Vitamin C is a water soluble vitamin that is chemically very unstable and only penetrates the skin in small amounts. In cosmetics, the derivative is favoured and is only divided into ascorbic acid in the skin, and as such, ensures better stability. The following are predominant:

liposoluble Ascorbyl Palmitate, vitamin C esterified palmitic acid
Sodium Ascorbyl Phosphate, a water soluble ascorbic acid salt

Vitamin C stimulates the metabolism of the connective tissue and the enzymes that are responsible for the production of collagen - simultaneously the depletion of collagen is inhibited. It has healing and regenerating effects on damaged connective tissues. Vitamin C stabilizes the skin's barrier function and improves inflammatory, impure skin conditions and reduces age spots.

Cosmetic properties:

• stimulates the metabolism of the connective tissue
• stimulates collagen production, inhibiting collagen depletion
• heals damaged connective tissues
• reduces age spots

see  Heike Käser 2010, "Naturkosmetische Rohstoffe", Linz, Verlag Freya, 3. Edition 2012