鞣花酸和尿石素类代谢产物的生物活性及其对肠道健康的作用研究进展

鞣花酸（ellagicacid,EA）作为一种天然抗氧化剂,是一种广泛存在于众多蔬菜、水果及坚果中的多酚类化合物,可经过肠道微生物的代谢生成尿石素类物质。但EA在肠道中的利用度较低;而其代谢产物尿石素类较易被肠道吸收,故被认为是发挥EA抗氧化作用的物质基础。动物模型及临床试验研究表明,EA及其代谢产物尿石素可有效改善肠道微生物菌群、促进肠道健康、预防或抑制肠道疾病的发生发展。EA及尿石素的营养生理作用主要包括抗氧化、抗炎及微生物菌群调控等作用。本文综述了EA及尿石素的结构、代谢途径、生物活性及其在肠道疾病研究中的应用。     

Natural Dibenzo-α-Pyrones: Friends or Foes?

Natural dibenzo-α-pyrones (DAPs) can be viewed from two opposite angles. From one angle, the gastrointestinal metabolites urolithins are regarded as beneficial, while from the other, the emerging mycotoxin alternariol and related fungal metabolites are evaluated critically with regards to potential hazardous effects. Thus, the important question is: can the structural characteristics of DAP subgroups be held responsible for distinct bioactivity patterns? If not, certain toxicological and/or pharmacological aspects of natural DAPs might yet await elucidation. Thus, this review focuses on comparing published data on the two groups of natural DAPs regarding both adverse and beneficial effects on human health. Literature on genotoxic, estrogenic, endocrine-disruptive effects, as well as on the induction of the cellular anti-oxidative defense system, anti-inflammatory properties, the inhibition of kinases, the activation of mitophagy and the induction of autophagy, is gathered and critically reviewed. Indeed, comparing published data suggests similar bioactivity profiles of alternariol and urolithin A. Thus, the current stratification into hazardous Alternaria toxins and healthy urolithins seems debatable. An extrapolation of bioactivities to the other DAP sub-class could serve as a promising base for further research. Conclusively, urolithins should be further evaluated toward high-dose toxicity, while alternariol derivatives could be promising chemicals for the development of therapeutics.     

Bacterial metabolism as responsible of beneficial effects of phytoestrogens on human health

Abstract

Phytoestrogens (PE) are compounds found in plants such as soy (isoflavones), flax seeds and cereals (lignans) and pomegranates (ellagitannins). PE have shown estrogenic/antiestrogenic, antioxidant, anti-inflammatory, antineoplastic and apoptotic activities. The human studies are showing promising although inconsistent results about the beneficial effects of PE on ameliorating the menopausal symptoms or reducing the risk of certain cancers, cardiovascular disease or diabetes. The effects of PE on the organism are mediated by the intestinal microbiota, which transforms them into bioactive PE such as genistein, equol, enterolignans and certain urolithins. In this work, we review the most recent findings about the bacteria able to metabolize PE, together with the latest studies on the effects of PE on health. In addition, we describe the possible factors hindering the demonstration of the beneficial effect of PE on health, evincing the importance of measuring the actual circulating PE in order to encompass the variability of PE metabolism due to the intestinal microbiota. With this in mind, we also explore an approach to ensure the access to bioactive PE.     

鞣花酸代谢产物——尿石素的研究进展

鞣花单宁和鞣花酸是广泛分布于多种蔬菜、水果和坚果中的多酚类抗氧化剂,其在胃肠道的吸收较差,生物利用率较低,但部分会被哺乳动物肠道微生物转化为更易吸收的尿石素类代谢产物。因此,人们推测这些代谢产物可能为鞣花单宁及鞣花酸发挥生物学活性的最终物质基础。本文对近年来国内外有关尿石素化学性质和抗氧化、抗炎、抗癌以及调节肠道菌群等生物活性的研究进行综述,以期为富含鞣花单宁及鞣花酸类食品的科学利用提供借鉴。     

Metabolic and microbial modulation of phenolic compounds from raspberry leaf extract under in vitro digestion and fermentation

Raspberry leaves, by-products in raspberry production, are also a rich source of bioactive phytochemicals. In this study, the changes of phenolic compounds in raspberries leaf extract (RLE) under in vitro digestion and colonic fermentation were further studied by HPLC-MS analysis and 16S rRNA. The results showed that the phenolic compounds in RLE were relatively stable during in vitro gastric digestion; however, in the subsequent intestinal digestion and colonic fermentation, their content decreased sharply. A large amount of hydroxyphenylpropionic acid, hydroxyphenylacetic acid and urolithins were produced under the action of gut microbiota. Moreover, compared with corresponding control, RLE significantly reduced the ratio of Firmicutes/Bacteroidetes in all volunteers, increased the relative abundances of some beneficial bacteria, Enterococcus, Prevotella, and decreased the relative abundances of potential pathogens, Clostridium and Faecalibacterium. These findings suggest that RLE during in vitro digestion and fermentation has positive effects on gut microbiota and potential value of maintaining intestinal health.     

Where to Look into the Puzzle of Polyphenols and Health? The Postbiotics and Gut Microbiota Associated with Human Metabotypes

The full consensus on the role of dietary polyphenols as human‐health‐promoting compounds remains elusive. The two‐way interaction between polyphenols and gut microbiota (GM) (i.e., modulation of GM by polyphenols and their catabolism by the GM) is determinant in polyphenols’ effects. The identification of human metabotypes associated with a differential gut microbial metabolism of polyphenols has opened new research scenarios to explain the inter‐individual variability upon polyphenols consumption. The metabotypes unequivocally identified so far are those involved in the metabolism of isoflavones (equol and(or) O‐desmethylangolesin producers versus non‐producers) and ellagic acid (urolithin metabotypes, including producers of only urolithin‐A (UM‐A), producers of urolithin‐A, isourolithin‐A, and urolithin‐B (UM‐B), and non‐producers (UM‐0)). In addition, the microbial metabolites (phenolic‐derived postbiotics) such as equol, urolithins, valerolactones, enterolactone, and enterodiol, and 8‐prenylnaringenin, among others, can exert differential health effects. The knowledge is updated and position is taken here on i) the two‐way interaction between GM and polyphenols, ii) the evidence between phenolic‐derived postbiotics and health, iii) the role of metabotypes as biomarkers of GM and the clustering of individuals depending on their metabotypes (metabotyping) to explain polyphenols’ effects, and iv) the gut microbial metabolism of catecholamines to illustrate the intersection between personalized nutrition and precision medicine.