Stability, morphology, and effects of in vitro digestion on the antioxidant properties of polyphenol inclusion complexes with  -cyclodextrin

Ntuli, Sunday; Leuschner, Machel; Bester, Megan; Serem, June Cheptoo

Stability, morphology, and effects of in vitro digestion on the antioxidant properties of polyphenol inclusion complexes with -cyclodextrin

Ntuli, Sunday; Leuschner, Machel; Bester, Megan; Serem, June Cheptoo

Date: 2022-06-14

Abstract:

Polyphenols are inversely associated with the incidence of chronic diseases, but therapeutic use is limited by poor stability and bioaccessibility. Encapsulation has been shown to overcome some of these limitations. A selection of polyphenols (catechin, gallic acid, and epigallocatechin gallate) and their combinations were encapsulated in beta-cyclodextrin (CD). Encapsulation was characterized and the thermal and storage stability was evaluated using the 2,2-azinobis (3-ethylbenzothiazoline- 6-sulfonic acid) (ABTS) assay. The samples were then subjected to in vitro digestion using a simple digestion (SD) model (gastric and duodenal phases) and a more complex digestion (CD) model (oral, gastric, and duodenal phases). Thereafter, the chemical (oxygen radical absorbance capacity assay) and cellular (dichlorofluorescein diacetate assay in Caco-2 cells) antioxidant and antiglycation (advanced glycation end-products assay) activities were determined. Inclusion complexes formed at a 1:1 molar ratio with a high encapsulation yield and efficiency. Encapsulation altered the morphology of the samples, increased the thermal stability of some and the storage stability of all samples. Encapsulation maintained the antioxidant activity of all samples and significantly improved the antiglycation and cellular antioxidant activities of some polyphenols following SD. In conclusion, the formed inclusion complexes of CD with polyphenols had greater storage stability, without altering the beneficial cellular effects of the polyphenols.

Description:

DATA AVAILABILTY STATEMENT : Some data is available as supplementary material and the rest under the UPSpace institutional repository, URI: http://hdl.handle.net/2263/84453 (date dissertation was available online 11 March 2022).

SUPPLEMENTARY MATERIAL : FIGURE S1: Enhanced product ions scan mass spectrum of CD inclusion complexes with (a) CAT, (b) GA, and (c) EGCG. CD—beta cyclodextrin, CAT—catechin, GA—gallic acid, EGCG—epigallocatechin gallate; FIGURE S2: Inhibition of AGEs formation by non-digested (ND) and following simple (SD) and complex (CD) digestion of nonencapsulated and encapsulated CAT/GA, CAT/EGCG, and GA/EGCG combinations evaluated with the (a) BSA-MGO and (b) BSA-FRU models at 100 M for each polyphenol in each sample. The data is represented as the mean SEM of at least five experiments performed in duplicates. ND—nondigested, SD—simple digestion, CD—complex digestion, AGEs—advanced glycation end-products, BSA—bovine serum albumin, MGO—methylglyoxal, FRU—fructose, CAT—catechin, GA—gallic acid, EGCG—epigallocatechin gallate. The * and + represent significant (p < 0.05) differences between non-encapsulated and encapsulated ND compared with the respective SD or CD samples. The denotes significant (p < 0.05) differences between the non-encapsulated and encapsulated for each treatment; TABLE S1: Polyphenol–polyphenol interactions on antioxidant activity (ORAC assay ( M TE)); TABLE S2: Polyphenol–polyphenol interactions on antiglycation activity (AGEs assay (%)); TABLE S3: Polyphenol–polyphenol interactions on cellular antioxidant activity (DCFH-DA assay (%)).

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