Histone-deacetylase inhibition and butyrate formation: Fecal slurry incubations with apple pectin and apple juice extracts.
OBJECTIVE
Butyrate plays a major role among the short-chained fatty acids formed by the microbial flora of the colon. It is considered to be an important nutrient of the colon mucosa and has been shown to trigger differentiation and apoptosis of colon-derived cells in culture. Inhibition of histone deacetylase (HDAC) seems to play a central role in these effects. Butyrate was thus suggested to act as a chemopreventive metabolite that can prevent the occurrence of colorectal cancer, one of the most abundant types of cancer in Western industrialized countries. Some polymeric carbohydrates such as pectin, resistant to digestion in the small intestine, have been shown to serve as substrates for butyrate formation by the microflora of the colon.


METHODS
In this study we investigated fermentation supernatants (FSs) from incubations of human fecal slurry with apple pectin and with polyphenol-rich apple juice extracts (AJEs).


RESULTS
We found that FSs from fermentations with pectin were rich in butyrate and very active in HDAC inhibition in nuclear extracts prepared from the colon tumor cell lines HT-29 and Caco-2 and in intact HeLa Mad 38 cells bearing a reporter gene driven by HDAC inhibition. The butyrate levels explained most of the HDAC-inhibitory potency in FSs from pectin-rich fermentations. FSs from fermentations with AJEs showed lower butyrate yields but comparable HDAC inhibition. Combined incubations of pectin with AJEs led to effects similar to those with FSs from incubations with pectin as the only substrate added. These effects could not be explained by a direct HDAC-inhibitory potency of AJEs. Furthermore, the FSs were not cytotoxic at the HDAC-inhibitory concentrations.


CONCLUSIONS
These findings suggest that butyrate is the most relevant HDAC inhibitor formed in fermentations of human fecal slurry with apple pectin, whereas addition of AJEs leads to the formation of butyrate and other, yet unknown, HDAC inhibitors.
Waldecker
Markus
M
Food Chemistry and Toxicology, University of Kaiserslautern, Kaiserslautern, Germany.
Kautenburger
Tanja
T
Daumann
Heike
H
Veeriah
Selveraju
S
Will
Frank
F
Dietrich
Helmut
H
Pool-Zobel
Beatrice Louise
BL
Schrenk
Dieter
D
D000107:Acetylation / Q000187:drug effects; D002087:Butyrates / Q000378:metabolism / Q000494:pharmacology*; D018938:Caco-2 Cells; D003106:Colon / Q000378:metabolism / Q000382:microbiology; D004791:Enzyme Inhibitors / Q000494:pharmacology; D005232:Fatty Acids, Volatile / Q000096:biosynthesis / Q000494:pharmacology; D005243:Feces / Q000382:microbiology*; D005285:Fermentation; D019073:HT29 Cells; D006367:HeLa Cells; D056572:Histone Deacetylase Inhibitors; D006657:Histones / Q000378:metabolism; D006801:Humans; D027845:Malus / Q000737:chemistry*; D010368:Pectins / Q000378:metabolism*; D010936:Plant Extracts / Q000737:chemistry / Q000378:metabolism
D002087:Butyrates; D004791:Enzyme Inhibitors; D005232:Fatty Acids, Volatile; D056572:Histone Deacetylase Inhibitors; D006657:Histones; D010936:Plant Extracts; D010368:Pectins