Prenatal developmental toxicity study with 7-hydroxymatairesinol potassium acetate (HMRlignan) in rats

Phytoestrogens and Health Effects

Phytoestrogens are literally estrogenic substances of plant origin. Although these substances are useful for plants in many aspects, their estrogenic properties are essentially relevant to their predators. As such, phytoestrogens can be considered to be substances potentially dedicated to plant-predator interaction. Therefore, it is not surprising to note that the word phytoestrogen comes from the early discovery of estrogenic effects in grazing animals and humans. Here, several compounds whose activities have been discovered at nutritional concentrations in animals and humans are examined. The substances analyzed belong to several chemical families, i.e., the flavanones, the coumestans, the resorcylic acid lactones, the isoflavones, and the enterolignans. Following their definition and the evocation of their role in plants, their metabolic transformations and bioavailabilities are discussed. A point is then made regarding their health effects, which can either be beneficial or adverse depending on the subject studied, the sex, the age, and the physiological status. Toxicological information is given based on official data. The effects are first presented in humans. Animal models are evoked when no data are available in humans. The effects are presented with a constant reference to doses and plausible exposure.

Aluminum reproductive toxicity: a summary and interpretation of scientific reports

Publications addressing aluminum (Al)-induced reproductive toxicity were reviewed. Key details were compiled in summary tables. Approximate systemic Al exposure, a measure of bioavailability, was calculated for each exposure, based on the Al percentage in the dosed Al species, Al bioavailability, and absorption time course reports for the exposure route. This was limited to laboratory animal studies because no controlled-exposure human studies were found. Intended Al exposure was compared to unintended dietary Al exposure. The considerable and variable Al content of laboratory animal diets creates uncertainty about reproductive function in the absence of Al. Aluminum-induced reproductive toxicity in female mice and rats was evident after exposure to ≥25-fold the amount of Al consumed in the diet. Generally, the additional daily Al systemic exposure of studies that reported statistically significant results was greater than 100-fold above the typical human daily Al dietary consumption equivalent. Male reproductive endpoints were significantly affected after exposure to lower levels of Al than females. Increased Al intake increased fetus, placenta, and testes Al concentrations, to a greater extent in the placenta than fetus, and, in some cases, more in the testes than placenta. An adverse outcome pathway (AOP) was constructed for males based on the results of the reviewed studies. The proposed AOP includes oxidative stress as the molecular initiating event and increased malondialdehyde, DNA and spermatozoal damage, and decreased blood testosterone and sperm count as subsequent key events. Recommendations for the design of future studies of reproductive outcomes following exposure to Al are provided.

Iron Absorption in Celiac Disease and Nutraceutical Effect of 7-Hydroxymatairesinol. Mini-Review

Anemia is the main extra-gastrointestinal symptom in inflammatory bowel diseases (IBDs). Interleukin-6 (IL-6) and other cytokines are secreted and act in the microenvironment of the small intestine mucous membrane of IBD patients. Iron is essential for multiple cell functions and its homeostasis is regulated by the hepcidin–ferroportin axis. Hepcidin (HEPC) is mainly produced by the liver in response to iron needs but is also an acute phase protein. During inflammation, hepcidin is upregulated by IL-6 and is responsible for iron compartmentalization within cells, in turn causing anemia of inflammation. Tissues other than liver can produce hepcidin in response to inflammatory stimuli, in order to decrease iron efflux at a local level, then acting in an autocrine–paracrine manner. In IBDs and, in particular, in celiac disease (CeD), IL-6 might trigger the expression, upregulation and secretion of hepcidin in the small intestine, reducing iron efflux and exacerbating defective iron absorption. 7-Hydroxymatairesinol (7-HMR) belongs to the family of lignans, polyphenolic compounds produced by plants, and has nutraceutical antioxidant, anti-inflammatory and estrogenic properties. In this mini-review we revise the role of inflammation in IBDs and in particular in CeD, focusing our attention on the close link among inflammation, anemia and iron metabolism. We also briefly describe the anti-inflammatory and estrogenic activity of 7-HMR contained in foods that are often consumed by CeD patients. Finally, considering that HEPC expression is regulated by iron needs, inflammation and estrogens, we explored the hypothesis that 7-HMR consumption could ameliorate anemia in CeD using Caco-2 cells as bowel model. Further studies are needed to verify the regulation pathway through which 7-HMR may interfere with the local production of HEPC in bowel.

Fractionation of polyphenols from thermomechanical pulp mill process water by flotation and membrane integrated process

Fractionation of phenolic compounds in thermomechanical pulp mills was performed with a coupling of a prior treatment realized by flotation and a ceramic membrane process. Two lines of membranes filtration were tested. After a common 150 kDa clarification, 1 kDa filtration was performed with or without previous 5 kDa filtration. Flotation was shown to be inevitable to retain lipophilic compounds which cause severe membrane fouling. 150 kDa permeate flux was 20% higher when process water was firstly floated and was around 260 L h^-1 m^-2. 1 kDa membrane was fouled with 31% of irreversible fouling without previous 5 kDa filtration and phenolic compounds purity reached only 26% in this 1 kDa permeate. Phenolic compounds as lignin-like substances which might be attached to hemicelluloses were recovered in 5 kDa retentate. Retentate of 1 kDa might contain a major fraction of lignin derivatives with molecular weights around 1 kDa free or linked with phenolic acids. Permeate of 1 kDa contained 14% of phenolic compounds such as lignans and free phenolic acids purified at 50%.

Hydroxymatairesinol and its mammalian metabolite enterolactone reduce the growth and metastasis of subcutaneous AH109A hepatomas in rats

Both epidemiological and experimental evidence is accumulating to show that a lignan-rich diet may reduce the risk of human breast cancer. Possible anti-cancer effects of dietary lignans on hepatomas or hepatoma cells have not been the topic of earlier studies. In the present study, we examined the effect of 7-hydroxymatairesinol (HMR) and its mammalian metabolite, enterolactone (ENL), on AH109A hepatoma cell proliferation and invasion in vitro. HMR and ENL inhibited the proliferation and invasion of AH109A hepatoma cells in vitro. The 50% inhibitory concentration (IC50) of hepatoma cell proliferation was lower for ENL (10 microM) than HMR (> 200 microM). Likewise, IC50 of hepatoma cell invasion was lower for ENL (9 microM) than HMR (144 microM). ENL suppressed hepatoma cell proliferation by accumulating cells in G1 phase and elongating doubling time of these cells, and by increasing the rate of apoptosis. Subsequently, we investigated in vivo the effect of dietary HMR and ENL on growth and metastasis of AH109A hepatomas in rats. Both of these compounds reduced the growth and metastasis of solid AH109A hepatomas in rats. These in vitro and in vivo findings suggest that HMR has inhibitory activities on tumor growth and metastasis in the hepatoma-bearing rats, and that this anti-tumor effect is mediated at least partially by ENL, a metabolite of HMR.

Structural determinants of plant lignans for growth of mammary tumors and hormonal responses in vivo

Low risk of breast cancer (BC) has been proposed to be associated with high intake of lignans. Some plant lignans are converted to mammalian lignans, e.g., enterolactone (ENL), suggested to be the biologically active lignan forms. Until now, little attention has been paid to the possible biological activities of plant lignans, even though some plant lignans are absorbed and present in serum and urine. In this study, we have investigated the antitumorigenic and endocrine-modulatory activities of different plant lignans in order to clarify the structure-activity relationships. 7-Hydroxymatairesinol (HMR) is [corrected] converted to ENL, and both HMR and ENL inhibit the growth of 7,12-dimethylbenz[a]-anthracene (DMBA)-induced mammary cancer. Nortrachelogenin (NTG) resembles HMR, but has a hydroxyl group at C-8 instead of C-7 and is not converted to ENL. In DMBA-model, NTG showed no inhibition of tumor growth, but increased the uterine weight. Furthermore, life-long exposure to NTG increased uterine weight in immature females and ventral prostate weight in adult males. In contrast, life-long exposure to HMR had no effects on uterine or prostate weights at any age. Our results indicate that a difference in the position of one hydroxyl group results in distinct biological responses in vivo, as well as different lignan metabolite profiles.

A thirteen week dietary toxicity study with 7-hydroxymatairesinol potassium acetate (HMRlignan) in rats

Plant lignan 7-hydroxymatairesinol (7-HMR) is a novel precursor of the mammalian lignan enterolactone. A 13 week toxicity study at dietary levels of 0, 0.25, 1, and 4% (w/w) of potassium acetate complex of 7-HMR (HMRlignan) was conducted in the Wistar rat. These dietary levels resulted in an average daily intake of 160, 640, and 2600 mg HMRlignan/kg body weight/day, respectively. A considerable systemic exposure of HMRlignan was verified by dose-related increases in plasma total (conjugated and unconjugated) concentration of 7-HMR and metabolites enterolactone, 7-hydroxyenterolactone, and matairesinol. Enterolactone appeared to be the major metabolite. Most (>96%) of the circulating 7-HMR and enterolactone was in conjugated form as measured from the low-dose rat plasma samples. HMRlignan exposure did not significantly affect clinical signs, ophthalmoscopy or neurobehavioural observations, and motor activity. Transient reductions in food intake and body weight gain in the mid-and high-dose group were ascribed to decreased palatability of the test feed. Only in males of the high-dose group the body weights remained slightly reduced throughout the study. In the high-dose group the number of thrombocytes (females), and total white blood cell count (males) were increased. Plasma triglycerides were dose-dependently depressed in males of all test groups and in females of the mid- and high-dose group, while plasma total cholesterol, and phospholipids were decreased in high-dose males. These changes, which have also been reported for other (flaxseed) lignans, were not considered to represent adverse effects. The relative weight of the kidneys was increased in males of the high-dose group. The weight of the full and empty caecum showed dose-related increases in males of all treatment groups and in females of the high-dose group. Absolute ovary weights were decreased in all treatment groups while decreases in relative ovary weights were confined to the mid- and high-dose group. In addition, a marginal lengthening of the estrus cycle was noted in high-dose females. Apart from prevention of hyaline droplet nephropathy in all high-dose male rats, there were no treatment-related histopathological alterations. It was concluded that HMRlignan showed weak antiestrogen-like activity which may be mediated through enterolactone metabolite. Based on declined ovary weight, the no observed adverse effect level of HMRlignan was set at 0.25% in feed corresponding to 160 mg/kg body weight/day.