Binding and distribution of water molecules in DPPC bilayers doped with β-sitosteryl sulfate

Ananda Kafle; Masaaki Akamatsu; Avinash Bhadani; Kenichi Sakai; Chihiro Kaise; Teruhisa Kaneko; Hideki Sakai

doi:10.1016/j.colsurfb.2022.112748

Binding and distribution of water molecules in DPPC bilayers doped with β-sitosteryl sulfate

Colloids Surf B Biointerfaces. 2022 Oct:218:112748. doi: 10.1016/j.colsurfb.2022.112748. Epub 2022 Aug 1.

Authors

Ananda Kafle¹, Masaaki Akamatsu², Avinash Bhadani³, Kenichi Sakai⁴, Chihiro Kaise⁵, Teruhisa Kaneko⁵, Hideki Sakai⁶

Affiliations

¹ Department of Pure and Applied Chemistry, Faculty of Science and Technology, Tokyo University of Science, 2641-Yamazaki, Noda, Chiba 278-8510, Japan. Electronic address: anandakafle@rs.tus.ac.jp.
² Department of Pure and Applied Chemistry, Faculty of Science and Technology, Tokyo University of Science, 2641-Yamazaki, Noda, Chiba 278-8510, Japan.
³ Research Institute for Science and Technology, Tokyo University of Science, 2641-Yamazaki, Noda, Chiba 278-8510, Japan.
⁴ Department of Pure and Applied Chemistry, Faculty of Science and Technology, Tokyo University of Science, 2641-Yamazaki, Noda, Chiba 278-8510, Japan; Research Institute for Science and Technology, Tokyo University of Science, 2641-Yamazaki, Noda, Chiba 278-8510, Japan.
⁵ L. V. M. C. Inc., Komagome-7-14-3, Toshima-ku, Tokyo 170-0003, Japan.
⁶ Department of Pure and Applied Chemistry, Faculty of Science and Technology, Tokyo University of Science, 2641-Yamazaki, Noda, Chiba 278-8510, Japan; Research Institute for Science and Technology, Tokyo University of Science, 2641-Yamazaki, Noda, Chiba 278-8510, Japan. Electronic address: hisakai@rs.noda.tus.ac.jp.

PMID: 35933887
DOI: 10.1016/j.colsurfb.2022.112748

Abstract

We have comparatively studied the behavior of water molecules associated with the DPPC (1,2-dipalmitoyl-sn-glycero-3-phosphocholine) bilayers in the presence and absence of β-sitosteryl sulfate (PSO₄) with the help of differential scanning calorimetry (DSC) and SAXS (small-angle x-ray scattering) techniques. The DSC heating endotherms were analyzed to understand the intermolecular interactions between water molecules and the lipid headgroups. The strongly bound, weakly bound, and free water (SB-Water, WB-Water, and FW-Water, respectively) were thus identified in the bilayers and the impact of incorporating PSO₄ was evaluated. The SAXS data provided the supporting evidence for the impact of PSO₄ on the intake of water into the bilayer. Regardless of the presence or absence of PSO₄, the SB-Water existed in the system as the non-freezable fraction. On the other hand, the WB-Water and FW-Water fractions, both of which are freezable, exhibited freezing and melting behaviors that differed from each other significantly. The enthalpies of fusion of the WB-Water, which differed from that of the FW-Water, also varied with the mole fractions of PSO_4. PSO₄ enhanced the fraction of WB -water in the bilayer while at the same time reducing the fractions of SB-Water and FW-Water. The optimum retainability and the ease of release of the available water makes this system efficient for maintaining skin homeostasis if used in cosmetic and pharmaceutical formulations.

Keywords: Bilayer; Bound water; Drug delivery system; Hydration; Phosphatidylcholine; Phytosterol.

MeSH terms

1,2-Dipalmitoylphosphatidylcholine* / chemistry
Calorimetry, Differential Scanning
Lipid Bilayers* / chemistry
Pharmaceutical Preparations
Scattering, Small Angle
Sulfates
Water / chemistry
X-Ray Diffraction

Substances

Lipid Bilayers
Pharmaceutical Preparations
Sulfates
Water
1,2-Dipalmitoylphosphatidylcholine