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Chemopreventive Agents
Published in David E. Thurston, Ilona Pysz, Chemistry and Pharmacology of Anticancer Drugs, 2021
Enterolactone (Figure 12.18) is a mammalian lignan formed by the action of intestinal bacteria on plant lignan precursors in the diet. Many dietary plant lignans, such as seco-isolariciresinol, matairesinol, lariciresinol, pinoresinol, and sesamin, can be metabolized by gut microbes to enterolactone. The richest dietary sources of enterolactone precursors are flaxseed, sesame seeds, and cereals. Since enterolactone is produced by specific species of gut microbiota, it is interesting that the capacity to produce it varies between individuals. Also, the capacity to produce enterolactone in the gut can be significantly reduced by antibiotic treatments, a situation that can take many months to recover from.
Formulated Natural Selective Estrogen Receptor Modulators: A Key To Restoring Women’s Health
Published in Megh R. Goyal, Durgesh Nandini Chauhan, Plant- and Marine-Based Phytochemicals for Human Health, 2018
A. Anita Margret, S. Aishwarya, J. Theboral
Diets high in lignans may help maintain good cognitive function in postmenopausal women who have anticancer and antiviral effects. They influence gene expression and may protect against estrogen-related diseases such as osteoporosis.42, 65, 82 In postmenopausal women, estrogen deficiency is the major risk factor for osteoporosis. The studies suggest that the mammalian lignans of flax mimic the endogenous estrogens and bind to ERs of bone and hence improve osteocalcin;3 reduce the risk of uterine fibroids in middle-aged women;6 reduce breast cancer risk in women, and reduce the risk of acute fatal coronary events100 and prostate cancer103 in men. SDG is an antioxidant that scavenges hydroxyl ion free radicals.9 Enterolactone activates the pregnane X receptor, which is involved in the metabolism of bile acids, steroid hormones, and has the ability to affect the metabolism of some drugs.39 A study suggested that lignans, along with enterodiol and enterolactone, affect hormone receptors in breast tissue and reduce the risk of breast cancer. They inhibit the activity of aromatase, an enzyme involved in the production of estrogens, and protect against breast cancer.12, 105
Prognostic associations of circulating phytoestrogens and biomarker changes in long-term survivors of postmenopausal breast cancer
Published in Nutrition and Cancer, 2020
Stefanie Jaskulski, Audrey Y. Jung, Marianne Huebner, Gernot Poschet, Rüdiger Hell, Anika Hüsing, Sandra Gonzalez-Maldonado, Sabine Behrens, Nadia Obi, Heiko Becher, Jenny Chang-Claude
Plant-derived phytoestrogens (PEs) in particular lignans (i.e., oilseeds, whole grains) and flavonoids (including isoflavones i.e., soy products), the two major subgroups (1–3), have been studied with respect to their potential association with risk for breast cancer occurrence and survival. The evidence from meta-analyses indicates that lignan and isoflavone exposure may be associated with a lower risk of breast cancer (4–8), overall mortality (9, 10), breast cancer-specific mortality (9), and risk of recurrence (REC) (6, 10). In the studies of breast cancer prognosis, PE exposure has been predominantly measured by estimated pre- or postdiagnosis dietary PE intake based on food frequency questionnaires (6, 10–12). Biomarkers account for both dietary intake level and individual variation in metabolism, absorption, and bioavailability (13, 14). To date, only circulating levels of enterolactone (ENL), the major lignan metabolite, have been measured and consistently found to be associated with improved survival (9, 15–18).
Role of the microbiota in circadian rhythms of the host
Published in Chronobiology International, 2020
Plant-derived fiber and polyphenols are the major components to resist intestinal digestion and reach the large intestine where they regulate the gut microbiome. Microbes manage to transform some polyphenols to metabolites that could induce circadian entrainment (Parkar et al. 2019). One of those is secoisolariciresinol (SECO), which is contained in, for example, flaxseed. SECO reaches the large intestine where it is metabolized to enterolactone by some Firmicutes. Enterolactone was shown to increase the expression of Clock and decrease that of Per3 in the murine uterus with a single dose of 10mg/kg body weight. Though, such high concentrations are not achievable by flaxseed gavage. If direct administration of SECO and subsequent microbial metabolization is sufficient remains to be elucidated as well (Clavel et al. 2005; Parkar et al. 2019). Not only microbiota-derived bioactive polyphenolic metabolites but also diet-derived polyphenols themselves influence host circadian rhythms in peripheral tissues. For example, resveratrol is an activator of SIRT1, and proanthocyanidins regulate Bmal1 and nicotinamide phosphoribosyltransferase (NAMPT). Beyond that, SIRT1 also regulates RORs and influences NAD+ levels, (Ribas-Latre and Eckel-Mahan 2016). Diet-derived polyphenols can also cause a modulation in the growth of some commensals that generate bioactive SCFAs or polyphenolic metabolites (Parkar et al. 2019).
Effect of Dietary Flaxseed Intake on Circulating Sex Hormone Levels among Postmenopausal Women: A Randomized Controlled Intervention Trial
Published in Nutrition and Cancer, 2019
Vicky C. Chang, Michelle Cotterchio, Beatrice A. Boucher, David J. A. Jenkins, Lucia Mirea, Susan E. McCann, Lilian U. Thompson
As expected and reported by others (52,53), daily flaxseed intake significantly increased serum enterolignan levels. Our study further demonstrated that changes in enterolignans, especially enterolactone (primary SDG metabolite), are positively correlated with changes in 2-hydroxyestrone and 2:16α-hydroxyestrone ratio among women consuming flaxseed. This suggests that flaxseed intake led to changes in the estrogen profile by increasing enterolignans (12). Brooks et al. also reported a positive correlation between change in total urinary lignan excretion and change in 2:16α-hydroxyestrone ratio (r = 0.58; P = 0.02) among women supplemented with flaxseed; however, specific enterolignans were not examined (32). Our finding of a stronger correlation with enterolactone than enterodiol may be explained by the shorter half-life of enterodiol, which is further metabolized into enterolactone (7,8). Additionally, in vitro and in vivo studies have demonstrated differential effects of enterolactone and enterodiol on estrogen-related pathways in cancer development (54–56).