Antioxidants and Radical Scavengers Flashcards
What 3 things does urate scavenge and what does it bind to for chelation from the body?
It scavenges singlet oxygen, hydroxyl radicals, and peroxyl radicals in addition to binding transition metals that may initiate LDL oxidation.
What is the MOST important free radical scavenger endogenously and where does it come from?
Uric acid; product of purine metabolism
Urate can be ________ by Vit C.
reduced
True/False: Urate can reduce a-tocopherol?
FALSE! Unlike Vit C, urate cannot reduce a-tocopherol
Coenzyme Q (ubiquinone) is found in which cells of the body?
ALL cells! They are present in the membrane. It is the most important membrane antioxidant.
Where does CoQ come from and what is its half-life?
Dietary uptake is limited and its half-life is 49-125 hours.
What are 4 functions of CoQ?
- It is an electron carrier in the respiratory chain,
- It is an effective lipid-soluable antioxidant (incorporated into micelles)
- Protects LDL from oxidation
- Can regenerate Vit C
What does CoQ prevent?
Oxidation of lipids, proteins, and DNA
How does CoQ exert anti-inflammatory effects?
It influences gene expression and stimulates the release of nitric oxide.
Bioactive compounds derived from plants are…
phytochemicals
Plant-derived phenolic compounds serve what three potential purposes?
antioxidant, anti-inflammatory, and anti-cancer
More of what chemical group gives a compound greater antioxidant capacity?
Hydroxyl groups
Where does the yellow color of turmeric come from?
It comes from the fat-soluble phenolics known as curcuminoids.
Bioavailablity of curcumin is _____.
Low
What are the inhibitory actions of curcumin?
- oxidative DNA damage in GI tract
- phospholipase A2, COX2, and 5-LOX
- expression of COX2 and inducible NO synthase genes
Curcumin is a scavenger of?…
ROS and RNOS in vitro
What activity does curcumin increase?
May increase GSH levels and increase activity of phase 2 enzymes
Polyphenol flavonoids are not produced in the body and have 4000-6000 natural occurring types, how do they occur in the body?
They occur free or conjugated to a sugar.
Quercetin is a ___________ and is found mostly as a ________.
falvonol; glycoside
What determines distribution or absorption of quercetin?
It depends on form: free quercetin or conjugates
How does quercetin help with elimination of ROS and products that produce ROS?
Quercetin is able to donate electrons to ROS and chelate ROS-producing metal ions.
High concentrations of quercetin __________ oxidative stress and cytotoxicity; this creates _______
increases; ROS
Conjugates of quercetin have __________ activity than parent compounds.
lower; their half-life is 28 hrs.
What is beneficial about quercetin in regards to cancer?
It induces apoptosis in cancer cell lines at doses greater than 40mM.
