Combretum leprosum Mart. (Combretaceae): potential as an antiproliferative and anti-inflammatory agent.

Combretum leprosum is a species that is popularly used in Brazil as a healing agent to treat skin problems and lesions. In this study we investigated the possible potential of this extract to treat inflammatory and hyperproliferative skin conditions. Classical models of skin inflammation such as TPA- and croton oil-induced mouse ear oedema were applied in order to verify the potential topical anti-inflammatory activity of the ethanolic extract from flowers of Combretum leprosum. Topical application of ethanolic extract promoted a dose-dependent inhibition of phorbol ester-induced ear oedema, reduced myeloperoxidase activity and IL-6 tissue levels with inhibition comparable to dexamethasone (positive control). Histological and immunohistochemical analysis revealed that ethanolic extract also suppressed cell infiltration. Ethanolic extract altered inflammatory parameters on a chronic skin inflammation model induced by repeated applications of croton oil, decreasing ear oedema, epidermal hyperproliferation and cell infiltration. In addition, immunohistochemical analysis showed that the extract decreased PCNA expression on the epidermis. Taken together, these results suggest that the extract from flowers of Combretum leprosum could be considered as a new potential tool for the treatment of several skin inflammatory diseases since it reversed the skin inflammatory and hyperproliferative process in a very significant manner. Further investigations are needed in order to verify the cellular mechanism and safety of Combretum leprosum extract.