A peptide of formula: R1-X1-X2-X3-X4-X5-R2, wherein X1 is T； S2 is L； X3 is K； X4 is T, S, K, R or no amino acid； X5 is V, A, Y, M or no amino acid； R1 represents a primary amine function of the N-terminal amino acid； and R2 represents a hydroxyl function of the C-terminal amino acid, is capable of activating cytochrome C. The peptide can be included in cosmetic and pharmaceutical compositions intended to stimulate the functions of the mitochondria and increase intracellular ATP levels. Such compositions are useful to help protect the skin from external aggression, reduce and treat skin damage caused by UV radiation and combat cutaneous signs of aging.
