Characterization and antioxidant activity of the inclusion complexes of different types of cyclic oligosaccharides and cetirizine dihydrochloride in aqueous solution by Spectroscopy

Cyclodextrins (CDs) are cyclic oligosaccharides consisting of six (alpha-cyclodextrin), seven (beta-cyclodextrin), and eight (gamma-cyclodextrin) glucopyranose units linked by a-(1,4) bonds. These compounds contain a hydrophobic internal cavity which provides a microenvironment for appropriate sized molecules and a hydrophilic outer surface which makes them water soluble. As a result, CDs are able to form inclusion complexes with a wide variety of drug substances by including a whole drug molecule, or some part of it into their cavity [1]. In this work study on host-guest inclusion complex formation of α, β and γ-cyclodextrine with Cetirizine was performed exprimentally. Complexation properties of cetirizine dihydrochloride (cetirizine) with cyclodextrines (CDs) were investigated by ultra violet (UV) and fourier transform infrared (FTIR) spectroscopies at tempereture room. The UV absorption maximum of cetirizine and its complex with CDs appears at 230 nm in pH~7 [2]. The use of the continuous variation method (Job s plot), applied on UV data [2], demonstrated 1:1 complex stoichiometry for all cetirizine/ α‐CD, cetirizine/β‐CD and cetirizine/γ‐CD. The stability constant was calculated by using a modified Benesi-Hildebrand equation at 25°C [3]. Antioxidant activity studies by the scavenging of stable radical 2,2′-diphenyl-1-picrylhydrazyl (DPPH·)[2] revealed that Cetirizine in complex forming with cyclodextrins was the most reactive than its free form into antioxidant activity. We have chosen simple, highly sensitive and selective methods for the characterization of inclusion complexes such as fourier transform-infrared (FTIR) spectrometry, proton nuclear magnetic resonance (1HNMR) spectrometry and ultraviolet-visible (UV-Vis) spectrometry.