Saponins
Saponins at a glance
Saponins are plant ingredients that produce a durable foam when mixed with water. The term is derived from the Latin “sapo”, which means soap. Saponins are found in many plants because they have a fungicidal effect and thus protect the plants from fungal attack. Scientists now also know how this protection works: If the fungi come into contact with the saponins, the chemical and physical properties of their cell membrane change. As a result, pores form in the membrane through which liquid can flow in, whereupon the fungal cell dissolves. The strong surface activity of saponins is caused by the coexistence of non-polar and polar groups in one molecule.
Saponins are mainly found in the parts of plants that are particularly rich in nutrients, i.e., in the leaves and flowers, the roots and tubers, but also in the seeds.
In total, more than 90 different plant families can boast saponins. The concentration is particularly high in the bark of the South American soap bark tree (Quillaja saponaria). However, plants such as the daisy, cyclamen, ivy, primrose, lungwort, and horse chestnut also contain saponins. The nutshells of the soap nut tree (Sapindus mukorossi), which are also used for washing in our country, are of increasing ecological interest. Interestingly, saponins are also found in many starchy vegetable plants: in peas and lentils, for example, spinach and potatoes, or in onions and asparagus.
Scientifically, saponins are glycosides of steroid alkaloids (nitrogenous steroids), triterpenes or steroids. In this context, the terms steroidal alkaloid saponins, triterpene saponins and steroid saponins have also become established. The basic structure of the substances is a lipophilic ring system, which is also called aglycone. Due to the enormous structural variability of aglycones as well as the multitude of possible carbohydrate structures, saponins are characterised by a unique structural diversity and an impressive variability in terms of biological properties.
Saponins have a bitter or sweet taste and are toxic to fish (piscicidal) because their surface activity impairs gill respiration. The substances complex cholesterol and exhibit haemolytic activity.
Saponins in herbal medicine
In herbal medicine, saponins play an important role as a component of many well-known medicinal plants. The different structures are useful for many different applications. For example, they can be used as anti-fungal, anti-inflammatory, expectorant or diuretic. A well-known example: the saponins in the horse chestnut are able to stabilise the cell walls of the veins and inhibit the breakdown of collagen.
In the meantime, there are many pharmacological research results regarding the exact mode of action of the saponins. Among other things, antiviral, analgesic, antitumour, cardiovascular, immunomodulatory, hepatoprotective, molluscicidal, sedative and spermicidal properties have been demonstrated. In principle, however, saponins must not enter the bloodstream, as many of them have a haemolytic effect in higher concentrations, i.e., they destroy the red blood cells. Conversely, however, the haemolytic properties are also used positively: for example, as a standard method in blood tests. Good to know: The haemolytic effect can hardly be achieved by eating plants or foods rich in saponins, because the bioavailability of the substances is extremely low.
Saponins in cosmetics
Saponin complexes are mainly used in cosmetics for thorough and gentle skin cleansing because they have antibacterial and immunostimulating effects. As natural skin cleansing agents, they can even dissolve fat.
However, saponins also reduce the surface tension of water and promote the skin’s ability to absorb ingredients in herbal cosmetic products. In addition, some saponins can inhibit the growth of fungi and bacteria. Glycine saponin, which is derived from the soybean, is a cosmetic active ingredient that stimulates the body’s own production of hyaluronic acid by stimulating fibroblasts. The substance can therefore be used very well to combat signs of skin ageing and deep-seated wrinkles. In contrast to the foaming capacity that exists in principle in combination with water, the haemolytic properties of the saponins are very different, sometimes they are even completely absent as in Glycyrrhiza glabra.
Saponins in soap nuts: the gentle organic detergent
The soap nut tree (Sapindus saponaria) is also known colloquially as the soap tree and is native to Central and South America and the Caribbean. The fruit of the tree has been used for washing for thousands of years. No wonder, because the fruit shell and the seeds contain 15 to 30 percent saponin. The exact amount depends on the age of the tree and the time of harvest. Soap nuts are extremely skin-friendly and also suitable for allergy sufferers and babies.
Depending on the water hardness and washing temperature, three to seven soap nuts (i.e. the dried nut-hard fruit shells) are placed in a cotton bag in the washing machine. When the shells or nuts come into contact with the water in the washing machine, a slightly foaming, soapy and mild lye is formed. They do not give off any odours to the laundry and clean very gently and naturally. In addition, the washing-active substances are considered to be easily biodegradable. If soap nuts are boiled in water, the decoction can be used as a shower gel, hair shampoo or even as a mild all-purpose cleaner for the household. This is also interesting because the water extract has a good effect against various phytopathogenic fungi. The remaining peel after use can be composted without hesitation. Instead of commercially available aggressive products, soap nuts can also be used as a dishwashing detergent: To do this, put them in a small bag directly into the cutlery compartment of the dishwasher. Alternatively, they can also be used as a skin-friendly hand dishwashing detergent, but the decoction of the boiled nuts is used for this.
Saponins from the soap bark tree
The evergreen soap bark tree (Quillaja saponaria Molina) was originally native only to South America, but is now also cultivated in India and California. It forms so-called bellow fruits, of which five are always connected in a collective bellow fruit. However, the dried bark of the trunk and branches is used. The South American natives traditionally used it as a substitute for soap and to clean textiles. It is rich in saponins (up to ten percent) and contains tannins and calcium oxolate. Also obtained from the bark of the soap bark tree is quillaja extract, a food additive approved in the EU (E 999), which is used in soft drinks as well as in cider and perry.
Soap bark in powdered form or as an aqueous-alcoholic extract lends itself to the production of tooth powders and gargles, but is also frequently used as a foaming agent. Since the saponins ensure a very stable soap-like foam, soap bark is also suitable for the production of shower gels, shampoos, detergents and cleaning agents. In addition, it is a proven ingredient in stain remover.
Profile of some saponins
The soap nut
INCI: Sapindus Trifoliatus Fruit Extract
CAS number: 223748-41-2
Origin: from the soap tree family
Description: an extract from the fruit of the Sapindus trifoliatus L. (Indian soap nut tree)
Applications: as a mild detergent and cleanser, for body washes, shampoos, skin care products and bath additives
Effect: very good and gentle cleaning power
The soap bark
INCI: Quillaja saponaria extract
CAS number: 68990-67-0
EINECS/ELINCS-Nummer: 273-620-4
Alternative names: Panama wood, Chilean soap bark tree
Description: Vegetable wood extract from the Chilean soap bark tree (Quillaja saponaria).
Effect: foaming, emulsifying, cleansing, skin care, anti-dandruff agent
Ingredients: bisdesmosidic triterpene saponins with gypsogenic acid, tannins, calcium oxalate, quillaic acid arabinose
Applications: For soaps, hair shampoos, mouth and toothwash, for gentle cleansing of the facial skin.
The desert date
INCI: Balanites aegyptiaca
Origin: from the yoke-leaf family (Zygophyllaceae)
Indications: Traditionally used to treat diseases such as jaundice, malaria, syphilis, epilepsy, constipation, diarrhoea, dysentery, haemorrhoids, stomach ache, fever and asthma; due to the saponins it contains, it is an ingredient in many soaps.
Tall gypsophila
INCI: Gypsophila paniculata
CAS number: 94167-03-0
EC number: 303-401-1
Applications: as a mild detergent (especially for wool), for medicinal use (expectorant and diuretic)
Acacia concinna fruit extract
INCI: Acacia concinna
CAS number: 202148-87-6
Origin: plant species from the acacia genus.
Fields of application: The dried and ground fruits are traditionally used to make an Ayurvedic shampoo known as shikakai; the extract is also suitable for soap and cleansing products
Effect: cleanses and cares for the hair, antibacterial and anti-inflammatory
Saponins for high-quality and biodegradable cleansing products
Saponins are often referred to as organic detergents and cleansers. And indeed, the plant substances are very suitable for natural and gentle cleaning products. Let us advise you – preferably today.
Literature:
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Saponins of Korean Red Ginseng May Protect Human Skin from Adipokine-Associated Inflammation and Pigmentation Resulting from Particulate Matter Exposure.
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