Characterizing the natural canthaxanthin/2-hydroxypropyl-β-cyclodextrin inclusion complex.

A fundamental study on the phase-solubility, storage stability and antioxidant activity of the inclusion complex of 2-hydroxypropyl-β-cyclodextrin (HP-β-CD) with canthaxanthin (CTX) biosynthesized by Dietzia natronolimnaea HS-1 in a continuous bioreactor was designed. A variety of in vitro chemical methods including reducing power (RP), nitrite-scavenging activity (NSA), and 1,1-diphenyl-2-picryl-hydrazyl (DPPH), 2,2'-azinobis-3-ethylbenzothiazoline-6-sulphonic acid (ABTS) and hydroxyl radicals scavenging capacities was used to determine antioxidant activities of the CTX and CTX/HP-β-CD complex. Results revealed that the apparent stability constant of the inclusion complex was 669 M(-1) in a 1:1 stoichiometric ratio. The complexation of CTX with HP-β-CD significantly improved its water solubility and storage stability. An increased dose-dependent manner was found for the NSA and RP values of the CTX and CTX/HP-β-CD complex. The CTX/HP-β-CD complex showed higher scavenging capacity than native CTX against DPPH, ABTS and hydroxyl radicals. It can be used as a promising strategy to improve the food application of CTX.