This study evaluated the antioxidant and protective effects of bioactive compounds isolated from pressurized steam-treated Corni Fructus (PSC). We had previously tested the protective effects of the furan fraction containing 5-hydroxymethylfurfural (5-HMF), polyphenol fraction containing gallic acid, and iridoid glycoside fraction containing morroniside and loganin. We measured the potency of antioxidant activities of the bioactive compounds isolated from PSC via oxygen radical absorbance capacity (ORAC), 2,2-diphenyl-1-picrylhydrazyl (DPPH) radical scavenging, and 2,2'-azino-bis(3-ethylbenzothiazoline-6-sulfonic acid) (ABTS) radical scavenging assays. One fraction in particular (named F-2) not only contained high amounts of phenolics but also had potent antioxidant activities. The protective effects of F-2 were evaluated by measuring the levels of the collagen-degrading enzyme, matrix metalloproteinase-1 (MMP-1), and the marker of collagen biosynthesis, procollagen type I C-peptide (PIP), in UVB-treated HS68 fibroblasts. MMP-1 levels decreased in an F-2 concentration-dependent manner, and PIP secretion from the cultured HS68 cells was significantly higher than that from the UVB-irradiated cultures alone. Further, F-2 attenuated UVB-induced MMP-1 and ameliorated UVB-downregulated collagen type I alpha 1 mRNA expression in HS68 cells. Therefore, F-2 isolated from PSC is a good candidate for the prevention of skin damage from free radicals in various skin conditions.
Keywords: 5-hydroxymethylfurfural; gallic acid; iridoid glycoside.