title: Isolation of alpha-linolenic acid from Sutherlandia frutescens and its inhibition of Mycobacterium tuberculosis' shikimate kinase enzyme.
abstract: BACKGROUND
  Sutherlandia frutescens (L) R.Br. is one of traditional herbal medicines that formed the basis of primary health care systems since the earliest days and is still widely used. Sutherlandia is prescribed for people with tuberculosis (TB), but is still not known which compound(s) acts against M. tuberculosis and its mode of action. The aim of this study was to identify and isolate antimycobacterial compounds from S. frutescens extracts against shikimate kinase, a drug target for M. tuberculosis.
  
  
  METHODS
  S. frutescens were dried, ground and extracted with ethanol, dichloromethane: methanol and water. Fractionation and separation of compounds was done with column chromatography. Chromatograms were developed in butanol/acetic acid/water (BAW) [21:6:3]; chloroform/methanol/water/formic acid (CMWF1) [60:15:2:1] and (CMWF2) [21:9:1:0.3]. Separation and isolation of active compounds were done using preparative HPLC. The activity of the plant extracts were also screened against shikimate kinase enzyme (MtbSK) using the MtbSK inhibition assay.
  
  
  RESULTS
  The DCM: MeOH (1:1) extract showed a high percentage inhibition (with an IC50 of 0.1 μg/ml) of MtbSK and the purified inhibitor was an Alpha-Linolenic Acid (ALA) compound and it had a significant IC50 of 3.7 μg/ml.
  
  
  CONCLUSIONS
  This study demonstrated that ALA from S. frustescens is an inhibitor of shikimate kinase a good drug target for M. tuberculosis.
authors.affiliation: Department of Biochemistry, Microbiology and Biotechnology, University of Limpopo, Private Bag X1106, Sovenga, 0727, South Africa. Peter.Masoko@ul.ac.za.
authors.forename: Peter
authors.initials: P
authors.lastname: Masoko
authors.affiliation: Department of Biochemistry, Microbiology and Biotechnology, University of Limpopo, Private Bag X1106, Sovenga, 0727, South Africa.
authors.forename: Itumeleng H
authors.initials: IH
authors.lastname: Mabusa
authors.affiliation: University of Mpumalanga, C/O R40 White River Rd & D725 Rd, Riverside, Private Bag X11283, Mbombela, 1200, South Africa.
authors.forename: Rachmond L
authors.initials: RL
authors.lastname: Howard
mesh_terms: D001426:Bacterial Proteins / Q000037:antagonists & inhibitors*; D007887:Fabaceae / Q000737:chemistry*; D009169:Mycobacterium tuberculosis / Q000201:enzymology*; D017853:Phosphotransferases (Alcohol Group Acceptor) / Q000037:antagonists & inhibitors*; D010936:Plant Extracts / Q000737:chemistry; D017962:alpha-Linolenic Acid / Q000302:isolation & purification* / Q000494:pharmacology*
chemical_list: D001426:Bacterial Proteins; D010936:Plant Extracts; D017962:alpha-Linolenic Acid; D017853:Phosphotransferases (Alcohol Group Acceptor); C022642:shikimate kinase
keywords: Mycobacterium tuberculosis; Shikimate kinase; Sutherlandia frutescens