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 non-saponifiable 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 W(2) and Dd(2) 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 W(2) clone in 100%, between 24 and 72 h, at concentrations of 8.2 μg/mL and 3.1 μg/mL, respectively. Under the same conditions, the parasitaemia of Dd(2) clone provoked by the andiroba oil showed inhibition of 31% (IC(50) >82 μg/mL) with a time-dependent relationship of 24h and inhibition of 88% (IC(50) 8.4 μg/mL) after 72 h, while for the limonoid-rich fraction the inhibition of Dd(2) clone was 56% (IC(50) 2.8μg/mL) at 24h and 82% (IC(50) 0.4 μg/mL) after 72 h. Andiroba oil in acute toxicity test with a fixed dose (LD(50) >2000 mg/kg) was not toxic The limonoids identified in the oil were gedunin, 6α-acetoxygedunin, 7-deacetoxy-7-oxogedunin, 7-deacetylgedunin, 1,2-dihydro-3β-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.
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