Ampelopsis brevipedunculata (Vitaceae) extract stimulates collagen synthesis through superoxide generation in the serum-free cultures of rat dermal fibroblasts and Ito cells

We describe the effects of an ethanol-extracted fraction of berries of Ampelopsis brevipedunculata (Maxim.) Trautv. (Vitaceae), a plant used in folk medicine to treat liver disease, on the synthesis of non-collagenous proteins and collagen by rat collagen-producible cells such as dermal fibroblasts and liver non-parenchymal Ito cells. The generation of superoxide and hydroxyl radical was assessed by measuring the reduction of cytochrome c and the formation of thiobarbituric acid-reactive substances from deoxyribose, respectively. The synthesis of non-collagenous proteins and collagen as evaluated by measuring the extent of [H-3]tryptophan incorporation into a total protein fraction of culture products and the [H-3]proline-incorporating rate into a collagenase-digestible protein fraction, respectively. Both types of cells promptly synthesized only collagen in response to a dialyzable fraction of the extract. Major activity to generate oxygen free radicals accumulated in the dialyzable fraction whereas activity to decrease ferrous iron-mediated generation of the radicals accumulated in an undialyzable fraction of the extract. Stimulation of collagen synthesis was caused by superoxide because addition of superoxide dismutase but not pyruvate, an antioxidant of hydrogen peroxide, or dimethyl sulfoxide, an antioxidant of the hydroxyl radical, abrogated the stimulatory effect. The extract may arrest the progress of liver injury mediated by oxygen free radicals generated in the presence of ferrous iron. (C) 1997 Elsevier Science Ireland Ltd.