Combining two antitubercular drugs, clofazimine and 4-aminosalicylic acid, in order to improve clofazimine aqueous solubility and 4-aminosalicylic acid thermal stability

Four forms of a salt combining two antitubercular drugs, clofazimine and 4-aminosalicylic acid, are reported and the crystal structure of two of these forms are described. TG/DSC analysis of all four forms demonstrate an increase in the temperature at which degradation (upon decarboxylation) occurs in comparison to pure 4-aminosalicylic acid. Water solubility evaluation indicates a significant increase of the amount of clofazimine detected in water (10.26 ± 0.52 mg/mL for form I, 12.27 ± 0.32 mg/mL for form II, 7.15 ± 0.43 mg/mL for form III and 8.50 ± 1.24 mg/mL for form IV) in comparison to pure clofazimine (0.20 ± 0.03 mg/mL

Design and synthesis of a new soluble natural β-carboline derivative for preclinical study by intravenous injection

Harmine is a natural β-carboline compound showing several biological activities, including antiproliferative properties, but this soluble natural molecule lacks selectivity. Harmine derivatives were reported to overcome this problem, but they are usually poorly soluble. Here, we designed and synthesized a new 2, 7, 9-trisubstituted molecule (1-methyl-7-(3-methylbutoxy)-9-propyl-2-[(pyridin-2-yl)methyl]-9H-pyrido[3,4-b]indol-2-ium bromide) with a solubility of 1.87 ± 0.07 mg/mL in a simulated injection vehicle. This compound is stable for at least 72 h in acidic and physiological conditions (pH 1.1 and 7.4) as well as in a simulated injection vehicle (physiological liquid + 0.1% Tween80®). Solubility in those media is 1.06 ± 0.08 mg/mL and 1.62 ± 0.13 mg/mL at pH 7.4 and 1. The synthesized molecule displays a significant activity on five different cancer cell lines (IC50 range from 0.2 to 2 µM on A549, MDA-MB-231, PANC-1, T98G and Hs683 cell lines). This compound is also more active on cancer cells (MDA-MB-231) than on normal cells (MCF-10a) at IC50 concentrations. Due to its high activity at low concentration, such solubility values should be sufficient for further in vivo antitumoral activity evaluation via intravenous injection

Salt and Cocrystals Combining Sulfathiazole with Pyrimethamine

Dihydrofolate reductase inhibitors, such as pyrimethamine, are known to have synergistic effects with sulfonamides. Four new solid forms combining pyrimethamine and sulfathiazole, one cocrystal (pyrimethamine-sulfathiazole (1:1)) and three solvated salt cocrystals (in which pyrimethamine and sulfathiazole are in a 1:2 molar ratio), are determined and characterized. Desolvation of the salt cocrystals leads to either a physical mixture of the starting compounds or the formation of the cocrystal (1:1) with an excess of sulfathiazole. The pyrimethamine sulfathiazole binary phase diagram was determined, which reveals that the pyrimethamine-sulfathiazole (1:2) composition point corresponds to a metastable eutectic. Obtaining this metastable eutectic as a pure powder is therefore rather difficult since it converts to a stable mixture of the (1:1) cocrystal + sulfathiazole. The abovementioned drug–drug multicomponent systems are characterized in terms of thermal stability (by TGA/DSC) and solubility. Both pyrimethamine-sulfathiazole (1:1) cocrystal and pyrimethamine-sulfathiazole (1:2) ethanol-solvated salt cocrystal result in an increase of the parent drugs’ solubility

Structural study of bioisosteric derivatives of 5-(1 H-indol-3-yl)-benzotriazole and their ability to form chalcogen bonds

Recently, inter­est in the isosteric replacement of a nitro­gen atom to selenium, sulfur or oxygen atoms has been highlighted in the design of potential inhibitors for cancer research. In this context, the structures of 5-(1H-indol-3-yl)-2,1,3-benzotriazole derivatives [5-(1H-indol-3-yl)-2,1,3-benzo­thia­diazole (bS, C(14)H(9)N(3)S) and 5-(1H-indol-3-yl)-2,1,3-benzoxa­diazole (bO, C(14)H(9)N(3)O)], as well as a synthesis inter­mediate of the selenated bioisostere [5-[1-(benzensulfon­yl)-1H-indol-3-yl]-2,1,3-benzoselena­diazole (p-bSe, C(20)H(13)N(3)O(2)SSe)] were determined using single-crystal X-ray diffraction (SCXRD) analyses. Despite being analogues, different crystal packing, torsion angles and supra­molecular features were observed, depending on the substitution of the central atoms of the benzotriazole. In particular, chalcogen inter­actions were described in the case of p-bSe and not in the bS and bO derivatives. An investigation by ab initio computational methods was therefore conducted to understand the effect of the substitution on the ability to form chalcogen bonds and the flexibility of the compounds