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Toxicology > Exercises > Flashcards

Exercises Flashcards

1
Q

How can you get in contact with carbon monoxide and why is it toxic?

A

Incomplete combustion, photochemical reactions in troposphere,
metabolism of hemoglobin, metabolism of xenobiotics
(dichloromethane)
 It binds to hemoglobin and blocks the oxygen transfer

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2
Q

How can you get in contact with cyanides and why is it toxic?

A

ccidentally uptake of cyanide salts, e.g., NaCN or KCN.
 Metabolism of nitriles (Bitter almond, crushed flax seeds, improperly
cooked cassava)
 It binds to the heme group of cytochrome c oxidase in mitochondria,
and thus blocks the energy transfer (respiration chain)

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3
Q

How can you get in contact with hydrogen sulfide and why is it toxic?

A

Microbial degradation of organic matters under anaerobic conditions,
swamps and sewers.
 Volcano gases, natural gas, thermal springs, human metabolism
 Similar as HCN, it binds to the heme group of cytochrome c oxidase
in mitochondria, and thus blocks the energy transfer

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4
Q

What is the toxicity mechanism of 4-fluorobutyl acetate?

A

It metabolizes into fluoroacetic acid, which then blocks the citric acid
cycle

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5
Q

What is the toxicity mechanism of 1-chloroprop-2-yl butyrate?

A

The major risk comes from the metabolized α-chloroketone, which is a
strong alkylating agent/electrophile.

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6
Q

How does Dinoseb disturb the cell’s energy production?

A

It’s an uncoupler, which blocks the production of ATP.

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7
Q

Where do you find nitrite? How can it give rise to toxic effects?

A

Processed meats, bacons, sausages, fish
 Bacterial conversion from nitrate
 It can react with amines in the stomach to form carcinogenic N-
nitrosamines
 It can oxidize Fe(II) to Fe(III) in the hemoglobin to cause
methemoglobinemia (can be used to treat cyanide poisoning)

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8
Q

Describe the mechanism for how aromatic amines give rise to

methaemoglobinemia.

A

It can be metabolized into hydroxyamines, which can then oxidize
Fe(II) to Fe(III) in the hemoglobin to cause methemoglobinemia
 Hydroxylamines can also generate radicals and electrophilic species
after further metabolism.

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9
Q

What are base pair substitutions, frame-shift mutations, and chromosome
mutations?

A
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10
Q

What are the downsides of antioxidants?

A

Phenolics can stabilise radicals but sometimes can act as prooxidants. Some can decrease our bodyguard glutathione, decrease glutathione S transferase activity

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11
Q

What downside of oxidation can happen, and when using p450?

A

Generating ROS

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12
Q

What are the four types of oxidation?

A

Alkenes and aromatics (double bonds) can be epoxides
Carbon hydroxylation (not all carbons can be)
Heteroatom oxidation
Oxidation of alcohol and aldehydes

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13
Q

Which enzyme used to oxidise double bond ?

A

p450 (FeV centre in enzyme)

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14
Q

If you see a double bond what should you think?

A

Epoxidation

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15
Q

This course we can assume that if it is possible then it will happen, we don’t have to think about what’s more likely

A

That’s right

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16
Q

Epoxides are…

A

electrophilic

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17
Q

What is metabolic activation

A

That’s the molecule becomes toxic when metabolised

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18
Q

benzene can be epoxidised and then be oxidised to

A

phenol

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19
Q

Not all CH bonds can undergo hydroxylation, which ones can?

A

Using P450

  • allylic hydrogen, the CH bond is connected to a double bond (next to unsaturation)
  • next to heteroatom (alfa hydroxylation)
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20
Q

Carbon bound to heteroatom on either side is called a

A

hemiacetal

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21
Q

Hemiacetal (carbon bound to two heteroatoms) is unstable and will form two products, which?

A

aldehyde and alcohol/amine/thiol/HCl

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22
Q

What is oxidative dehydrohalogenation?

A

Carbon hydroxylation when carbon bound to Cl and O

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23
Q

What is oxidative dealkylation?

A

Carbon hydroxylation when carbon bound to oxygen and oxygen/sulfur/nitrogen, the hydroxylation forms a hemiacetal which is unstable and forms aldehyde and alcohol/amine/tiol

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24
Q

In oxidative dehydrohalogenation, what happens to primary, secondary and tertiary halides?

A

primary forms alcohol and HCl
secondary forms ketone and HCl
tertiary has no Alfa carbon so no reaction

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25
Q

chloroform can be metabolised into

A

phosgene

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26
Q

there is a synergistic effect between chloroform and which compound?

A

ethanol

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27
Q

Some groups behave like halogens, what are they?

A

acetonitrile forms formaldehyde and hydrogen cyanide

methane thiol

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28
Q

beta oxidation of fatty acids

A

beta carbon to carboxylic acid is oxidised and fatty acid is cleaved into acetic acid and a shorter acid (this is primary metabolism)

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29
Q

in which oxidation do we chop fatty acids, two off every time?

A

beta oxidation of fatty acids

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30
Q

which products do beta oxidation of fatty acids form?

A

acetic acid and a shorter acid

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31
Q

where do we make use of acetic acid?

A

in the citric acid cycle

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32
Q

whenever you see a fatty acid what should you do?

A

chop off acetic acid (two carbons) and two more untill you only have carboxylic acid left (which can undergo further reactions)

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33
Q

beta hydroxylation will chop off how many carbons?

A

two

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34
Q

Fenton and Haber Weiss reactions generate what?

A

ROS

35
Q

What can lipid peroxidations form?

A

can generate metabolites that are electrophilic (Michael acceptors)

36
Q

What can vitamin E do?

A

quench radicals

37
Q

which heteroatoms do we talk about in heteroatom oxidation?

A

nitrogen and sulfur

38
Q

imine is not stable, it will form …

A

formaldehyde and amine

39
Q

allylamine can be metabolised to …

A

acrolein

40
Q

Why are aromatic amines so toxic?

A

hydroxylamine can be both a strong electrophile and form ROS

41
Q

which of the four forms of amine/nitro is the most toxic?

A

hydroxylamine

42
Q

the line with X means whatever structure

A
43
Q

hydroxylamine can be conjugated with

A

sulfate, creates a very good leaving group

44
Q

whenever a leaving group is connected to a heteroatom, it’s leaving ability becomes much …

A

stronger

45
Q

hydrogen in hydroxylamine can be easily abstracted by peroxidase and form …

A

ROS

46
Q

a minor pathway of hydroxylamine is a …

A

Michael acceptor

47
Q

what are the four electrophilic types

A

good leaving group
cyclic esters cyclic ethers
Michael acceptor
acid chloride

48
Q

aromatic amines are very bad because they form three out of four … and …

A

three out of four electrophiles: good leaving group, Michael acceptor, cyclic ether and radical oxygen species

49
Q

acylated aromatic amine can also form an electrophile because…

A

the acyl group can move to oxygen instead of sitting on N and then it forms a very good leaving group. acetate is only a good leaving group because connected to a heteroatom

50
Q

which enzymes perform oxidation of alcohol and aldehyde?

A

alcohol dehydrogenase (NAD+ needed) and aldehyde dehydrogenase

51
Q

in our bodies we have a … concentration of NAD+ and a … concentration of NADH

A

high NAD+

low NADH

52
Q

secondary alcohol metabolism reversible and determined by NAD+ levels and forms

A

ketones

53
Q

aldehyde can be reduced, but can acid be reduced?

A

no

54
Q

what is the major metabolite of DDT?

A

DDA can be excreted in kidneys

55
Q

DDT is very lipophilic, no polar groups and what does this mean for uptake?

A

it doesn’t not dissolve in stomach and that is why you can eat it without much problem

56
Q

hydrolysis of epoxides, water can open epoxide to form a …

A

dihydroximolecule

57
Q

epoxide hydrolase is an enzyme that opens up …

A

epoxides. there are certain substrates that do not fit the enzyme and therefore travel through our body as epoxides.

58
Q

hydrolysis of esters form two products, which?

A

acetic acid and alcohol

59
Q

COOR means?

A

Ester bond

60
Q

what does ester become when cleaved?

A

carboxylic acid and alcohol

61
Q

amide can be …

A

cleaved

62
Q

what is an amide?

A

like ester but with nitrogen and double bound oxygen

63
Q

what is the phase 2 reaction for electrophile?

A

glutathione GSH

64
Q

cysteine is part of our body guard…

A

glutathione GSH

65
Q

GSH glutathione is not very effective with acrolein because

A

acrolein can be regenerated in the kidneys which prolongs circulation time of acrolein

66
Q

conjugation with sulphate is primarily for…

A

alcohol and phenol

67
Q

what is PAPS?

A

an activated sulphate. used to conjugate to phenol

68
Q

what are alcohols, phenols, carboxylic acid, aromatic amines, sulfonamide conjugated with?

A

glucoronic acid (already fairly large above 200 molecular weight)

69
Q

if molecular weight larger than 500 the molecule is excreted in…

A

liver

70
Q

conjugation with amino acids is primarily for

A

carboxylic acid

71
Q

carboxylic acid can be conjugated with

A

glucoronic acid and with amino acid (glycine)

72
Q

glucoronic acid can bind with a lot, what is the downside?

A

it’s slow

73
Q

when you get rid of urine and CO2, do you get rid of acid and increase pH?

A

yes

74
Q

ester, amides, alcohol and aldehydes can be metabolised to acids in the body which can lead to…

A

acidosis. they are masked acids.

75
Q

what is feeling drunk actually?

A

non specific effect on CNS. molecules trapped in cell membranes and disturbs signals to nerve cells.

76
Q

why is methanol toxic?

A

metabolised into formic acid and formaldehyde. can cause acidosis. but slowly metabolised because so hydrophilic.

77
Q

Respiratory chain is blocked when HCN or H2S bind to …

A

the heme group of enzyme complex IV

78
Q

the uncoupling effect of the respiratory chain can likened to what in a car?

A

adding gas while the clutch is down

79
Q

signal within a nerve cell is … and the signals between nerve cells (at synapsis) are …

A

electrical and chemical

80
Q

lipophilic molecules below molecular weight …. can pass membrane of cells

A

1000

81
Q

why can ions not pass cell membranes?

A

they are not alone, usually complexed with water

82
Q

what does asbestos do in the lungs?

A

stimulate cell growth and create a thick layer which does not allow blood gas exchange

83
Q

what molecules can pass bbb, their molecular weight must be below … to be efficient and below
.. to pass at all, their log p value must be above …

A

300 and 400 and 1.5

84
Q

some molecules can be trapped after the BBB because they are … into a form that does not pass

A

transformed/metabolised

Toxicology (3 decks)

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