title: Antimicrobial activity against Helicobacter pylori strains and antioxidant properties of blackberry leaves (Rubus ulmifolius) and isolated compounds.
abstract: Rubus spp. (Rosaceae) provide extracts used in traditional medicine as antimicrobial, anticonvulsant, muscle relaxant and radical scavenging agents. Resistance to antibiotics used to treat Helicobacter pylori infection as well as their poor availability in developing countries prompted us to test the antimicrobial activity of Rubus ulmifolius leaves and isolated polyphenols against two H. pylori strains with different virulence (CagA+ strain 10K and CagA(-) strain G21). The antioxidant activity (TEAC values) of the tested compounds ranged from 4.88 (gallic acid) to 1.60 (kaempferol), whilst the leaf extract gave a value of 0.12. All the isolated polyphenols as well as the leaf extract showed antibacterial activity against both of the H. pylori strains. The minimum bactericidal concentrations (MBCs) of the extract for H. pylori strains G21 and 10K, respectively, were 1200 microg/mL and 1500 microg/mL after 24h of exposure and 134 microg/mL and 270 microg/mL after 48 h exposure. Ellagic acid showed very low MBC values towards both of the H. pylori strains after 48 h (2 microg/mL and 10 microg/mL for strains G21 and 10K, respectively) and kaempferol toward G21 strain (MBC=6 microg/mL). A relationship between antimicrobial activity and antioxidant capacity was found only for H. pylori strain G21 CagA(-) strain.
authors.affiliation: Dipartimento Farmaco Chimico Tecnologico, Università di Siena, Via Aldo Moro 2, 53100 Siena, Italy. martinis@unisi.it
authors.forename: Silvia
authors.initials: S
authors.lastname: Martini
authors.forename: Claudia
authors.initials: C
authors.lastname: D'Addario
authors.forename: Andrea
authors.initials: A
authors.lastname: Colacevich
authors.forename: Silvia
authors.initials: S
authors.lastname: Focardi
authors.forename: Francesca
authors.initials: F
authors.lastname: Borghini
authors.forename: Annalisa
authors.initials: A
authors.lastname: Santucci
authors.forename: Natale
authors.initials: N
authors.lastname: Figura
authors.forename: Claudio
authors.initials: C
authors.lastname: Rossi
mesh_terms: D000595:Amino Acid Sequence; D000900:Anti-Bacterial Agents / Q000302:isolation & purification / Q000494:pharmacology*; D000975:Antioxidants / Q000302:isolation & purification / Q000494:pharmacology*; D005419:Flavonoids / Q000302:isolation & purification / Q000494:pharmacology; D016480:Helicobacter pylori / Q000187:drug effects*; D006801:Humans; D008826:Microbial Sensitivity Tests; D050296:Microbial Viability; D008969:Molecular Sequence Data; D010636:Phenols / Q000302:isolation & purification / Q000494:pharmacology; D010936:Plant Extracts / Q000302:isolation & purification / Q000494:pharmacology*; D018515:Plant Leaves / Q000737:chemistry*; D059808:Polyphenols; D027824:Rosaceae / Q000737:chemistry*; D013997:Time Factors
chemical_list: D000900:Anti-Bacterial Agents; D000975:Antioxidants; D005419:Flavonoids; D010636:Phenols; D010936:Plant Extracts; D059808:Polyphenols