From Volume 14, issue 3, June 2005, Chinese Cosmetology
At present, there are many kinds of natural or synthetic compounds with certain anti-aging effect in cosmetics, and the main ones with definite effect are sunscreen, humectant, cuticle peeling agent, decolorizer, antioxidant, retinoic acid compound, estrogen, active ingredients and cytokines extracted from natural products or synthesized artificially. Here is the introduction:
1 sunscreen
Ultraviolet radiation in sunlight is the most important exogenous factor causing premature aging of skin, and it is also an important reason for multiple skin tumors in the exposed area. In fact, the skin of exposed area is generally 30 years older than that of non exposed area in appearance; therefore, sun protection is the most important basic link to prevent skin aging. Traditional sunscreens include physical sunscreens and chemical sunscreens, and the newly developed bionic sunscreens also have good application prospects. We will focus on some knowledge of sunscreen cosmetics in the next lecture.
2 Moisturizer
Human skin has a natural moisturizing system, which is composed of water natural moisturizing factor (NMF) - lipids. When the skin is aging, the water loss increases, resulting in cell shrinkage and aging, tissue shortage and atrophy, and the appearance of histological structure and morphological changes, leading to the gradual appearance of fine wrinkles. Humectants play an important role in maintaining skin moisture and repairing skin barrier function, and are widely used in medicine and cosmetics.
3 Cuticle Remover
When the skin is aging, the rate of metabolism of the epidermis slows down, and the cuticle often fails to fall off in time, which makes the skin surface rough. The use of mild cuticle peeling agent can reduce the bond force between the cells in the aging cuticle, accelerate the speed of cell renewal and promote the separation of dead cells, etc. to achieve the purpose of improving the skin state, which has the effect of making the skin surface smooth, tender and soft. It has anti wrinkle and anti-aging effect on skin. The commonly used exfoliators in cosmetics are alpha hydroxyacids (AHAs) and beta hydroxyacids (BHA). Alpha hydroxyacids include hydroxyacetic acid, lactic acid, citric acid, malic acid, phenylglycolic acid and tartaric acid, most of which are found in fruits (lemon, apple, grape, etc.), commonly known as fruit acids. High concentration of AHAS can be used for chemical exfoliation of epidermis, while low concentration of AHAS can thicken the active epidermis, reduce the adhesion of keratinocytes, increase the content of mucopolysaccharide and hyaluronic acid in dermis, increase the formation of collagen, reduce skin wrinkles, increase the smoothness and tenacity of skin, and improve the performance of skin aging caused by light aging. β - hydroxy acid is mainly extracted from natural growth plants, such as willow bark, holly leaves and birch bark. It is a new generation of fat soluble fruit acid. It has stronger affinity and permeability than traditional water-soluble fruit acid and skin, has slow-release effect, can dissolve keratinized substances in the hair follicle mouth, and make the pores narrow. The use concentration is only one fifth of the traditional fruit acid, mild and efficient. At present, the "plant essence" mentioned in cosmetics also has a certain exfoliation effect.