title: Photodynamic inactivation of yeast and bacteria by extracts of Alternanthera brasiliana.
abstract: This study was undertaken to evaluate the effect of Alternathera brasiliana (Amaranthaceae) extracts as photosensitizing agents in photodynamic antimicrobial therapies (PACT) against Staphylococcus aureus, Staphylococcus epidermidis and Candida dubliniensis. The crude hexane and ethanol extracts were obtained from A. brasiliana whole plant and showed absortion from 650 to 700 nm. Also, singlet molecular oxygen (1O2) production (type II photosensitization reaction) was examined, and the results show that 1,3-diphenylisobenzofuran photodegradation was greatly enhanced in the presence of the A. brasiliana extracts. One plate in each assay was irradiated while the other was not irradiated, the number of colony-forming units per milliliter (CFU/mL) was obtained, and data analyzed by the Tukey test. The chemical composition of the extracts was determined by chromatographic and spectrometric techniques; steroids, triterpenes, and flavonoids were identified. Laser irradiation alone at 685 nm using diode laser, output power of 35 mW, and energy of 28 J/cm2, or non-irradiated crude extracts in sub-inhibitory concentration did not reduce the number of CFU/mL significantly, whereas irradiated hexane and ethanol extracts, in sub-inhibitory concentrations, inhibited the growth of these microorganisms. The photoactivation of hexane and ethanol extracts of A. brasiliana, in sub-inhibitory concentrations, using red laser radiation at 685 nm had an antimicrobial effect.
authors.affiliation: Department of Plant Biology, Course of Pharmacy and BTPB Program, Institute of Biology, State University of Campinas 13083-970, Cx Postal 6109, Campinas, SP, Brazil.
authors.forename: Nathalia L
authors.initials: NL
authors.lastname: Andreazza
authors.forename: Caroline C
authors.initials: CC
authors.lastname: de Lourenco
authors.forename: Carlos A T
authors.initials: CA
authors.lastname: Siqueira
authors.forename: Alexandra C H F
authors.initials: AC
authors.lastname: Sawaya
authors.forename: Tadia F
authors.initials: TF
authors.lastname: Lapinski
authors.forename: Adriana
authors.initials: A
authors.lastname: Gasparetto
authors.forename: Sonia
authors.initials: S
authors.lastname: Khouri
authors.forename: Stella R
authors.initials: SR
authors.lastname: Zamuner
authors.forename: Egberto
authors.initials: E
authors.lastname: Munin
authors.forename: Marcos Jose
authors.initials: MJ
authors.lastname: Salvador
mesh_terms: D027703:Amaranthaceae / Q000737:chemistry*; D000900:Anti-Bacterial Agents / Q000737:chemistry / Q000494:pharmacology*; D000935:Antifungal Agents / Q000737:chemistry / Q000494:pharmacology*; D001419:Bacteria / Q000187:drug effects*; D002175:Candida / Q000187:drug effects; D000431:Ethanol; D005419:Flavonoids / Q000032:analysis; D005658:Fungi / Q000187:drug effects*; D006586:Hexanes; D010778:Photochemotherapy; D017319:Photosensitizing Agents / Q000737:chemistry / Q000494:pharmacology*; D010936:Plant Extracts / Q000737:chemistry / Q000494:pharmacology*; D026082:Singlet Oxygen / Q000378:metabolism; D013210:Staphylococcus / Q000187:drug effects; D013256:Steroids / Q000032:analysis; D014315:Triterpenes / Q000032:analysis
chemical_list: D000900:Anti-Bacterial Agents; D000935:Antifungal Agents; D005419:Flavonoids; D006586:Hexanes; D017319:Photosensitizing Agents; D010936:Plant Extracts; D013256:Steroids; D014315:Triterpenes; D026082:Singlet Oxygen; D000431:Ethanol