title: Cytotoxic sesquiterpene lactones from the leaves of Vernonia guineensis Benth. (Asteraceae).
abstract: BACKGROUND
  Vernonia guineensis Benth. (Asteraceae) preparations are used in folk medicine in Cameroon to treat a number of ailments, including prostate cancer and malaria, and is used as an anthelmintic, adaptogen and antidote. The aim of this study was to continue the validation of the activity of Vernonia guineensis Benth. extracts and isolated molecules against cancer cell lines following the previous isolation of an anti-prostate cancer sugar ester from the root extract.
  
  
  METHODS
  Acetone extracts of Vernonia guineensis Benth. leaves were tested for activity against 10 cancer cell lines (Breast-MDA-MB-231, Breast-MCF-7, Colon-HCT-116, Leukemia-HL-60, Lung-A549, Melanoma-A375, Ovarian-OVCAR3, Pancreas-Mia-paca, Prostate-PC-3 and Prostate-DU-145). The acetone extract was subjected to bioactivity guided fractionation. Anti-proliferation and clonogenic activity of the isolated compounds were tested. The WST-1 assay was used for the anti-proliferation activity, while the standard clonogenic test was used to determine the clonogenic activity.
  
  
  RESULTS
  The acetone extract of Vernonia guineensis Benth. demonstrated in vitro activity ranging from IC50 4-26μg/mL against the 10 cell lines. Activity guided fractionation of this extract yielded two sesquiterpene lactones, isolated for the first time from the genus Vernonia. The compounds were characterized using spectroscopic experiments, including a combination of 1D and 2D NMR data. Vernopicrin (1) and Vernomelitensin (2) demonstrated in vitro activity against human cancer cell lines with IC50 ranging from 0.35-2.04μM (P<0.05) and 0.13-1.5μM (P<0.05), respectively, between the most and least sensitive cell lines for each compound. Vernopicrin was most active against the human melanoma (A375) cell line and least active against the lung cancer (A549) cell line, while Vernomelitensin was also most active against the human melanoma (A375) cell line and least active against the breast cancer (MCF-7) cell line. Both compounds also demonstrated anticlonogenic activity.
  
  
  CONCLUSIONS
  The cytotoxicity demonstrated by the crude extract and isolated sesquiterpenes against cancer cell lines highlights the medicinal potential of V. guineensis. The selective anti-proliferation and dose dependent anticlonogenic activities suggest that the identified sesquiterpenes could be potential antitumor agents.
authors: Virgin Botanicals and Biotech Incorporated, Columbia, MD, USA; Institute of Human Virology, University of Maryland School of Medicine, Baltimore, MD, USA. ntoyang@som.umaryland.edu
authors: Ngeh J
authors: NJ
authors: Toyang
authors: Hippolyte K
authors: HK
authors: Wabo
authors: Eugene N
authors: EN
authors: Ateh
authors: Harry
authors: H
authors: Davis
authors: Pierre
authors: P
authors: Tane
authors: Luc B
authors: LB
authors: Sondengam
authors: Joseph
authors: J
authors: Bryant
authors: Rob
authors: R
authors: Verpoorte
mesh_terms: D000970:Antineoplastic Agents / Q000494:pharmacology*; D002163:Cameroon; D045744:Cell Line, Tumor; D049109:Cell Proliferation / Q000187:drug effects; D006801:Humans; D007783:Lactones / Q000494:pharmacology*; D016488:Medicine, African Traditional; D010936:Plant Extracts / Q000494:pharmacology*; D018515:Plant Leaves; D012717:Sesquiterpenes / Q000494:pharmacology*; D035741:Vernonia
chemical_list: D000970:Antineoplastic Agents; D007783:Lactones; D010936:Plant Extracts; D012717:Sesquiterpenes; C583060:vernomelitensin; C583061:vernopicrin
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