Topical antiinflammatory effects of the ether extract from Protium kleinii and alpha-amyrin pentacyclic triterpene

Abstract

Protium kleinii (Burseraceae), a native Brazilian medicinal plant is claimed to be useful to treat some inflammatory states. Now we reported that topical application of either the ether extract or the main active constituent from P. kleinii the pentacyclic triterpene alpha-amyrin, all caused a dose-related inhibition of both ear oedema (ID50 values are 0.55 and 0.31 mg/ear, respectively) and influx of polymorphonuclear cells (ID50 values are 0.72 and 0.45 mg/ear, respectively) in response to topical application of 12-O-tetradecanoylphorbol-acetate (TPA) in the of mice ear. In terms of the efficacy, the maximal obtained inhibition for both ear oedema and neutrophil influx was very similar to that produced by the topical application of the steroidal antiinflammatory drug dexamethasone (DE; with inhibition of 70+/-5%, 66+/-3%, and 87+/-4% for oedema and 83+/-6%, 73+/-5%, and 91+/-3% for neutrophil influx, for the ether extract, alpha-amyrin, and dexamethasone, respectively). Likewise, both the ether extract and alpha-amyrin given topically dose-dependently prevented the increase of the proinflammatory cytokine interleukin-1beta levels in response to topical application of TPA. The calculated mean ID50 values are 1.81 and 0.53 mg/ear, respectively. Again, the efficacy of the extract and alpha-amyrin was very similar to that produced by dexamethasone (63+/-6%, 61+/-5%, and 74+/-5%, respectively). In marked contrast to phenidone, a lipo and cyclooxygenase inhibitor, neither the ether extract nor the alpha-amyrin inhibited arachidonic acid-mediated ear oedema in mice. Collectively, these results indicate that the active constituents present in the ether extract of P. kleinii including the pentacyclic triterpene alpha-amyrin are good candidates to develop a skin permeable antiinflammatory drug.