Dehydration can lead to a host of skin problems. If your skin is too dehydrated, it can become rough, causing a defect in the skin barrier that allows harmful 

substances to enter the skin, and can lead to serious skin problems, which can be improved by using moisturizers.

Moisturizing is also generally considered the first step in the fight against aging, helping to maintain skin's appearance and elasticity and strengthening its barrier against harmful environmental factors.

Polysaccharides, oils, saponins, flavonoids and polyphenols were the main moisturizing extracts.In plants, there are sugar groups in the structure of water-soluble components such as polysaccharides and glycosides, which have good properties of absorbing and retaining water through hydrogen bonding. The phenolic hydroxyl structure in flavonoids and polyphenols also has the ability to absorb and retain water through hydrogen bonding. Vegetable oils, on the other hand, retain moisture and prevent dry skin by forming a thin layer of oil on the skin.

Most plant polysaccharides have the properties of hygroscopicity and moisture retention. Plant polysaccharides have been widely used in various cosmetics as moisturizers. The moisturizing ability of plant polysaccharides is mainly affected by the structure, composition and molecular weight of its glycosylates. Polysaccharides from many plant extracts improve skin hydration and reduce water loss even in low concentrations.

Saponins are widely distributed in higher plants and have rich structural and functional diversity.Most saponins are a combination of hydrophobic aglycogens and hydrophilic sugar groups, so saponins have a high degree of amphoteric affinity and have the properties of moisturizing, foaming and emulsifying.

Flavonoids in plants not only have certain hygroscopicity, but also have a variety of biological activities. Adding flavonoids to your makeup helps restore elasticity and shine to dry, sagging skin.In addition to moisturizing, many flavonoid-rich plant extracts have biological activities such as antioxidant, anti-aging and anti-inflammatory.

Polyphenols are also widely found in plants. The main ingredient of tea extract is tea polyphenols, which are typically moisturizing polyphenols. Tea polyphenols not only have the functions of moisturizing, sunscreen, inhibiting tyrosinase and anti-photoaging, but also promote the differentiation of keratinocytes and the formation of skin barrier, and promote wound healing. In addition, tea polyphenols can also shift the moisture - rich skin tissue fluid, reducing the viscosity of intercellular space. When the humidity is relatively low, tea polyphenols have better moisture absorption ability and water retention ability. When used in cosmetic formulations, it works better in relatively dry conditions.

Polysaccharides, saponins, flavonoids and polyphenols are the main moisturizing components in plant extracts. In addition to moisturizing, these ingredients often have antioxidant and anti-inflammatory properties. Although plant extracts have many advantages as moisturizing ingredients, there are still some problems: first, except for vegetable oil, the content of moisturizing ingredients in plant extracts is usually not very high, so it is necessary to refine these moisturizing ingredients to improve their moisturizing effect; Second, there are differences in the absorption effects of plant extracts, especially macromolecular polysaccharides, polysaccharide-based saponins, and polyphenol polymers, so it is necessary to adopt different methods or dosage forms to solve the problems of skin permeability and bioavailability. The application of plant extracts in moisturizing products still needs to be explored and improved.