Solid inclusion complex of terpinen‐4‐ol/β‐cyclodextrin: kinetic release, mechanism and its antibacterial activity

Abstract

Terpinen‐4‐ol has several biological properties, but its low stability and water‐solubility limit its use. This study reports the formation of a solid terpinen‐4‐ol/β‐cyclodextrin (β‐CD) inclusion complex via lyophilization. Release experiments were performed at various temperatures (40, 60, 80, and 100°C) with humidity of 70%. The release of terpinen‐4‐ol was significantly increased with rising temperature. Avrami's equation was used to analyse release kinetics and a good fit was observed for terpinen‐4‐ol release. In addition, the complex enhanced antibacterial activity against Staphylococcus aurueus, Pseudomonas aeruginosa and Escherichia coli, with concentration ranging from 1.25 mg/ml to 5 mg/ml. To explain the experimental data, physico‐chemical techniques have been utilized to investigate the inclusion complex of terpinen‐4‐ol with β‐CD. Finally, the possible structure of the complex was proposed by quantum chemical calculations. The results indicated that enhanced thermal stability and antibacterial activity of terpinen‐4‐ol could be attributed to the weak interactions of hydrogen bonds between terpinen‐4‐ol and β‐CD. Copyright © 2014 John Wiley & Sons, Ltd.

Preparation and release behaviour of the inclusion complexes of phenylethanol with β‐cyclodextrin

“…The results indicated that the inclusion ratio is relatively high owing to the high aqueous solubility of guest molecules. The result is in agreement with previously reported data for terpinen‐4‐ol . The size distribution of the complexes was recorded on a laser particle size analyser.…”

“…As previously reported, an O⋅⋅⋅H distance of O‐H⋅⋅⋅O interaction is less than or equal to 3.2 Å, angle at H is greater than 90 o and stabilization energy is 16–25 kJ/mol. As Table shown, based on the ONIOM2 methods, the optimized geometries revealed that the nearest distance between the oxygen atom of hydroxyl in 1‐PE and the hydrogen atom of the secondary hydroxyl group was 2.594 Å, and the nearest distance between the oxygen atom of hydroxyl in 2‐PE and the hydrogen atom of the secondary hydroxyl group was 2.749 Å.…”

“…The FTIR spectra of 1‐PE and 2‐PE showed the following characteristic absorption bands: 3300 cm ‐1 (–OH); 2920, 2870 cm ‐1 (−CH 2 ); 1462, 1509 and 1575 cm ‐1 (the framework vibration of aromatic ring) and 1350 cm ‐1 (C‐O). The characteristic absorption bands of β ‐CD were observed at 3410 cm ‐1 (–OH), 2920 cm ‐1 (−CH 2 ), 1630 cm ‐1 (H‐O‐H bending), 1164 cm ‐1 (C‐O) and 1030 cm ‐1 (C‐O‐C) . As the amounts of guest molecules included in the inclusion complexes do not exceed 10%, and the FTIR spectrum of the guest molecules can be obscured by β ‐CD .…”

“…Meanwhile, the release profile of the guest molecules could be controlled as well. Therefore, they have been widely applied in the food, cosmetics and pharmaceutical industries . Among three major types of CDs, β ‐CD (Fig.…”

Captisol®: an efficient carrier and solubilizing agent for essential oils and their components

“…CDs might enhance the solubility of EOs and their components thus higher concentrations could be used, produce easy measurable dosage forms, facilitate their dispersion and protect them from interactions with other excipients . CDs could also retain and allow a controlled release for EOs, offer them thermal, oxidative, light and chemical stability and increase their oral bioavailability . To the best of our knowledge no previous study attempted to investigate the inclusion complexes of Captisol® (sulfobutylether‐β‐cyclodextrin, SBE‐β‐CD) and Captisol‐G® (sulfobutylether‐γ‐cyclodextrin, SBE‐γ‐CD) with EOs and their components while, compared to native CDs, these CDs exhibit greater water solubility and a more desirable safety profile …”