title: Antibacterial activity of plant extracts from northwestern Argentina.
abstract: OBJECTIVE
  To determine the antibacterial and cytotoxic activities of aqueous and ethanolic extracts of northwestern Argentinian plants used in folk medicine. To compare the mentioned activities with those of five commercial antibiotics. To identify the compounds responsible for the antibacterial activity.
  
  
  RESULTS
  Plant extracts were prepared according to traditional uses in northwestern Argentina. Antibacterial activity was assayed by agar dilution in Petri dishes and broth dilution in 96-well plates. Lethal dose 50 (LD(50)) was determined by the Artemia salina assay. Phytochemical analysis was performed by sample adsorption on silica gel, thin-layer chromatography (TLC), bioautography and UV-visible spectra. The results showed that Tripodanthus acutifolius aqueous extracts have lower minimal inhibitory concentrations (MIC) (502 and 506 microg of extracted material (EM) per ml for infusion and decoction, respectively) than cefotaxim MIC (640 microg ml(-1)) against Acinetobacterfreundii (303). These data were lower than their LD(50). Tripodanthus acutifolius tincture showed lower MIC (110 microg of EM per ml) and minimal bactericidal concentration (MBC) (220 microg of EM per ml) than cefotaxim (MIC and MBC of 320 microg ml(-1)) for Pseudomonasaeruginosa. This extract also showed a MIC/MBC of 110/220 microg of EM per ml, lower than oxacillin (MIC/MBC of 160/220 microg ml(-1)) for Staphylococcus aureus (ATCC 25923). The cytotoxicity of all extracts were compared with that of commercial antibiotics. Rutin (3,3',4',5,7-pentahydroxyflavone 3-beta-rhamnosilglucoside), iso-quercitrin (3,3',4',5,7-pentahydroxyflavone 3-beta-glucoside) and a terpene would be partially responsible for the antibacterial activity of T. acutifolius infusion.
  
  
  CONCLUSIONS
  Tripodanthus acutifolius extracts had the ability to inhibit bacterial growth. The antibacterial activity differs with the applied extractive method, and it could be partially attributed to glycoflavonoids. This paper contributes to the knowledge of antibacterial capacity of plants from northwestern Argentina.
  
  
  CONCLUSIONS
  These antibacterial activities support further studies to discover new chemical structures that can contribute to alleviate or cure some illnesses.
authors.affiliation: Cátedra de Fitoquímica, Instituto de Estudios Vegetales Dr. A.R. Sampietro, Facultad de Bioquímica, Química y Farmacia Universidad Nacional de Tucumán Ayacucho 471 (4000) San Miguel de Tucumán, Argentina.
authors.forename: J R
authors.initials: JR
authors.lastname: Soberón
authors.forename: M A
authors.initials: MA
authors.lastname: Sgariglia
authors.forename: D A
authors.initials: DA
authors.lastname: Sampietro
authors.forename: E N
authors.initials: EN
authors.lastname: Quiroga
authors.forename: M A
authors.initials: MA
authors.lastname: Vattuone
mesh_terms: D000900:Anti-Bacterial Agents / Q000494:pharmacology*; D001118:Argentina; D024881:Drug Resistance, Bacterial; D006090:Gram-Negative Bacteria / Q000187:drug effects; D006094:Gram-Positive Bacteria / Q000187:drug effects; D031332:Leonurus / Q000737:chemistry; D028183:Loranthaceae / Q000737:chemistry; D008519:Medicine, Traditional; D008826:Microbial Sensitivity Tests; D010936:Plant Extracts / Q000494:pharmacology*; D010946:Plants, Medicinal / Q000737:chemistry*; D011794:Quercetin / Q000031:analogs & derivatives / Q000494:pharmacology; D012431:Rutin / Q000494:pharmacology; D029630:Santalaceae / Q000737:chemistry
chemical_list: D000900:Anti-Bacterial Agents; D010936:Plant Extracts; C012526:quercitrin; D012431:Rutin; D011794:Quercetin