Whitening and freckle-removing agents refer to substances that can inhibit the formation of melanin to achieve the reduction of skin pigmentation. Freckle-removing and whitening cosmetics can improve local blemishes such as dull skin tone, unevenness, and pigmentation. Appropriate use of freckle-removing and whitening cosmetics can help lighten spots.
According to the chemical structure and source, the commonly used active ingredients for freckle removal and whitening mainly include the following categories:
This method is mainly an enzyme inhibition method. According to the mechanism of melanin formation, the whitening efficacy of the sample is evaluated by measuring whether the activity of the key enzyme of melanin formation in the cell is inhibited.
By culturing specific cell models in vitro (mouse melanocyte-keratinocyte co-culture, A375 cell-HaCaT cell co-culture, normal human keratinocyte-melanocyte co-culture), and using the MTT colorimetric method (detection The inhibitory effect of whitening ingredients on the growth of melanocytes) or high-tech cell image analysis technology (light microscope, electron microscope) and other methods to measure cytotoxicity, intracellular tyrosinase activity and melanin content in the model, etc. The whitening efficacy of the tested substances was evaluated.
For some whitening ingredients with clear whitening mechanism and dose-effect relationship, analytical instruments can be used to measure the type and content of whitening ingredients in cosmetics, so as to indirectly characterize their whitening efficacy. After the pre-treatment of the cosmetics to be tested, high-performance liquid chromatography (HPLC), gas chromatography (GC) and other analytical and detection instruments are used to detect the characteristic components in the test products to judge their whitening effect. Physicochemical methods are only suitable for evaluating cosmetics containing known whitening ingredients, such as arbutin, niacinamide, ascorbic acid and its derivatives and other whitening ingredients.
1. Brown or black adult guinea pigs are used as experimental animals. There are melanosomes in their skin, which will produce pigmentation after being irradiated by UV light. The experimental process is to irradiate the depilatory site with UVB to cause pigmentation on the skin, apply the test substance continuously, and observe the fading process of the pigmentation from the naked eye or histology.
2. There are three kinds of pigment cells in the neural crest of zebrafish, which are melanocytes, yellow pigment cells and rainbow cells differentiated from intermediate progenitor cells. Therefore, the zebrafish body surface has pigments and can be used as an animal model for whitening efficacy evaluation.
Human body test is the most direct and objective method to reflect the effect of cosmetics. It can be divided into two types: subjective evaluation and objective instrumental evaluation. Subjective evaluation methods can be divided into visual evaluation (dermatologists compare color cards) and self-evaluation of volunteers (Questionnaire) 2 methods.
CD Formulation has been conducting cosmetic inspection work for a long time, including patch test, human trial test, sunscreen cosmetics sun protection index test, etc. At the same time, according to the requirements of cosmetics companies, we can conduct research on the safety of cosmetics on the human body and the efficacy of cosmetic sensory evaluations such as freckle removal, moisturizing, whitening, acne removal, oil control, dandruff removal, and hair.
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