Analytical characterization of a ferulic acid/gamma-cyclodextrin inclusion complex.
Ferulic acid (FA) is a well-known antioxidant of natural source with promising properties as photoprotective agent (approved in Japan as sunscreen) and its derivatives (alkyl ferulates) are under screening for the prevention of photoinduced skin tumours. In the present work we describe the preparation of a solid inclusion complex between ferulic acid and gamma-cyclodextrin (gamma-CD) and its characterization by different analytical techniques: differential scanning calorimetry (DSC), X-ray diffractometry (XRD), nuclear magnetic resonance spectroscopy (1H NMR) and by supporting information of molecular modelling. All these approaches indicate that ferulic acid is able to form an association complex with gamma-CD but only 1H NMR and molecular modelling studies give an unequivocal evidence that the antioxidant molecule is embedded into the gamma-CD cavity to form an inclusion complex. In detail it is entrapped inside the hydrophobic core of gamma-CD with the lipophilic aromatic ring and the ethylenic moieties, leaving the more polar functional groups close to wider rim or outside the cavity.
Anselmi
Cecilia
C
Dipartimento Farmaco Chimico Tecnologico, Università di Siena, Via Aldo Moro, 53100 Siena, Italy. anselmic@unisi.it
Centini
Marisanna
M
Ricci
Maurizio
M
Buonocore
Anna
A
Granata
Paola
P
Tsuno
Takuo
T
Facino
Roberto Maffei
RM
D000975:Antioxidants / Q000737:chemistry*; D002152:Calorimetry, Differential Scanning; D002626:Chemistry, Pharmaceutical; D002851:Chromatography, High Pressure Liquid; D003373:Coumaric Acids / Q000737:chemistry*; D018360:Crystallography, X-Ray; D005079:Excipients / Q000737:chemistry*; D009682:Magnetic Resonance Spectroscopy; D008958:Models, Molecular; D047408:gamma-Cyclodextrins / Q000737:chemistry*
D000975:Antioxidants; D003373:Coumaric Acids; D005079:Excipients; D047408:gamma-Cyclodextrins; C004999:ferulic acid