title: Synthesis and characterization of acetylated amylose and development of inclusion complexes with rifampicin.
abstract: Amylose (AM) tends to form single helical inclusion complexes with suitable agents. These complexes are considered promising biomaterial carrier since the guest molecules can be released later, leading to many applications, especially in the pharmaceutical industry. Rifampicin (RIF) has long been recognized as an active drug against Mycobacterium tuberculosis, however, the administration of RIF in high dosages can originate unwanted side-effects. Due to the fact that the use of native amylose (AM) in the formation of complexes is limited by their low water solubility, it was acetylated with a medium degree of substitution (DS), allowing solubilizing (0.5gL-1) acetylated amylose (AMA) in water at neutral pH, in opposition to that observed with native amylose (trace solubility). The resulting acetylated amylose was characterized by means of Fourier Transform Infrared (FT-IR) spectroscopy and Scanning Electron Microscopy (SEM). FT-IR results indicated that the acetylation of anhydroglucose units of amylose corresponds to a low DS, whereas SEM results suggested that the smooth surfaces of amylose granules were changed into rougher surfaces after acetylation. Ultraviolet absorption spectroscopy (UV-vis) analysis confirmed the formation and allowed the quantification of both native (AM-RIF) and acetylated (AMA-RIF) amylose inclusion complexes. Their characterization in solution was performed by dynamic light scattering (DLS) and zeta potential (ZP) measurements. The average size of inclusion complexes as determined by DLS, ranged between 70 and 100nm. Besides, ZP analysis showed that both complexes are more stable in the presence of RIF. This study may lead to the development of an effective method for the preparation of amylose inclusion complexes, which is beneficial to their further application in drug delivery systems.
authors.affiliation: Group of Studies of the Laboratory of Instrumentation and Molecular Dynamics (LINDIM), Chemistry Institute, Federal University of Rio Grande do Sul, 91501-970 Porto Alegre, RS, Brazil.
authors.forename: Andresa C
authors.initials: AC
authors.lastname: Ribeiro
authors.affiliation: Institute for Bioengineering and Biosciences, Department of Bioengineering, Instituto Superior Técnico, Universidade de Lisboa, Av. Rovisco Pais 1, 1049-001 Lisboa, Portugal.
authors.forename: Ângelo
authors.initials: Â
authors.lastname: Rocha
authors.affiliation: Group of Studies of the Polymeric Biomaterials (POLI-BIO), Chemistry Institute, Federal University of Rio Grande do Sul, 91501-970 Porto Alegre, RS, Brazil.
authors.forename: Rosane M D
authors.initials: RMD
authors.lastname: Soares
authors.affiliation: Institute for Bioengineering and Biosciences, Department of Bioengineering, Instituto Superior Técnico, Universidade de Lisboa, Av. Rovisco Pais 1, 1049-001 Lisboa, Portugal.
authors.forename: Luís P
authors.initials: LP
authors.lastname: Fonseca
authors.affiliation: Group of Studies of the Laboratory of Instrumentation and Molecular Dynamics (LINDIM), Chemistry Institute, Federal University of Rio Grande do Sul, 91501-970 Porto Alegre, RS, Brazil. Electronic address: nadya@iq.ufrgs.br.
authors.forename: Nádya P
authors.initials: NP
authors.lastname: da Silveira
mesh_terms: D000107:Acetylation; D000688:Amylose / Q000138:chemical synthesis* / Q000737:chemistry; D000067493:Dynamic Light Scattering; D008855:Microscopy, Electron, Scanning; D012293:Rifampin / Q000737:chemistry*; D012995:Solubility; D017550:Spectroscopy, Fourier Transform Infrared
chemical_list: D000688:Amylose; D012293:Rifampin
keywords: Acetylation; Amylose; Drug delivery system; Inclusion complexes; Rifampicin