Stabilization of α-lipoic acid by complex formation with chitosan

Kyoko Kofuji; Michiko Nakamura; Takashi Isobe; Yoshifumi Murata; Susumu Kawashima

doi:10.1016/j.foodchem.2007.11.078

Stabilization of α-lipoic acid by complex formation with chitosan

Food Chem. 2008 Jul 1;109(1):167-71. doi: 10.1016/j.foodchem.2007.11.078. Epub 2007 Dec 14.

Authors

Kyoko Kofuji¹, Michiko Nakamura², Takashi Isobe², Yoshifumi Murata², Susumu Kawashima²

Affiliations

¹ Faculty of Pharmaceutical Sciences, Hokuriku University, Ho-3, Kanagawa-machi, Kanazawa 920-1181, Japan. Electronic address: k-kofuji@hokuriku-u.ac.jp.
² Faculty of Pharmaceutical Sciences, Hokuriku University, Ho-3, Kanagawa-machi, Kanazawa 920-1181, Japan.

PMID: 26054278
DOI: 10.1016/j.foodchem.2007.11.078

Abstract

α-Lipoic acid (ALA) is an essential cofactor in mitochondrial multi-enzyme complexes related to energy production. However, it is unstable under light or heat, and its decomposition is accompanied by an unpleasant odor. Therefore, its stabilization by complex formation with the cationic polymer chitosan (CS) was investigated. The ALA dissolved in demineralized water was efficiently adsorbed on the precipitated insoluble CS particles, and an ALA-CS complex was obtained. The amount of ALA adsorbed on CS was affected by the CS species and the quantity ratio of ALA to CS. The ALA from the ALA-CS complex was released immediately by changing the pH. When ALA was incubated at 65°C, it melted and polymerized. In addition, some decomposition of ALA was also observed in the physical mixture of ALA with CS. However, the ALA-CS complex did not decompose at all under the same conditions. Thus, the stabilization of ALA was achieved by complex formation with CS. CS is useful as a material for the stabilization of ALA, leading to its clinical use.

Keywords: Chitosan; Complex; Stability; α-Lipoic acid.