Cytotoxicity of an unprecedented brominated oleanolide and a new furoceramide from the Cameroonian spice, Echinops giganteus

Abstract

A preliminary study on Echinops giganteus (Asteraceae) showed that the methanolic extract has interesting cytotoxicities against a panel of cancer cell lines. From this extract, a lignan, a flavonoid and a polyacetylenic thiophene identified were three times less cytotoxic than the extract. In the search of the metabolites responsible for the bioactivity, a new harvested E. giganteus was subjected to a phytochemical study using chromatographic methods. In the course of the work, two new compounds: a brominated oleanolide (1) and a tetrahydrofurano-ceramide (2) were obtained along with β-amyrin acetate (3), 2-(penta-1,3-diynyl)-5-(4-hydroxybut-1-ynyl)-thiophene (4), 2-(penta-1,3-diynyl)-5-(3,4-dihydroxybut-1-ynyl)-thiophene (5) and 4-hydroxy-2,6-di-(3′,4′-dimethoxyphenyl)-3,7-dioxabicyclo-(3.3.0)octane (6). Their structures were determined on the basis of NMR spectroscopy and mass spectrometry data in conjunction with those reported in the literature. The cytotoxicity of 1, 2 and 5 was evaluated by employing resazurin assay against a panel of cancer cell lines with IC₅₀ values in range 6.12 ± 0.46–46.96 ± 3.61 μM.

Keywords:

• Asteraceae
• Echinops giganteus
• brominated triterpene
• furoceramide
• cytotoxicity

Acknowledgement

V. K. is very grateful to the Alexander von Humboldt foundation for 18 months fellowship through the ‘Georg Foster Research Fellowship for Experienced Researcher’ programme.

Disclosure statement

No potential conflict of interest was reported by the authors.