Triterpenes from birch bark extract beneficially affect wound healing

Triterpenes are the active compounds in birch bark extract which was shown to exert wound healing effects in patients. In this study we investigated the wound healing activity of a triterpene extract (TE) prepared from the outer bark of birch and three of its components, betulin, lupeol and betulinic acid using the scratch assay and 3T3 Swiss albino mouse fibroblasts. The whole extract as well as the three isolated triterpenes enhanced cell numbers in the artificial wound in a concentration-dependent manner. Noteworthy, addition of all three single effects resulted in a similar effect as observed for the whole extract. Cell proliferation as well as cell migration was influenced, with a higher impact on proliferation.

Moreover, studies on the underlying molecular mechanism were undertaken. During the inflammatory phase of wound healing, a variety of proinflammatory compounds like cytokines, chemokines and prostaglandins (PG) such as PGE₂ are released [1]. The key enzyme for the PGE₂ production is COX-2. Interestingly, measurement of COX-2 mRNA levels by qRT-PCR in HaCaT cells treated with the birch bark extract revealed a time-dependent increase of COX-2 mRNA, which is mainly caused by betulin. TNFα-prestimulated HaCaT cells, representing a model of inflammatory skin, showed synergistic effects on COX-2 mRNA levels under the extract stimulation. Further studies are in progress to clarify the molecular mechanism of the wound healing effect.

Acknowledgements: Financial support from the Federal Ministry of Economics and Technology is gratefully acknowledged.

References: 1. Futagami, A. et al. (2008) Lab Invest, 28(11):1503–13.