Asiaticoside induces human collagen I synthesis through TGFbeta receptor I kinase (TbetaRI kinase)-independent Smad signaling

Planta Med. 2006 Mar;72(4):324-8. doi: 10.1055/s-2005-916227.


Skin aging appears to be principally related to a decrease in the levels of type I collagen, the primary component of the skin dermis. Asiaticoside, a saponin component isolated from Centella asiatica, has been shown to induce type I collagen synthesis in human dermal fibroblast cells. However, the mechanism underlying asiaticoside-induced type I collagen synthesis, especially at a molecular level, remains only partially understood. In this study, we have attempted to characterize the action mechanism of asiaticoside in type I collagen synthesis. Asiaticoside was determined to induce the phosphorylation of both Smad 2 and Smad 3. In addition, we detected the asiaticoside-induced binding of Smad 3 and Smad 4. In a consistent result, the nuclear translocation of the Smad 3 and Smad 4 complex was induced via treatment with asiaticoside, pointing to the involvement of asiaticoside in Smad signaling. In addition, SB431542, an inhibitor of the TGFbeta receptor I (TbetaRI) kinase, which is known to be an activator of the Smad pathway, was not found to inhibit both Smad 2 phosphorylation and Type 1 collagen synthesis induced by asiaticoside. Therefore, our results show that asiaticoside can induce type I collagen synthesis via the activation of the TbetaRI kinase-independent Smad pathway.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Blotting, Western
  • Centella*
  • Collagen Type I / biosynthesis
  • Collagen Type I / drug effects*
  • Fibroblasts / drug effects
  • Fibroblasts / metabolism
  • Humans
  • Keratolytic Agents / administration & dosage
  • Keratolytic Agents / pharmacology*
  • Keratolytic Agents / therapeutic use
  • Phytotherapy*
  • Plant Extracts / administration & dosage
  • Plant Extracts / pharmacology*
  • Plant Extracts / therapeutic use
  • Protein Serine-Threonine Kinases / metabolism
  • Receptor, Transforming Growth Factor-beta Type I
  • Receptors, Transforming Growth Factor beta
  • Signal Transduction
  • Skin Aging
  • Smad3 Protein / metabolism
  • Smad4 Protein / metabolism
  • Triterpenes / administration & dosage
  • Triterpenes / pharmacology*
  • Triterpenes / therapeutic use


  • Collagen Type I
  • Keratolytic Agents
  • Plant Extracts
  • Receptors, Transforming Growth Factor beta
  • Smad3 Protein
  • Smad4 Protein
  • Triterpenes
  • Protein Serine-Threonine Kinases
  • Receptor, Transforming Growth Factor-beta Type I
  • asiaticoside