Human gut microbiota stratified by (+)-catechin metabolism dynamics reveals colon region-dependent metabolic profile

Mathematical modeling of fluid dynamics in in vitro gut fermentation systems: A new tool to improve the interpretation of microbial metabolism

In vitro systems are widely employed to assess the impact of dietary compounds on the gut microbiota and their conversion into beneficial bacterial metabolites. However, the complex fluid dynamics and multi-segmented nature of these systems can complicate the comprehensive analysis of dietary compound fate, potentially confounding physical dilution or washout with microbial catabolism. In this study, we developed fluid dynamics models based on sets of ordinary differential equations to simulate the behavior of an inert compound within two commonly used in vitro systems: the continuous two-stage PolyFermS system and the semi-continuous multi-segmented SHIME® system as well as into various declinations of those systems. The models were validated by investigating the fate of blue dextran, demonstrating excellent agreement between experimental and modeling data (with r2 values ranging from 0.996 to 0.86 for different approaches). As a proof of concept for the utility of fluid dynamics models in in vitro system, we applied generated models to interpret metabolomic data of procyanidin A2 (ProA2) generated from the addition of proanthocyanidin (PAC)-rich cranberry extract to both the PolyFermS and SHIME® systems. The results suggested ProA2 degradation by the gut microbiota when compared to the modeling of an inert compound. Models of fluid dynamics developed in this study provide a foundation for comprehensive analysis of gut metabolic data in commonly utilized in vitro PolyFermS and SHIME® bioreactor systems and can enable a more accurate understanding of the contribution of bacterial metabolism to the variability in the concentration of target metabolites.

Extraction of (+)-catechin from oak (Quercus spp.) bark: Optimization of pretreatment and extraction conditions

Oaks (Quercus L., Fagaceae) are a widespread tree species worldwide, and in Hungary they account for nearly 30 % of the forests. Their wood is valuable, but their bark is considered as a by-product. Oak bark, available in large quantities but with no dedicated use, contains a significant amount of valuable extractives. Its (+)-catechin content is around 1 %. (+)-Catechin is mostly used for food industry, medicine and many other industrial purposes, representing a significant financial value. The aim of the present research was to compare the (+)-catechin concentrations in the bark of the most important oak species found in Hungary and to optimize sample pretreatment (conservation) and extraction methods in order to achieve fast and efficient extraction. From these species the highest concentrations were measured in Q. robur and Q. robur ssp. slavonica (8-12 mg (+)-catechin/g dry bark). The combination of microwave sample pretreatment and microwave assisted extraction proved to be the most time- and cost-effective method. The utilization of the extracted bark powder for energetic purposes requires further investigations.

The gut-derived metabolites as mediators of the effect of healthy nutrition on the brain

Nutrition is now well recognized to be an environmental factor which positively or negatively influences the risk to develop neurological and psychiatric disorders. The gut microbiota has recently been shown to be an important actor mediating the relationship between environmental factors, including nutrition, and brain function. While its composition has been widely studied and associated with the risk of brain diseases, the mechanisms underlying the relationship between the gut and brain diseases remain to be explored. The wide range of bioactive molecules produced by the gut microbiota, called gut-derived metabolites (GDM), represent new players in the gut to brain interactions and become interesting target to promote brain health. The aim of this narrative review is to highlight some GDMs of interest that are produced in response to healthy food consumption and to summarize what is known about their potential effects on brain function. Overall, GDMs represent future useful biomarkers for the development of personalized nutrition. Indeed, their quantification after nutritional interventions is a useful tool to determine individuals' ability to produce microbiota-derived bioactive compounds upon consumption of specific food or nutrients. Moreover, GDMs represent also a new therapeutic approach to counteract the lack of response to conventional nutritional interventions.