Overcoming the Hydrophobic Nature of Zinc Phenylacetate Through Co-Crystallization with Isonicotinamide

Zinc phenylacetate (Zn-PA), a substitute for sodium phenylacetate as an ammonia-scavenging drug is hydrophobic, which poses problems for drug dissolution and solubility. We were able to co-crystallize the zinc phenylacetate with isonicotinamide (INAM) and produce a novel crystalline compound (Zn-PA-INAM). The single crystal of this new crystal was obtained, and its structure is reported here for the first time. Zn-PA-INAM was characterized computationally by ab initio, Hirshfeld calculations, CLP-PIXEL lattice energy calculation, and BFDH morphology analysis, and experimentally by PXRD, Sc-XRD, FTIR, DSC, and TGA analyses. Structural and vibrational analyses showed a major modification in intermolecular interaction of Zn-PA-INAM compared to Zn-PA. The dispersion-based pi-stacking in Zn-PA is replaced by coulomb-polarization effect of hydrogen bonds. As a result, Zn-PA-INAM is hydrophilic, improving the wettability and powder dissolution of the target compound in an aqueous solution. Morphology analysis revealed, unlike Zn-PA, Zn-PA-INAM has polar groups exposed on its prominent crystalline faces, reducing the hydrophobicity of the crystal. The shift in average water droplet contact angle from 128.1° (Zn-PA) to 27.1° (Zn-PA-INAM) is strong evidence of a marked decrease in hydrophobicity of the target compound. Finally, HPLC was used to obtain the dissolution profile and solubility of Zn-PA-INAM compared to Zn-PA.

Versatile Solid Modifications of Multicomponent Pharmaceutical Salts: Novel Metformin-Rhein Salts Based on Advantage Complementary Strategy Design

This study aimed to develop an effective treatment for diabetes and diabetic complications, based on the advantage complementary strategy of drug-drug salt, by designing and synthesizing the multicomponent molecular salts containing metformin (MET) and rhein (RHE). Finally, the salts of MET-RHE (1:1), MET-RHE-H₂O (1:1:1), MET-RHE-ethanol-H₂O (1:1:1:1), and MET-RHE-acetonitrile (2:2:1) were obtained, indicating the polymorphism of salts formed by MET and RHE. The structures were analyzed by the combination of characterization experiments and theoretical calculation, and the formation mechanism of polymorphism was discussed. The obtained results of in vitro evaluation showed that MET-RHE had a similar hygroscopicity with metformin hydrochloride (MET·HCl), and the solubility of the component of RHE increased by approximately 93 times, which laid a foundation for improving the bioavailability of MET and RHE in vivo. The evaluation of hypoglycemic activity in mice (C57BL/6N) indicated that MET-RHE exhibited better hypoglycemic activity than the parent drugs and the physical mixtures of MET and RHE. The above findings demonstrate that this study achieved the complementary advantages of MET and RHE through the multicomponent pharmaceutical salification technique, and provides new possibilities for the treatment of diabetic complications.

Crystal structure and Hirshfeld surface analysis of N-{N-[amino-(di-methyl-amino)-meth-yl]carbamimido-yl}-3-bromo-benzene-sulfonamide

The title compound, C10H14BrN5O2S, is the bromo-benzene-sulfonamide derivative of the type 2 diabetes drug metformin. The asymmetric unit contains two mol-ecules with almost identical conformations but a different orientation of the bromo-phenyl moiety. Both mol-ecules exhibit intra-molecular N-H⋯N and N-H⋯O hydrogen bonds. The mol-ecular packing features chain formation in the a-axis direction by alternating N-H⋯N and N-H⋯O inter-actions. In addition, ring motifs consisting of four mol-ecules and π-π inter-actions between the phenyl rings contribute to the three-dimensional architecture. A Hirshfeld surface analysis shows that the largest contributions to surface contacts arise from contacts in which H atoms are involved.

Solid-state landscape and biopharmaceutical implications of novel metformin-based salts

Three new metformin salts were prepared, allowing the optimization of the drug's pharmaceutical profile and diversifying the API solid-state landscape.

Optimization of Sibipiruna activated carbon preparation by simplex-centroid mixture design for simultaneous adsorption of rhodamine B and metformin

The present paper reports the application of augmented simplex-centroid mixture design to obtain a high BET surface area activated carbon using as reactants KOH, K₂CO₃ and K₂C₂O₄. The optimum mixture composition was 2.51 g of KOH, 0.49 g of K₂CO₃ and absence of K₂C₂O₄, generating an optimized AC (AC_op) with S_BET value equals to 1984 m² g^-1. The results herein obtained show that low amounts of K₂CO₃ can catalyze the pore development in the presence of KOH, increasing the surface area. Furthermore, the fractal dimensions of AC_op are greater than 2.72, indicating the material has a complex pore structure with irregularities self-similar upon variations of resolution, as seen by SEM images. The TPD curves showed that the AC_op has different oxygenated molecular fragments, which agrees with the pH_PZC value (5.05). The AC_op was applied in the adsorption of rhodamine B (RhB) and metformin (Met) in both binary and monocomponent systems. The simultaneous adsorption at 30 °C reveals that the adsorption capacity of RhB is 630.94 mg g^-1, while for Met the value is 103.83 mg g^-1.

Biguanides: Species with versatile therapeutic applications

Biguanides are compounds in which two guanidine moieties are fused to form a highly conjugated system. Biguanides are highly basic and hence they are available as salts mostly hydrochloride salts, these cationic species have been found to exhibit many therapeutic properties. This review covers the research and development carried out on biguanides and accounts the various therapeutic applications of drugs containing biguanide group-such as antimalarial, antidiabetic, antiviral, anticancer, antibacterial, antifungal, anti-tubercular, antifilarial, anti-HIV, as well as other biological activities. The aim of this review is to compile all the medicinal chemistry applications of this class of compounds so as to pave way for the accelerated efforts in finding the drug action mechanisms associated with this class of compounds. Importance has been given to the organic chemistry of these biguanide derivatives also.

A thermodynamic relationship and phase transition study involving two polymorphs of sulfamethoxazole: form I vs. form II

Two sulfamethoxazole polymorphs (form I and II) have been studied. The form II → form I transformation is observed via milling and dissolution in acetonitrile. A phase transition mechanism is proposed based on their supramolecular geometries.

Mechanochemical Synthesis and Structure of the Tetrahydrate and Mesoporous Anhydrous Metforminium(2+)-N,N'-1,4-Phenylenedioxalamic Acid (1:2) Salt: The Role of Hydrogen Bonding and n→π * Charge Assisted Interactions

A new organic salt of metformin, an antidiabetic drug, and N,N'-(1,4-phenylene)dioxalamic acid, was mechanochemically synthesized, purified by crystallization from solution and characterized by single X-ray crystallography. The structure revealed a salt-type crystal hydrate composed of one dicationic metformin unit, two monoanionic units of the acid and four water molecules, namely H2Mf(HpOXA)2∙4H2O. X-ray powder, IR, 13C-CPMAS, thermal and BET adsorption-desorption analyses were performed to elucidate the structure of the molecular and supramolecular structure of the anhydrous microcrystalline mesoporous solid H2Mf(HpOXA)2. The results suggest that their structures, conformation and hydrogen bonding schemes are very similar. To the best of our knowledge, the selective formation of the monoanion HpOXA-, as well as its structure in the solid, is herein reported for the first time. Regular O(δ-)∙∙∙C(δ), O(δ-)∙∙∙N+ and bifacial O(δ-)∙∙∙C(δ)∙∙∙O(δ-) of n→π * charge-assisted interactions are herein described in H2MfA organic salts which could be responsible of the interactions of metformin in biologic systems. The results support the participation of n→π * charge-assisted interactions independently, and not just as a short contact imposed by the geometric constraint due to the hydrogen bonding patterns.

Metformin Affects Heme Function as a Possible Mechanism of Action

Metformin elicits pleiotropic effects that are beneficial for treating diabetes, as well as particular cancers and aging. In spite of its importance, a convincing and unifying mechanism to explain how metformin operates is lacking. Here we describe investigations into the mechanism of metformin action through heme and hemoprotein(s). Metformin suppresses heme production by 50% in yeast, and this suppression requires mitochondria function, which is necessary for heme synthesis. At high concentrations comparable to those in the clinic, metformin also suppresses heme production in human erythrocytes, erythropoietic cells and hepatocytes by 30–50%; the heme-targeting drug artemisinin operates at a greater potency. Significantly, metformin prevents oxidation of heme in three protein scaffolds, cytochrome c, myoglobin and hemoglobin, with Kd values < 3 mM suggesting a dual oxidation and reduction role in the regulation of heme redox transition. Since heme- and porphyrin-like groups operate in diverse enzymes that control important metabolic processes, we suggest that metformin acts, at least in part, through stabilizing appropriate redox states in heme and other porphyrin-containing groups to control cellular metabolism.

Characterization of drug–drug salt forms of metformin and aspirin with improved physicochemical properties

A salt between two old drugs was synthesized and two phases were discovered with improved physicochemical properties.

A gallic acid–succinimide co-crystal landscape: polymorphism, pseudopolymorphism, variable stoichiometry co-crystals and concomitant growth of non-solvated and solvated co-crystals

A design aspect for selective formation of diverse solid forms such as solvates, hydrates and anhydrous forms has been successfully investigated in a gallic acid–succinimide co-crystal landscape.

Exocyclic self-assembly behavior of carboxylic acid and lariat ether macrocyclic hosts: regulation by pendent arm

An exocyclic supramolecular building block through O–H⋯N hydrogen bonding interaction for the assembly of di-sidearm dibenzo-diazacrown ethers bearing a flexibility sidearm with PTA acid.

Synthesis and preliminary investigations into novel 1,2,3-triazole-derived androgen receptor antagonists inspired by bicalutamide

A versatile and high yielding synthesis of novel androgen receptor (AR) antagonists is presented. Using this methodology, six 1,4-substituted-1,2,3-triazole derived bicalutamide mimics were synthesised in five steps and in isolated overall yields from 41% to 85%. Evaluation of these compounds for their anti-proliferative properties against androgen dependent (LNCaP) and independent (PC-3) cells showed promising IC50 values of 34-45 μM and 29-151 μM, respectively. The data suggest that the latter compounds may be an excellent starting point for the development of prostate cancer therapeutics for both androgen dependent and independent forms of this disease. Docking of these compounds (each enantiomer) in silico into the T877A mutated androgen receptor, as possessed by LNCaP cells, was also undertaken.