Evaluation of the Antiplasmodial Activity of vobtusine isolated from Voacanga thouarsii (nkahlo wa tsovo)

• DOI: https://doi.org/10.22533/at.ed.813512507013

• Palavras-chave: Voacanga thouarsii , vobtusine, antiplasmodial activity, antimicrobial resistance

• Keywords: Voacanga thouarsii , vobtusine, antiplasmodial activity, antimicrobial resistance

• Abstract:

  Voacanga thouarsii is a medicinal plant native to the southern region of Africa and Madagascar that occurs throughout tropical Africa, from which indolic alkaloids with various biological properties have been isolated, including antiplasmodial, antibacterial, antifungal, antitumor and antiviral activity. The aim of this study was to evaluate the antiplasmodial activity of the major compound in V. thouarsii. Samples of the plant collected in the district of Gondola, Manica province were used to prepare extracts by methanolic maceration from 3300g of shade-dried material, resulting in a yield of 288.9g (8.75%). The crude extract was dissolved in CH2Cl2, followed by extraction of the basic layer in different solvents, with yields of: Et2O 43.4g (15.02%), 18.6g (6.43%) CH2Cl(2) 4.9g (1.69%) EtOAc and n-butanol 29.3g (10.14%). The extracts from EtOAc and CH2Cl2 were then submitted to a chromatographic column for structural identification using mass spectrometry, UV and (1)H and 13C NMR of the isolated compounds. The major compound isolated and characterized, with the molecular formula C43H50N4O6, was identified as vobtusine; a bisindolic alkaloid . The antiplamodial activity of vobtusine was tested at concentrations of 1000, 500, 100 and 10 nM in the blood phase, and the average inhibitory concentration of 500 nM was determined. The results indicate a relative activity of vobtusine against Plasmodium falciparum in the liver stage, showing IC50 at a concentration of 65 µM and in the blood stage it only shows a slight activity at a concentration of 5 µM. However, given the common use of the plant by communities for the treatment of various ailments, its medicinal interest is maintained and it is recommended that similar studies are also carried out against pathogenic microorganisms, as well as the synthesis of compounds derived from vobtusine to verify their anti-plasmodial potential in animal models.