Saponins

What Are Saponins?

Saponins are triterpene and steroid glycosides that produce foam in aqueous solutions, resembling soap. When hydrolyzed with acids or enzymes, they break down into aglycone sapogenin and sugar. Widely distributed across numerous plant species, saponins likely protect plants against molds due to their fungicidal properties. Triterpene saponins are prevalent in many dicotyledon families, while steroid saponins are found in subtropical and tropical monocotyledons and specific dicotyledons, such as foxglove (Digitalis) and fenugreek (Trigonella).

Properties and Uses

Saponins possess a unique molecular structure with hydrophilic and hydrophobic components, enabling them to reduce surface tension in heterogeneous systems. This results in foaming, emulsifying, and dispersing properties. Historically, wild chestnut seed saponins were used to wash delicate silk and wool fabrics, but today, saponins are primarily used in the food and cosmetics industries as emulsifiers and stabilizers. Their hemolytic effect, which damages erythrocyte cell membranes by binding to proteins and lipids, releasing hemoglobin, makes them unsuitable for intravenous use. An exception is escin, a saponin complex from wild chestnut, used cautiously. When taken orally, saponins are not absorbed by the body, but strict adherence to recommended doses is essential.

Pharmacological Benefits

Saponins exhibit diverse pharmacological effects. They facilitate expectoration by thinning thick mucus and stimulating gland secretions in the bronchi and digestive tract through mucosal irritation. They also promote diuresis by stimulating renal epithelium, enhancing the diuretic effects of flavonoids. Saponins, particularly triterpene saponins from plants like soapwort, great mullein, and scarlet pimpernel, are known for their antibiotic, antifungal, and antiviral properties. Wild chestnut and butcher’s broom saponins reduce fluid retention and support venous health. Licorice saponins have anti-inflammatory effects similar to corticosteroids and are beneficial in viral diseases, such as chronic hepatitis. Ivy saponins ease coughing and relieve bronchial spasms.