New Cocrystals of Ligustrazine: Enhancing Hygroscopicity and Stability.

Ligustrazine (TMP) is the main active ingredient extracted from Rhizoma Chuanxiong, which is used in the treatment of cardiovascular and cerebrovascular diseases, with the drawback of being unstable and readily sublimated. Cocrystal technology is an effective method to improve the stability of TMP. Three benzoic acid compounds including P-aminobenzoic acid (PABA), 3-Aminobenzoic acid (MABA), and 3,5-Dinitrobenzoic acid (DNBA) were chosen for co-crystallization with TMP. Three novel cocrystals were obtained, including TMP-PABA (1:2), TMP-MABA (1.5:1), and TMP-DNBA (0.5:1). Hygroscopicity was characterized by the dynamic vapor sorption (DVS) method. Three cocrystals significantly improved the hygroscopicity stability, and the mass change in TMP decreased from 25% to 1.64% (TMP-PABA), 0.12% (TMP-MABA), and 0.03% (TMP-DNBA) at 90% relative humidity. The melting points of the three cocrystals were all higher than TMP, among which the TMP-DNBA cocrystal had the highest melting point and showed the best stability in reducing hygroscopicity. Crystal structure analysis shows that the mesh-like structure formed by the O-H⋯N hydrogen bond in the TMP-DNBA cocrystal was the reason for improving the stability of TMP.

Optimized solubility and bioavailability of genistein based on cocrystal engineering.

With various potential health-promoting bioactivities, genistein has great prospects in treatment of a series of complex diseases and metabolic syndromes such as cancer, diabetes, cardiovascular diseases, menopausal symptoms and so on. However, poor solubility and unsatisfactory bioavailability seriously limits its clinical application and market development. To optimize the solubility and bioavailability of genistein, the cocrystal of genistein and piperazine was prepared by grinding assisted with solvent based on the concept of cocrystal engineering. Using a series of analytical techniques including single-crystal X-ray diffraction, powder X-ray diffraction, Fourier transform infrared spectroscopy, differential scanning calorimetry and thermogravimetric analysis, the cocrystal was characterized and confirmed. Then, structure analysis on the basis of theoretical calculation and a series of evaluation on the stability, dissolution and bioavailability were carried out. The results indicated that the cocrystal of genistein and piperazine improved the solubility and bioavailability of genistein. Compared with the previous studies on the cocrystal of genistein, this is a systematic and comprehensive investigation from the aspects of preparation, characterization, structural analysis, stability, solubility and bioavailability evaluation. As a simple, efficient and green approach, cocrystal engineering can pave a new path to optimize the pharmaceutical properties of natural products for successful drug formulation and delivery.

Influences of MAA on the porous morphology of P(St-MAA) latex particles produced by batch soap-free emulsion polymerization followed by stepwise alkali/acid post-treatment.

Soap-free P(St-MAA) latex particles with variable styrene (St)/methacrylic acid (MAA) ratio were synthesized by batch emulsion copolymerization at 70 degrees C for 7h, and the particles with porous structure were obtained after stepwise alkali/acid post-treatment. The effects of MAA amount on the particle morphologies after the alkali and the stepwise alkali/acid post-treatments were investigated by transmission electron microscopy (TEM) and scanning electron microscopy (SEM). Results indicated that the alkali-treated latex particles showed anomalous structure with rough surface, and no hollow was clearly identified inside them. When these alkali-treated particles were further treated with acid solution, the particle surface became much smoother, and porous morphology appeared. It was found that when the MAA amount was less than or equal to 4mol%, no obvious morphological variation was observed; while the latex particles showed clearly porous structure as the MAA amount increased to 6mol%; with the further increase of MAA amount to 8mol%, the pore size decreased distinctly.