abstract Crystal structures, NMR and IR spectra and EI-MS+ of 2-hydroxyacetophenone arylhydrazones, 2-HOC6H4C(Me) = NNHC6H4Y (1: Y = 2-O2N, 3-O2N, 4-O2N, 4-Me, 4-MeO, H and 4-I) are reported. Two polymorphs of (1: Y = 2-O2N), triclinic and orthorhombic forms, have been identified. While strong intramolecular O–H · · · N(H) hydrogen bonds and layers of molecules are found for all solid 1, supramolecular arrangements of individual members are various and are derived from different combinations of intermolecular interactions, which include C–H · · · O(H), C–H · · · O(NO), N–H · · · O(H), N–H · · · O(NO) and C–H · · · π hydrogen bonds, as well as π · · · π stacking interactions. Intermolecular N–H · · · O hydrogen-bonds involving the phenolic OH group are present in (1: Y = H, 4-O2N, 4-Me, 4-MeO and 4-I), but are absent in ortho-and tri-(1: Y = 2-O2N) and (1: Y = 3-O2N). Instead, ortho-(1: Y = 2-O2N) exhibits intermolecular C–H · · · O(H) hydrogen bonds, while no intermolecular hydrogen bonds involving the OH group occur in either triclinic-(1: Y = 2-O2N) or (1: Y = 3-O2N). EI+-MS revealed the presence of oligomeric species, such as (nM + M′)+, where n is up to 4, and M′ = H, Na or K.

Synthesis of Per- and Poly-Substituted Trehalose Derivatives: Studies of Properties Relevant to Their Use as Excipients for Controlled Drug Release

Per- and poly-substituted oligosaccharide derivatives, with trehalose cores, have been prepared and assessed for their potential for use as excipients in controlled-release formulations. The synthesized compounds, generally with acyl and amido substituents, included 6,6′-N,N′ -diamido-6,6′ -dideoxy-α,α -trehalose derivatives, 6,6′ -bis(1,2,3,4-tetra-O-acetyl-β -D-glucopyranuronyl)-α, α -trehalose derivatives, 2,2′,3,3′ -tetra-O-acetyl-6,6′ -bis-(1,2,3,4-tetra-O-acetyl-β-D-glucopyranuronyl)-4,4′ -di-O-acyl-α,α-trehalose, 2, 2′, 3, 3′ -tetra-O-acetyl-6-(1,2,3,4-tetra-O-acetyl-β-D-glucopyranuronyl)-4,4′,6′ -tri-O-acyl-α,α-trehalose, and 2,2′,3,3′,4,4′ -hexa-O-acetyl-6,6′ -bis-(1,2,3,4-tetra-O-acetyl-6-O-succinyl-β-D-glucopyranuronyl)-α,α-trehalose. Compounds were characterized by NMR, IR, MS and optical rotations; elemental analyses; or HRMS. The compounds formed amorphous materials either on fast quenching of melts or on spray drying. Properties, used in the initial assessment of the potential as controlled-release excipients, were log10 P and glass transition, Tg, values.

In Vitro Maturation of a Humanized Shark VNAR Domain to Improve Its Biophysical Properties to Facilitate Clinical Development

Molecular engineering to increase the percentage identity to common human immunoglobulin sequences of non-human therapeutic antibodies and scaffolds has become standard practice. This strategy is often used to reduce undesirable immunogenic responses, accelerating the clinical development of candidate domains. The first humanized shark variable domain (VNAR) was reported by Kovalenko and colleagues and used the anti-human serum albumin (HSA) domain, clone E06, as a model to construct a number of humanized versions including huE06v1.10. This study extends this work by using huE06v1.10 as a template to isolate domains with improved biophysical properties and reduced antigenicity. Random mutagenesis was conducted on huE06v1.10 followed by refinement of clones through an off-rate ranking-based selection on target antigen. Many of these next-generation binders retained high affinity for target, together with good species cross-reactivity. Lead domains were assessed for any tendency to dimerize, tolerance to N- and C-terminal fusions, affinity, stability, and relative antigenicity in human dendritic cell assays. Functionality of candidate clones was verified in vivo through the extension of serum half-life in a typical drug format. From these analyses the domain, BA11, exhibited negligible antigenicity, high stability and high affinity for mouse, rat, and HSA. When these attributes were combined with demonstrable functionality in a rat model of PK, the BA11 clone was established as our clinical candidate.

1,3-Diphenyl-4,5-dihydro-1H-pyrazol-5-one

In the title pyrazolone derivative, C15H12N2O, the five-membered ring is approximately planar (r.m.s. deviation = 0.018 Å), and the N- and C-bound benzene rings are inclined to this plane [dihedral angles = 21.45 (10) and 6.96 (10)°, respectively] and form a dihedral angle of 20.42 (10)° with each other. Supramolecular layers are formed in the crystal structure via C—H⋯O and C—H⋯N interactions, and these are assembled into double layers by C—H⋯π and π–π interactions between the pyrazole and C-bound benzene rings [ring centroid–centroid distance = 3.6476 (12) Å]. The double layers stack along the a axis being connected by π–π interactions between the N- and C-bound benzene rings [ring centroid–centroid distance = 3.7718 (12) Å].

Supramolecular structures of substituted α,α′-trehalose derivatives

The structures of five substituted α,α′-trehalose trehalose derivatives have been determined, and these are compared with those of four previously published analogues. In 2,2′,3,3′,4,4′-hexaacetato-6,6′-bis-O-methylsulfonyl-α,α′-trehalose, C26H38O21S2, where the molecules lie across twofold rotation axes in the space group C2, a single C—H⋯O=S hydrogen bond links the molecules into sheets. 2,2′,3,3′,4,4′-Hexaacetato-6,6′-bis-O-(4-toluenesulfonyl)-α,α′-trehalose, C38H46O21S2, crystallizes with Z′ = 2 in the space group P212121 and a combination of three C—H⋯O hydrogen bonds, each having a carbonyl O atom as an acceptor, and a C—H⋯π(arene) hydrogen bond link the molecules into a three-dimensional framework. 2,2′,3,3′,4,4′-Hexaacetato-6,6′-diazido-α,α′-trehalose, C24H32N6O15, crystallizes as a partial ethanol solvate and three C—H⋯O hydrogen bonds link the substituted trehalose molecules into a three-dimensional framework. In 2,2′,3,3′-tetraacetato-6,6′-bis(N-acetylamino)-α,α′-trehalose dihydrate, C24H36N2O15·2H2O, the substituted trehalose molecules lie across twofold rotation axes in the space group P21212 and a three-dimensional framework is generated by the combination of O—H⋯O and N—H⋯O hydrogen bonds. The diaminotrehalose molecules in 6,6′-diamino-α,α′-trehalose dihydrate, C12H24N2O9.2(H2O), lie across twofold rotation axes in the space group P43212: a single O—H⋯N hydrogen bond links the trehalose molecules into sheets, which are linked into a three-dimensional framework by O—H⋯O hydrogen bonds.

Structural studies of (E)-2-(benzylidene)- 2,3-dihydro-1H-inden-1-one derivatives: crystal structures and Hirshfeld surface analysis

Abstract Crystal structures are reported of (E)-2-(4-hydroxybenzylidene)-2,3-dihydro-1H-inden-1-one, 1, (E)-2-(4-dimethylaminobenzylidene)-2,3- dihydro-1H-inden-1-one, 2, (E)-2-(4-cyanobenzylidene)-2,3-dihydro-1H-inden-1-one, 3, and monoclinic-(E)- 2-(3-nitrobenzylidene)-2,3-dihydro-1H-inden-1-one, monoclinic-4, all from data collected at 100 K and (E)-2-(4-hydroxy-3,5-dimethylbenzylidene)-2,3-dihydro-1H-indan-1-one, 6, from data collected at 299 K. An earlier triclinic form of 4 has been reported. Also reported herein are the Hirshfeld suface calculations for these five compounds, as well as that of 2-(4-methoxybenzylidene)-2,3-dihydro-1H-inden-1-one, 5,whose crystal structure has been previously reported. The three rings in each of the compounds, 1–4 and 6, are essentially planar, including the five-membered ring containing a formally hydridized sp3 atom. The molecules exhibit slight deviations from overall planarity as shown by the dihedral angles, >8.15(6)° between the 2,3-dihydro-1H-inden-1-one fragments and the phenyl fragments. The main intermolecular interactions in compounds 1 and are classical O–H···O1(carbonyl) hydrogen bonds. The carbonyl oxygen atom in compounds 1–4 are involved in non-classical C–H···O intermolecular hydrogen bonds. Intermolecular C–H---π interactions are present in 2, 3 and 6, while π···π are present in 2–4 and 6. As noted in the structure determinations of these compounds, different π···π motifs are possible. The Hirshfeld surface calculations, while generally concurring with the intermolecular interactions indicated by PLATON analyses, also reveal significant interactions, which fall below the PLATON radar.

1,2,3,4-Tetra-O-acetyl-α-d-gluco­pyran­uron­amide

The title compound, C14H19NO10, forms strong hydrogen bonds via amido groups in the [100] direction; soft C—H⋯O bonds also act to give chains along both [100] and [001], which combine to form a two-dimensional layer.

Crystal structures and Hirshfeld surface analyses of seven 7-aryl-4,7-dioxoheptanoic acids: differing carboxylic acid interactions leading to dimers, chains and three-dimensional arrays

Abstract Crystal structures and Hirshfeld surface analysis are reported of seven aryl-CO–CH2CH2COCH2CH2CO2H derivatives, namely aryl=4-ClC6H4, 1: 2-HOC6H4, 2: (2,4-(MeO)2C6H3, 3: 3,5-Me2-4-MeOC6H2, 4: 4-MeC6H4, 5: C6H5, 6: 2,4-(HO)2C6H3, 7. There are significant differences in their molecular conformations and their crystal packing. Within the group of compounds, three different types of carboxylic acid intermolecular interactions are exhibited, all involving O–H···O hydrogen bonds. These three types are (i) symmetric R22(8) dimers formed from pairs of O–H···O hydrogen bonds in compounds 1–5, (ii) infinite 1D homo-assemblies of carboxylic groups (homo-AA,A catemers), and (iii), a 3-D array, in which there are no direct carboxylic acid–carboxylic acid interactions, generated from O–H···O interactions of each carboxylic acid group with the hydroxyl and carbonyl groups of other molecules in 7. Each of the carboxylic acid groups in the catemer exhibit anti arrangements with all the carboxylic acid oxygen atoms lying in a plane. Disorder is exhibited in the carboxylic acid groups in 2 and 6. With the variety of oxygen substituents present in 1–7, a large number of O–H···O and C–H···O hydrogen bonds are exhibited, resulting in all cases in three dimension assemblies. In 1–5, interlayer contacts between the carboxylic acid R22(8) dimers in rows, with differing sets of weaker C–H···O and/or C–H···π interactions, result in the formation of two-molecular wide columns and/or infinite sheets. While column and sheet sub structures can also be designated in compound 6, on linking the carboxylic acid groups with other substituents via C–H···O, C–H···π and C=O···π interactions, these differ from those in 1–5 due to the different arrangements of the CO2H groups.