As natural, green, healthy and safe cosmetics with added plant extracts are gaining more and more attention, the development of active substances from plant resources and the development of purely natural cosmetics has become one of the most active themes in the development of the cosmetics industry. The redevelopment of plant resources is not a simple restoration of history, but rather a way to both uphold the traditional Chinese culture and integrate the traditional theories of Chinese medicine, as well as to use modern biochemical technology to develop new plant-derived cosmetics and provide green raw materials for the development of scientific and safe natural cosmetic products. In addition, plant extracts are widely used in pharmaceuticals, food supplements, functional foods, beverages, cosmetics and other fields.
Plant Extracts (PE) refers to plant products with biological small molecules and macromolecules formed for the purpose of separating and purifying one or more active ingredients in plant raw materials by physical, chemical and biological means. Compared with traditional cosmetics, cosmetics formulated with plant extracts as active ingredients have many advantages: they overcome the shortcomings of traditional cosmetics that rely on chemical synthetics, making the products safer; the natural components are more easily absorbed by the skin, making the products more effective; and the functionality is more prominent, etc.
Selecting the right plant extracts and using the right amount of plant extracts to add to cosmetic products is the only way to maximize their effects. The main roles of plant extracts in cosmetics are: moisturizing, anti-aging, spot removal, sunscreen, antiseptic, etc. And plant extracts are green and safe.
Moisturizing effect
The moisturizing properties in cosmetics are mainly achieved in two ways: one is the water locking effect of the formation of hydrogen bonds between moisturizers and water molecules; the other is the formation of a closed film of oil on the skin surface.
The so-called moisturizing cosmetics are cosmetics that contain moisturizing ingredients to maintain the water content of the stratum corneum in order to restore the skin's luster and elasticity. Moisturizing cosmetics are mainly divided into two types according to their characteristics: one is the use of water-retaining substances that can strongly bond with water on the skin surface to moisturize the stratum corneum, called humectants, such as glycerin; the other is a substance insoluble in water that forms a lubricating film on the skin surface and acts as a seal to prevent water loss, thus maintaining a certain amount of moisture in the stratum corneum, called emollients or conditioning agents, such as petroleum jelly, oils, waxes .
There are quite a number of plants with hydrating and moisturizing effects, such as aloe vera, seaweed, olive, chamomile, etc. all have good moisturizing effects. Zhang Qi et al. studied the moisturizing properties of aloe vera by extracting aloe vera glycosides: aloe vera glycosides have good moisturizing and hygroscopic properties. It shows a certain linear relationship with time. The hygroscopic performance of aloin in high humidity environment is better than the moisturizing performance in low humidity environment. Adding aloe vera moisturizing ingredients to moisturizing skin care products is non-toxic, harmless, green and healthy.
Anti-aging effect
As we grow older, the skin starts to show an aging state, mainly including the content of collagen, elastin and mucopolysaccharide in the skin decreases to different degrees, the blood vessels supplying skin nutrients shrink, the elasticity of the blood vessel wall decreases, the skin epidermis gradually thins and bulges, and the subcutaneous fat decreases, which intuitively manifests as the appearance of wrinkles, chloasma and age spots. At present, the causes of human aging have been summarized in the following aspects: First, the increase of free radicals and aging, free radicals (freeradical) are atoms or molecules with unpaired electrons due to covalent bond cleavage, which are highly chemically active and generate lipid peroxide (LPO) by peroxidation with unsaturated lipids, the end product of which is malondialdehyde (LPO). The end product malondialdehyde (MDA) can react with most substances in living cells, leading to a decrease in biofilm permeability, damage to D NA molecules, and cell death or mutation. Secondly, medium-wave ultraviolet (UVB) and long-wave ultraviolet (UVA) rays in sunlight cause skin photoaging. And UV radiation causes skin aging mainly through the following mechanisms: (i) damage to DNA; (ii) cross-linking of collagen; (iii) reduction of immune response by inducing the inhibitory pathway of antigen stimulation response; (iv) cell and tissue damage by generating highly reactive free radicals interacting with various intracellular structures; (v) direct inhibition of epidermal Langerhans' cell function, causing photoimmunosuppression and diminished. In addition to this, non-enzymatic glycosylation, metabolic dysregulation, and matrix metalloproteinase aging can also affect skin aging.
Toshiya Masuda et al. extracted effective anti-free radical DPPH from edible plants and applied it to suitable cosmetic products with good results. Li Xiaojing et al. used hot water maceration to extract the crude extract from Tigris tigris, and then obtained the crude extract after using polyamide column chromatography, and performed a series of qualitative and quantitative analyses. The results of the study showed that the extract of C. tigrinus had a certain inhibitory effect on elastase, thus providing an anti-aging and anti-wrinkle effect.
Anti-spot effect
The difference of human skin color usually depends on the content and distribution of epidermal melanin, dermal blood circulation and the thickness of the stratum corneum. Dark skin or dark spots are mainly influenced by the accumulation of melanin, skin oxidation, keratinocyte deposits, poor skin microcirculation and toxin accumulation in the body.
Nowadays, the effect of spot removal is mainly achieved by affecting the formation and proliferation of melanin, one is tyrosinase inhibitor. In the conversion from tyrosine to dopa and dopa to dopaquinone, both are catalyzed by tyrosinase, which directly controls the start and speed of melanin synthesis and determines whether the subsequent steps can proceed. Brenner M et al. showed that arbutin can inhibit tyrosinase activity and block dopa synthesis in a concentration range that is not melanocytotoxic, thereby inhibiting melanogenesis. Cheng Liang, Yeon Jae Ho et al. studied the chemical constituents in black tiger rhizomes and their whitening effects while evaluating skin irritation. The results of the study showed that 17 compounds (HLH-1 to 17) were isolated, of which HLH-3 inhibited melanin formation, thus achieving whitening effect, while the extract had low irritation to skin objects. Ren Hongrong et al. proved through experiments that perfumed lotus alcohol extract has a significant inhibitory effect on melanin formation, and it can be used as a new type of plant-derived whitening agent formulated into suitable creams to make functional cosmetics for skin care, anti-aging and spot removal.
Another kind of melanocytotoxic agents, such as endothelin antagonists found in plant extracts, can competitively inhibit the binding of endothelin to melanocyte membrane receptors, inhibit the differentiation and proliferation of melanocytes, thus achieving the purpose of inhibiting melanogenesis caused by UV radiation. extract can effectively inhibit the proliferation of melanocytes, and its addition to suitable cosmetic formulations has a significant effect on skin whitening and brightening. Zhang M. et al. extracted and studied herbal extracts of Scutellaria baicalensis, Radix et Rhizoma tigrinum and Radix et al. The results showed that their extracts could inhibit cell proliferation to varying degrees and had a significant inhibitory effect on intracellular tyrosinase activity, which could significantly reduce the content of intracellular melanin, thus achieving the efficacy of spot whitening.
Sunscreen role
Generally speaking, sunscreens commonly used in sunscreen cosmetics are divided into two categories: one is UV absorbers, which are organic compounds such as ketones; the other is UV shielding agents, which are physical sunscreens such as TiO2 and ZnO. However, these two types of sunscreens can cause problems such as skin irritation, skin allergy and clogging of skin pores. However, many natural plants have good absorption of UV rays and indirectly enhance the sunscreen performance of products by reducing the radiation damage caused by UV rays to the skin. In addition, sunscreen ingredients in plant extracts have the advantages of less skin irritation, photochemical stability, safety and reliability compared with traditional chemical and physical sunscreens. Zheng Hongyan et al. selected three natural plant extracts, dermatophyllin, resveratrol and arbutin, and studied the safety and UVB and UVA protection effects of their compounded sunscreen cosmetics through human testing. The results showed that some natural plant extracts exhibited good UV protection. Direction et al. used buckwheat flavonoids as raw material, the sunscreen performance of flavonoids was studied. It was found that: the application of flavonoids to actual emulsions, and physical and chemical sunscreens for compounding, providing a theoretical basis for the future application of plant sunscreens in cosmetics.