title: Inhibitory activity of flavonoids from Lychnophora sp. on generation of reactive oxygen species by neutrophils upon stimulation by immune complexes.
abstract: Formation of circulating immune complexes (ICs) is essential for clearance of invading agents. In some circumstances ICs might deposit on host tissues, leading to an inflammatory process that involves massive activation of neutrophils (PMNs), release of reactive oxygen species (ROS) and lysosomal enzymes and damage to the host tissue. Extracts of plants from Lychnophora sp. are used in Brazilian folk medicine as antiinflammatory agents. In this study, we evaluated the effect of eight flavonoids isolated from L. granmongolense, L. salicifolia and L. ericoides on the generation of ROS by rabbit PMNs stimulated with two kinds of ICs: particles of serum-opsonized zymosan (OZ) and insoluble ICs (ICIgG). ROS production was measured by chemiluminescence (CL) assay. We observed that 5- and 7- dihydroxylated compounds at 5 micromol/L inhibited almost totally ICIgG- and OZ-triggered luminol-CL and OZ-triggered lucigenin-CL. The degree of inhibitory effect among the other flavonoids was different, depending on the kind of ICs used to trigger ROS generation by PMNs and the number and position of methoxy groups. Moreover, under the conditions assessed, the studied flavonoids were not toxic to the rabbit PMNs. These results suggest that the actions of flavonoids on ROS generation by stimulated PMNs are highly dependent on their structures.
authors.affiliation: Departamento de Física e Química, Faculdade de Ciências Farmacêuticas de Ribeirão Preto - USP Ribeirão Preto, SP, Brasil.
authors.forename: A
authors.initials: A
authors.lastname: Kanashiro
authors.forename: L M
authors.initials: LM
authors.lastname: Kabeya
authors.forename: A C M
authors.initials: AC
authors.lastname: Polizello
authors.forename: N P
authors.initials: NP
authors.lastname: Lopes
authors.forename: J L C
authors.initials: JL
authors.lastname: Lopes
authors.forename: Y M
authors.initials: YM
authors.lastname: Lucisano-Valim
mesh_terms: D000818:Animals; D000936:Antigen-Antibody Complex; D019659:Asteraceae; D002645:Chickens; D005260:Female; D005419:Flavonoids / Q000008:administration & dosage / Q000494:pharmacology* / Q000627:therapeutic use; D008163:Luminescent Measurements; D009504:Neutrophils / Q000187:drug effects* / Q000378:metabolism; D008517:Phytotherapy; D010936:Plant Extracts / Q000008:administration & dosage / Q000494:pharmacology* / Q000627:therapeutic use; D011817:Rabbits; D017382:Reactive Oxygen Species / Q000037:antagonists & inhibitors / Q000378:metabolism*; D013329:Structure-Activity Relationship; D015054:Zymosan
chemical_list: D000936:Antigen-Antibody Complex; D005419:Flavonoids; D010936:Plant Extracts; D017382:Reactive Oxygen Species; D015054:Zymosan