title: Helichrysum arenarium subsp. arenarium: phenolic composition and antibacterial activity against lower respiratory tract pathogens.
abstract: The aim of this study was to investigate the phenolic content and antibacterial activity of the methanol extract from Helichrysum arenarium (L.) Moench subsp. arenarium inflorescences against lower respiratory tract pathogens (standard strains and clinical isolates). The extract was characterised by a total phenolic content of 160.17 mg/g. Several caffeic acid conjugates (chlorogenic acid and dicaffeoylquinic acids) and flavonoids (apigenin, naringenin, apigenin-7-O-glucoside and naringenin-O-hexosides) were identified as major constituents by HPLC-DAD-ESI-MS. Staphylococcus aureus ATCC 25923 was more susceptible to Helichrysum extract than Streptococcus pneumoniae ATCC 49619 (minimum inhibitory concentration [MIC] = 0.62  and 1.25 mg/mL, respectively). The extract exhibited similar antibacterial effects against methicillin-resistant S. aureus and penicillin-resistant S. pneumoniae clinical isolates (MIC = 2.5 mg/mL) displaying a higher activity against ampicillin-resistant Moraxella catarrhalis isolate (MIC = 0.15 mg/mL). The combination with ciprofloxacin exhibited additivity against both standard strains (fractional inhibitory concentration [FIC] index = 0.75 and 0.73) and S. aureus isolates (FIC index = 0.62) and synergy against S. pneumoniae isolates (FIC index = 0.5).
authors.affiliation: a Faculty of Pharmacy, University of Medicine and Pharmacy Grigore T. Popa-Iasi , Universitatii Str. 16, 700115 Iasi , Romania.
authors.forename: Adina C
authors.initials: AC
authors.lastname: Gradinaru
authors.forename: Mihaela
authors.initials: M
authors.lastname: Silion
authors.forename: Adriana
authors.initials: A
authors.lastname: Trifan
authors.forename: Anca
authors.initials: A
authors.lastname: Miron
authors.forename: Ana C
authors.initials: AC
authors.lastname: Aprotosoaie
mesh_terms: D000900:Anti-Bacterial Agents / Q000737:chemistry / Q000302:isolation & purification* / Q000494:pharmacology*; D002939:Ciprofloxacin / Q000494:pharmacology; D036562:Helichrysum / Q000737:chemistry*; D006801:Humans; D055624:Methicillin-Resistant Staphylococcus aureus / Q000187:drug effects; D008826:Microbial Sensitivity Tests; D001936:Moraxella catarrhalis / Q000187:drug effects; D010636:Phenols / Q000032:analysis / Q000494:pharmacology*; D011550:Pseudomonas aeruginosa / Q000187:drug effects; D012137:Respiratory System / Q000187:drug effects / Q000382:microbiology; D013211:Staphylococcus aureus / Q000187:drug effects; D013296:Streptococcus pneumoniae / Q000187:drug effects
chemical_list: D000900:Anti-Bacterial Agents; D010636:Phenols; D002939:Ciprofloxacin
keywords: HPLC-DAD-ESI-MS; ciprofloxacin; clinical isolates; penicillin-resistant Streptococcus pneumoniae; synergistic effects