Antioxidants

Question 1

Antioxidants

Answer 1

Antioxidants = play a central role in detoxification by converting free radicals / ROS to stable, non-toxic molecules. They can be divided into three main groups:

1. Antioxidant enzymes.
2. Chain-breaking antioxidants ― the chain of ROS can be broken when a molecule can accept or donate an electron without needing to rectify its gain or loss.
3. Transition metal-binding proteins.

Question 2

Antioxidant enzymes:
Superoxide dismutase (SOD)

Answer 2

A group of enzymes that convert superoxide to hydrogen peroxide.
* Hydrogen peroxide (also a ROS) must then be detoxified by catalase or glutathione peroxidase.

Zinc, copper, manganese

Question 3

Antioxidant enzymes:
Catalase

Answer 3

Converts hydrogen peroxide to H2O and O2

Iron

Question 4

Antioxidant enzymes:
Glutathione peroxidase

Answer 4

Same as for catalase.

Note: Mercury can suppress selenium activity in the body.

Selenium

Question 5

Antioxidant enzymes:
Glutathione reductase

Answer 5

Regenerates glutathione that has been oxidised.

Vitamin B3

Question 6

Chain-breaking antioxidants:
Vitamin E

Answer 6

Sunflower seeds, almonds, pine nuts, olive oil, avocado, sweet potato, spinach.

Question 7

Chain-breaking antioxidants:
Vitamin C

Answer 7

Peppers, kiwi fruit, papaya, currants, berries, citrus, crucifers, mangoes, tomatoes

Question 8

Chain-breaking antioxidants:
Flavonoids

Answer 8

E.g., quercetin (red onions, apples), anthocyanins (red grapes), catechins (green tea), kaempferol (kale, spinach)

Question 9

Chain-breaking antioxidants:
Carotenoids

Answer 9

Yellow, orange, and red fruits and vegetables. Green vegetables.