Abstract
The almost forgotten crop amaranth has gained renewed interest in recent years due to its immense nutritive potential. Health beneficial effects of certain plants are often attributed to secondary plant metabolites such as phenolic compounds. As these compounds undergo significant metabolism after consumption and are in most cases not absorbed very well, it is important to gain knowledge about absorption, biotransformation, and further metabolism in the human body.
Whilst being hardly found in other edible plants, caffeoylisocitric acid represents the most abundant low molecular phenolic compound in many leafy amaranth species. Given that this may be a potentially bioactive compound, gastrointestinal microbial degradation of this substance was investigated in the present study by performing in vitro fermentation tests using three different fecal samples as inocula. The (phenolic) metabolites were analyzed using high-performance liquid chromatography/electrospray ionization tandem mass spectrometry (HPLC-ESI-MS/MS). Furthermore, quantitative polymerase chain reaction (qPCR) analyses were carried out to study the influence on the microbiome and its composition. The in vitro fermentations led to different metabolite profiles depending on the specific donor. For example, the metabolite 3-(4-hydroxyphenyl)propionic acid was observed in one fermentation as the main metabolite, whereas 3-(3-hydroxyphenyl)propionic acid was identified in the other fermentations as important. A significant change in selected microorganisms of the gut microbiota however was not detected.
In conclusion, caffeoylisocitric acid from amaranth, which is a source of several esterified phenolic acids in addition to chlorogenic acid, can be metabolized by the human gut microbiota, but the metabolites produced vary between individuals.
Whilst being hardly found in other edible plants, caffeoylisocitric acid represents the most abundant low molecular phenolic compound in many leafy amaranth species. Given that this may be a potentially bioactive compound, gastrointestinal microbial degradation of this substance was investigated in the present study by performing in vitro fermentation tests using three different fecal samples as inocula. The (phenolic) metabolites were analyzed using high-performance liquid chromatography/electrospray ionization tandem mass spectrometry (HPLC-ESI-MS/MS). Furthermore, quantitative polymerase chain reaction (qPCR) analyses were carried out to study the influence on the microbiome and its composition. The in vitro fermentations led to different metabolite profiles depending on the specific donor. For example, the metabolite 3-(4-hydroxyphenyl)propionic acid was observed in one fermentation as the main metabolite, whereas 3-(3-hydroxyphenyl)propionic acid was identified in the other fermentations as important. A significant change in selected microorganisms of the gut microbiota however was not detected.
In conclusion, caffeoylisocitric acid from amaranth, which is a source of several esterified phenolic acids in addition to chlorogenic acid, can be metabolized by the human gut microbiota, but the metabolites produced vary between individuals.
| Original language | English |
|---|---|
| Pages (from-to) | 375-384 |
| Number of pages | 10 |
| Journal | Food Research International |
| Volume | 100 |
| Issue number | 3 |
| Early online date | 3 Jun 2017 |
| DOIs | |
| Publication status | Published - Oct 2017 |
Bibliographical note
PL, FF, and SHD receive financial support from the ScottisMoh Government Rural and Environmental Sciences and Analytical Services (RESAS). Parts of this work were financially supported by the project “Horticultural Innovation and Learning for Improved Nutrition and Livelihood in East Africa” (FZK 031A248J and FKZ 031A248K), funded within the global food security (GlobE) initiative of the German Federal Ministry of Education and Research and the German Federal Ministry of Economic Cooperation and Development.Keywords
- amaranth
- caffeoylisocitric acid
- chlorogenic acid
- in vitro fermentation
- gastrointestinal microbiome
Access to Document
- Accepted Manuscript
© 2017. This manuscript version is made available under the CC-BY-NC-ND 4.0 license http://creativecommons.org/licenses/by-nc-nd/4.0/