Antiplasmodial compounds from the stem bark of Neoboutonia macrocalyx pax

Abstract

Ethnopharmacological relevance: The plant Neoboutonia macrocalyx has been reported in traditional medicine to be used in the treatment of malaria.

Aim of the study: To study the in vitro antiplasmodial activity of compounds from the stem bark of Neoboutonia macrocalyx.

Materials and methods: Compounds were extracted and purified from stem bark of Neoboutonia macrocalyx and their structure identified and confirmed by spectroscopic methods. The crude ethyl acetate extract, aqueous extract and the isolated compounds were evaluated for antiplasmodial activity against the chloroquine sensitive Sierra Leone I (D6) and chloroquine-resistant Indochina I (W2) strains of Plasmodium falciparum.

Results: Chemical investigation of the ethyl acetate extract of Neoboutonia macrocalyx bark resulted in the identification of one new diterpenoid; neoboutomacroin (1) in addition to the four known compounds which included, a phenanthrene; 3,6-dihyroxy-1,7-dimethyl-9-methoxyphenanthrene (2), a sterol; 3-O-Acetyloleuritolic acid (3) and two diterpenoids; simplexin (4) and montanin (5). Compounds 1 and 5 displayed good antiplasmodial activity of IC50 values less than 10 μg/mL against both strains. However, all the compounds tested displayed high cytotoxic activity against MRC5 cell line with IC50 less than 10 μM.

Conclusions: Despite an indirect in vitro antiplasmodial activity of some compounds isolated from the stem bark of Neoboutonia macrocalyx, the identification of these bioactive compounds indicates that they may play a role in the pharmacological properties of this plant.

Keywords: Antiplasmodial activity; Diterpenoids; Euphorbaceae; Neoboutonia macrocalyx; Phenanthrene; Sterol.