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Inhibitory activity of flavonoids from Lychnophora sp. on generation of reactive oxygen species by neutrophils upon stimulation by immune complexes
Author(s) -
Kanashiro A.,
Kabeya L. M.,
Polizello A. C. M.,
Lopes N. P.,
Lopes J. L. C.,
LucisanoValim Y. M.
Publication year - 2004
Publication title -
phytotherapy research
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.019
H-Index - 129
eISSN - 1099-1573
pISSN - 0951-418X
DOI - 10.1002/ptr.1368
Subject(s) - reactive oxygen species , zymosan , opsonin , stimulation , luminol , chemiluminescence , immune system , chemistry , biochemistry , pharmacology , in vitro , biology , immunology , hydrogen peroxide , organic chemistry , neuroscience
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 inammatory 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 antiinammatory agents. In this study, we evaluated the effect of eight avonoids 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 µmol/L inhibited almost totally ICIgG‐ and OZ‐triggered luminol‐CL and OZ‐triggered lucigenin‐CL. The degree of inhibitory effect among the other avonoids 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 avonoids were not toxic to the rabbit PMNs. These results suggest that the actions of avonoids on ROS generation by stimulated PMNs are highly dependent on their structures. Copyright © 2004 John Wiley & Sons, Ltd.