Proanthocyanidins: Impact on Gut Microbiota and Intestinal Action Mechanisms in the Prevention and Treatment of Metabolic Syndrome

A-type proanthocyanidins: Sources, structure, bioactivity, processing, nutrition, and potential applications

A-type proanthocyanidins (PAs) are a subgroup of PAs that differ from B-type PAs by the presence of an ether bond between two consecutive constitutive units. This additional C-O-C bond gives them a more stable and hydrophobic character. They are of increasing interest due to their potential multiple nutritional effects with low toxicity in food processing and supplement development. They have been identified in several plants. However, the role of A-type PAs, especially their complex polymeric form (degree of polymerization and linkage), has not been specifically discussed and explored. Therefore, recent advances in the physicochemical and structural changes of A-type PAs and their functional properties during extraction, processing, and storing are evaluated. In addition, discussions on the sources, structures, bioactivities, potential applications in the food industry, and future research trends of their derivatives are highlighted. Litchis, cranberries, avocados, and persimmons are all favorable plant sources. Α-type PAs contribute directly or indirectly to human nutrition via the regulation of different degrees of polymerization and bonding types. Thermal processing could have a negative impact on the amount and structure of A-type PAs in the food matrix. More attention should be focused on nonthermal technologies that could better preserve their architecture and structure. The diversity and complexity of these compounds, as well as the difficulty in isolating and purifying natural A-type PAs, remain obstacles to their further applications. A-type PAs have received widespread acceptance and attention in the food industry but have not yet achieved their maximum potential for the future of food. Further research and development are therefore needed.

Mechanism of procyanidins for health functionality by improving the intestinal environment

Procyanidins are one of the polyphenols consisting of multiple flavan-3-ols (eg epicatechin). They have a complex chemical structure, with the degree of polymerization and linked position of flavan-3-ols varying among various foods, such as apples and chocolate. Physiological functional studies of procyanidins have investigated their mechanisms in cells and animals based on their antioxidant effects. Recently, the intestinal environment, including the intestinal microflora, has played an important role in the energy metabolism and health status of the host. Regulation of the intestinal environment by dietary polyphenols is becoming a new concept in health functions, and we have begun to investigate the mechanism of apple procyanidins, focusing on the gut microbiota and metabolites in our functional research. In this minireview, we will discuss the effects of procyanidin ingestion on the gut microbiota and metabolites.

Natural products for gastric carcinoma prevention and treatment: Focus on their antioxidant stress actions in the Correa's cascade

BACKGROUND

Correa's cascade is a pathological process beginning from gastritis to gastric precancerous lesions, and finally to gastric carcinoma (GC). While the pathogenesis of GC remains unclear, oxidative stress plays a prominent role throughout the entire Correa's cascade process. Studies have shown that some natural products (NPs) could halt and even reverse the development of the Correa's cascade by targeting oxidative stress.

METHODS

To review the effects and mechanism by which NPs inhibit the Correa's cascade through targeting oxidative stress, data were collected from PubMed, Embase, Web of Science, ScienceDirect, and China National Knowledge Infrastructure databases from initial establishment to April 2023. NPs were classified and summarized by their mechanisms of action.

RESULTS

NPs, such as terpenoid, polyphenols and alkaloids, exert multistep antioxidant stress effects on the Correa's cascade. These effects include preventing gastric mucosal inflammation (stage 1), reversing gastric precancerous lesions (stage 2), and inhibiting gastric carcinoma (stage 3). NPs can directly impact the conversion of gastritis to GC by targeting oxidative stress and modulating signaling pathways involving IL-8, Nrf2, TNF-α, NF-κB, and ROS/MAPK. Among which polyphenols have been studied more and are of high research value.

CONCLUSIONS

NPs display a beneficial multi-step action on the Correa's cascade, and have potential value for clinical application in the prevention and treatment of gastric cancer by regulating the level of oxidative stress.

Multi-Omics Analysis to Understand the Effects of Dietary Proanthocyanidins on Antioxidant Capacity, Muscle Nutrients, Lipid Metabolism, and Intestinal Microbiota in Cyprinus carpio

Proanthocyanidins (Pros), a natural polyphenolic compound found in grape seed and other plants, have received significant attention as additives in animal feed. However, the specific mechanism by which Pros affect fish health remains unclear. Therefore, the aim of this study was to investigate the potential effects of dietary Pro on common carp by evaluating biochemical parameters and multi-omics analysis. The results showed that Pro supplementation improved antioxidant capacity and the contents of polyunsaturated fatty acids (n-3 and n-6) and several bioactive compounds. Transcriptomic analysis demonstrated that dietary Pro caused an upregulation of the sphingolipid catabolic process and the lysosome pathway, while simultaneously downregulating intestinal cholesterol absorption and the PPAR signaling pathway in the intestines. Compared to the normal control (NC) group, the Pro group exhibited higher diversity in intestinal microbiota and an increased relative abundance of Cetobacterium and Pirellula. Furthermore, the Pro group had a lower Firmicutes/Bacteroidetes ratio and a decreased relative abundance of potentially pathogenic bacteria. Collectively, dietary Pro improved antioxidant ability, muscle nutrients, and the diversity and composition of intestinal microbiota. The regulation of lipid metabolism and improvement in muscle nutrients were linked with changes in the intestinal microbiota.

Antioxidative Effects of Black Currant and Cornelian Cherry Juices in Different Tissues of an Experimental Model of Metabolic Syndrome in Rats

A Western-style diet, rich in fat and simple sugars, is the main risk factor for a significant number of chronic diseases and disorders, as well as for a progression of metabolic syndrome (MetS). One of the key mechanisms involved in MetS development is increased oxidative stress caused by the accumulation of body fat. Some dietary polyphenols have shown a protective role in preventing oxidative-stress-induced damage. We investigated the difference in the oxidative response of plasma, liver, and visceral adipose tissue in rats fed with a high-fat high-fructose (HFF) diet for ten weeks, and the effectiveness of polyphenol-rich juices (black currant (BC) and cornelian cherry (CC)) in HFF-diet-induced oxidative stress prevention. The most prominent impact of the HFF diet on redox parameters was recorded in the liver, whereas adipose tissue showed the most potent protection mechanisms against oxidative stress. Consumption of both juices decreased advanced oxidation protein product (AOPP) level in plasma, increased paraoxonase1 (PON1) activity in the liver, and significantly decreased total oxidative status (TOS) in adipose tissue. BC exerted stronger antioxidative potential than CC and decreased the superoxide anion radical (O₂^•-) level in the liver. It also reduced TOS, total antioxidative status (TAS), and malondialdehyde (MDA) concentration in adipose tissue. The multiple linear regression analysis has shown that the best predictors of MetS development, estimated through the increase in visceral adiposity, were superoxide dismutase (SOD), AOPP, TOS, and TAS. The consumption of polyphenol-rich juices may provide a convenient approach for the systemic reduction of oxidative stress parameters.