title: Bioactive extracts of red seaweeds Pterocladiella capillacea and Osmundaria obtusiloba (Floridophyceae: Rhodophyta) with antioxidant and bacterial agglutination potential.
abstract: OBJECTIVE
  To evaluate the antioxidant, antibacterial and bacterial cell agglutination activities of the hexane (Hex) and 70% ethanol (70% EtOH) extracts of two species of red seaweeds Pterocladiella capillacea (P. capillacea) and Osmundaria obtusiloba.
  
  
  METHODS
  In vitro antioxidant activity was determined by DPPH radical scavenging assay, ferric-reducing antioxidant power assay, ferrous ion chelating assay, β-carotene bleaching assay and total phenolic content quantification. Antimicrobial activity was tested using the method of disc diffusion on Mueller-Hinton medium. The ability of algal extracts to agglutinate bacterial cells was also tested.
  
  
  RESULTS
  The 70% EtOH extract of the two algae showed the highest values of total phenolic content compared to the Hex extract. The results of DPPH for both extracts (Hex, 70% EtOH) of Osmundaria obtusiloba (43.46% and 99.47%) were higher than those of P. capillacea (33.04% and 40.81%) at a concentration of 1000 μg/mL. As for the ferrous ion chelating, there was an opposite behavior, extracts of P. capillacea had a higher activity. The extracts showed a low ferric-reducing antioxidant power, with optical density ranging from 0.054 to 0.180. Antioxidant activities of all extracts evaluated for β-carotene bleaching were above 40%. There was no antibacterial activity against bacterial strains tested. However, the extracts of both species were able to agglutinate bacterial Gram positive cells of Staphylococcus aureus and Gram negative cells of Escherichia coli, multidrug-resistant Salmonella and Vibrio harveyi.
  
  
  CONCLUSIONS
  This is the first report of the interaction between these algal extracts, rich in natural compounds with antioxidant potential, and Gram positive and Gram negative bacterial cells.
authors.affiliation: Laboratório de Produtos Naturais Marinhos, Departamento de Engenharia de Pesca, Universidade Federal do Ceará, Campus do Pici, Av. Mister Hull, s/n, Caixa Postal 6043, 60455-970 Fortaleza, CE, Brazil. Electronic address: daniellpesca@gmail.com.
authors.forename: Daniel Barroso
authors.initials: DB
authors.lastname: de Alencar
authors.affiliation: Laboratório de Microbiologia Ambiental e do Pescado, Instituto de Ciências do Mar, Universidade Federal do Ceará, Av. da Abolição 3207, 60165-081, Fortaleza, CE, Brazil.
authors.forename: Fátima Cristiane Teles
authors.initials: FCT
authors.lastname: de Carvalho
authors.affiliation: Laboratório de Microbiologia Ambiental e do Pescado, Instituto de Ciências do Mar, Universidade Federal do Ceará, Av. da Abolição 3207, 60165-081, Fortaleza, CE, Brazil.
authors.forename: Rosa Helena
authors.initials: RH
authors.lastname: Rebouças
authors.affiliation: Laboratório de Microbiologia Ambiental e do Pescado, Instituto de Ciências do Mar, Universidade Federal do Ceará, Av. da Abolição 3207, 60165-081, Fortaleza, CE, Brazil.
authors.forename: Daniel Rodrigues
authors.initials: DR
authors.lastname: Dos Santos
authors.affiliation: Laboratório de Produtos Naturais Marinhos, Departamento de Engenharia de Pesca, Universidade Federal do Ceará, Campus do Pici, Av. Mister Hull, s/n, Caixa Postal 6043, 60455-970 Fortaleza, CE, Brazil.
authors.forename: Kelma Maria
authors.initials: KM
authors.lastname: Dos Santos Pires-Cavalcante
authors.affiliation: Laboratório de Produtos Naturais Marinhos, Departamento de Engenharia de Pesca, Universidade Federal do Ceará, Campus do Pici, Av. Mister Hull, s/n, Caixa Postal 6043, 60455-970 Fortaleza, CE, Brazil.
authors.forename: Rebeca Larangeira
authors.initials: RL
authors.lastname: de Lima
authors.affiliation: Laboratório de Produtos Naturais Marinhos, Departamento de Engenharia de Pesca, Universidade Federal do Ceará, Campus do Pici, Av. Mister Hull, s/n, Caixa Postal 6043, 60455-970 Fortaleza, CE, Brazil.
authors.forename: Bárbara Mendes
authors.initials: BM
authors.lastname: Baracho
authors.affiliation: Laboratório de Produtos Naturais Marinhos, Departamento de Engenharia de Pesca, Universidade Federal do Ceará, Campus do Pici, Av. Mister Hull, s/n, Caixa Postal 6043, 60455-970 Fortaleza, CE, Brazil.
authors.forename: Rayssa Mendes
authors.initials: RM
authors.lastname: Bezerra
authors.affiliation: Laboratório de Cromatografia, Departamento de Química, Universidade do Estado do Rio Grande do Norte, Campus Universitário Central, Setor III, Rua Prof. Antônio Campos, 59633-010, Mossoró, RN, Brazil.
authors.forename: Francisco Arnaldo
authors.initials: FA
authors.lastname: Viana
authors.affiliation: Laboratório de Microbiologia Ambiental e do Pescado, Instituto de Ciências do Mar, Universidade Federal do Ceará, Av. da Abolição 3207, 60165-081, Fortaleza, CE, Brazil.
authors.forename: Regine Helena Silva
authors.initials: RHS
authors.lastname: Dos Fernandes Vieira
authors.affiliation: Laboratório de Produtos Naturais Marinhos, Departamento de Engenharia de Pesca, Universidade Federal do Ceará, Campus do Pici, Av. Mister Hull, s/n, Caixa Postal 6043, 60455-970 Fortaleza, CE, Brazil.
authors.forename: Alexandre Holanda
authors.initials: AH
authors.lastname: Sampaio
authors.affiliation: Laboratório de Microbiologia Ambiental e do Pescado, Instituto de Ciências do Mar, Universidade Federal do Ceará, Av. da Abolição 3207, 60165-081, Fortaleza, CE, Brazil.
authors.forename: Oscarina Viana
authors.initials: OV
authors.lastname: de Sousa
authors.affiliation: Laboratório de Produtos Naturais Marinhos, Departamento de Engenharia de Pesca, Universidade Federal do Ceará, Campus do Pici, Av. Mister Hull, s/n, Caixa Postal 6043, 60455-970 Fortaleza, CE, Brazil.
authors.forename: Silvana
authors.initials: S
authors.lastname: Saker-Sampaio
keywords: Antioxidant; Bacterial agglutination; Bioactive compounds; Rhodophyta