What are the Benefits of Plant-Derived Saponins For Hair?


You may have noticed the ingredients “saponins” in many shampoos, do you know what’s it? Saponins are a type of polyhydroxy acid that can be obtained from plants, and a class of plant metabolites compounds containing both hydrophilic and hydrophobic properties and surfactant properties. They got their name’saponins’ derived from the Latin word ‘sapo,’ which means soap as they form a soapy lather when agitated with water. They are obtained from different plant species in a wide range of plant parts such as roots, stems, leaves, bark and seeds which is produced to defend against pathogens and as a chemical barrier in the defense system of herbivores. As a result, saponins are found in plant tissues more vulnerable to attack by bacteria, fungi or insects. The content of these plants varies and can reach up to 10-20% dry matter, which makes natural source extraction potentially commercially feasible and sustainable. Saponin is a nonionic surfactant, one of the earliest cleaning ingredients used, and is also used in folk remedies. They are also widely used in various industries, including pharmaceuticals, food, cosmetics, and many others, saponins based products are often found in health products for oily skin and hair because they have good foaming power and deep cleansing.

Natural source of saponins

The main saponins are triterpenoid and steroidal glycosides that show a variety of aglycone backbone structures ranging from C-3 to C-26 or C-28 positions with carbohydrate groups attached at both ends (monodesmosidic and bidesmosidic saponins). Steroidal and triterpenic saponins contain additional functional groups: -OH, -COOH and -CH3 that give them additional diversity in physicochemical properties.
Saponins are found in different plants. Sterane saponins are mainly found in monocotyledonous plants (agavaceae, Compositae, balanidae, obturator ginger, Dioscoreaceae, legumes, liliaceae, Rosaceae, Solanaceae, and Sophoraceae), while triterpenoid saponins are mainly found in Gemini families (legumes, Compositae, and Dianthus). The main food sources of saponins are soybeans, peas, chickpeas, peanuts, beans, lentils, oats, garlic, asparagus, tea, spinach, beets, quinoa and yams. Non-food sources used in industrial and health applications include soap bark tree (Quillaja saponaria), fenutrium (Trigonella foenum-graceum), alfalfa (Medicago sativa), European horse chestnut (Aesculus) hippocastanum), Licorice (Glycyrrhiza glabra), soapgrass (Saponaria officinalis), Mojave Yucca (Yucca schidigera), Smilax China L (Smilax regelii) And other strictly related species of Smilax) and ginseng (Panax).

Applications of Saponins for hair

There is a growing demand for natural surfactants due to their high foaming and emulsifying activity and environmental concerns.  Saponins, due to their physicochemical properties such as foaming, emulsification, dissolution, sweetness and other properties, as well as biological activities such as hemolysis, antibacterial, anti-inflammatory, anti-tumor, analgesic, insecticidal, antioxidant, anti-diabetic and anti-obesity properties, have a variety of application potential directly related to the types of saponins, and many studies have been conducted to identify new uses for these natural compounds.

Foaming and emulsifying properties

Saponins are a group of plant compounds that show foaming and emulsifying properties in aqueous solution, which make them suitable for cosmetic formulations, because the surfactant property of saponins is attributed to their amphiphilic structure. They are a combination of hydrophilic polar glycone moieties and hydrophobic non-polar aglycone moieties. This feature is attributed to the presence of a lipid-soluble aglycone and water-soluble sugar chain. Foaming property is determined by the height and persistence of froth produced when the extract is shaken with distilled water in a test tube. The monodesmosidic saponins (with one sugar unit) exhibit the best foaming characteristics, whereas bidesmosidic and tridesmosidic saponins (with two or three sugar units) produce lesser foaming strength. This structural feature resembles that of synthetic surfactants.

Antimicrobial activity

Saponins derived from plant sources are known to have a wide variety of biological and physicochemical properties. They are a natural alternative to the synthetic surfactants and can be a viable option in the formulation of cosmetics. These biomolecules have gained much research interest owing to their superior features over their chemical and synthetic counterparts, such as versatility, low toxicity, and different biological roles. Moreover, they exhibit antimicrobial, antifungal, anti-proliferative, and antiviral activities that have the potential to combat various diseases.

Antioxidant activity

The search for an effective, safe and non-irritating substitute for these common chemical tensioactive agents has been ongoing in the cosmetic industry. Saponins are a group of non-ionic surfactants that have a hydrophilic component (usually sugar chains) and a hydrophobic component (steroids or triterpenoids). These chemical compounds exhibit various surfactant-relevant properties, including reducing surface tension, micellization, foaming, cleaning, dilution, wetting, stabilizing, solubilizing, emulsifying, etc. Traditionally, these compounds have been used as detergents and additives in washing powders, liquid/powder cleaning, and solid surface cleansing. In addition, the physiochemical properties of saponins are also utilized in food processing, particularly in the selective precipitation of fat globule membranes from cheese whey. These processes are considered eco-friendly and less costly than the use of synthetic surfactants.