Retinoic acid is also called tretinoin. Its molecular formula is C20H28O2. It is a metabolic intermediate product of vitamin A in the body. It mainly affects bone growth and promotes epithelial cell proliferation, differentiation, and keratolysis. It is used to treat acne vulgaris, psoriasis, ichthyosis, lichen planus, pityriasis red, keratosis follicularis, squamous cell carcinoma and melanoma.
Epidermal keratinocytes, melanocytes and dermal fibroblasts are all important target cells for the action of tretinoin. Tretinoin can affect the melanin production of melanocytes. Its effect is multi-site, and it has inhibitory effect on the activities of three types of catalytic enzymes such as tyrosine hydroxylase, dopa oxidase and dihydroxyindole oxidase. Reduce the formation of melanin and reduce skin pigmentation.