TY - JOUR
T1 - Inclusion complexes of rosmarinic acid and cyclodextrins
T2 - Stoichiometry, association constants, and antioxidant potential
AU - Medronho, Bruno
AU - J. M. Valente, Artur
AU - Costa, Patrícia
AU - Romano, Anabela
N1 - Funding Information:
P. Costa and B. Medronho acknowledge grants from the Portuguese Science and Technology Foundation, FCT, (SFRH/BD/63505/2009 and SFRH/BPD/74540/2010, respectively). NMR data was obtained at the Nuclear Magnetic Resonance Laboratory of the Coimbra Chemistry Center ( www.nmrccc.uc.pt ), Universidade de Coimbra, supported in part by grant REEQ/481/QUI/2006 from FCT, POCI-2010, and FEDER, Portugal.
PY - 2014/4/1
Y1 - 2014/4/1
N2 - The interaction between β-cyclodextrin (β-CD) and the polyphenol rosmarinic acid (RA) is here reported by 1H NMR titration experiments. The formation of an aqueous soluble inclusion complex is confirmed and valuable information regarding mode of penetration of guest into β-CD, stoichiometry, and stability of the complex is obtained. The analysis by the continuous variation method shows the undoubted formation of 1:1 β-CD/RA complex. Additionally, the estimated apparent association constants reveal the importance of the asymmetry of the RA in the complexation; the incorporation of the catechol moiety closer to the carboxylic group is more favorable (K∈=∈2,028 M-1) than from the other end of the RA molecule (K∈=∈1,184 M-1). Finally, we have also investigated the antioxidant activity and storage stability of the β-CD/RA complexed system; the presence of β-CD was found to produce a remarkable enhancement on the antioxidant activity.
AB - The interaction between β-cyclodextrin (β-CD) and the polyphenol rosmarinic acid (RA) is here reported by 1H NMR titration experiments. The formation of an aqueous soluble inclusion complex is confirmed and valuable information regarding mode of penetration of guest into β-CD, stoichiometry, and stability of the complex is obtained. The analysis by the continuous variation method shows the undoubted formation of 1:1 β-CD/RA complex. Additionally, the estimated apparent association constants reveal the importance of the asymmetry of the RA in the complexation; the incorporation of the catechol moiety closer to the carboxylic group is more favorable (K∈=∈2,028 M-1) than from the other end of the RA molecule (K∈=∈1,184 M-1). Finally, we have also investigated the antioxidant activity and storage stability of the β-CD/RA complexed system; the presence of β-CD was found to produce a remarkable enhancement on the antioxidant activity.
KW - Antioxidant activity
KW - Association constant
KW - Continuous variation method
KW - Cyclodextrin
KW - Rosmarinic acid
UR - http://www.scopus.com/inward/record.url?scp=84898883776&partnerID=8YFLogxK
U2 - 10.1007/s00396-013-3124-5
DO - 10.1007/s00396-013-3124-5
M3 - Article
AN - SCOPUS:84898883776
SN - 0303-402X
VL - 292
SP - 885
EP - 894
JO - Colloid and Polymer Science
JF - Colloid and Polymer Science
IS - 4
ER -