W8 - Anti-oxidant Supplements

Question 1

What are free radicals?

Answer 1

A type of reactive species

Question 2

Environmental sources of oxidants

Answer 2

UV radiation

Pollution

Smoking

Burnt food

Question 3

Cellular sources of oxidants

Answer 3

Oxidase enzymes

Mitochondrial respiration

Question 4

What happens when reactive species exposure exceeds anti-oxidant defences?

Answer 4

Damage to lipids

Damage to body proteins

DNA damage

Triggers inflammation

Question 5

When reactive species exposure exceeds antioxidant defences

What comes under damage to lipids?

Answer 5

Peroxidation

Damage to cell membranes –> Dysfunctional cells

Red NO bioavailability –> Impaired bv function

Question 6

When reactive species exposure exceeds antioxidant defences

What comes under damage to body proteins?

Answer 6

Oxidative modification

Altered function –> ageing

Question 7

What are the anti-oxidant systems available to combat the effects of reactive species

Answer 7

Endogenous antioxidants (enzymatic + non-enzymatic i.e uric acid)

Nutritional (VC,E+ carotene, minerals i.e copper + zinc, polyphenols i.e flavonoids)

Question 8

What are polyphenols?

Answer 8

A nutritional source of potential antioxidants

Question 9

What comes under polyphenols

Answer 9

Flavonoids

Lignans

Phenolic Acids

Stilbenes

Question 10

What is the direct antioxidant property?

Answer 10

Radical scavengers

Question 11

What is the challenge faced by polyphenols acting as radical scavengers?

Answer 11

Their bioavailability is poor

Question 12

Develop of the poor bioavailability of polyphenols

i.e if a cherry reaches the intestines

Answer 12

Only ~5-10% of the polyphenols consumed will actually make it into circulation.

Reminder will continue down GI tract to colon due to not being able to be broken down to be absorbed.

Once in colon, broken down + exposed to the microbiome which can help break down more polyphenols to become bioavailable.

Question 13

Uric acid in plasma

Answer 13

Uric acid is present in high levels within plasma (150-450μM)

Question 14

Uric acid in plasma and radical scavenging capacity

Answer 14

Confers ~60% of the radical scavenging capacity of the plasma.

Question 15

Peak plasma phenolic conc

Answer 15

<10μM.

Question 16

What is it thought polyphenols are converted to?

Answer 16

Into a stable radical i.e pro-oxidants

Question 17

What are pro-oxidant compounds called?

Answer 17

Semiquinones

Quinones

Question 18

What do pro-oxidants semiquinones and quinones do?

Answer 18

Trigger increased synthesis of endogenous antioxidants

= Triggering cells to prod more of the enzymatic antioxidant systems

Question 19

What does evidence suggest about phenolic compounds absorbed from polyphenols?

Answer 19

That they are able to inhibit the prod of ROS

• Meaning they can inhibit enzymes such as NADPH oxidase

Question 20

When is there an increased generation of ROS + NOS

Answer 20

During exercise

Question 21

Half-life of reactive species

Answer 21

VERY SHORT

Question 22

Indirect markers of reactive species

Answer 22

Looking at compounds that are indicative or are markers of oxidative damage.

i.e Protein carbonyls and nitrotyrosine or MDA.

Question 23

Direct markers of reactive species

Answer 23

e- paramagnetic spin resonance which are like spin traps for specific radicals whereby it fixes them in time, preventing them from changing

Question 24

What is meant by oxidative stress?

Answer 24

When the generation of reactive species overwhelms the antioxidant defences

Question 25

ROS + NOS exposure contributes to fatigue development in various ways causing issue to...

Answer 25

Ionic gradients E-C coupling Central drive Substrate depletion By-product accumulation Muscle perfusion —— Their relative contribution will depend on the intensity and duration of the exercise.

Question 26

What does ROS exposure trigger?

Answer 26

Incr prod of antioxidant enzymes due to particular signalling mechanisms involving the nuclear transcription factor nrf2 which is normally bound to another protein called KEAP1.

Question 27

Can the nrf2 and KEAP1 complex enter the nucleus?

Answer 27

NO

Question 28

Why does the nrf2 and KEAP1 complex need to enter the nucleus?

Answer 28

To incr prod of antioxidant enzymes

Question 29

What happens when the nrf2 and KEAP1 complex is exposed to ROS + NOS

Answer 29

It dissociates = Allows nrf2 to become small enough to enter the nucleus where it triggers a cascade of signalling through a whole series of proteins incl. a system called the antioxidant response element.

Question 30

What happens when the antioxidant response element is activated?

Answer 30

Triggers prod of incr level os some of our key antioxidant enzymes.

Question 31

Levels of what are sig higher in trained individuals than in sedentary individuals

Answer 31

Dismutase Catalase Peroxiredoxin

Question 32

What is N-acetylcysteine

Answer 32

A direct oxidant scavenger

Question 33

What can the thiol containing compound in the N-acetylcysteine do?

Answer 33

Donate a cysteine to support the function of 1 of our antioxidant systems glutathione.

Question 34

What is suggested about supplementing N-acetylcysteine?

Answer 34

That it can reduce exposure to reactive species + Reduce the inflammatory response post-exercise.

Question 35

N-acetylcysteine (NAC) supplementation and cycling sprint performance

Answer 35

Improved Better tolerance of increased training intensity

Question 36

NAC supplementation for endurance and sprint performance

Answer 36

Some studies suggest NAC is better for endurance rather than sprint performance.

Question 37

Purported properties of quercetin

Answer 37

Anti-oxidant Anticarcinogenic Cardioprotective Ergogenic

Question 38

500-1000mg quercetin a day...

Answer 38

Provided a 2.8% increase in endurance perf.

Question 39

7 days cherry supplementation and cycling TT perf

Answer 39

Cycling TT perf was enhanced -- Possibly via improved muscle perfusion. Plausible mechanisms for a favourable influence on cognitive function or decision making during exercise.

Question 40

Rationale as to why we think its worth exploring antioxidants in regards to ergogenic effects

Answer 40

Seen that oxidative stress + inflammation are contributing factors to the process of muscle damage, so can antioxidants protect against muscle damage +/or improve recovery from muscle damage? - Benefit for athletes during intensive training +/or intense competition.

Question 41

Antioxidant vitamin supplementation on recovery from intensive exercise

Answer 41

NO sig effects

Question 42

Functional recovery from intensive exercise after 7 days pre-loading with Montmorency cherry concentrate (~550mg anthocyanin/d)

Answer 42

Enhanced functional recovery