In vitro and in vivo antimalarial potential of oleoresin obtained from Copaifera reticulata Ducke (Fabaceae) in the Brazilian Amazon rainforest

Background: In view of the wide variety of the flora of the Amazon region, many plants have been studied in the search for new antimalarial agents. Copaifera reticulata is a tree distributed throughout the Amazon region which contains an oleoresin rich in sesquiterpenes and diterpenes with β-caryophyllene as the major compound. The oleoresin has demonstrated antiparasitic activity against Leishmania amazonensis. Because of this previously reported activity, this oleoresin would be expected to also have antimalarial activity.

Purpose: In this study we evaluated the in vitro and in vivo antimalarial potential of C. reticulata oleoresin.

Methods: In vitro assays were done using P. falciparum W2 and 3D7 strains and the human fibroblast cell line 26VA Wi-4. For in vivo analysis, BALB/c mice were infected with approximately 10⁶ erythrocytes parasitized by P. berghei and their parasitemia levels were observed over 7 days of treatment with C. reticulata; hematological and biochemical parameters were analyzed at the end of experiment.

Results: The oleoresin of C. reticulata containing the sesquiterpenes β-caryophyllene (41.7%) and β-bisabolene (18.6%) was active against the P. falciparum W2 and 3D7 strains (IC₅₀ = 1.66 and 2.54 µg/ml, respectively) and showed low cytotoxicity against the 26VA Wi-4 cell line (IC₅₀ > 100 µg/ml). The C. reticulata oleoresin reduced the parasitemia levels of infected animals and doses of 200 and 100 mg/kg/day reached a rate of parasitemia elimination resembling that obtained with artemisinin 100 mg/kg/day. In addition, treatment with oleoresin improved the hypoglycemic, hematologic, hepatic and renal parameters of the infected animals.

Conclusion: The oleoresin of C. reticulata has antimalarial properties and future investigations are necessary to elucidate its mechanism of action.