Non-sunscreen chelating agents (I) must give (a) at least 50% inhibition of Fe-catalysed hydroxyl radical formation in an in-vitro soln. radical assay based on ethylene prodn. from methional and/or (b) a 20% redn. in skin wrinkle grade in an in-vivo mouse skin wrinkling test. (I) is 2,6-pyridinedicarboxylic acid, 1,2-dimethyl-3-hydroxy-4-pyridone, 1-hydroxy-4-methyl-6-(2,4,4-trimethylpentyl)- 2(1H)-pyridone (Ia) or 6-cyclohexyl-1-hydroxy-4-methyl- 2(1H)-pyridone. The compsns. may also contain 1-20% of a sunscreen agent, 0.1-10% of an antiinflammatory agent and/or 1-5% tocopherol sorbate.
Photoprotection compositions comprising chelating agents