CAS 175357-18-3 Undecylenoylphenylalanine is a skin-lightening ingredient popular for its ability to inhibit the production of melanin, the pigment responsible for dark spots and uneven skin tone. This compound works by targeting the enzyme responsible for melanin synthesis, helping to reduce the appearance of hyperpigmentation and discoloration. By adding this ingredient to skin care products, consumers can achieve a brighter complexion and address issues related to sun damage and age spots.