%0 Journal Article
%T Inclusion Complexes of Sunscreen Agents with ¦Â-Cyclodextrin: Spectroscopic and Molecular Modeling Studies
%A Nathir A. F. Al-Rawashdeh
%A Khaled S. Al-Sadeh
%A Mohammad Bassam Al-Bitar
%J Journal of Spectroscopy
%D 2013
%R 10.1155/2013/841409
%X The inclusion complexes of selected sunscreen agents, namely, oxybenzone (Oxy), octocrylene (Oct), and ethylhexyl-methoxycinnamate (Cin) with ¦Â-cyclodextrin (¦Â-CD) were studied by UV-Vis spectroscopy, differential scanning calorimetry (DSC), 13C NMR techniques, and molecular mechanics (MM) calculations and modeling. Molecular modeling (MM) study of the entire process of the formation of 1£¿:£¿1 stoichiometry sunscreen agent/¦Â-cyclodextrin structures has been used to contribute to the understanding and rationalization of the experimental results. Molecular mechanics calculations, together with 13C NMR measurements, for the complex with ¦Â-CD have been used to describe details of the structural, energetic, and dynamic features of host-guest complex. Accurate structures of CD inclusion complexes have been derived from molecular mechanics (MM) calculations and modeling. The photodegradation reaction of the sunscreen agents' molecules in lotion was explored using UV-Vis spectroscopy. It has been demonstrated that the photostability of these selected sunscreen agents has been enhanced upon forming inclusion complexes with ¦Â-CD in lotion. The results of this study demonstrate that ¦Â-CD can be utilized as photostabilizer additive for enhancing the photostability of the selected sunscreen agents' molecules. 1. Introduction Cyclodextrins (CDs) are cyclic oligosaccharides composed of glucopyranose units linked together by oxygen bridges at the 1 and 4 positions (¦Á,1,4-glycoside bonds) [1]. This class of organized media possesses a hydrophilic exterior and a hydrophobic cavity due to C3H, C5H, and C6H hydrogens and O4 ether oxygen which enables the CDs to extract a variety of organic guest molecules of appropriate size and hydrophobicity from the bulk aqueous solution [2¨C4]. The most familiar members are ¦Á-, ¦Â-, and ¦Ã-CDs consisting of six, seven, and eight glucose units, respectively. Complexation of various compounds with CDs leads to an enhancement in some of the characteristics of the guest molecules, such as thermalstability and photostability, bioavailability, membrane permeability, and solubility [5]. Thus, CDs and their derivatives have been employed in a variety of fields such as catalysis, electrochemical analysis, pharmaceutical and food industries [6¨C12], separation sciences [13¨C18], and biotechnology [19, 20]. In cosmetics the use of CDs is still having a shortage in the literature information in comparison with other areas, whereas most publications are patents. It is noteworthy to mention that significant alterations in the physicochemical properties of
%U http://www.hindawi.com/journals/jspec/2013/841409/