title: Effect of the isocoumarin paepalantine on the luminol and lucigenin amplified chemiluminescence of rat neutrophils.
abstract: Paepalantine (9,10-dihydroxy-5,7-dimethoxy-1H-naphto(2,3c)pyran-1-one), a natural isocoumarin isolated from the capitula of Paepalanthus bromelioides (Eriocaulaceae), was assessed for its effect on the respiratory burst (zymosan-stimulated luminol-enhanced chemiluminescence and PMA-stimulated lucigenin-enhanced chemiluminescence) of polymorphonuclear neutrophils in vitro. Special attention was devoted to establishing the IC(50) for neutrophils. Paepalantine was able to decrease luminol and lucigenin chemiluminescence, reflecting an inhibitory effect on the respiratory burst, with an ED(50) of 0.44+/-0.05 and 0.84+/-0.15 microg/ml, respectively. A cell-free system was performed with paepalantine on myeloperoxidase/H(2)O(2) and myeloperoxidase/H(2)O(2)/Cl(-) systems. Paepalantine inhibited luminol oxidation in both systems. This inhibition was related to the interaction of paepalantine-myeloperoxidase and its scavenger effect on HOCl.
authors.affiliation: Instituto de Química de Araraquara, Universidade Estadual Paulista Júlio de Mesquita Filho, Rua Prof. Francisco Degni, s/n, CP 355, 14801-970 Araraquara, SP, Brazil.
authors.forename: Rodrigo Rezende
authors.initials: RR
authors.lastname: Kitagawa
authors.forename: Maria Stella Gonçalves
authors.initials: MS
authors.lastname: Raddi
authors.forename: Najeh Maissar
authors.initials: NM
authors.lastname: Khalil
authors.forename: Wagner
authors.initials: W
authors.lastname: Vilegas
authors.forename: Luiz Marcos
authors.initials: LM
authors.lastname: da Fonseca
mesh_terms: D000166:Acridines; D000818:Animals; D000975:Antioxidants / Q000494:pharmacology*; D002470:Cell Survival / Q000187:drug effects; D003374:Coumarins / Q000494:pharmacology*; D006997:Hypochlorous Acid / Q000494:pharmacology; D066298:In Vitro Techniques; D049934:Isocoumarins; D008163:Luminescent Measurements; D008165:Luminol; D008297:Male; D009504:Neutrophils / Q000187:drug effects* / Q000201:enzymology; D009195:Peroxidase / Q000378:metabolism; D051381:Rats
chemical_list: D000166:Acridines; D000975:Antioxidants; D003374:Coumarins; D049934:Isocoumarins; C108025:paepalantine; C033472:10,10'-dimethyl-9,9'-biacridinium; D008165:Luminol; D006997:Hypochlorous Acid; D009195:Peroxidase