In order to develop new anti-photoaging agents, we examined the inhibitory effects of 29 seaweed extracts on transcriptional activities of NF-kappaB and AP-1, and MMP-1 expression. The extracts from 3 species of Alariaceae, Eisenia bicyclis, Ecklonia cava and Ecklonia stolonifera, have showed strong inhibition of both NF-kappaB and AP-1 reporter activity, which were well correlated with their abilities to inhibit MMP-1 expression. In addition, MMP-1 expression was dramatically attenuated by treatment with eckol or dieckol which were purely isolated from E. stolonifera, indicating that these compounds are active principles to inhibit MMP-1 expression in human dermal fibroblasts. Taken together, our data demonstrate the inhibitory effect of eckol and dieckol from Ecklonia species on MMP-1 expression in human dermal fibroblasts and provide a possibility to develop as an agent for the prevention and treatment of skin aging.