Antiparasitic activity of Eryngium bourgatii Gouan: Fractionation and isolation of constituents from roots and aerial parts

Abstract

Ethnopharmacological relevance: Medicinal plants are rich in bioactive compounds with diverse properties that can preserve human health. Eryngium bourgatii is used in traditional medicine to purify the blood. Species of this genus have been used for their antibacterial, antitumor, antifungal or antiparasitic properties among others.

Aim of the study: In this work, the antiparasitic properties against Leishmania donovani, Trypanosoma cruzi, and Plasmodium falciparum were evaluated.

Materials and methods: Methyl tert-butyl ether (MTBE), dichloromethane (DCM), and ethyl acetate (EtOAc) extracts of the roots and the non-flowering aerial parts were obtained by maceration at room temperature. Some of them were partitioned with solvents of increasing polarity, specifically n-hexane (n-Hex), dichloromethane (DCM), and ethyl acetate (EA) to isolate different fractions. Growth inhibition assays were performed against the three protozoa (L. donovani, T. cruzi, and P. falciparum). The active fractions were subsequently separated by chromatography to determine the secondary metabolites responsible for the activity. In addition, GC-MS studies were performed to further analyse the composition of the extracts and fractions.

Results: Regarding the roots, the MTBE extract was the most potent leishmanicidal (77.7 % inhibition at 10 μg/mL). The activity increased in its n-Hex fraction (95.3 % inhibition), and in the DCM fraction, both leishmanicidal (93.6 %) and anti-Chagas activity (92.2 %) improved. Furanone 12, a new natural compound, was the main component of the extract and the most potent leishmanicide (96.7 %), sixteen times less than the reference drug, Amphotericin B. 11-Acetoxyfalcarindiol (19) was the most potent anti-Chagas (89.1 % inhibition). Regarding the aerial parts, the DCM extract was the most potent leishmanicide (83.3 %), which improved in its DCM fraction (95.7 %), mainly attributed to compound 12. The DCM fraction of the MTBE extract produced the best antichagasic result (93.3 % inhibition), attributed to falcarindiol (17). Practically, the same compounds were identified in the roots as in the aerial parts, but in different proportions. Nine pure compounds were isolated; 34 were identified in roots and 37 in the aerial parts by GC-MS, with alkyne compounds leading, followed by sesquiterpenes and fatty acids.

Keywords: Acetylenes; Anti-plasmodial activity; Eryngium bourgatii; Leishmanicidal; Structural characterization; Trypanocidal.