Effects of unripe apple polyphenols on the expression of matrix metalloproteinase-1 and type-1 procollagen in ultraviolet irradiated human skin fibroblasts

Bioassay-guided isolation of an aqueous ethanolic extract from the unripe fruits of Malus pumila cv. Fuji using matrix metalloproteinase-1 (MMP-1) inhibition and type-1 procollagen inducing assays led to isolation of eight phenolic compounds, reynoutrin (1), quercitrin (2), isoquercitrin (3), phloridzin (4), phloretin-2′-O-xyloglucoside (5), 5-O-p-courmaroylquinic acid (6), chlorogenic acid methyl ester (7), and chlorogenic acid (8). The structures were established on the basis of nuclear magnetic resonance and mass spectroscopic data interpretations. All isolates were evaluated for their inhibitory effects on MMP-1, and compounds 1, 2, and 6 exhibited potent inhibitory effects on MMP-1 with IC₅₀ values of 1.3±0.1, 1.4±0.1, and 3.2±0.6 μM, respectively. When evaluated for their effects on type I procollagen synthesis on human fibroblast cells, compounds 1 and 3 were respectively found to display potent activity for induction of type-1 procollagen by 78.5 and 78.6% at the tested concentration of 12.5 M.