The Effect of Tomatine on Gene Expression and Cell Monolayer Integrity in Caco-2.

More understanding of the risk-benefit effect of the glycoalkaloid tomatine is required to be able to estimate the role it might play in our diet. In this work, we focused on effects towards intestinal epithelial cells based on a Caco-2 model in order to analyze the influence on the cell monolayer integrity and on the expression levels of genes involved in cholesterol/sterol biosynthesis (LDLR), lipid metabolism (NR2F2), glucose and amino acid uptake (SGLT1, PAT1), cell cycle (PCNA, CDKN1A), apoptosis (CASP-3, BMF, KLF6), tight junctions (CLDN4, OCLN2) and cytokine-mediated signaling (IL-8, IL1ß, TSLP, TNF-α). Furthermore, since the bioactivity of the compound might vary in the presence of a food matrix and following digestion, the influence of both pure tomatine and in vitro digested tomatine with and without tomato fruit matrix was studied. The obtained results suggested that concentrations <20 µg/mL of tomatine, either undigested or in vitro digested, do not compromise the viability of Caco-2 cells and stimulate cytokine expression. This effect of tomatine, in vitro digested tomatine or in vitro digested tomatine with tomato matrix differs slightly, probably due to variations of bioactivity or bioavailability of the tomatine. The results lead to the hypothesis that tomatine acts as hormetic compound that can induce beneficial or risk toxic effects whether used in low or high dose.

Functional Starters for Functional Yogurt.

In this study, we investigated the multifunctionality (microbial starters and probiotics) of Lactobacillus plantarum WCFS1 and Lactobacillus plantarum CECT 8328 strains used as microbial starters for the production of yogurt in combination with Lactobacillus delbrueckii ssp. bulgaricus and Streptococcus thermophilus. The ability of the probiotic strains to survive oro-gastrointestinal stresses was monitored by an in vitro assay simulating the human digestive tract. The transcriptional level of several genes involved in the immune response suggested that the probiotic strains may have a favorable influence on immunomodulation. Overall, this study revealed that the tested Lactobacilli exhibited suitable technological features for yogurt production and might be used to formulate novel food with immunomodulating effects.

Probiotic abilities of riboflavin-overproducing Lactobacillus strains: a novel promising application of probiotics.

The probiotic potential of Lactobacillus plantarum and Lactobacillus fermentum strains, capable of overproducing riboflavin, was investigated. The riboflavin production was quantified in co-cultures of lactobacilli and human intestinal epithelial cells, and the riboflavin overproduction ability was confirmed. When milk and yogurt were used as carrier matrices, L. plantarum and L. fermentum strains displayed a significant ability to survive through simulated gastrointestinal transit. Adhesion was studied on both biotic and abiotic surfaces. Both strains adhered strongly on Caco-2 cells, negatively influenced the adhesion of Escherichia coli O157:H7, and strongly inhibited the growth of three reference pathogenic microbial strains. Resistance to major antibiotics and potential hemolytic activity were assayed. Overall, this study reveals that these Lactobacillus stains are endowed with promising probiotic properties and thus are candidates for the development of novel functional food which would be both enriched in riboflavin and induce additional health benefits, including a potential in situ riboflavin production, once the microorganisms colonize the host intestine.

Barley ß-glucans-containing food enhances probiotic performances of beneficial bacteria.

Currently, the majority of prebiotics in the market are derived from non-digestible oligosaccharides. Very few studies have focused on non-digestible long chain complex polysaccharides in relation to their potential as novel prebiotics. Cereals ß-glucans have been investigated for immune-modulating properties and beneficial effects on obesity, cardiovascular diseases, diabetes, and cholesterol levels. Moreover, ß-glucans have been reported to be highly fermentable by the intestinal microbiota in the caecum and colon, and can enhance both growth rate and lactic acid production of microbes isolated from the human intestine. In this work, we report the effects of food matrices containing barley ß-glucans on growth and probiotic features of four Lactobacillus strains. Such matrices were able to improve the growth rate of the tested bacteria both in unstressed conditions and, importantly, after exposure to in vitro simulation of the digestive tract. Moreover, the effect of ß-glucans-containing food on bacterial adhesion to enterocyte-like cells was analyzed and a positive influence on probiotic-enterocyte interaction was observed.