L-Proline-  Latest scientific findings demonstrate that the different structured amino acids L-arginine, L-lysine hydrochloride, L-glycine, sodium glutamate, L-proline and L-threonine may penetrate into human skin, whereby an adequate concentration time profile is obtained in the living epidermis if special humeactans are added. In skin the amino acids will contribute to the natural moisturizing factors. L-proline demonstrates the highest hydration grade of all amino acids tested