title: (2R,3R)-2-(3',4'-dihydroxybenzyl)-3-(3'',4''-dimethoxybenzyl)butyrolactone suppresses fMLP-induced superoxide production by inhibiting fMLP-receptor binding in human neutrophils.
abstract: This study investigated the mechanism underlying the inhibiting effect of (2R,3R)-2-(3',4'-dihydroxybenzyl)-3-(3'',4''-dimethoxybenzyl) butyrolactone (PP-6), a lignan from Piper philippinum, on superoxide anion production induced by the chemotactic peptide formyl-methionyl-leucyl-phenylalanine (fMLP) in human neutrophils. Human neutrophils were stimulated with fMLP (1 microM), PMA (100 nM) or leukotriene B(4) (LTB(4); 1 microM) and induced superoxide anion release. PP-6 specifically inhibited fMLP-induced superoxide anion production in a concentration-dependent manner with an IC(50) value of 0.3+/-0.1 microM. Intracellular signaling caused by fMLP, PMA or LTB(4) were evaluated. PP-6 specifically inhibited fMLP-induced intracellular calcium mobilization and ERK (p42/p44), Akt and p38 phosphorylation. Moreover, PP-6 specifically inhibited fMLP-induced Mac-1 expression without affecting this caused by LTB(4) or PMA. PP-6 did not increase cAMP level in human neutrophils. PP-6 did not inhibit superoxide anion production by NaF (20 mM), a direct activator of G-protein, the target of the inhibitory action of PP-6 appears to be a component of the signal transduction pathway upstream of G-protein. PP-6 inhibited FITC-fMLP binding to neutrophils in a concentration-dependent manner with an IC(50) of 1.5+/-0.2 microM. PP-6 did not bring a parallel shift in the concentration response of fMLP-induced superoxide anion. Additionally, the inhibiting effect of PP-6 on fMLP-induced superoxide anion was reversed when PP-6 was washed out. These experimental results suggest that PP-6 exerts non-competitive and reversible antagonistic effect on fMLP receptor.
authors.affiliation: Graduate Institute of Natural Products, College of Medicine, Chang Gung University, Taiwan.
authors.forename: Yi-Jia
authors.initials: YJ
authors.lastname: Huang
authors.forename: Ih-Sheng
authors.initials: IS
authors.lastname: Chen
authors.forename: Ching-Ping
authors.initials: CP
authors.lastname: Tseng
authors.forename: Yuan-Ji
authors.initials: YJ
authors.lastname: Day
authors.forename: Yin-Chou
authors.initials: YC
authors.lastname: Lin
authors.forename: Chang-Hui
authors.initials: CH
authors.lastname: Liao
mesh_terms: D015107:4-Butyrolactone / Q000031:analogs & derivatives* / Q000494:pharmacology; D000328:Adult; D002118:Calcium / Q000378:metabolism; D000242:Cyclic AMP / Q000378:metabolism; D004305:Dose-Response Relationship, Drug; D048049:Extracellular Signal-Regulated MAP Kinases / Q000378:metabolism; D005260:Female; D006801:Humans; D017705:Lignans / Q000494:pharmacology*; D016177:Macrophage-1 Antigen / Q000032:analysis; D008297:Male; D009240:N-Formylmethionine Leucyl-Phenylalanine / Q000037:antagonists & inhibitors*; D009504:Neutrophils / Q000187:drug effects / Q000378:metabolism; D010766:Phosphorylation; D031701:Piper / Q000737:chemistry*; D044042:Receptors, Formyl Peptide / Q000037:antagonists & inhibitors* / Q000378:metabolism; D013481:Superoxides / Q000378:metabolism*
chemical_list: C527774:(2R,3R)-2-(3',4'-dihydroxybenzyl)-3-(3'',4''-dimethoxybenzyl)butyrolactone; D017705:Lignans; D016177:Macrophage-1 Antigen; D044042:Receptors, Formyl Peptide; D013481:Superoxides; D009240:N-Formylmethionine Leucyl-Phenylalanine; D000242:Cyclic AMP; D048049:Extracellular Signal-Regulated MAP Kinases; D015107:4-Butyrolactone; D002118:Calcium