Lenmag Lignán irodalom:

 

L.1.        Flaxseed Lignans as Important Dietary Polyphenols for Cancer Prevention and Treatment: Chemistry,

Pharmacokinetics, and Molecular Targets - Pharmaceuticals 2019, 12, 68; doi:10.3390/ph12020068

S. Franklyn De Silva * and Jane Alcorn

 

Abstract: Cancer causes considerable morbidity and mortality across the world. Socioeconomic, environmental, and lifestyle factors contribute to the increasing cancer prevalence, bespeaking a need for effective prevention and treatment strategies. Phytochemicals like plant polyphenols are generally considered to have anticancer, anti-inflammatory, antiviral, antimicrobial, and immunomodulatory effects, which explain their promotion for human health. The past several decades have contributed to a growing evidence base in the literature that demonstrate ability of polyphenols to modulate multiple targets of carcinogenesis linking models of cancer characteristics (i.e., hallmarks and nutraceutical-based targeting of cancer) via direct or indirect interaction or modulation of cellular and molecular targets. This evidence is particularly relevant for the lignans, an ubiquitous, important class of dietary polyphenols present in high levels in food sources such as flaxseed. Literature evidence on lignans suggests potential benefit in cancer prevention and treatment. This review summarizes the

relevant chemical and pharmacokinetic properties of dietary polyphenols and specifically focuses on the biological targets of flaxseed lignans. The consolidation of the considerable body of data on the diverse targets of the lignans will aid continued research into their potential for use in combination with other cancer chemotherapies, utilizing flaxseed lignan-enriched natural products.

 

L.2.        Probiotic Bacteria for Healthier Aging: Immunomodulation and Metabolism of Phytoestrogens

José María Landete, Pilar Gaya, Eva Rodríguez, Susana Langa, Ángela Peirotén,

Hindawi BioMed Research International Volume 2017, Article ID 5939818,

 

Abstract

Age-related degeneration gives rise to a number of pathologies, many of them associated with imbalances of the microbiota and the gut-associated immune system.Thus, the intestine is considered a key target organ to improve the quality of life in senescence. Gut microbiota can have a powerful impact in the deterioration linked to aging by its nutritional and immunomodulatory activity. Reduced numbers of beneficial species and low microbial biodiversity in the elderly have been linked with pathogenesis of many diseases. A healthy lifestyle with an elderly customized diet including probiotics can contribute to reducing the chronic proinflammatory status and other age-related pathologies. Beneficial effects of probiotic lactic acid bacteria and bifidobacteria

to alleviate some of these disorders based on their immunomodulatory properties as well as their capacity to produce bioactive metabolites from dietary phytoestrogens are summarized. On one hand, the preservation of gut barrier integrity and an increased ability to fight infections are the main reported immune benefits of probiotics. On the other hand, the intake of a diet rich in

phytoestrogens along with the presence of selected probiotic bacteria may lead to the production of equol, enterolignans, and urolithins, which are considered protective against chronic diseases related to aging.

 

L.4. A lignánok elválasztása, azonosítása és mennyiségi meghatározása natív növényi mintákban és a

lignántermelés fokozása Forsythia in vitro sejttenyészetben

Doktori értekezés-Sedlák Éva Semmelweis Egyetem Gyógyszertudományok Doktori Iskola 2011

 

L.5.Metabolism of Plant Lignans by Human Intestinal Bacteria by Seth C Yoder

A thesis submitted in partial fulfillment of the requirements for the degree of Master of Science

University of Washington 2013

 

L.6.Linus Pauling Institute on Lignans

• Lignans are polyphenolic compounds found in plants.

• Lignan precursors are found in a wide variety of plant-based foods, including seeds, whole grains, legumes, fruit, and vegetables.

• Flaxseeds are the richest dietary source of lignan precursors.

• When consumed, lignan precursors may be converted to the enterolignans, enterodiol and enterolactone, by bacteria that normally colonize the human intestine.

• Enterodiol and enterolactone have weak estrogenic activity but may also exert biological effects through non-estrogenic mechanisms.

• Lignan-rich foods are part of a healthy diet, but the roles of lignans in the prevention of hormone-associated cancers, osteoporosis, and cardiovascular disease are not yet clear.

• The enterolignans, enterodiol and enterolactone (Figure 1), are formed by the action of intestinal bacteria on lignan precursors found in plants (1). Because enterodiol and enterolactone can mimic some of the effects of estrogens, their plant-derived precursors are classified as phytoestrogens. Lignan precursors that have been identified in the human diet include pinoresinol, lariciresinol, secoisolariciresinol, matairesinol, and others (Figure 2). Secoisolariciresinol and matairesinol were among the first lignan precursors identified in the human diet and are therefore the most extensively studied. Lignan precursors are found in a wide variety of foods, including flaxseeds, sesame seeds, legumes, whole grains, fruit, and vegetables. While most research on phytoestrogen-rich diets has focused on soy isoflavones, lignans are the principal source of dietary phytoestrogens in the typical Western diet (2, 3).

 

 

Metabolism and Bioavailability

When plant lignans are ingested, they can be metabolized by intestinal bacteria to the enterolignans, enterodiol and enterolactone, in the intestinal lumen and then absorbed into the bloodstream (4). Enterodiol can also be converted to enterolactone by intestinal bacteria. Thus, enterolactone levels measured in blood and urine reflect the activity of intestinal bacteria in addition to dietary intake of plant lignans. Not surprisingly, antibiotic use has been associated with lower serum enterolactone concentrations (5).

Because data on the lignan content of foods are limited, blood and urinary enterolactone levels are sometimes used as markers of dietary lignan intake. A pharmacokinetic study that measured plasma and urinary levels of enterodiol and enterolactone after a single dose (0.9 mg/kg of body weight) of secoisolariciresinol, the principal lignan in flaxseed, found that at least 40% was available to the body as enterodiol and enterolactone (6). Plasma enterodiol concentrations peaked at 73 nanomoles/liter (nmol/L) an average of 15 hours after ingestion of secoisolariciresinol, and plasma enterolactone concentrations peaked at 56 nmol/L an average of 20 hours after ingestion. Thus, substantial amounts of ingested plant lignans are available to humans in the form of enterodiol and enterolactone.

Considerable variation among individuals in urinary and serum enterodiol:enterolactone ratios has been observed in flaxseed feeding studies, suggesting that some individuals convert most enterodiol to enterolactone, while others convert relatively little (1). Individual differences in the metabolism of lignans, likely due to differing composition and activities of gut microbes, can influence the biological activities and health effects of these compounds (7). Several other factors, including antibiotic use, age, BMI, and smoking, may also help explain the variation of circulating enterolignan concentrations among individuals (7); these and other potential confounding factors should be controlled for in observational studies.