Zinc PCA (Pyrrolidone carboxylic acid) or zinc salt is s synthetic ingredient derived from zinc. It has skin-conditioning properties that slow down the signs of aging by stopping destructive enzymes in the skin that can damage the surface of the skin. As a humectant it is able to bind water in the skin reducing transepidermal water loss and has been shown to be very effective for treating pimples, breakouts, reducing redness, sebum secretion and supporting the general healing process of the skin.