Wednesday, 17 August 2016

pH and temperature stability of (−)-epigallocatechin-3-gallate-β-cyclodextrin inclusion complex-loaded chitosan nanoparticles

Published Date

20 September 2016, Vol.149:340–347, doi:10.1016/j.carbpol.2016.04.100

Title

pH and temperature stability of (−)-epigallocatechin-3-gallate-β-cyclodextrin inclusion complex-loaded chitosan nanoparticles

Author

Fei Liu^a,b

Hamid Majeed^a

John Antoniou^a

Yue Li^a

Yun Ma^a

Wallace Yokoyama^b

Jianguo Ma^a

Fang Zhong^a,^,

aState Key Laboratory of Food Science and Technology, School of Food Science and Technology, Jiangnan University, Wuxi 214122, People’s Republic of China
bWestern Regional Research Center, ARS, U.S. Department of Agriculture, Albany, CA 94710, United States

Received 6 March 2016. Revised 12 April 2016. Accepted 22 April 2016. Available online 28 April 2016.

Highlights

•
Oxidative stability of EGCG incorporated into ICs and CSNs were both investigated.
•
EGCG-ICs and related CSNs were physically unstable at higher pH and temperature.
•
Antioxidant activities of CSNs decreased more compared to EGCG-ICs and free EGCG.
•
Extreme entrapment of EGCG in aggregated CSNs inhibited the antioxidant activities.
•
Nanostructure of CSNs was lost but the activity of encapsulated EGCG may remain.

Abstract

The oxidative stability of (−)-epigallocatechin-3-gallate (EGCG) incorporated as inclusion complexes (ICs) in sulfobutylether-β-cyclodextrin sodium (SBE-β-CD) and then ionotropically crosslinked with chitosan hydrochloride (CSH) into nanoparticles were investigated. EGCG-loaded CSH-SBE-β-CD nanoparticles (CSNs) were physically unstable at higher pH and temperature. The particle size of CSNs was unchanged in the pH range of 3–5, but the microenvironment of EGCG-IC appeared to be intact until the pH increased to 6.5 by fluorescence spectroscopy. The physical structure of EGCG-ICs was also affected during storage in addition to CSNs, which was further affected as temperature increased from 25 to 55 °C. The decrease in antioxidant activities of EGCG-ICs and free EGCG with increasing pH, storage time and temperature were modest compared to the prominent decreases in antioxidant activities of EGCG-loaded CSNs. The extreme entrapment of EGCG-ICs and/or free EGCG in the aggregated CSNs restricted the release of EGCG, thus inhibiting the antioxidant activities.