Exploring Tyramine's Role in the Formation of Supramolecular Adducts with Nonsteroidal Anti-Inflammatory Drugs

In pharmaceutical crystal engineering, salification and co-crystallization are well-established strategies to enhance the physicochemical properties of nonsteroidal anti-inflammatory drugs (NSAIDs), which typically exhibit low aqueous solubility. This study introduces three new multicomponent crystalline systems of NSAIDs (S-naproxen, flurbiprofen, and ketoprofen) with the co-former tyramine, designed using knowledge-based methods. Additionally, a new polymorph of the diflunisal-tyramine system, synthesized via mechanochemical techniques, is reported. The new multicomponent systems were thoroughly characterized using solid-state NMR and single-crystal X-ray diffraction. Aqueous solubility tests conducted through solution 1H NMR experiments revealed increased equilibrium solubility for all samples, highlighting the efficacy of crystal engineering in modulating the physicochemical properties of drugs.

Enhancing the solubility and antibacterial activity of novel molecular salts of enrofloxacin drug with isomeric pyridinedicarboxylic acids

Enrofloxacin (EFX) is a third-generation synthetic fluoroquinolone with a broad spectrum of antibacterial activity but suffers from low water solubility, affecting its bioavailability. This study attempts to enhance the physicochemical and biological properties of enrofloxacin by converting it into multicomponent forms using crystal engineering concepts. Cocrystallization of enrofloxacin with isomeric pyridine-2,n-dicarboxylic acids (n = 3,4,5,6) resulted in four new crystalline salts (1:1): EFX·Py2,3DCA, EFX·Py2,4DCA, EFX·Py2,5DCA·H2O and EFX·Py2,6DCA·H2O; two of these are monohydrates. The protonation of the nitrogen atom of the piperazine moiety and the presence of crystallization water molecules were confirmed by single-crystal X-ray diffraction and Fourier transform infrared spectroscopy. Thermogravimetric analysis provided information on the thermal behaviour of multicomponent forms. The biological studies showed that the obtained salts are characterized by high antibacterial activity against Gram-positive and Gram-negative bacteria, and their haemolytic activity is low. The new salts demonstrate significantly greater solubility in water compared to the parent drug, along with enhanced antibacterial activity; hence, pyridinedicarboxylic acids appear to be efficient cocrystallizing agents for improving the efficacy of pharmaceutical ingredients.

Multicomponent Solvate Crystals of 3,5-Dinitrobenzoic Acid and Acetamide and CSD Analysis of Solvates

Twelve multicomponent solvate crystals (cocrystal solvates) of 3,5-dinitrobenzoic acid and acetamide were synthesized via slow evaporation method. All crystalline materials were characterized by single-crystal X-ray diffraction. All cocrystal solvates are isostructural, and crystal packing forms continuous channels where some solvent molecules are connected via weak intermolecular interactions with 3,5-dinitrobenzoic acid and acetamide. All multicomponent solvate crystals encompass amide-amide dimer homo synthons and form R₂² (8) motifs. Moreover, the phase purity of solvate crystals was analyzed by powder X-ray diffraction. Further, most of the cocrystal solvates were analyzed by nuclear magnetic resonance and differential scanning calorimetry. Cambridge structural database analysis categorizes solvate propensity in single-crystal structures. The importance of hydrogen bond donor/acceptor nature, size, and shape of solvents is also discussed in the context of crystallization and crystal packing.

Synthesis and Bioactivities of Novel Piperonylic Acid Derivatives Containing a Sulfonic Acid Ester Moiety

The crop loss caused by bacteria has increased year by year due to the lack of effective control agents. In order to develop efficient, broad-spectrum, and structurally simple agricultural bactericide, the structure of piperonylic acid was modified and a series of novel piperonylic acid derivatives containing a sulfonic acid ester moiety was synthesized. Bioassay results indicated the compounds exhibited significantly antibacterial activities. Among them, compound 41 exhibited excellent antibacterial activities against Pseudomonas syringae pv. Actinidiae (Psa), with inhibitory value 99 and 85% at 100 μg/ml and 50 μg/ml, respectively, which was higher than that of thiodiazole-copper (84 and 77%) and bismerthiazol (96 and 78%). In addition, some compounds also showed moderate insecticidal activity against Spodoptera frugiperda. The abovementioned results confirm the broadening of the application of piperonylic acid, with reliable support for the development of novel agrochemical bactericide.