Improvement of the stabilities and antioxidant activities of polyphenols from the leaves of Chinese star anise (Illicium verum Hook. f.) by β-cyclodextrin based metal-organic frameworks (β-CD-MOFs)

Background: Polyphenols extracted from plants are usually highly unstable and rapidly transformed into various reaction products during food and drug processing, thus limiting their applications. To improve the stability and solubility of the polyphenols from the leaves of Chinese star anise (Illicium verum Hook. f.), and hence to expand their application to food and medicine, the extracted anise leaf polyphenols (ALP) were microencapsulated by β-cyclodextrins (β-CD) and cyclodextrin-based metal-organic frameworks (β-CD-MOFs) materials.

Results: The optimum inclusion rate of ALP/β-CD-MOFs was 97.80% at the core-wall ratio of 1:10. Meanwhile, the stabilities, the solubility and antioxidant activities of the polyphenols before and after inclusion were compared. The results showed both the stabilities and solubility of ALP/β-CD-MOFs were significantly improved compared with those of ALP and ALP/β-CD, suggesting the potential of β-CD-MOFs as newer and better carriers than β-CD for polyphenols in food industry applications. The free radical (including superoxide, hydroxyl and DPPH radicals) scavenging activities were also improved by microencapsulation. Superoxide radical scavenging reaction also showed slow-release property of ALP/β-CD-MOFs. The formation of the inclusion complex was further confirmed by FTIR characterization.

Conclusion: The microencapsulation with β-CD-MOFs could expand the application scope of ALP, and it is more effective than β-CD. This information is important for a better understanding and application of this useful traditional Chinese plant. As a new material with high efficiency and edibility, β-CD-MOFs is not only limited in the chemical field, but also stepping into new areas of food, medicine and health care products. This article is protected by copyright. All rights reserved.

Keywords: Illicium verum Hook. f; antioxidant activities; polyphenols; stabilities; β-CD-MOFs.