Antimelanoma Potential of Cladonia mitis Acetone Extracts - Comparative in Vitro Studies in Relation to Usnic Acid Content

In this study, the cytotoxic activity of acetone extracts of Cladonia mitis was assessed with respect to the content of usnic acid, a secondary metabolite commonly present in this species. Following quantitative HPLC analysis of the extracts, usnic acid was isolated by preparative chromatography. The study of cytotoxic activity was performed using the MTT test on three melanoma cell lines - HTB140, A375 and WM793. The selectivity of action was also assessed by comparing the effect towards normal human keratinocytes HaCaT. The results showed a dose-dependent cytotoxic activity of the extracts tested and usnic acid itself, but no relationship was found between the content of usnic acid and the activity of the extracts. Furthermore, the extracts showed varied, but rather low anti-tyrosinase activity. Other in vitro and in vivo studies are necessary to demonstrate that C. mitis extracts may be useful in the adjuvant external treatment of skin melanoma.

Automated summary

This study evaluated the cytotoxic activity of acetone extracts of Cladonia mitis and its main constituent, usnic acid, on melanoma cells. The results showed dose-dependent cytotoxic activity of the extracts and usnic acid, but no correlation between usnic acid content and extract activity. The extracts also exhibited low anti-tyrosinase activity. Further research is needed to confirm the potential of C. mitis extracts in adjuvant treatment of skin melanoma.