Solar UV radiation damages human skin, affecting skin tone and resiliency, and leading to premature ageing (photoageing). Skin damage by oxidants may lead to activation of PKC, thus increasing matrix metalloproteinase
(MMPs) expression and collagen degradation. Administration of Chlorella has been shown to play some biochemical functions as well as in vitro inhibition of MMP1 activity. MMP1 secretion was evaluated following PMA treatment or UVB irradiation in the presence of Resilient Factor (RF, aqueous extract fraction of Chlorella), vitamin C, or vitamin E in human skin fibroblasts. Expression levels of MMP1 and elastin protein and of MMP1, TIMP1, and pro- ollagenmRNAwere also investigated. PMA-induced MMP1 production, protein, and gene expression were suppressed in the presence of RF. Elastin protein diminished after UVB exposure and RF treatment appeared able to counteract the effect ofUVBirradiation. Our results also suggest that RF may increase pro-collagen mRNA expression following UVB exposure. This study shows that application of RF prevents MMP1 production via the inhibition of protein and gene expression. In addition, RF prevents the UVB-suppressed elastin protein and pro-collagen gene expression. These findings indicate that RF may exert a protective effect against UVB irradiation-induced damage in the skin.