Antimalarial evaluation of the leaf latex of Aloe citrina and its major constituent

BACKGROUND: Malaria is one of the major obstacles to the socioeconomic development of several developing countries. Adequate treatment of the disease is becoming increasingly difficult due to the worsening problems of drug resistance in many parts of the world. Therefore, increased efforts in antimalarial drug discovery are urgently needed. OBJECTIVES: This study was designed to evaluate the antimalarial activity of the leaf latex of Aloe citrina Carter and Brandham and its major constituent. MATERIALS AND METHODS: The leaf latex of A. citrina was dissolved in methanol and subjected to preparative thin layer chromatography. Structure of the isolated compound was determined on the basis of its electrospray-ionization tandem mass spectrometry, (1)H, (13)C NMR and DEPT spectral data. The latex and its isolated compound were tested for their in vivo antimalarial activity using a 4-day suppressive test against chloroquine sensitive ANKA strain of Plasmodium berghei in mice. RESULTS: Homonataloin A/B was isolated as a major component of the latex. Both the latex and isolated compound exhibited significant (P < 0.001) antimalarial activity at a dose of 400 mg/kg with parasite suppression of 60.59% and 67.52%, respectively. No significant adverse signs of toxicity were observed in mice treated with the leaf latex up to the highest dose (5000 mg/kg). CONCLUSION: The results of this study indicate that the antimalarial activity of the plant is attributed in part or in full to the presence of homonataloin A/B in the latex. It also validates the traditional use of the plant as an antimalarial agent.