Human dermal fibroblast proliferation activity of usimine-C from Antarctic lichen Ramalina terebrata.

Type I collagen is the major structural protein in dermis and its presence is used to monitor skin cell proliferation and aging. Recently, novel usimine compounds have been found in the Antarctic lichen Ramalina terebrata. In the present study, usimine-C induced cell proliferation of human dermal fibroblast, CCD-986SK, up to 1.6-fold after treating with 90 microg/ml for 48 h. Type I procollagen synthesis was significantly increased 1.3-fold, 3-fold, and 5-fold after treating with 0.14, 0.72, and 3.6 microg usimine-C/ml for 24 h, respectively, whereas no significant increase in type I procollagen was observed after treating with usimine-A or -B. Usimines are usnic acid derivatives. Considering that the difference among the derivatives is a side chain, the proliferation activity may be related to this side chain, triggering an internal signal for type I procollagen expression. Further studies still remain to clarify the signaling pathways for the type I procollagen induction, which is activated by usimine-C.