A benzoxazole derivative as an inhibitor of anaerobic choline metabolism by human gut microbiota

Identification of Polymethoxyflavones (PMFs) from Orange Peel and Their Inhibitory Effects on the Formation of Trimethylamine (TMA) and Trimethylamine-N-oxide (TMAO) Using cntA/B and cutC/D Enzymes and Molecular Docking

This study investigates the inhibitory effects of polymethoxyflavones (PMFs) on enzymes involved in the production of trimethylamine (TMA) and trimethylamine-N-oxide (TMAO). PMFs were isolated from Valencia orange peel and identified using column separation and NMR techniques. The findings reveal that nobiletin and 3,6,7,8,2',5'-hexamethoxyflavone significantly suppress cntA/B and cutC/D, respectively. Furthermore, 3,6,7,8,2',5'-hexamethoxyflavone decreases the level of TMAO formation by suppressing the FMO3 mRNA level. This study elucidates that specific structural features of PMFs can contribute to their interactions with enzymes. Our study represents the first demonstration of the ability of PMFs to mitigate the risk of cardiovascular disease (CVD) by inhibiting enzymes responsible for TMA production, which are generated by gut microbiomes. Furthermore, we introduce a novel model system utilizing TMA-induced HepG2 cells to assess and compare the inhibitory effects of PMFs on TMAO production. These findings could pave the way for the development of novel therapeutic approaches to manage CVD.

Targeting the human gut microbiome with small-molecule inhibitors

The human gut microbiome is a complex microbial community that is strongly linked to both host health and disease. However, the detailed molecular mechanisms underlying the effects of these microorganisms on host biology remain largely uncharacterized. The development of non-lethal, small-molecule inhibitors that target specific gut microbial activities enables a powerful but underutilized approach to studying the gut microbiome and a promising therapeutic strategy. In this Review, we will discuss the challenges of studying this microbial community, the historic use of small-molecule inhibitors in microbial ecology, and recent applications of this strategy. We also discuss the evidence suggesting that host-targeted drugs can affect the growth and metabolism of gut microbes. Finally, we address the issues of developing and implementing microbiome-targeted small-molecule inhibitors and define important future directions for this research.

Contribution of Trimethylamine N-Oxide (TMAO) to Chronic Inflammatory and Degenerative Diseases

Trimethylamine N-oxide (TMAO) is a metabolite produced by the gut microbiota and has been mainly associated with an increased incidence of cardiovascular diseases (CVDs) in humans. There are factors that affect one's TMAO level, such as diet, drugs, age, and hormones, among others. Gut dysbiosis in the host has been studied recently as a new approach to understanding chronic inflammatory and degenerative diseases, including cardiovascular diseases, metabolic diseases, and Alzheimer's disease. These disease types as well as COVID-19 are known to modulate host immunity. Diabetic and obese patients have been observed to have an increase in their level of TMAO, which has a direct correlation with CVDs. This metabolite is attributed to enhancing the inflammatory pathways through cholesterol and bile acid dysregulation, promoting foam cell formation. Additionally, TMAO activates the transcription factor NF-κB, which, in turn, triggers cytokine production. The result can be an exaggerated inflammatory response capable of inducing endoplasmic reticulum stress, which is responsible for various diseases. Due to the deleterious effects that this metabolite causes in its host, it is important to search for new therapeutic agents that allow a reduction in the TMAO levels of patients and that, thus, allow patients to be able to avoid a severe cardiovascular event. The present review discussed the synthesis of TMAO and its contribution to the pathogenesis of various inflammatory diseases.

Gut Microbial-Derived Metabolites as Immune Modulators of T Helper 17 and Regulatory T Cells

The gut microbiota and its derived metabolites greatly impact the host immune system, both innate and adaptive responses. Gut dysbiosis and altered levels of microbiota-derived metabolites have been described in several immune-related and immune-mediated diseases such as intestinal bowel disease, multiple sclerosis, or colorectal cancer. Gut microbial-derived metabolites are synthesized from dietary compounds ingested by the host or host-produced metabolites, and additionally, some bacterial products can be synthesized de novo. In this review, we focus on the two first metabolites families including short-chain fatty acids, indole metabolites, polyamines, choline-derived compounds, and secondary bile acids. They all have been described as immunoregulatory molecules that specifically affect the adaptive immune system and T helper 17 and regulatory T cells. We discuss the mechanisms of action and the consequences in health and diseases related to these gut microbial-derived metabolites. Finally, we propose that the exogenous administration of these molecules or other compounds that bind to their immunoregulatory receptors in a homologous manner could be considered therapeutic approaches.

The Role of Gut Microbiota and Trimethylamine N-oxide in Cardiovascular Diseases

Changes in the intestinal flora and its metabolites have been associated with cardiovascular disease (CVD). Short-chain fatty acids, bile acids, and especially trimethylamine N-oxide (TMAO), an endothelial toxic factor produced by gut microbiota from phosphatidylcholine in meat, have been identified to be closely related to endothelial cell dysfunction as well as tightly affiliated with CVD, the two main types being coronary artery disease (CAD) and coronary microvascular disease (CMVD). We discuss how changes in the gut flora and the metabolite TMAO contribute to the development of CAD and CMVD. The above insight might serve as a stepping stone for novel CAD and CMVD diagnostics and therapies centered on microbiota.

Understanding Choline Bioavailability and Utilization: First Step Toward Personalizing Choline Nutrition

Choline is an essential macronutrient involved in neurotransmitter synthesis, cell-membrane signaling, lipid transport, and methyl-group metabolism. Nevertheless, the vast majority are not meeting the recommended intake requirement. Choline deficiency is linked to nonalcoholic fatty liver disease, skeletal muscle atrophy, and neurodegenerative diseases. The conversion of dietary choline to trimethylamine by gut microbiota is known for its association with atherosclerosis and may contribute to choline deficiency. Choline-utilizing bacteria constitutes less than 1% of the gut community and is modulated by lifestyle interventions such as dietary patterns, antibiotics, and probiotics. In addition, choline utilization is also affected by genetic factors, further complicating the impact of choline on health. This review overviews the complex interplay between dietary intakes of choline, gut microbiota and genetic factors, and the subsequent impact on health. Understanding of gut microbiota metabolism of choline substrates and interindividual variability is warranted in the development of personalized choline nutrition.