A brightening hydrator with stabilized vitamin c derivative vitamin c is an effective antioxidant brightens the skin tone and reduces signs of ageing in its pure form vitamin c is unstable in water magnesium ascorbyl phosphate map is a water soluble derivative of vitamin c it is more stable in water but it is less potent than direct l ascorbic acid it is compatible with water but higher concentrations cannot be offered in a low viscosity serum format and requires emulsification to form