Antimicrobial and cytotoxic properties of the Copaifera reticulata oleoresin and its major diterpene acids

The oleoresin of Brazilian Copaifera reticulata (Fabaceae) is traditionally used for the treatment of skin and urinary tract infections, respiratory diseases, rheumatism, ulcer and tumors. Thus, playing an important role in the primary health care of the indigenous population [1],[2].

As previous pharmacological tests used the crude oleoresin and only a few studies dealt with pure chemically defined compounds, the aim of this study was to systematically evaluate the antimicrobial and cytotoxic properties of the oleoresin and to assign traditional uses to specific secondary metabolites.

Whereas no cytotoxic activity was detected, the oleoresin showed activity against gram-positive bacteria Enterococcus faecium (IC₅₀ value of 4.2 μg/mL) and methicillin-resistant Staphylococcus aureus (MRSA, IC₅₀ value of 5.3 μg/mL). Fractionation of the oleoresin yielded two dicarboxylic diterpene acids and the four major diterpene acids, comprising three different diterpene scaffolds. Interestingly, the activity was not restricted to a certain diterpene-type but rather correlated with the compounds’ lipophilicity, with the most active compound, (13E)-ent-labda-7,13-dien-15-oic acid, displaying IC₅₀ values of 1.6 (E. faecium) and 2.5 μg/mL (MRSA), respectively. The major diterpenoid, ent-polyalthic acid, was significantly active against dermatophytes with IC₅₀ values of 6.8 μg/mL (Trichophyton rubrum) and 4.3 μg/mL (T. mentagrophytes).

The present study proved the antimicrobial effects of the C. reticulata oleoresin and its diterpenoid constituents, supporting its wide use in folk medicine for the treatment of skin and urinary tract infections and provides potential lead structures for the treatment of two clinically relevant bacterial strains.

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• References

• 1 Veiga Junior VF, Pinto AC. . O genero Copaifera L. Quim. Nova 2002; 25: 273-286
• 2 Leandro LM, de Sousa Vargas F, Souza Barbosa PC, Oliveira Neves JK, da Silva JA, da Veiga-Junior VF. Chemistry and biological activities of terpenoids from copaiba (Copaifera spp.) oleoresins. Molecules 2012; 17: 3866