title: Inhibitory activity of liposomal flavonoids during oxidative metabolism of human neutrophils upon stimulation with immune complexes and phorbol ester.
abstract: OBJECTIVE
  The massive production of reactive oxygen species by neutrophils during inflammation may cause damage to tissues. Flavonoids act as antioxidants and have anti-inflammatory effects. In this study, liposomes loaded with these compounds were evaluated as potential antioxidant carriers, in attempt to overcome their poor solubility and stability.
  
  
  METHODS
  Liposomes containing quercetin, myricetin, kaempferol or galangin were prepared by the ethanol injection method and analyzed as inhibitors of immune complex (IC) and phorbol ester-stimulated neutrophil oxidative metabolism by luminol (CLlum) and lucigenin-enhanced (CLluc) chemiluminescence (CL) assays. The mechanisms involved this activity of liposomal flavonoids, such as cytotoxicity and superoxide anion scavenging capacity, and their effect on phagocytosis of ICs were also investigated.
  
  
  CONCLUSIONS
  The results showed that the inhibitory effect of liposomal flavonoids on CLlum and CLluc is inversely related to the number of hydroxyl groups in the flavonoid B ring. Moreover, phagocytosis of liposomes by neutrophils does not seem to necessarily promote such activity, as the liposomal flavonoids are also able to reduce CL when the cells are pretreated with cytochalasin B. Under assessed conditions, the antioxidant liposomes are not toxic to the human neutrophils and do not interfere with IC-induced phagocytosis.
  
  
  CONCLUSIONS
  The studied liposomes can be suitable carriers of flavonoids and be an alternative for the treatment of diseases in which a massive oxidative metabolism of neutrophils is involved.
authors.affiliation: Departamento de Física e Química, Faculdade de Ciências Farmacêuticas de Ribeirão Preto, Universidade de São Paulo, Ribeirão Preto, SP, Brazil.
authors.forename: Ana Paula
authors.initials: AP
authors.lastname: Landi-Librandi
authors.forename: Ana Elisa
authors.initials: AE
authors.lastname: Caleiro Seixas Azzolini
authors.forename: Carlos Alberto
authors.initials: CA
authors.lastname: de Oliveira
authors.forename: Yara Maria
authors.initials: YM
authors.lastname: Lucisano-Valim
mesh_terms: D000818:Animals; D000936:Antigen-Antibody Complex / Q000502:physiology*; D002645:Chickens; D004305:Dose-Response Relationship, Drug; D005260:Female; D005419:Flavonoids / Q000494:pharmacology*; D006801:Humans; D008081:Liposomes; D008297:Male; D009504:Neutrophils / Q000187:drug effects* / Q000378:metabolism; D018384:Oxidative Stress / Q000187:drug effects* / Q000502:physiology; D010703:Phorbol Esters / Q000494:pharmacology*; D017382:Reactive Oxygen Species / Q000037:antagonists & inhibitors / Q000378:metabolism
chemical_list: D000936:Antigen-Antibody Complex; D005419:Flavonoids; D008081:Liposomes; D010703:Phorbol Esters; D017382:Reactive Oxygen Species