Journal of Chromatography B, 926 (2013) 21–27 Contents lists available at SciVerse ScienceDirect Journal of Chromatography B j ourna l ho me page: www.elsevier.com/locate/chromb Reversed phase High Performance Liquid Chromatography used for the physicochemical and thermodynamic characterization of piceatannol/-cyclodextrin complex Hanane Messiad a,b , Habiba Amira-Guebailia a,∗ , Omar Houache c a Laboratory of Applied Chemistry, 8 Mai 1945 Guelma University, Guelma 24000, Algeria b Unité de Recherche en Technologie Industrielle (URTI/CSC), BP1037, site de l’Université Badji Mokhtar, Chaiba, Annaba 23000, Algeria c Petroleum & Chemical Engineering Department, P.O. Box 33, Al Khoud 123, Sultan Qaboos University, Muscat, Oman a r t i c l e i n f o Article history: Received 27 September 2012 Accepted 21 February 2013 Available online 27 February 2013 Keywords: Piceatannol -Cyclodextrin Mobile phase Solubility Apparent formation constant Thermodynamic parameters a b s t r a c t Piceatannol is one of resveratrol derivatives having health promoting potential. However, its low water- solubility and bioavailability could limit its use in both food and pharmaceutical fields. The aim of this work is the study of piceatannol complexation by -cyclodextrin (-CD) in aqueous media. The complex formed could improve the bioavailability, the solubility and the stability of piceatannol. The method used was based on RP-HPLC in which, -CD was added to methanol/water mixtures mobile phases. The apparent formation constant of piceatannol/-cyclodextrin complex was determined. Within the concentration interval studied (0–4 mM), whenever the concentration of -CD increased, retention time of piceatannol decreased; indicating an enhancement of solubility due to the formation of the piceatannol/-CD complex. The formation constants (K F ) of the piceatannol/-CD complex varied sig- nificantly with both the methanol concentration in the water–methanol mixture and the temperature. Moreover, in all the physicochemical conditions tested, the stoichiometry of piceatannol/-CD complex was 1:1. Finally, the thermodynamic parameters were determined: G ◦ = -13.123 kJ mol -1 , H ◦ = -33. 265 kJ mol -1 and S ◦ = -67.559 J mol -1 K -1 . © 2013 Elsevier B.V. All rights reserved. 1. Introduction In the pharmaceutical field, cyclodextrins have been recog- nized as powerful candidates to overcome some drawbacks of drug molecules, such as low hydrosolubility, stability and bioavailabil- ity through the formation of host–guest complexes in which, each guest molecule is enclosed in the hydrophobic cavity of B-CD. This can result in the alteration of physical, chemical and biological fea- tures of guest molecules [1]. Cyclodextrins consist of glucose monomers arranged in a donut shape ring. The naturally occurring cyclodextrins are alpha, beta, and gamma CDs [2]. All the hydroxyl groups in CDs are ori- ented to the outside of the ring while the glycosidic oxygen and two rings of the non-exchangeable hydrogen atoms are directed towards the interior of the cavity. This combination gives cyclodex- trins a hydrophobic inner cavity and a hydrophilic exterior. The hydrophobic internal cavity provides the capability to form inclu- sion complexes with a variety of guest hydrophobic molecules (e.g. ∗ Corresponding author. Tel.: +213 795164562. E-mail addresses: amira h g@yahoo.co.uk, guebailia habiba@yahoo.fr (H. Amira- Guebailia). aromatics, alcohols, halides, fatty acids, esters, etc.) [3–5]. The use of CDs in both food and pharmaceutical industries is increasing owing to their capacity to improve the bioavailability, stability, and hydrosolubility of a wide range of biological active compounds [6,7]. Many physico-chemical methods have been used for the study of cyclodextrin–guest complexes among them; High Performance Liquid Chromatography. In this technique, the complex formation is confirmed by the modifications of the retention properties of guest molecules in presence of increasing CDs concentrations, different mobile phases composition, and under different physico-chemical conditions of PH and temperature [8,9]. Resveratrol, a compound with promising biological activities, has been the most studied stilbene in terms of its interaction with CDs. López-Nicolás et al. studied the complexation of resveratrol with -CD using HPLC with methanol–water mixtures [10], and pure water [11], as mobile phases. Besides resveratrol, results on the retention behavior in RP-HPLC, in the presence and absence of CDs in the mobile phase, have been recently reported for other stilbenes such as: oxyresveratrol [12], pterostilbene [13] and pinosilvin [14]. Piceatannol (trans-3,5,3 ′ ,4 ′ -tetrahydroxystilbene, A in Fig. 1) is a naturally occurring stilbene present in the skin of grapes, stems 1570-0232/$ – see front matter © 2013 Elsevier B.V. All rights reserved. http://dx.doi.org/10.1016/j.jchromb.2013.02.024