Diverse roles of microbial indole compounds in eukaryotic systems

Abstract

Indole and its derivatives are widespread across different life forms, functioning as signalling molecules in prokaryotes and with more diverse roles in eukaryotes. A majority of indoles found in the environment are attributed to bacterial enzymes converting tryptophan into indole and its derivatives. The involvement of indoles among lower organisms as an interspecies and intraspecies signal is well known, with many reports showing that inter-kingdom interactions involving microbial indole compounds are equally important as they influence defence systems and even the behaviour of higher organisms. This review summarizes recent advances in our understanding of the functional properties of indole and indole derivatives in diverse eukaryotes. Furthermore, we discuss current perspectives on the role of microbial indoles in human diseases such as diabetes, obesity, atherosclerosis, and cancers. Deciphering the function of indoles as biomarkers of metabolic state will facilitate the formulation of diet-based treatments and open unique therapeutic opportunities.

Antibacterial and Antibiofilm Activities of Chloroindoles Against Vibrio parahaemolyticus

“…Interestingly, the four halogenated indoles dose-dependently inhibited indole production in V. parahaemolyticus (Figure 3C). Indole plays important roles in various bacterial phenotypes and even in eukaryotic immunity (Lee and Lee, 2010;Lee et al, 2015;Kumar et al, 2021). Particularly, indole has been considered as a possible quorum sensing molecule that modulate biofilm formation and virulence in various bacteria (Lee et al, 2015(Lee et al, , 2016.…”

“…Indole and its aromatic heterocyclic structure are popularly used as synthetic starting points in the pharmaceutical industry. Moreover, indole acts as an interspecies and interkingdom signaling molecule that directs various bacterial functions (Lee and Lee, 2010;Lee et al, 2012bLee et al, , 2015Kumar et al, 2021). Indole and its derivatives are viewed as potential antivirulence compounds against antibiotic-resistant pathogens because of their ability to inhibit quorum sensing and the production of virulence factors.…”

The Anticancer Agent 3,3'-Diindolylmethane Inhibits Multispecies Biofilm Formation by Acne-Causing Bacteria and Candida albicans

“…Indole is synthesized from tryptophan by tryptophanase by many gut and environmental bacteria, and is present in animal intestinal tracts and human skin ( 11 ). Indole and its derivatives act as interspecies and interkingdom signaling molecules and play important roles in bacterial pathogenesis and eukaryotic immunity ( 12 , 13 ). In particular, indole controls quorum sensing and biofilm formation of its own species and in other bacterial species ( 12 ).…”

Machine Learning Aided Construction of the Quorum Sensing Communication Network for Human Gut Microbiota

“…AI-2 also ranks rst with the highest genus-level counts (138 genus) than the other languages, which is in line with what has been broadly observed 13 . Many overlaps of the languages being spoken (between different microbes) include AI-2 or indole for various genus, which also indicates that both of them are widely recognizable languages playing a major role for inter-specie communications 54,55 . We found that those traditionally often considered as intraspecies languages (AHLs, CAI-1, HAQs, and DSFs) may also be involved in some interspecies communications.…”