Use of at least one skin aging protective substance inhibiting or at least reducing, preferably slowing the light induced skin aging, for reducing and/or inhibiting the light induced skin aging, is claimed. The skin aging protective substance is selected such that it: inhibits or at least reduces the light induced decrease of endogenous hyaluronic acid synthesis taking place in the skin cells; and/or inhibits or at least reduces the light induced decrease of hyaluronic acid secretion from the skin cells into the extracellular matrix of the skin. Use of at least one skin aging protective substance inhibiting or at least reducing, preferably slowing the light induced skin aging, for reducing and/or inhibiting the light induced skin aging, is claimed. The skin aging protective substance is selected such that it: inhibits or at least reduces the light induced decrease of endogenous hyaluronic acid synthesis taking place in the skin cells; inhibits or at least reduces the light induced decrease of hyaluronic acid secretion from the skin cells into the extracellular matrix of the skin; and/or increases or at least maintains or at least reduces the decrease of endogenous hyaluronic acid synthesis in the skin cells and/or hyaluronic acid secretion from the skin cells into the extracellular matrix of the skin, preferably endogenous synthesis of collagen, preferably collagen 1~a1, collagen 1~c1 and/or collagen 3~a1, decreasing under the effect of light. Independent claims are also included for: (1) a composition, preferably a cosmetic composition, for topical cosmetic treatment, preferably for reducing and/or inhibiting the light induced skin aging, preferably UV-B-induced skin aging, comprising at least one skin aging protective substance; (2) cosmetic treatment for reducing and/or inhibiting the light induced skin aging, preferably the UV-B-induced skin aging, comprising preventing or at least reducing the light induced decrease of the endogenous hyaluronic acid synthesis in the skin cells, and/or increasing the endogenous hyaluronic acid synthesis in the skin cells and/or hyaluronic acid secretion from the skin cells into the extracellular matrix of the skin or at least maintaining or at least reducing the decrease of endogenous hyaluronic acid synthesis in the skin cells and/or hyaluronic acid secretion from the skin cells into the extracellular matrix of the skin, preferably endogenous synthesis of collagen, preferably collagen 1~a1, collagen 1~c1 and/or collagen 3~a1, under the conditions of light induced skin aging; (3) detecting and/or identifying the skin aging protective substance, comprising (a) providing a suitable test system, with which the efficacy and/or the quality of at least one test substance comprising the skin aging protective substance can be detected, (b) exposing the test substance to the test system provided in the process step (a), and (c) analyzing with suitable methods adapted for the respective test system, preferably with respect to the existence of the regulation and/or the influence of the test substance on the endogenous synthesis of hyaluronic acid and/or on hyaluronic acid secretion from the skin cells into the extracellular matrix and/or on the endogenous synthesis of collagen, preferably collagen 1~a1, collagen 1~c1 and/or collagen 3~a1; and (4) the skin aging protective substance obtainable by the above method. ACTIVITY : Dermatological. MECHANISM OF ACTION : Ras homolog gene family, member A activator; Rho-associated, coiled-coil containing protein kinase 1-activator; (Lin-11-Isl1-Mec-3)-kinase activator; Cofilin-P-activator; (E twenty-six)-1-activator; Hyaluronic acid 2 synthase activator. The ability of the skin aging protective substance to activate hyaluronic acid synthase 2 was tested in two lines of human dermal fibroblasts. The results showed that the skin aging protective substance exhibited a reduction of the suppression of the hyaluronic acid synthase 2 by 75.6 \ 2.95%.