title: Improved stability of (+)-catechin and (-)-epicatechin by complexing with hydroxypropyl-β-cyclodextrin: Effect of pH, temperature and configuration.
abstract: The stability and bioavailability of catechins, a kind of tea polyphenols with health benefit, could be improved by complexing with cyclodextrins. The aim of this study was to investigate the complexation of two geometrical isomers, (+)-catechin and (-)-epicatechin, with hydroxypropyl-β-cyclodextrin (HP-β-CD) in tris-HCl buffer solutions at pH 6.8-8.0 using isothermal titration calorimetry, fluorescence and proton nuclear magnetic resonance spectroscopy. Experimental results showed that these inclusion interactions are primarily enthalpy-driven processes. The complexation constant (KC) of EC+HP-β-CD complex was less than that of CA+HP-β-CD at the same temperature and pH value. Temperature and pH studies showed that the KC value decreased with the rise of temperature and pH. Stability study indicated that HP-β-CD showed a stronger protection effect on CA than that on EC. The different inclusion modes between CA and EC were discussed in terms of the discrepancy in their molecular structures.
authors.affiliation: School of Chemistry and Chemical Engineering, Liaocheng University, Liaocheng 252059, China; Institute of BioPharmceutical Research, Liaocheng University, Liaocheng 252059, China. Electronic address: panpanliumin@163.com.
authors.forename: Min
authors.initials: M
authors.lastname: Liu
authors.affiliation: School of Chemistry and Chemical Engineering, Liaocheng University, Liaocheng 252059, China.
authors.forename: Yan
authors.initials: Y
authors.lastname: Zheng
authors.affiliation: School of Chemistry and Chemical Engineering, Liaocheng University, Liaocheng 252059, China.
authors.forename: Chunmei
authors.initials: C
authors.lastname: Wang
authors.affiliation: School of Chemistry and Chemical Engineering, Liaocheng University, Liaocheng 252059, China.
authors.forename: Jimin
authors.initials: J
authors.lastname: Xie
authors.affiliation: Institute of BioPharmceutical Research, Liaocheng University, Liaocheng 252059, China.
authors.forename: Bingquan
authors.initials: B
authors.lastname: Wang
authors.affiliation: Institute of BioPharmceutical Research, Liaocheng University, Liaocheng 252059, China.
authors.forename: Zhengping
authors.initials: Z
authors.lastname: Wang
authors.affiliation: Institute of BioPharmceutical Research, Liaocheng University, Liaocheng 252059, China.
authors.forename: Jun
authors.initials: J
authors.lastname: Han
authors.affiliation: School of Chemistry and Chemical Engineering, Liaocheng University, Liaocheng 252059, China.
authors.forename: Dezhi
authors.initials: D
authors.lastname: Sun
authors.affiliation: School of Chemistry and Chemical Engineering, Liaocheng University, Liaocheng 252059, China. Electronic address: niumeiju@lcu.edu.cn.
authors.forename: Meiju
authors.initials: M
authors.lastname: Niu
mesh_terms: D000073738:2-Hydroxypropyl-beta-cyclodextrin; D002392:Catechin / Q000737:chemistry*; D015394:Molecular Structure; D013050:Spectrometry, Fluorescence / Q000379:methods*; D013696:Temperature; D047392:beta-Cyclodextrins / Q000737:chemistry*
chemical_list: D047392:beta-Cyclodextrins; D000073738:2-Hydroxypropyl-beta-cyclodextrin; D002392:Catechin
keywords: (+)-Catechin; (+)-Catechin (PubChem CID: 9064); (−)-Epicatechin; (−)-Epicatechin (PubChem CID: 72276); Dimethyl sulfoxide-d(6) (PubChem CID: 75151); Fluorescence spectroscopy; Hydroxypropyl-β-cyclodextrin; Hydroxypropyl-β-cyclodextrin (PubChem CID: 90479739); Isothermal titration calorimetry; Stability; Tris (hydroxymethyl) aminomethane (PubChem CID: 6503)