title: Antimicrobial activity and cytotoxicity of triterpenes isolated from leaves of Maytenus undata (Celastraceae).
abstract: BACKGROUND
  Plants of the genus Maytenus belong to the family Celastraceae and are widely used in folk medicine as anti-tumour, anti-asthmatic, analgesic, anti-inflammatory, antimicrobial and anti-ulcer agents, and as a treatment for stomach problems. The aim of this study was to isolate and identify active compounds with antifungal activity from Maytenus undata after a preliminary study highlighted promising activity in crude extracts.
  
  
  METHODS
  Sequential extracts of M. undata leaves prepared using hexane, dichloromethane (DCM), acetone and methanol (MeOH) were tested for activity against Cryptococcus neoformans, a fungal organism implicated in opportunistic infections. Bioassay-guided fractionation of the hexane extract using C. neoformans as test organism was carried out to isolate antifungal compounds. The cytotoxicity of compounds isolated in sufficient quantities was evaluated using a tetrazolium-based colorimetric cellular assay (MTT) and a haemagglutination assay (HA).
  
  
  RESULTS
  The hexane extract was most active with an MIC of 20 μg/ml against C. neoformans. The triterpene compounds friedelin (1), epifriedelanol (2), taraxerol (3), 3-oxo-11α-methoxyolean-12-ene-30-oic acid (4), 3-oxo-11α-hydroxyolean-12-ene-30-oic acid (5) and 3,11-dihydroxyolean-12-ene-30-oic acid (6) were isolated. Compound 6 was isolated for the first time from a plant species. The antimicrobial activity of compounds 1, 3, 5 and 6 was determined against a range of bacteria and fungi implicated in opportunistic and nosocomial infections. Compounds 5 and 6 were the most active against all the tested microorganisms with MIC values ranging between 24 and 63 μg/ml, except against Staphylococcus aureus which was relatively resistant. Compounds 1 and 3 had a low toxicity with an LC50 > 200 μg/ml towards Vero cells in the MTT assay. Compounds 5 and 6 were toxic with LC50 values of 6.03±0.02 and 2.98±0.01 μg/ml, respectively. Compounds 1 and 3 similarly were not toxic to the red blood cells (RBCs) but compounds 5 and 6 were toxic, showing HA titer values of 1.33 and 0.67 respectively.
  
  
  CONCLUSIONS
  Compounds 5 and 6 were the most active but were also relatively cytotoxic to monkey kidney cells and red blood cells, while the other isolated compounds were less active and less cytotoxic.
authors.affiliation: Department of Paraclinical Sciences, Phytomedicine Programme, Faculty of Veterinary Science, University of Pretoria, Private Bag X04, Onderstepoort, 0110, South Africa.
authors.forename: Tsholofelo Abednego
authors.initials: TA
authors.lastname: Mokoka
authors.forename: Lyndy Joy
authors.initials: LJ
authors.lastname: McGaw
authors.forename: Ladislaus Kakore
authors.initials: LK
authors.lastname: Mdee
authors.forename: Victor Patrick
authors.initials: VP
authors.lastname: Bagla
authors.forename: Ezekiel Olugbenga
authors.initials: EO
authors.lastname: Iwalewa
authors.forename: Jacobus Nicolaas
authors.initials: JN
authors.lastname: Eloff
mesh_terms: D000818:Animals; D000890:Anti-Infective Agents / Q000737:chemistry / Q000302:isolation & purification / Q000494:pharmacology*; D029753:Celastraceae / Q000737:chemistry*; D002460:Cell Line; D049109:Cell Proliferation / Q000187:drug effects; D002470:Cell Survival / Q000187:drug effects; D002522:Chlorocebus aethiops; D003455:Cryptococcus neoformans / Q000187:drug effects; D003603:Cytotoxins / Q000737:chemistry / Q000302:isolation & purification / Q000494:pharmacology*; D004912:Erythrocytes / Q000187:drug effects / Q000276:immunology; D006386:Hemagglutination Tests; D006736:Horses; D008826:Microbial Sensitivity Tests; D010936:Plant Extracts / Q000737:chemistry / Q000302:isolation & purification / Q000494:pharmacology*; D018515:Plant Leaves / Q000737:chemistry; D013211:Staphylococcus aureus / Q000187:drug effects; D014315:Triterpenes / Q000737:chemistry / Q000302:isolation & purification / Q000494:pharmacology*; D014709:Vero Cells
chemical_list: D000890:Anti-Infective Agents; D003603:Cytotoxins; D010936:Plant Extracts; D014315:Triterpenes