Antiplasmodial activity of the andiroba (Carapa guianensis Aubl., Meliaceae) oil and its limonoid-rich fraction

Abstract

Ethnopharmacological relevance: From seeds of Carapa guianensis the Amazon native people extracts the andiroba oil, which is traditionally used as febrifuge, anti-malarial, insecticidal and repellant. The nonsaponifiable fraction separated from the oil is rich in limonoids, which assigns its pharmacological effects. Materials and methods: The andiroba oil and its limonoid-rich fraction were submitted to in vitro antiplasmodial bioassay using W2 and Dd2 strains of Plasmodium falciparum. The acute toxicity of andiroba oil was evaluated. The limonoid-rich fraction was subjected to fractionation and identified its major constituents. Results: Andiroba oil and its limonoid-rich fraction inhibited the growth of W2 clone in 100%, between 24 and 72 h, at concentrations of 8.2 mg/mL and 3.1 mg/mL, respectively. Under the same conditions, the parasitaemia of Dd2 clone provoked by the andiroba oil showed inhibition of 31% (IC50 482 mg/mL) with a time-dependent relationship of 24 h and inhibition of 88% (IC50 8.4 mg/mL) after 72 h, while for the limonoid-rich fraction the inhibition of Dd2 clone was 56% (IC50 2.8 mg/mL) at 24 h and 82% (IC50 0.4 mg/mL) after 72 h. Andiroba oil in acute toxicity test with a fixed dose (LD50 42000 mg/kg) was not toxic The limonoids identified in the oil were gedunin, 6a-acetoxygedunin, 7-deacetoxy-7-oxogedunin, 7-deacetylgedunin, 1,2-dihydro-3b-hydroxy-7-deacetoxy-7-oxogedunin and andirobin. Gedunin and derivatives has been reputed as anti-malarials. Conclusion: The results support the traditional use of andiroba oil as antiplasmodial, which additionally proved not to be toxic in bioassays conducted with mice