Table 2.
List of metabolites released by microbiota
| Metabolite | Effect on DNA methylation |
|---|---|
| p-Cresol | It induces the expression of DNA methyltransferases 1, 3a, and 3b and it is associated with CpG hypermethylation of Klotho gene [152], a regulator of vitamin D metabolism [153]. |
| Hydrogen sulphide (H2S) | Involved in the neutralisation of ROS. It increases DNA methylation [154]. |
|
Riboflavin (vitamin B2) Pyridoxine (vitamin B6) Cobalamin (vitamin B12) |
Cofactor involved in DNA methylation metabolism [155, 156]. |
| Folate (vitamin B9) | It acts as a methyl donor involved in DNA methylation metabolism [155, 156]. |
| It reduces the activity of DNA methyltransferase [157]. | |
| Choline | It acts as a methyl donor that can be recruited by human gut microbiota, reducing its availability [158]. |
| Involved in DNA methylation and gene expression in murine colitis model, an inflammatory disease [159]. | |
| Betaine | It acts as a methyl donor involved in DNA methylation reactions [156, 160]. |
| Associated with changes in DNA methyltransferases and coupled with changes in DNA methylation [161]. | |
| Ammonium (NH4) | Inverse correlation between faecal NH3 and LINE-1 gene methylation [162]. |
| α-ketoglutarate | Involved in (de)methylation as a co-factor of histone demethylases and TET family [163, 164]. |
| L-ascorbic acid (vitamin C) | It exerts a strong influence on active DNA demethylation. It enhances TET-mediated generation of 5-hydroxymethylation [165]. |
ROS reactive oxygen species, NH3 ammonia, LINE-1 long interspersed element-1, TET ten–eleven translocation
Adapted from Mischke et al. [147]