INTERACTION BETWEEN BETA-CAROTENE AND LIPOXYGENASE IN HUMAN SKIN

beta-Carotene is widely used in skin care therapy. Its effects on skin are unclear, but actions on lipid peroxidation pathways may be an imp ortant element of any protection activities it exerts. This study exam ines the possible effects of beta-carotene on enzymatic lipid peroxida tion by lipoxygenase in human skin, using in vitro and ex vivo models. The effects of beta-carotene on lipid peroxidation in human skin were studied in skin homogenates and in a semi-in vivo model of skin penet ration, using [1-C-14]-arachidonic acid or [1-C-14]-linoleic acid as s ubstrate. When relatively low concentrations (about 0.3 mu M) of beta- carotene were added to epidermal homogenates, the major metabolites of arachidonic acid (12-hydroxy-cis-5,8,14,trans-10-eicosatetraenoic aci d and 15-hydroxy-cis-5,8,11,trans-13-eicosatetraenoic acid) and of lin oleic acid (13-hydroxy-cis-9,trans-11-octadeca dienoic acid and 9-hydr oxy-trans-10,cis-12-octadeca dienoic acid) were significantly decrease d. Following [1-C-14]-linoleic acid penetration through the semi in vi vo model layers, the skin surface was the main site in which the major linoleate product, 13-hydroxy-cis-9,trans-11-octadeca dienoic acid wa s detected. Furthermore, its level was inhibited by up to 80%, compare d with the control, when beta-carotene was added to the system. The da ta presented in this study suggest possible interactions between beta- carotene and human epidermal lipoxygenase. beta-carotene may effect li pid peroxidation in human skin, either as a free radical scavenger or as a specific lipoxygenase inhibitor. Copyright (C) 1996 Elsevier Scie nce Ltd