Sweeteners' Influence on In Vitro α-Glucosidase Inhibitory Activity, Cytotoxicity, Stability and In Vivo Bioavailability of the Anthocyanins from Lingonberry Jams

Abstract

Several lines of evidence demonstrate the multiple health-promoting properties of anthocyanins, but little is known regarding the bioavailability of these phytochemicals. Therefore, the stability during storage and bioavailability of anthocyanins from lingonberries jams were determined by HPLC, together with the impact of used sweeteners on their adsorption. Further, the in vitro α-glucosidase inhibition using spectrophotometric methods and cytotoxicity determined on normal and colon cancer cells were communicated. The content of anthocyanins was significantly decreased during storage in coconut sugar-based jam, but was best preserved in jam with fructose and stevia. Fructose and stevia-based jams showed the highest inhibition activity upon α-glucosidase. Lingonberry jams showed no cytotoxic effects on normal cells, but at low concentration reduced the tumor cells viability. Anthocyanins were still detectable in rats' blood streams after 24 h, showing a prolonged bioavailability in rats. This study brings important results that will enable the development of functional food products.

Keywords: anthocyanins; bioavailability; cytotoxicity; lingonberry jams; sweeteners; α-glucosidase.

Figure 1

HPLC profile (532 nm) of anthocyanins in lingonberry jams: (1) cyanidin-3-galactoside; (2) cyanidin-3-glucoside; (3) cyanidin-3-arabinoside.

Figure 2

Changes in HPLC profile of individual anthocyanins from fructose-based jam under different storage conditions: (a)refrigeration; (b) light; (c) dark.

Figure 3

The percentage enzyme inhibition of lingonberry jams. The sweeteners used in jams were Jam 1—sucrose, Jam 2—fructose, Jam 3—erythritol, Jam 4—brown sugar, Jam 5—coconut sugar, Jam 6—stevia, Jam 7—saccharine. Asterisk symbols signify the following levels of statistical significance of differences between jams with sweeteners and unsweetened jam according to one way ANOVA: ** p < 0.0001, * p < 0.001.

Figure 4

Comparative cell viability in the normal fibroblast cell cultures and colon cancer CACO2 cell line treated with each jam extract in concentrations ranging from 0 to 200 µg/mL; upper panels—fibroblasts, lower panels—CACO2 cells. Data are presented as % of the untreated controls, for each experiment mean ± SD, n = 3 is presented. Jam 1 = white sugar, Jam 2 = fructose, Jam 3 = erythritol, Jam 4 = brown sugar, Jam 5 = coconut sugar, Jam 6 = stevia, Jam 7 = saccharine, Jam 8 = unsweetened jam.

Figure 5

Plasma anthocyanin concentration profiles in rats after administration of lingonberry jams. Cy-3-gal: cyanidin-3-galactoside; Cy-3-glu: cyanidin-3-glucoside; Cy-3-ara: cyanidin-3-arabinoside. The sweeteners used in jams were Jam 1—sucrose, Jam 2—fructose, Jam 3—erythritol, Jam 4—brown sugar, Jam 5—coconut sugar, Jam 6—stevia, Jam 7—saccharine. Data are presented as mean ± SD (n = 3).