Abuse of laxatives and melanosis coli Despite the name "melanosis," the pigment isn't melanin. The Pigment: It is actually lipofuscin, a "wear and tear" pigment. The Process: Anthraquinone laxatives cause apoptosis (cell death) of the colonic epithelial cells. Pigmented Lesions and Melanoma Plastic Surgery KeyPlastic Surgery Key Melanosis Coli Understanding Melanosis Eye: Symptoms, Causes, and Treatments Northwest Eye