nac or l-glutathione L -Glutathione Collagen Detoxification Whitening Antioxidant Should You Pick NAC or

Both tertiary structures were visualized with the UCSF-Chimera package

Other (less serious) concerns are if EGF can properly penetrate the skin (as it is a medium-sized, polar molecule, so a special delivery system is probably needed), if it can affect collagen synthesis (or just works on the surface plumping up only the upmost layers of the skin) and if it has beneficial effects at all when used in isolation versus when used in a "conditioned media" that contains lots of growth factors resembling the synergistic balance found in the skin

Melanotan Peptides Help protect skin from UV damage and promote even pigmentation

This represents the most common starting point in practical protocols and aligns with the midpoint of clinical dosing ranges adjusted for average body composition