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The human gastrointestinal tract is inhabited by a vast number of microorganisms that are called as the microbiota. Each individual harbors a unique gut microbial composition, this composition evolves throughout the host's lifetime and it is easily affected by internal or external changes. It has been shown that gut microbiota plays a crucial role in host's health and as this complex community has the ability to interact with each other and with the host's immune system, the presence or absence of some major species can affect the homeostasis. Diet can be considered as one of the pivotal factors in modulating the functionality, integrity, and composition of the gut microbiota as the gastrointestinal tract is the first organ exposed to components of the diet. In this review, we have focused on the effects of polyphenols, key compounds of a healthy diet with several biological activities, on the gut microbial composition, their biotransformation by the gut microbiota, and the effect of their reciprocal interactions in human health and disease. K E Y W O R D S biotransformation, gut microbiota, host health, polyphenolsThis is an open access article under the terms of the Creative Commons Attribution License, which permits use, distribution and reproduction in any medium, provided the original work is properly cited.

A complete set of temperature-dependent physical-chemical property data (aqueous solubility (S W), octanol−water partition coefficient (K OW), vapor pressure (P), Henry's law constant (H), octanol−air partition coefficient (K OA), and octanol solubility (S O)) for α-, β-, and γ-hexachlorocyclohexane (HCH) is derived by evaluating, averaging, and regressing all experimentally obtained values reported in the literature. Properties for each isomer are adjusted slightly to ensure thermodynamic consistency. That adjustment is sized according to, and is smaller than, the uncertainty apparent from the range of reported experimental values. The data analysis confirms that an unsually high K OA and an unusually low H reported for β-HCH are in agreement with the measured S W and P values when these are converted to the liquid state. Linear solvation energy relationships fail to predict the observed differences in the partitioning behaviors of the three isomers.

Triclosan (TCS) is a high-volume chemical used as an antimicrobial ingredient in more than 2000 consumer products, such as toothpaste, cosmetics, kitchenware, and toys. We report that brief exposure to TCS, at relatively low doses, causes low-grade colonic inflammation, increases colitis, and exacerbates colitis-associated colon cancer in mice. Exposure to TCS alters gut microbiota in mice, and its proinflammatory effect is attenuated in germ-free mice. In addition, TCS treatment increases activation of Toll-like receptor 4 (TLR4) signaling in vivo and fails to promote colitis in mice. Together, our results demonstrate that this widely used antimicrobial ingredient could have adverse effects on colonic inflammation and associated colon tumorigenesis through modulation of the gut microbiota and TLR4 signaling. Together, these results highlight the need to reassess the effects of TCS on human health and potentially update policies regulating the use of this widely used antimicrobial.

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