Increase of collagen synthesis by obovatol through stimulation of the TGF-β signaling and inhibition of matrix metalloproteinase in UVB-irradiated human fibroblast

Summary Background Alterations of the extracellular matrix (ECM) is critical in the photo and age-damaged skin. Thus any compounds keep ECM can protected from photo and aged-damaged skin. ECM is predominantly composed of type I and type III collagens in the dermis. Transforming growth factor (TGF-β)s play important roles in cellular biosynthesis of extracellular matrix. Activator protein 1 (AP-1) and Smad are significant factors that mediate TGF-β. Objective We have investigated increasing effects of obovatol, a biphenolic compound isolated from leaves of Magnolia obovata on the collagen synthesis through stimulation of the TGF-β signaling and inhibition of matrix metalloproteinase, thereby protect against from UV damages via maintain of collagen in the UVB irradiated human fibroblast cells. Methods The fibroblasts were pretreated with obovatol for 24h and then the cells were irradiated with UVB. UVB-exposed cells were further cultured for 24h. Type I procollagen, MMP-3, TGF-β and Smad as well as phosphorylation of MAPK family expression were determined by Western blot. The activation of AP-1 was investigated using EMSA. The released type I procollagen and TGF-β into cell culture medium were determined by Western blot after concentration of these proteins. Results The results showed that obovatol stimulated type I procollagen, TGF-β, and Smad expression and inhibited matrix metalloproteinase-3 (MMP-3) in dose-dependent manner (1–5μM) in UVB-irradiated human fibroblast cells. Obovatol also inhibited UVB-induced activation of AP-1 and MAP kinases. Conclusion These results suggest that obovatol increases collagen synthesis through stimulation of the TGF-β signaling and inhibition of matrix metalloproteinase in UVB-irradiated human fibroblast, thus obovatol could be effective against photo-damaged skin.