Isolation and structure determination of a sesquiterpene lactone (vernodalinol) from Vernonia amygdalina extracts

Objective: A sesquiterpene lactone, vernodalinol, was isolated from VA leaves. The first reported source of vernodalinol was in 2009 from a different plant, only <SU1</SUH NMR spectrum and no detailed structural analysis were carried out. No whole spectroscopic data were provided. Materials and methods: VA dried leaves were extracted with 85% ethanol followed by further separation into four fractions by liquid--liquid extraction technique using various solvents: hexane, chloroform, and n-butanol. Vernodalinol was separated from the n-butanol fraction by column chromatography. The biological activity of vernodalinol was evaluated in estrogen receptor-positive (ER<SU++</SU) human breast carcinoma cells (MCF-7) in vitro. Results: Results indicated that vernodalinol (25 and 50 mu mu g/mL) inhibited breast cancerous cell growth (DNA synthesis) by 34% (P < 0.025) and 40% (P < 0.025), respectively. It is reasonable to expect an LC50 of 70--75 mu mu g/mL for vernodalinol in MCF-7 cells. Discussion and conclusion: Vernodalinol structure was confirmed using a battery of spectroscopic methods, 1D and 2D NMR, high-resolution mass spectrometry (HR-MS), UV, IR, and X-ray. These results suggest that vernodalinol, although it has some biological activity, is likely to work in concert with other ingredients responsible for the anticancer activity exhibited of VA.