title: Physicochemical properties and antimicrobial activity of Roselle (Hibiscus sabdariffa L.).
abstract: BACKGROUND
  The therapeutic action of a plant depends on its chemical constituents. In this study, experiments were carried out in order to evaluate the effect of extraction conditions on the antioxidative and antimicrobial activities of Roselle (Hibiscus sabdariffa L.).
  
  
  RESULTS
  Roselle was found to be rich in malic acid, anthocyanins, ascorbic acid and minerals, especially Ca and Fe, but low in glucose. More than 18 volatile compounds were identified by gas chromatography and gas chromatography-mass spectrometry. This herb, which is rich in phenolic compounds and displays DPPH radical scavenging activity, could be a good source of natural antioxidants. The antimicrobial activity of the Roselle water and ethanol extracts was tested with Bacillus subtilis (ATCC6633), Staphylococcus aureus (ATCC6538) and Escherichia coli (ATCC 8739). The inhibition of the Roselle ethanol extract against B. subtilis and S. aureus was slightly higher than that of water extract but this difference was not significant. However, E. coli was strongly inhibited by the Roselle water extract at concentrations of 25 and 50 mg mL(-1) as determined by a paper disc method.
  
  
  CONCLUSIONS
  The obtained results indicated that antioxidant and antimicrobial activity was related to different methods of extraction and Roselle extracts could be a source of therapeutically useful products.
authors.affiliation: Department of Food and Nutrition, Sookmyung Women's University, Seoul, 140-742, Korea.
authors.forename: EunKyung
authors.initials: E
authors.lastname: Jung
authors.forename: YoungJun
authors.initials: Y
authors.lastname: Kim
authors.forename: Nami
authors.initials: N
authors.lastname: Joo
mesh_terms: D000872:Anthocyanins / Q000032:analysis / Q000494:pharmacology; D000900:Anti-Bacterial Agents / Q000032:analysis / Q000494:pharmacology*; D000975:Antioxidants / Q000032:analysis / Q000494:pharmacology*; D001205:Ascorbic Acid / Q000032:analysis / Q000494:pharmacology; D001407:Bacillus / Q000187:drug effects; D001419:Bacteria / Q000187:drug effects*; D001713:Biphenyl Compounds / Q000378:metabolism; D004926:Escherichia coli / Q000187:drug effects; D031584:Hibiscus / Q000737:chemistry*; D008293:Malates / Q000032:analysis; D008903:Minerals / Q000032:analysis; D009822:Oils, Volatile / Q000032:analysis / Q000494:pharmacology; D010636:Phenols / Q000032:analysis / Q000494:pharmacology; D010851:Picrates / Q000378:metabolism; D010936:Plant Extracts / Q000737:chemistry / Q000494:pharmacology*; D013211:Staphylococcus aureus / Q000187:drug effects
chemical_list: D000872:Anthocyanins; D000900:Anti-Bacterial Agents; D000975:Antioxidants; D001713:Biphenyl Compounds; D008293:Malates; D008903:Minerals; D009822:Oils, Volatile; D010636:Phenols; D010851:Picrates; D010936:Plant Extracts; C030298:malic acid; C004931:1,1-diphenyl-2-picrylhydrazyl; D001205:Ascorbic Acid
keywords: Roselle (Hibiscus sabdariffa L.); antimicrobial activity; antioxidant; radical scavenging activity