Stenger Moura Fernanda Cristina, Pinna Nicola, Vivani Riccardo, Nunes Gisele Elias, Schoubben Aurélie, Bellé Bresolin Tania Mari, Bechold Ivan Helmuth, Ricci Maurizio
Programa de Pós Graduação em Ciências-PPGCF, Universidade do Vale do Itajaí, Itajaí 88302-202, SC, Brazil.
Department of Pharmaceutical Sciences, University of Perugia, via Fabretti 48, 06123 Perugia, Italy.
Pharmaceutics. 2021 Aug 25;13(9):1328. doi: 10.3390/pharmaceutics13091328.
Taxifolin, also known as dihydroquercetin, possesses several interesting biological properties. The purpose of the study was to identify polymorphs of taxifolin prepared using crystallization in different solvents. Data from X-ray powder diffraction, differential scanning calorimetry, and thermogravimetry enabled us to detect six different crystalline phases for taxifolin. Besides the already known fully hydrated phase, one partially hydrated phase, one monohydrated phase, two anhydrous polymorphs, and one probably solvated phase were obtained. The unit cell parameters were defined for three of them, while one anhydrous polymorph was fully structurally characterized by X-ray powder diffraction data. Scanning electron microscopy and hot stage microscopy were also employed to characterize the crystallized taxifolin powders. The hydrate and anhydrous forms showed remarkable stability in drastic storage conditions, and their solubility was deeply evaluated. The anhydrous form converted into the hydrate form during the equilibrium solubility study and taxifolin equilibrium solubility was about 1.2 mg/mL. The hydrate taxifolin intrinsic dissolution rate was 56.4 μg cm min. Using Wood's apparatus, it was not possible to determine the intrinsic dissolution rate of anhydrous taxifolin that is expected to solubilize more rapidly than the hydrate form. In view of its high stability, its use can be hypothesized.
紫杉叶素，又称二氢槲皮素，具有多种有趣的生物学特性。本研究的目的是鉴定在不同溶剂中通过结晶制备的紫杉叶素多晶型物。来自X射线粉末衍射、差示扫描量热法和热重分析法的数据使我们能够检测到紫杉叶素的六种不同晶相。除了已知的完全水合相外，还获得了一个部分水合相、一个一水合相、两个无水多晶型物和一个可能的溶剂化相。确定了其中三种晶相的晶胞参数，同时通过X射线粉末衍射数据对一种无水多晶型物进行了完整的结构表征。还采用扫描电子显微镜和热台显微镜对结晶的紫杉叶素粉末进行表征。水合物和无水形式在剧烈的储存条件下表现出显著的稳定性，并对它们的溶解度进行了深入评估。在平衡溶解度研究期间，无水形式转变为水合形式，紫杉叶素的平衡溶解度约为1.2 mg/mL。水合紫杉叶素的固有溶解速率为56.4 μg cm min。使用伍德装置无法测定无水紫杉叶素的固有溶解速率，预计其溶解速度比水合形式更快。鉴于其高稳定性，可以推测其用途。
