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Vasoactive intestinal peptide, a singlet oxygen quencher.
1Department of Biomedical Sciences, College of Veterinary Medicine, Virginia Polytechnic Institute, Blacksburg 24061.
The Journal of Biological Chemistry
|September 15, 1990
Summary
Vasoactive intestinal peptide (VIP) does not scavenge superoxide or hydroxyl radicals. However, VIP effectively inhibits singlet oxygen (1O2) formation, suggesting it can protect against oxidative stress.
Area of Science:
- Biochemistry
- Immunology
- Cell Biology
Background:
- Vasoactive intestinal peptide (VIP) is a neuropeptide with diverse physiological roles, including vasodilation and immune modulation.
- While known for other functions, VIP's antioxidant properties have not been fully elucidated.
Purpose of the Study:
- To investigate the antioxidant potential of VIP, specifically its ability to scavenge reactive oxygen species.
- To determine if VIP can inhibit the formation of singlet oxygen (1O2).
Main Methods:
- VIP's ability to scavenge superoxide (O2-), hydroxyl radicals (OH.), and hydrogen peroxide (H2O2) was assessed.
- Singlet oxygen (1O2) generation was studied using photosensitizing systems (rose bengal, methylene blue).
- Electron paramagnetic resonance (EPR) spectroscopy was used to detect 2,2,6,6-tetramethylpiperidine N-oxyl (TEMPO) formation as a measure of 1O2.
Main Results:
- VIP showed no significant scavenging activity against O2-, OH., or H2O2.
- VIP dose-dependently inhibited 1O2-dependent TEMPO formation.
- Known singlet oxygen quenchers (beta-carotene, histidine, azide) inhibited TEMPO formation, while H2O2 and OH. scavengers did not.
Conclusions:
- VIP does not possess direct scavenging activity against major reactive oxygen species like superoxide and hydroxyl radicals.
- VIP acts as an effective scavenger/quencher of singlet oxygen (1O2).
- These findings suggest VIP may play a role in mitigating oxidative tissue injury caused by singlet oxygen.