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A large amount of the current literature dedicated to solid states of active pharmaceutical ingredients (APIs) pays special attention to polymorphism of flavonoids. Taxifolin (also known as dihydroquercetin) is an example of a typical flavonoid. Some new forms of taxifolin have been reported previously, however it is still unclear whether they represent polymorphic modifications. In this paper, we tried to answer the question about the taxifolin polymorphism. Taxifolin microtubes and taxifolin microspheres were synthesized from raw taxifolin API using several methods of crystal engineering. All forms were described with the help of spectral methods, scanning electron microscopy (SEM), X-ray powder diffraction (XRPD), and thermal analysis (TA). SEM reveals that the morphology of the solid phase is very specific for each sample. Although XRPD patterns of raw taxifolin and microtubes look similar, their TA profiles differ significantly. At the same time, raw taxifolin and microspheres have nearly identical thermograms, while XRPD shows that the former is a crystalline and the latter is an amorphous substance. Only the use of complex analyses allowed us to put the puzzle together and to confirm the polymorphism of taxifolin. This article demonstrates that taxifolin microtubes are a pseudopolymorphic modification of raw taxifolin.

Background: Synthesis of metal oxides nanoparticles with specific morphology and size has become the subject of many experimental protocols. Biosynthesis of the nanoparticles using plants is more preferable than physical and chemical methods because of its environmental friendliness. Objective: The purpose of this study was to report the potential for green synthesis of cerium oxide nanoparticles using plant extracts with a high content of phenolic metabolites. Methods: We have synthesized the CeO2 nano- and microparticles using Petroselinum crispum aqueous extract. The particles were characterized by UV-visible spectroscopy, IR spectroscopy, X-ray diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscope (TEM) and dynamic light scattering analysis. For detection the reduction capacity of the extract the evaluation of total phenolic and flavonoid content as well as high-performance liquid chromatography-mass spectrometry (HPLC-MS) were performed. Biological activity of the particles was identified by bioluminescent tests and bio tests with Triticum vulgare. Results: Testing on T. vulgare showed that biogenic cerium dioxide powders stimulated the growth of up to 5-11,4% relative to intact samples, significantly increased the length of the leaves of seedlings and the root length. When seedings were exposed to the biosynthesized CeO2 particles, the level of chlorophylls was more stable and even slightly higher than control. Noticeable protective properties of the biosynthesized CeO2 powder under oxidation conditions were observed on the plant T. vulgare after a brief exposure (from 4 to 24 h). Conclusion: Thus, biogenic CeO2 can be potentially utilized in oxidative damage protection of agricultural plants.

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