The INKEY List Alpha Arbutin Serum 30mlInterrupt Melanin at the Source with The INKEY List Alpha Arbutin Serum 30ml Not all brightening serums work the same way. Exfoliants remove already pigmented skin cells. Vitamin C blocks melanin while also working as an antioxidant. Alpha Arbutin does something more targeted: it inhibits tyrosinase the enzyme that converts amino acids into melanin. No tyrosinase activity means less melanin is produced, and existing dark spots, post acne marks and