PAHs Flashcards

1
Q

toxicity of PAHs

A

major concern is PAH carcinogenicity–becomes bioactivated via CYP450

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
2
Q

many PAHs bind to AhR

A

ya

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
3
Q

prototype of PAHs?

A

Benzo-[a]-pyrene, because it is especially carcinogenic

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
4
Q

mechanisms of action of PAHs

A
  1. nonpolar narcosis–at high conc, PAHs can cause acute tox due to altered fluidity of cell membranes (like sedatives)
  2. activation of AhR
  3. Bioactivation to ultimate carcs–e.g. BAP to 9,10-epoxide by CYP1A1
  4. bioactivation to quinone structure–>generates ROS
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
5
Q

describe nonpolar narcosis

A

nonspecific, reversible, binding of lipophil structures to lipid membranes–alters fluidity of membrane, which leads to loss of selective permeability of ions (e.g. Na+)

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
6
Q

what is the ultimate BaP carc?

A

7,8-diol-9,10-epoxide–>covalently binds to guanine; causes a GC to AT mutatin (G+BaP binds to A); if this occurs in tumor suppressor p53, can cause tumors–cancer

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
7
Q

how do PAHs generate ROS?

A

bioactivated to quinones via UV rxns or CYP activity;

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
8
Q

what can oxidoreductive stress lead to?

A

DNA ox, lipid ox, protein ox, signalling which leads to apoptosis gene expression–>circles back to redox stress

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
9
Q

what is the primary antioxidant defense in our body?

A

glutathione, GSH

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
10
Q

what exogenous antioxs also defend us against ROS?

A

vit E (alpha-tocopherol) and vitC (ascorbate)–>prevent propagation of lipid peroxides; vit E reduces lipids, and vit C restores vit E to its reduced form

How well did you know this?
1
Not at all
2
3
4
5
Perfectly