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Effects of oxygen radicals on the conformation of sulfhydryl groups on human polymorphonuclear leukocyte membranes
Abstract:
The healthy intact polymorphonuclear leukocytes (PMNs) were labeled with 4-maleimide-TEMPO spin labeling compound (MAL) to study the effects of oxygen radicals produced by phorbol myristate acetate (PMA)-stimulated PMNs on the conformation of sulfhydryl (SH) groups of PMN membrane proteins. The lipid peroxidation induced by PMA-stimulated PMNs was detected by evaluating the formation of malonaldehyde (MDA) with the thiobarbituric acid (TBA) test. From the experiments of luminol-dependent chemiluminescence (CL) and fluorometry, it was found that Chinese herbs schizandrin B (Sin B) and quercetin (Q) possessed scavenging properties for oxygen radicals produced during the PMN respiratory burst. These two herbs can also inhibit the conformation changes in SH binding sites on the PMN membrane proteins caused by oxygen radicals produced by the PMNs themselves. They also decreased the amount of MDA, which was a final product formed during lipid peroxidation.
Insights
Chinese herbs schizandrin B and quercetin protect against oxidative stress in polymorphonuclear leukocytes (PMNs). These compounds scavenge oxygen radicals and inhibit damage to PMN membrane proteins and lipid peroxidation.
Area of Science:
- Biochemistry
- Immunology
- Pharmacology
Background:
- Polymorphonuclear leukocytes (PMNs) generate oxygen radicals during respiratory bursts, potentially damaging cellular components.
- Oxidative stress and lipid peroxidation are implicated in various inflammatory conditions.
Purpose of the Study:
- To investigate the effects of oxygen radicals from stimulated PMNs on PMN membrane protein sulfhydryl (SH) groups.
- To evaluate the antioxidant and protective properties of Chinese herbs schizandrin B (Sin B) and quercetin (Q) against PMN-induced oxidative damage.
Main Methods:
- Labeling intact PMNs with 4-maleimide-TEMPO spin probe (MAL) to assess SH group conformation changes.
- Measuring lipid peroxidation via malonaldehyde (MDA) formation using the thiobarbituric acid (TBA) test.
- Assessing oxygen radical scavenging using luminol-dependent chemiluminescence (CL) and fluorometry.
Main Results:
- Sin B and Q demonstrated significant scavenging activity against oxygen radicals produced by PMA-stimulated PMNs.
- These herbs inhibited conformation changes in SH binding sites on PMN membrane proteins caused by PMN-derived oxygen radicals.
- Sin B and Q treatment led to a decrease in MDA formation, indicating reduced lipid peroxidation.
Conclusions:
- Schizandrin B and quercetin exhibit potent antioxidant properties, protecting PMNs from self-inflicted oxidative damage.
- These natural compounds mitigate PMN-induced conformational changes in membrane proteins and inhibit lipid peroxidation.
- Sin B and Q represent potential therapeutic agents for conditions associated with PMN oxidative stress.