Repechage C Serum Seaweed Filtrate is a lightweight, oil-free serum that helps reduce the appearance of fine lines and wrinkles and assists in maintaining proper moisture balance. Short for cyto-serum, C-Serum is a highly concentrated extract from Laminaria Digitata Seaweed, rich in 42 trace elements and minerals, 18 amino acids, 12 vitamins, phyto -hormones, and natural anti-oxidants..