In Vitro Models for Studying Secondary Plant Metabolite Digestion and Bioaccessibility

Abstract

There is an increased interest in secondary plant metabolites, such as polyphenols and carotenoids, due to their proposed health benefits. Much attention has focused on their bioavailability, a prerequisite for further physiological functions. As human studies are time consuming, costly, and restricted by ethical concerns, in vitro models for investigating the effects of digestion on these compounds have been developed and employed to predict their release from the food matrix, bioaccessibility, and assess changes in their profiles prior to absorption. Most typically, models simulate digestion in the oral cavity, the stomach, the small intestine, and, occasionally, the large intestine. A plethora of models have been reported, the choice mostly driven by the type of phytochemical studied, whether the purpose is screening or studying under close physiological conditions, and the availability of the model systems. Unfortunately, the diversity of model conditions has hampered the ability to compare results across different studies. For example, there is substantial variability in the time of digestion, concentrations of salts, enzymes, and bile acids used, pH, the inclusion of various digestion stages; and whether chosen conditions are static (with fixed concentrations of enzymes, bile salts, digesta, and so on) or dynamic (varying concentrations of these constituents). This review presents an overview of models that have been employed to study the digestion of both lipophilic and hydrophilic phytochemicals, comparing digestive conditions in vitro and in vivo and, finally, suggests a set of parameters for static models that resemble physiological conditions.

Biotransformation of anthocyanins from two purple-fleshed sweet potato accessions in a dynamic gastrointestinal system

“…In vitro GI models used to evaluate digestion of polyphenols such as anthocyanins have utilized dual enzyme pepsinpancreatin digestion to simulate gastric and small intestinal tract digestion that could also be coupled with batch colonic reactors with human gut microflora to assess the impact of human microbial metabolism (Alminger et al, 2014;Tarko, Duda-Chodak, & Zajac, 2013). Such studies have shown major variations in anthocyanin stability of different foods during digestive processes, which appear to be highly dependent on food matrix composition and structure.…”

“…To date, studies of anthocyanin digestion have not utilized computer-controlled dynamic multistage continuous digestion models that can better simulate in vivo conditions (Alminger et al, 2014). The dynamic in vitro digestion system mimics the in vivo dynamics of transit during digestion and considers the varying microbial or digestive conditions in different segments of the GI tract including the ascending colon, transverse colon and descending colon.…”

Estrogenic and Antiestrogenic Activities of Commercial Dietary Supplements Containing Herbal Ingredients and Isoflavones

“…Similarly, all 'IN SAMPLES' except for S2 showed higher antiestrogenic activities (table 3) as compared to the corresponding non-digested extracts at 400E equivalents (table 2). Although the in vitro GI digestion does not completely illustrate the in vivo digestion process, it represents a simple, affordable, and reproducible method for evaluating the availability of bioactive in the bloodstream [52]. The increased estrogenic and antiestrogenic activities of digested supplement extracts in this study show that the GI digestion increased the availability of phytoestrogens in those extracts.…”

Impact of the Pulsed Electric Field Treatment on Bioactive Food Compounds: Bioaccessibility and Bioavailability

“…Therefore, composition of food matrix and determination of the appropriate food processing method has a vital importance to understand bioaccessibility of bioactive compounds and interactions of food ingredients. Both in vitro and in vivo studies are more valuable and useful to estimate stability and bioaccessibility of bioactive compounds from food [56,80].…”