title: Antiplasmodial activity of sesquiterpene lactones and a sucrose ester from Vernonia guineensis Benth. (Asteraceae).
abstract: BACKGROUND
  Aqueous preparations of Vernonia guineensis Benth. (Asteraceae) are used in Cameroonian folk medicine as a general stimulant and to treat various illnesses and conditions including malaria, bacterial infections and helminthic infestations.
  
  
  METHODS
  Ten gram samples of the leaf and tuber powders of Vernonia guineensis were extracted separately using dichloromethane, methanol and distilled water. The extracts were dried in vacuo and used in bioassays. These extracts and three compounds previously isolated from Vernonia guineensis [vernopicrin (1), vernomelitensin (2) and pentaisovalerylsucrose (3)] were screened for antiplasmodial activity against chloroquine (CQ)-sensitive (Hb3) and CQ-resistant (Dd2) Plasmodium falciparum lines.
  
  
  RESULTS
  Crude extracts and pure compounds from Vernonia guineensis showed antiplasmodial activity against both Hb3 and Dd2. The IC50 values of extracts ranged from 1.64 to 27.2 µg/ml for Hb3 and 1.82-30.0 µg/ml for Dd2; those for compounds 1, 2 and 3 ranged from 0.47 to 1.62 µg/ml (1364-1774 nM) for Hb3 and 0.57-1.50 µg/ml (1644-2332nM) for Dd2. None of the crude extracts or pure compounds was observed to exert toxic effects on the erythrocytes used to cultivate the Plasmodium falciparum lines.
  
  
  CONCLUSIONS
  In Cameroonian folk medicine, Vernonia guineensis may be used to treat malaria in part due to the antiplasmodial activity of sesquiterpene lactones (1, 2), a sucrose ester (3) and perhaps other compounds present in crude plant extracts. Exploring the safety and antiplasmodial efficacy of these compounds in vivo requires further study.
authors.affiliation: Virgin Botanicals & Biotech, Inc., Columbia, MD, USA. ntoyang@som.umaryland.edu
authors.forename: Ngeh J
authors.initials: NJ
authors.lastname: Toyang
authors.forename: Michael A
authors.initials: MA
authors.lastname: Krause
authors.forename: Rick M
authors.initials: RM
authors.lastname: Fairhurst
authors.forename: Pierre
authors.initials: P
authors.lastname: Tane
authors.forename: Joseph
authors.initials: J
authors.lastname: Bryant
authors.forename: Rob
authors.initials: R
authors.lastname: Verpoorte
mesh_terms: D000962:Antimalarials / Q000494:pharmacology*; D002163:Cameroon; D004912:Erythrocytes / Q000187:drug effects; D007783:Lactones / Q000494:pharmacology; D016488:Medicine, African Traditional; D010936:Plant Extracts / Q000494:pharmacology*; D018515:Plant Leaves; D035281:Plant Tubers; D010963:Plasmodium falciparum / Q000187:drug effects*; D012717:Sesquiterpenes / Q000494:pharmacology; D013395:Sucrose / Q000494:pharmacology; D035741:Vernonia
chemical_list: D000962:Antimalarials; D007783:Lactones; D010936:Plant Extracts; D012717:Sesquiterpenes; C583060:vernomelitensin; C583061:vernopicrin; D013395:Sucrose
references.citation: Phytochemistry. 2002 Feb;59(4):371-4
references.pmid: 11830150
references.citation: J Ethnopharmacol. 2008 Dec 8;120(3):302-14
references.pmid: 18977424
references.citation: J Ethnopharmacol. 2013 Mar 27;146(2):552-6
references.pmid: 23376285
references.citation: Phytochemistry. 2003 Aug;63(7):841-6
references.pmid: 12877926
references.citation: Am J Trop Med Hyg. 2012 Aug;87(2):231-241
references.pmid: 22855752
references.citation: PLoS Med. 2011 Jan 25;8(1):e1000406
references.pmid: 21311579
references.citation: Phytother Res. 2003 Feb;17(2):123-8
references.pmid: 12601673
references.citation: Nature. 2005 Mar 10;434(7030):214-7
references.pmid: 15759000
references.citation: J Ethnopharmacol. 2012 Jun 14;141(3):866-71
references.pmid: 22465590
references.citation: Antimicrob Agents Chemother. 2004 May;48(5):1803-6
references.pmid: 15105138
references.citation: J Ethnopharmacol. 2012 Dec 18;144(3):700-4
references.pmid: 23107821
references.citation: Chem Pharm Bull (Tokyo). 2006 Oct;54(10):1437-9
references.pmid: 17015985
references.citation: Phytochemistry. 2010 Sep;71(13):1539-44
references.pmid: 20599237
references.citation: Molecules. 2009 Jun 08;14(6):2062-76
references.pmid: 19513006
references.citation: Phytochemistry. 2007 Apr;68(8):1200-5
references.pmid: 17408709
references.citation: Clin Pharmacol Ther. 2007 Nov;82(5):601-5
references.pmid: 17898709