Topical application of the hexane fraction of Lacistema pubescens reduces skin inflammation and cytokine production in animal model

Objectives The aim of this study was to investigate the acute topical anti‐inflammatory effect of the hexane fraction (HLP) of Lacistema pubescens in mice. Methods Ear oedema models induced by croton oil, arachidonic acid, phenol, histamine, ethyl phenyl propiolate and capsaicin. Histopathological analyses of ear tissue samples sensitized with croton oil were performed. Myeloperoxidase activity (MPO), the pro‐inflammatory cytokine‐inhibitory effect and dermatoxicity were also evaluated. Key findings HLP (1, 0.5 and 0.1 mg/ear) resulted in a substantial reduction in skin thickness or tissue weight on all models tested, except for capsaicin‐induced ear oedema, similar to dexamethasone (0.1 mg/ear) and/or indomethacin (0.5 mg/ear). Histopathological analyses and neutrophil‐mediated MPO activity confirmed the topical anti‐inflammatory effect of HLP. In addition, HLP reduced IL‐1β, IL‐6 and tumour necrosis factor‐α cytokine levels. Sitosterol‐rich fraction (SRF), obtained from HLP fractionation, reduced ear oedema on croton oil and phenol models at the same dose of dexamethasone (0.1 mg/ear). No dermotoxicity was observed. Conclusions The mechanism of action of HLP was associated with the inhibition of several pro‐inflammatory mediators, including cytokines, arachidonic acid metabolites and histamine, which suggested a glucocorticoid‐like effect, reinforced by the presence of the steroid sitosterol. This is the first report on anti‐inflammatory activity of L. pubescens leaves.