title: Screening for polyphenols, antioxidant and antimicrobial activitiesof extracts from eleven Helianthemum taxa (Cistaceae) used in folk medicine in south-eastern Spain.
abstract: BACKGROUND
  The Helianthemum genus contains approximately one hundred taxa. Some of them are important medicinal plants used in several countries for many different purposes. However, studies addressing the phytochemistry of many of these species or their biological activities are currently nonexistent.
  
  
  OBJECTIVE
  To perform a comparative analysis of the qualitative composition of secondary metabolites and biological activities of the leaves of the most commonly distributed and used Spanish Helianthemum taxa in order to find a relationship between chemotype, biological activity and uses.
  
  
  METHODS
  water and 80% methanolic extracts derived from 11 different Helianthemum taxa were analyzed for their phytochemical composition using standard methods. Furthermore, HPLC analysis was performed for the estimation of gallic acid, ellagic acid, tannins and flavonols as marker compounds. The antioxidant activity was measured by employing the scavenging activity on DPPH (2,2-diphenyl-1-picrylhydrazyl) and ABTS (2,2'-azinobis-3-ethylbenzothiazoline-6-sulfonate) radicals. The 80% methanolic extracts were evaluated for antibacterial (Gram-positive Staphylococcus aureus, Enterococcus faecalis and Listeria monocytogenes and Gram-negative Escherichia coli and Salmonella enterica) activity using the micro dilution technique.
  
  
  RESULTS
  The total polyphenolic content and antioxidant capabilities differed significantly among the Helianthemum leaf extracts. A strong correlation between total phenolic content, antioxidant properties and antimicrobial activity was found. The polyphenolic profile was specific for each taxon. Whereas Helianthemum alypoides, Helianthemum cinereum subsp. rotundifolium, Helianthemum hirtum, Helianthemum asperum, and Helianthemum marifolium subsp. marifolium were characterized by the presence of gallic acid, egallic derivatives and ellagitannins; the polyphenolic profile of Helianthemum apenninum subsp. cavanillesianum, Helianthemum syriacum and Helianthemum polygonoides was mostly based on flavonoids. Helianthemum cinereum, Helianthemum alypoides and Helianthemum marifolium consistently presented the strongest radical scavenging activity (in water extracts EC50 ranges from 29.88 to 38.1 against DPPH and from 8.11 to 20.8 against ABTS, and in 80% MeOH extracts from 25.3 to 31.8 against DPPH and from 6.15 to 8.6 against ABTS), total phenol content (>117mg GAE/l) and antimicrobial activities.
  
  
  CONCLUSIONS
  The Helianthemum taxa used in folk medicine did not cluster in a unique section, being equally distributed in two out of the four sections analysed. There was not a clear relationship between the chemotype, based on the polyphenolic composition of the taxa, and their taxonomical classification. However, the composition of the methanolic and water extracts from the leaves of plants belonging to the Helianthemum genus was strongly related to their medicinal uses.
authors.affiliation: Instituto Botánico, Universidad de Castilla-La Mancha, Campus Universitario s/n, 02071 Albacete, Spain.
authors.forename: Angela
authors.initials: A
authors.lastname: Rubio-Moraga
authors.forename: Javier
authors.initials: J
authors.lastname: Argandoña
authors.forename: Begoña
authors.initials: B
authors.lastname: Mota
authors.forename: Javier
authors.initials: J
authors.lastname: Pérez
authors.forename: Alonso
authors.initials: A
authors.lastname: Verde
authors.forename: José
authors.initials: J
authors.lastname: Fajardo
authors.forename: José
authors.initials: J
authors.lastname: Gómez-Navarro
authors.forename: Raquel
authors.initials: R
authors.lastname: Castillo-López
authors.forename: Oussama
authors.initials: O
authors.lastname: Ahrazem
authors.forename: Lourdes
authors.initials: L
authors.lastname: Gómez-Gómez
mesh_terms: D000900:Anti-Bacterial Agents / Q000494:pharmacology*; D000975:Antioxidants / Q000494:pharmacology*; D001419:Bacteria / Q000187:drug effects / Q000254:growth & development; D030601:Cistaceae / Q000235:genetics; D018744:DNA, Plant / Q000235:genetics; D008519:Medicine, Traditional; D008826:Microbial Sensitivity Tests; D010802:Phylogeny; D010936:Plant Extracts / Q000494:pharmacology*; D059808:Polyphenols / Q000494:pharmacology*; D013030:Spain
chemical_list: D000900:Anti-Bacterial Agents; D000975:Antioxidants; D018744:DNA, Plant; D010936:Plant Extracts; D059808:Polyphenols