Host-guest complexation of antioxidative caffeic and ferulic acid amides with a functionalized cyclophane

Claudia Virués*, Zaira Domínguez, Magali Salas, Rosa Elena Navarro, Enrique F. Velázquez, Samuel Cruz, Javier Hernández, Motomichi Inoue

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

2 Scopus citations

Abstract

Host-guest complexation has been studied by 1H NMR on the benzyl and phenethyl amides of ferulic and caffeic acids as the guests in chloroform and acetonitrile; the counter host is a cyclophane which integrates four phenylene rings, amino and amide groups in the macrocyclic framework and bears four pendant methyl acetate ester arms. CAPE, one of the best known natural antioxidants, also has been studied for comparison. Among the guests studied, ferulic acid benzyl amide shows NMR shifts due to the formation of a host-guest complex in chloroform. The complexation occurs in two steps with the formation constants K 1 = [HG]/[H][G] = 6 M -1 and β 2 = [HG 2]/[H][G] 2 = 87 M -2. Two guest molecules are bound on the surface of the macrocyclic framework of a host molecule by two hydrogen bonds, NH(host amide)⋯O=C(guest amide) and C=O(host ester)⋯HO(guest phenol). The latter hydrogen bond may protect the bioactive site, i.e.; phenol OH, of guest molecules captured in the complex against undesirable oxidation. This feature is observed only for ferulic acid benzyl amide in chloroform; the cyclophane ester interacts with this amide, distinctively from the other hydroxycinnamic acid derivatives.

Original languageEnglish
Pages (from-to)407-413
Number of pages7
JournalJournal of Inclusion Phenomena and Macrocyclic Chemistry
Volume74
Issue number1-4
DOIs
StatePublished - Dec 2012

Bibliographical note

Funding Information:
Acknowledgments C.⨯V. thanks CONACYT México for a postdoctoral fellowship. J. H. thanks CONACYT México and COVECYT México for financial support (VER-2009-C03-127523).

Keywords

  • Antioxidants
  • Caffeic acid
  • Cyclophanes
  • Ferulic acid
  • Host-guest complexes
  • Hydroxycinnamic acid derivatives

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