Carapa guianensis Aublet (Andiroba) Seed Oil: Chemical Composition and Antileishmanial Activity of Limonoid-Rich Fractions

Leishmaniasis is a complex of diseases caused by protozoa of the genus Leishmania and affects millions of people around the world. Several species of plants are used by traditional communities for the treatment of this disease, among which is Carapa guianensis Aubl. (Meliaceae), popularly known as andiroba. The objective of the present work was to conduct a chemical study of C. guianensis seed oil and its limonoid-rich fractions, with the aim of identifying its secondary metabolites, particularly the limonoids, in addition to investigating its anti-Leishmania potential. The chemical analyses of the C. guianensis seed oil and fractions were obtained by electrospray ionization mass spectrometry (ESI-MS). The cytotoxic activity was tested against peritoneal macrophages, and antileishmanial activity was evaluated against promastigotes and intracellular amastigotes of Leishmania amazonensis. All the C. guianensis seed oil samples analyzed exhibited the same pattern of fatty acids, while the limonoids 7-deacetoxy-7-hydroxygedunin, deacetyldihydrogedunin, deoxygedunin, andirobin, gedunin, 11β-hydroxygedunin, 17-glycolyldeoxygedunin, 6α-acetoxygedunin, and 6α,11β-diacetoxygedunin were identified in the limonoid-rich fractions of the oil. The C. guianensis seed oil did not exhibit antileishmanial activity, and cytotoxicity was higher than 1000 μg/mL. Three limonoid-rich oil fractions demonstrated activity against promastigotes (IC(50) of 10.53±0.050, 25.3±0.057, and 56.9±0.043μg/mL) and intracellular amastigotes (IC(50) of 27.31±0.091, 78.42±0.086, and 352.2±0.145 μg/mL) of L. amazonensis, as well as cytotoxicity against peritoneal macrophages (CC(50) of 78.55±1.406, 139.0±1.523, and 607.7±1.217 μg/mL). The anti-Leishmania activity of the limonoid-rich fractions of C. guianensis can be attributed to the limonoids 11β-hydroxygedunin and 6α,11β-diacetoxygedunin detected in the chemical analysis.