Anti-inflammatory effect of Pimenta racemosa var. ozua and isolation of the triterpene lupeol.

Pimenta racemosa var. ozua (Myrtaceae) is a tropical plant, used in different inflammatory processes by the folk medicine of the Caribbean region. From the methanol extract of the leaves a terpenic compound identified as lupeol has been isolated for the first time in this species. The anti-inflammatory activity of the extract has been evaluated against two experimental models of acute inflammation: paw edema in rats, using carrageenan or dextran as phlogogen agents, and ear edema in mice, inducing the inflammation with 12-o-tetradecanoylphorbol acetate (TPA). Myeloperoxidase activity (MPO) was also assayed as an indicator of leukocytary migration in the inflamed ears. In the carrageenan test, the methanol extract (125 and 250 mg kg(-1) p.o.) had a dose-dependent and significant effect at different time intervals. On the contrary, when the dextran was injected in paw, the extract did not reduce the inflammation provoked. This behavior was similar to indomethacine (25 mg kg(-1)) used as a standard drug. In the TPA-induced ear edema, the methanol extract (0.5, 1 and 3 mg ear(-1)) significantly reduced the inflammation. In the MPO assay a significant inhibition of the enzyme was observed in the inflamed tissue in all the samples assayed. These results show that the methanol extract from the leaves of Pimenta racemosa var. ozua, is effective against acute inflammation processes, by oral route and when topically applied. The anti-inflammatory behavior of the extract was similar to that exhibited by the selective cyclo-oxygenase inhibitor, indomethacin. On the other hand, the reduction of MPO activity shows that the action mechanism is clearly related with the neutrophil migration.