Chestnut wood extract in boar diet reduces intestinal skatole production, a boar taint compound

Abstract

Abandoning traditional practice of piglet castration will impact the pigmeat sector. As a consequence, there is a need for research aiming at reducing boar taint caused by androstenone and skatole. Skatole is metabolized by cytochrome P450 enzymes (CYP450) in the liver. Skatole hepatic clearance is believed to be hindered by androstenone. Diet ingredients may modify skatole metabolism. Therefore, we tested the effect of hydrolysable tannins. We fed 51 young boars with 1-3 % chestnut wood extract as supplementary diet. After slaughter, the tissues were collected to assess androstenone and skatole accumulation in fat and to measure CYP450 activities, gene, and protein expression in the liver and intestine. Protein expression of two enzymes involved in androstenone metabolism, 3-beta-hydroxysteroid dehydrogenase (3β-HSD) and sulfotransferase family 2A member 1 (SULT2A1), was assessed, and feces collected to evaluate skatole production. Results show that intestinal skatole production in boars supplemented with 3 % of chestnut wood extract was more than halved. The intestinal catalytic activities of CYP450 were tenfold lower than hepatic and were mainly unaffected by tannins. Findings indicate a potential effect of tannins on steroidogenesis, which in the absence of effect on 3β-HSD and SULT2A1 expression suggests lower synthesis of androstenone due to tannins.

Porcine cytochrome 2A19 and 2E1

“…These results suggested that hydrolysable tannins can be used to reduce skatole levels in pigs by induction of skatole‐metabolizing enzymes. However, later studies on dietary supplementation with hydrolysable tannins to conventional pig breeds did not show any effect on CYP2A19 and CYP2E1 mRNA expression . These contradictory results might indicate breed‐related differences in the response to dietary tannins.…”

“…Often, CYP2E1 protein expression and corresponding activity are regulated at the post‐transcriptional level . Thus, changes in porcine CYP2E1 mRNA expression are not always reflected in corresponding changes in CYP2E1 protein expression and activity . Early studies have shown that acetone and ethanol treatment induces CYP2E1 protein expression in rats because of stabilisation of the protein by inhibiting its degradation .…”

“…16,18 Thus, changes in porcine CYP2E1 mRNA expression are not always reflected in corresponding changes in CYP2E1 protein expression and activity. 29,40,41 Early studies have shown that acetone and ethanol treatment induces CYP2E1 protein expression in rats because of stabilisation of the protein by inhibiting its degradation. 42 In addition, CYP2E1 mRNA levels in human liver tissue, together with CYP2A6 and CYP2C9, showed no correlation with protein and enzymatic activity.…”

“…However, later studies on dietary supplementation with hydrolysable tannins to conventional pig breeds did not show any effect on CYP2A19 and CYP2E1 mRNA expression. 40,65 These contradictory results might indicate breed-related differences in the response to dietary tannins. It should also be emphasised that in the study of Bee et al 65 only mRNA expression, but not enzymatic activities, was measured.…”

Dietary Components, Microbial Metabolites and Human Health: Reading between the Lines

“…It is found that the oral charcoal adsorbent AST-120 binds indole in the intestinal lumen, and reduces the blood plasma indole sulfate levels, in turn decreasing kidney damage and atherosclerosis-related kidney injuries [ 61 ]. Another important product of tryptophan metabolized by mammalian gut microbiota is skatole, which has been proven to cause pulmonary edema in sheep, goats, and some strains of mice [ 62 ]. It selectively targets club cells, which are the key sites of cytochrome P450 enzymes in the lungs [ 62 ].…”