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International Journal of Medicinal Chemistry
Volume 2017, Article ID 4391078, 9 pages
Research Article

Usefulness of Urea as a Means of Improving the Solubility of Poorly Water-Soluble Ascorbyl Palmitate

Laboratory of Drug Safety Management, Faculty of Pharmacy and Pharmaceutical Sciences, Josai University, 1-1 Keyakidai, Sakado-shi, Saitama 3500295, Japan

Correspondence should be addressed to Yutaka Inoue;

Received 22 August 2017; Revised 12 October 2017; Accepted 19 October 2017; Published 6 November 2017

Academic Editor: Alain Gueiffier

Copyright © 2017 Yutaka Inoue et al. This is an open access article distributed under the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.


The aim of this study was to evaluate complexes of L-ascorbyl palmitate (ASCP) and urea (UR). This evaluation involved differential scanning calorimetry (DSC), powder X-ray diffraction (PXRD), scanning electron microscopy (SEM), near-infrared spectroscopy (NIR), a solubility test, a 1,1-diphenyl-2-picrylhydrazyl (DPPH) radical scavenging test, and a mushroom tyrosinase inhibition assay. Physicochemical evaluation revealed that ASCP/UR complexes form at a molar ratio of 1/12. The solubility test revealed that ASCP/UR complexes had increased solubility compared to ASCP. The DPPH radical scavenging test and mushroom tyrosinase inhibition assay revealed that the activity of ASCP/UR complexes was not impaired by complex formation. These results are probably due to the tetragonal crystal system of UR changing to a hexagonal crystal system and interaction with the alkyl group of ASCP.