Sodium L-ascorbyl-2-phosphate (SAP), with CAS number 66170-10-3, is a stable, water-soluble derivative of vitamin C (L-ascorbic acid). Its chemical structure features a phosphate group at the C-2 position, which significantly enhances its stability against oxidation, heat, and light compared to the parent ascorbic acid. This modification allows it to retain the biological activity of vitamin C upon enzymatic hydrolysis in vivo. The primary application of SAP is as a highly effective antioxidant and skin-brightening agent in cosmetic and personal care formulations. It functions by inhibiting tyrosinase activity, thereby reducing melanin production and mitigating hyperpigmentation. Its superior stability makes it a preferred ingredient in serums, creams, and lotions designed for anti-aging and skin tone correction. Concurrently, it is also utilized as a nutritional supplement and antioxidant in aquaculture and animal feed, particularly in fish and shrimp diets, to enhance growth, immune function, and stress resistance. As a stable source of vitamin C, it finds use in certain functional food and beverage applications where long shelf-life is required. Its safety profile is well-regarded, and it is considered a gentle yet potent alternative to pure ascorbic acid in topical products, minimizing the risk of irritation associated with low-pH vitamin C solutions.