Abstract
Intestinal transepithelial transport of glucose is mediated by glucose transporters, and affects postprandial blood-glucose levels. This study investigates the effect of wood extracts rich in hydrolyzable tannins (HTs) that originated from sweet chestnut (Castanea sativa Mill.) and oak (Quercus petraea) on the expression of glucose transporter genes and the uptake of glucose and HT constituents in a 3D porcine-small-intestine epithelial-cell model. The viability of epithelial cells CLAB and PSI exposed to different HTs was determined using alamarBlue®. qPCR was used to analyze the gene expression of SGLT1, GLUT2, GLUT4, and POLR2A. Glucose uptake was confirmed by assay, and LC–MS/ MS was used for the analysis of HT bioavailability. HTs at 37 µg/mL were found to adversely affect cell viability and downregulate POLR2A expression. HT from wood extract Tanex at concentrations of 4 µg/mL upregulated the expression of GLUT2, as well as glucose uptake at 1 µg/mL. The time-dependent passage of gallic acid through enterocytes was influenced by all wood extracts compared to gallic acid itself as a control. These results suggest that HTs could modulate glucose uptake and gallic acid passage in the 3D cell model.
Highlights
Finding a suitable natural bioactive substance that could effectively replace banned nutritive antibiotics is crucial to animal breeders, feed producers, and consumers [1]
Tannins can be classified as hydrolyzable tannins (HTs), which can be hydrolyzed to gallic acid and glucose, and condensed tannins (CTs), which are composed of flavonoids [4,5]
Viability of Cells Exposed to Wood Extracts
Summary
Finding a suitable natural bioactive substance that could effectively replace banned nutritive antibiotics is crucial to animal breeders, feed producers, and consumers [1]. The bioaccessibility of active nutrient components in the gastrointestinal tract, their bioavailability to the organism, and their activation of organic systems could positively affect animal performance [2]. Tannins can be classified as hydrolyzable tannins (HTs), which can be hydrolyzed to gallic acid and glucose, and condensed tannins (CTs), which are composed of flavonoids [4,5]. HTs are polyesters with organic acid and sugar moieties. The sugar component is usually glucose, and if the organic acid is gallic or ellagic acid, compounds are called gallotannins or ellagitannins. These compounds can be hydrolyzed using dilute acids, which cause hydrolytic cleavages of the respective sugar and acid moieties [6]
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