Structural determinants of plant lignans for the formation of enterolactone in vivo

Saarinen, Niina M.; Smeds, Annika; Mäkelä, Sari; Ämmälä, Jenni; Hakala, Kristo; Pihlava, Juha‐Matti; Ryhänen, Eeva-Liisa; Sjöholm, Rainer; Santti, Risto

doi:10.1016/s1570-0232(02)00339-2

Cited by 76 publications

(98 citation statements)

References 12 publications

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“…SDG-2 and strain ARC-1, can be used for preparation of (ϩ)-or (Ϫ)-form of END and ENL from the respective racemic precursors. Saarinen et al 29) confirmed that the absolute configurations at C-2 and C-3 of END and ENL were not changed during the microbial metabolism, as a result of the enantioselective dehydroxylation by intestinal bacteria, and we succeeded here to isolate two different bacteria responsible for enantioselective dehydroxylation. In connection with the metabolic processes of lignans to END and ENL, we already reported the isolation and characterization of a human intestinal bacterium, E. sp.…”

Section: Discussionsupporting

confidence: 55%

Enantioselective Dehydroxylation of Enterodiol and Enterolactone Precursors by Human Intestinal Bacteria

Jin

Zhao

Nakamura

et al. 2007

Biological & Pharmaceutical Bulletin

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Phytoestrogens are defined as plants-derived compounds with estrogen-like activities. Isoflavones and lignans have been categorized as phytoestrogens, based on their chemical structures and activities.1,2) Phytoestrogens have been explored in the field of metabolic degradation by intestinal bacteria. [3][4][5][6][7][8][9] In particular, the biotransformation of plant lignans, such as secoisolariciresinol diglucoside (SDG), pinoresinol diglucoside (PDG), arctiin, and matairesinol to mammalian lignans, enterodiol (END, 1) and enterolactone (ENL, 2) have extensively been studied. The metabolic processes by intestinal bacteria include deglucosylation, ring cleavage, demethylation, dehydroxylation and oxidation. Mammalian lignans lacking of phenolic hydroxyl groups at the para position of aromatic rings are different from plant lignans, 6) and dehydroxylation is an essential process on the metabolic conversion from plant lignans to mammalian lignans by intestinal bacteria.Eubacterium (E.) sp. strain SDG-2 was isolated by Wang et al. as a bacterium capable of reductive dehydroxylation in the processes of SDG to END (1) and ENL (2).10) E. sp. strain SDG-2 was similar in characteristics to E. lentum, which was reclassified to Eggerthella (Eg.) lenta by phylogenic identification.11) In this study, we determined phylogenic affiliation of E. sp. SDG-2 with 16S rRNA gene-based identification using polymerase chain reaction with proper primers.END (1) and ENL (2) have two enantiomeric, mirror image forms (1a and 1b; 2a and 2b) (Fig. 1). Secoisolariciresinol (SECO), prepared by incubation of PDG with intestinal bacteria, was a (Ϫ)-form. 9) On the other hand, SECO, aglycone of SDG isolated from flaxseed, was a (ϩ)-form. 10)Although there were a few reports on the biotransformation of these lignans by intestinal bacteria, 12-14) enantioselective conversion was not well confirmed. Therefore, metabolic specificity between enantimers raised our interest in investigation. We prepared two sets of enantiomers, such as (ϩ)-and (Ϫ)-dihydroxyenterodiol (DHEND, 3a and 3b, respectively), November 2007 2113 Enantioselective Dehydroxylation of Enterodiol and Enterolactone Precursors by Human Intestinal Bacteria

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Section: Discussionsupporting

confidence: 55%

Enantioselective Dehydroxylation of Enterodiol and Enterolactone Precursors by Human Intestinal Bacteria

Jin

Zhao

Nakamura

et al. 2007

Biological & Pharmaceutical Bulletin

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“…Previous results have shown that the activity of intestinal glycosidases is from enzymes of mammalian (Day et al 1998) and microbial (Saarinen et al 2002;Clavel et al 2006) origin. However, the ruminal epithelium is nonsecretory and epithelial cells were absent in our in vitro model, thus suggesting that the origin of intestinal glycosidases in the present experiment was from microbiota.…”

Section: Discussionmentioning

confidence: 98%

“…Large within-day and day-to-day variation may also be important as shown by Hausner et al (2004) for EL levels in human serum (56%) and urine (49%). Higher net production of SECO for GH than GS incubated with ruminal microbiota may result from the higher initial concentration of SDG in GH than GS [32AE0 vs 9AE2 nmol (100 mg )1 )] as hydrolysation of SDG is known to produce SECO under the action of intestinal glycosidases from microbial origin (Saarinen et al 2002). Rumen micro-organisms readily hydrolyse isoflavones present in the glycoside form (Lundh 1995) and SDG is the glycoside form of SECO (Johnsson et al 2000).…”

Section: Discussionmentioning

confidence: 99%

In vitrometabolism of flax lignans by ruminal and faecal microbiota of dairy cows

Côrtes

Gagnon

Benchaar

et al. 2008

Journal of Applied Microbiology

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Aims: To determine the in vitro conversion of plant lignans from two flax products (hull and seed) into the mammalian lignans, enterolactone and enterodiol, by bovine ruminal and faecal microbiota. Methods and Results: Flax seeds and hulls were incubated in vitro over a 96‐h time course with ruminal or faecal inoculum. Plant lignans in flax seeds and hulls averaged 9·2 and 32·0 nmol mg−1, respectively. The highest net production of enterodiol at 72 and 96 h of incubation was obtained with flax hulls incubated with faecal microbiota. There was no difference in net production of enterodiol between flax products within the first 24 h of incubation. In general, net production of enterolactone over the 96‐h time course was significantly higher for flax products incubated with ruminal than with faecal microbiota. Net production of enterolactone at 72 and 96 h of incubation was greater for flax hulls than flax seeds. Conclusions: Results of the present experiment suggest that, of the metabolites studied, the main mammalian lignan metabolite produced from flax hulls and seeds by ruminal microbiota is enterolactone while faecal microbiota leads mainly to the net production of enterodiol. Significance and Impact of the Study: This research will improve the understanding of the metabolic pathway of mammalian lignans in dairy cows, in order to enable targeted manipulation of their quantities in milk.

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“…Low daily intakes of flaxseed (38 to 50 g) have been shown to reduce serum cholesterol in human (Cunnane et al, 1995). Some results suggest that absorption of mammalian lignans is higher than that of plant lignans as shown by a five-fold increase in urine excretion of EL in rats fed pure EL compared with those fed plant lignans (Saarinen et al, 2002). This suggests that improved absorption of EL from enriched milk may contribute to increase blood EL concentration in human.…”

Section: Discussionmentioning

confidence: 99%

Concentration of the mammalian lignans enterolactone and enterodiol in milk of cows fed diets containing different concentrations of whole flaxseed

Petit

Gagnon

2009

Animal

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A total of 32 lactating Holstein cows with mean body weight of 622 kg (s.e. 5 24) were allotted, at week 25 of lactation, to eight groups of four cows blocked for similar days in milk. The objective of the experiment was to determine the effect of feeding four dietary concentrations (0, 50, 100 or 150 g/kg of dry matter) of whole flaxseed, which contains the plant lignan precursor secoisolariciresinol diglucoside (SDG), on concentrations of two mammalian lignans (enterodiol and enterolactone) in milk. The effects of the four diets on feed intake, milk production, milk composition and digestion were also studied. Cows within each block were assigned to one of the four isonitrogenous and isoenergetic total mixed diets and the experiment was carried out from week 25 to 29 of lactation. Diets were fed for ad libitum intake. Enterolactone was the mammalian lignan, of the two metabolites studied, detected in the milk of cows and its concentration in milk tended (P 5 0.08) to increase linearly with higher intake of SDG in the diet. Feed intake, milk yield and milk composition were similar among diets. Milk fatty acid profile was slightly improved by feeding flaxseed, as shown by higher concentrations of fatty acids (e.g. n-3) recognized as being beneficial for human health. Those results suggest that feeding of whole flaxseed may result in changes in milk fatty acid composition and enterolactone content, which offer benefits for consumers.

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Structural determinants of plant lignans for the formation of enterolactone in vivo

Cited by 76 publications

References 12 publications

Enantioselective Dehydroxylation of Enterodiol and Enterolactone Precursors by Human Intestinal Bacteria

Enantioselective Dehydroxylation of Enterodiol and Enterolactone Precursors by Human Intestinal Bacteria

In vitrometabolism of flax lignans by ruminal and faecal microbiota of dairy cows

Concentration of the mammalian lignans enterolactone and enterodiol in milk of cows fed diets containing different concentrations of whole flaxseed

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