Stability and biological activity of Merlot (Vitis vinifera) grape pomace phytochemicals after simulated in vitro gastrointestinal digestion and colonic fermentation

Abstract

a b s t r a c tGrape pomace is an abundant/accessible food industry by-product that contains a wide range of phenolic compounds, which have been related to several health benefits and bioactivities. The aim of this study was to mimic the gastrointestinal digestion and the colonic fermentation of Merlot grape pomace, in order to unravel possible phytochemical contents reductions and the processes associated with them, as a tentative to relate the phenolic compound profiles of the extracts with their biological properties. LC-DAD-ESI/MS suggested that the in vitro digestion process promoted drastic qualitative and quantitative reductions in the phenolic compounds profile of the Merlot grape pomace crude extract. Such alterations could be related to the decreases of some bioactivities of the extract, which seems to be the case of antioxidant and antibacterial properties, although not in a directly proportional manner. However, the simulated colonic fermentation seems to have a positive effect over the extract's antiproliferative potential.

Effects of in vitro gastrointestinal digestion and colonic fermentation on a rosemary (Rosmarinus officinalis L) extract rich in rosmarinic acid

“…Interestingly, the fermented rosemary extract exhibited a considerable cytotoxic activity (GI 50 = 116 µg/mL) against one of the cancer cell lines, namely the HeLa (cervical carcinoma). Corrêa, Haminiuk et al (2017), when analysing grape pomace preparations, reported a similar trend: the crude and digested extracts presented no antiproliferative effects against the same cell lines herein assessed. The corresponding grape pomace fermented extract displayed antiproliferative activity against all tumor cells, with a GI 50 value of 251 µg/mL against HeLa cells.…”

“…Correa, Gonçalves et al (2017), when assessing the antioxidant activity of mate beverages using the same set of techniques, reported that the in vitro digestion and fermentation processes caused a decrease in the antioxidant capabilities of their samples, except for the ABTS assay. Corrêa, Haminiuk et al (2017), on their turn, found that the digestion step did not cause such impacts on a grape pomace hydroalcoholic The results are presented as mean ± SD. In each line different letters mean significant statistical differences (p < 0.05).…”

“…Sagerinic acid and luteolin were the compounds with the most pronounced alterations in the fermentation step, suffering depletions around 42% and 55%, respectively. Correa, Gonçalves et al (2017) observed a more drastic decrease in the TP values for yerba mate tea (33%), whereas Corrêa, Haminiuk et al (2017) reported minimal changes in the total anthocyanin content of a grape pomace ethanolic extract submitted to in vitro fermentation posteriorly to simulated digestion. Zorić et al (2016) performed a comparative study on the stability of rosmarinic acid in water extracts of thyme, winter savory and lemon balm (all Lamiaceae species, such as rosemary) and the stability of pure rosmarinic acid after a two-phase in vitro digestion process using human gastric and duodenal juices.…”

A natural food ingredient based on ergosterol: optimization of the extraction fromAgaricus blazei, evaluation of bioactive properties and incorporation in yogurts

“…The MIC values reveal that the A. blazei ergosterol rich extract displayed excellent bacteriostatic effects against all tested bacteria, and also presented considerable bactericidal potential against these microorganisms, being especially potent against Enterobacter cloacae and Salmonella enteritidis (MBC values of 0.05 mg mL According to their MIC values, natural products can be considered strong inhibitors (MIC below 0.5 mg mL −1 ), moderate inhibitors (MIC between 0.6 and 1.5 mg mL −1 ), and weak inhibitors (MIC above 1.6 mg mL −1 ). 32,36 Thus, based on these parameters, the herein investigated A. blazei ergosterol rich extract can be classified as a strong inhibitor against all bacteria assessed. Moreover, the A. blazei extract was more effective than the antibiotic ampicillin at inhibiting all the tested bacteria, while it was more potent than streptomycin against M. flavus, E. cloacae, S. enteritidis and S. typhimurium.…”

Antioxidant and antimicrobial activities of a purified polysaccharide from yerba mate (Ilex paraguariensis)

“…Standard curves were constructed with trolox (r 2 = 0.99) and the results were expressed as mmol trolox equivalents (TE)/mg lyophilisate material. The DPPH and the ABTS assays were conducted as described previously [25]. The lyophilisate concentrations (mg/mL) providing 50% antioxidant activity were calculated from the graphs of antioxidant activity against the sample concentrations.…”