saponins Flashcards
What are saponins?
Saponins are large molecules that reduce the surface tension of water, causing it to foam. They contain a hydrophilic part (sugar) and a hydrophobic part (aglycone = triterpenoids).
What are phytoestrogens?
Phytoestrogens are phytochemicals with oestrogenic activity due to structural similarity to 17-β-Oestradiol. They are also known as dietary estrogens.
What are the two main classes of saponins?
- Steroidal saponins
- Triterpenoid saponins
Where are steroidal saponins mainly found?
They are mainly found in monocotyledons like Dioscoreaceae (Dioscorea spp.) and Agavaceae (Agave spp.) and in dicotyledons like fenugreek (Leguminosae) and Solanum (Solanaceae).
What is a key pharmacodynamic effect of saponins?
Saponins can cause haemolysis of red blood cells by dissolving their membranes.
What gastrointestinal effects do saponins have?
Saponins irritate gastrointestinal mucous membranes, leading to emetic and expectorant effects.
What is the effect of saponins on steroid hormone metabolism?
Saponins influence steroid hormone metabolism by affecting enzymes that regulate steroidal hormones.
What is glycyrrhetinic acid and its role?
Glycyrrhetinic acid (from Glycyrrhiza glabra) exerts mineralocorticoid activity and is used for inflammatory conditions.
What is a potential side effect of chronic use of glycyrrhizin?
Chronic use can lead to hypokalemia, hypertension, arrhythmia, and encephalopathy.
What are the main sources of phytoestrogens?
- Isoflavones (e.g., genistein, daidzein)
- Lignans (e.g., enterodiol, enterolactone)
What is the significance of isoflavones in the context of oestrogen?
Isoflavones act as partial agonists of oestrogen receptors, competing with oestradiol but with weaker stimulation.
What is the effect of isoflavones on breast cancer risk?
Consumption of soya isoflavones is associated with a reduced risk of breast cancer and lower risk of recurrence.
What is the role of intestinal metabolism in isoflavone bioavailability?
Intestinal metabolism of isoflavones to their aglycone form is essential for ensuring bioavailability and bioactivity.
What is a potential adverse effect of high intake of isoflavones?
High intake in therapeutic contexts may lead to adverse events, hence intake should be limited to dietary levels.
What is the relationship between saponins and cholesterol levels?
Saponin intake lowers plasma cholesterol levels in animal models, likely by inhibiting absorption.
What is the impact of phytoestrogens on menopausal symptoms?
Soya isoflavones can reduce menopausal symptoms such as hot flushes by up to 50% without significant effect on oestradiol levels.
True or False: Isoflavones have a greater binding affinity for ER-alpha than for ER-beta.
False
Fill in the blank: The presence of a phenolic ring and the distance between the two opposing oxygens are important structural features of _______.
phytoestrogens
