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.
