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Pharmacology & Medical Chemistry II > Exam 2: Lecture X, Medical Chemistry of Steroid Hormones I & II > Flashcards

Exam 2: Lecture X, Medical Chemistry of Steroid Hormones I & II Flashcards

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1
Q

Glucocorticoids regulate

A

carb, lipid and protein metabolism

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2
Q

Mineralocorticoids regulate

A

salt balance and water balance

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3
Q

5a-cholestane is..

A

trans-trans-trans

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4
Q

5b-cholestane is…

A

cis-trans-trans

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5
Q

1,2-diaxial or 1,2-diequatorial is

A

trans

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6
Q

1,2-equatorial-axial. is…

A

cis

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7
Q

pregnenolone formation

A

cholesterol converted in adrenal gland by enzymatic cleave into pregnenolone

this is precursor of adrenocorticoids

this done by complex of enzymes…CYP11A1, Adrenodoxin and Adrenodoxin reductase

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8
Q

Hydroxylation of pregnenolone at position 17 by the enzyme

A

17A-hydroxylase

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9
Q

Oxidation of 17A-hydroxypregnenolone to the 3-keto intermediate by

A

3b-hydroxy steroid dehydrogenase followed by isomerization of double bond by enzyme 3-oxo steroid-4,5 isomerase

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10
Q

The final step in the biosynthesis catalyzed by the enzyme

A

11B-hydroxylase leads to formation of hydrocortisone, the most potent endogenous glucocorticoid secreted by the adrenal cortex.

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11
Q

Cortisone, the inactive metabolite is formed by the oxidation of

A

11B-hydroxy group of hydrocortisone by 11-hydroxy steroid dehydrogenase .

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12
Q

Hydrocortisone and cortisone are biochemically interconvertible by the

A

11B-hydroxysteroid dehydrogenase, with the reaction equilibrium towards hydrocortisone.

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13
Q

Functionalities important for superior glucocorticoid activity:

A

Carbonyl group at C-3.
C=C between C-4 and C-5.
C=O or b-OH at C-11.
b-ketol side chain at C-17.

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14
Q

Glucocorticoid activity is inversely proportional to the size of halogen at

A

C-9

9a-F (Fludrocortisone) is approximately 11 times more potent (for treatment of rheumatoid arthritis) than cortisone acetate. but also 300-800 times increase mineralocorticoid activity

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15
Q

Methhylprednisolone

A

More potent than predinisolone.
Has improved glucocorticoid activity
and reduced mineralocorticoid activity.

Note: 6a-F group also increases gluco-
coritcoid activity, but it has less minera-
ocorticoid activity than 9a-F function.

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16
Q

Prednisone

A

Increase in potency related to change in geometry of ring A

possesses more potent antirheumatic and anti-allergic activity than hydrocortisone and produces fewer undesirable side effects.

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17
Q

Triamcinolone

A

Inserting 16a-hydroxy group into 9a-fluoroprednisolone

Resulted in glucocorticoid activity equivalent to prednisolone but with decreased mineralocorticoid activity.

9F - improve anti inflammatory, prevent oxidation 11-OH
Hydroxy group in any position reduce sodium retention

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18
Q

All trans (B/C and C/D) ring fusion is required

A

activity

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19
Q

The 17b ketol (-COCH2OH) side chain and 4 -3 ketone function are found in

A

clinically used adrenocorticoids and these groups do contribute to the potency.

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20
Q

Insertion of a double bond between 1 and 2 in hydrocortisone increases

A

glucocorticoid activity and longer half-life

21
Q

The 9a-F group increases

A

glucocorticoid activity and nearly prevents metabolic oxidation of the 11b-OH group to a ketone.

22
Q

The 6a-F also increases glucocorticoid activity, but it has less effect than the 9a-F on

A

sodium retention

23
Q

Highly active naturally occurring mineralocorticoids have no

A

OH function in position 11/17

24
Q

Conversion of 17a-hydroxy to either a 17a-ester or an ether with 16a, 17a- isopropylidenedioxy (acetonide) greatly enhances the

A

anti-inflammatory potency

25
Q

Cortisle induce production of….

A

lipocortin

26
Q

LH induces….

A

luteinization which leads to formation of corpus luteum which is responsible for the biosynthesis and secretion of progesterone.

27
Q

Estradiol has…

A

phenol at 3, OH at 17

28
Q

Progesterone has…

A

double bond O at 3, ketone at 17

29
Q

Testosterone has….

A

Double bond O at 3, OH at 17

30
Q

Estrone:Estradiol Premenopausaul women

A

1:2

31
Q

Estrone:Estradiol Postmenopausal women

A

2:1

32
Q

Placenta primary location of estrogen biosynthesis during…

A

pregnancy

33
Q

Estrogen biosynthesize in maturing….

A

dominant follicle and corpus lute in premenopausal women

34
Q

Estradiol key role in…

A

development of secondary sex characteristics
stimulation of mammary glands during pregnancy
thermoregulatory capacity

35
Q

Estradiol admin orally….

A

conjugated and oxidatively metabolized in liver = poor bioavail and therapeutic effectiveness

36
Q

Enterohepatic recycling Ethinyl Estradiol

A

bacteria in GI track hydrolyze the glucuronide and sulfate conjugates, permitting reabsorption of EE….main reason for antibacterial agents to have adverse effects on oral contraceptive efficacy

37
Q

SAR Estradiol

A

Aromatic Ring A and Hydroxyl group at C-3 essential for estrogenic activity

Enlargement of ring D greatly reduces estrogenic activity

Introduction of unsaturation into ring B boosts estrogenic potency

modification of 17a/16 position can lead to enhanced activity

adding hydroxyl group at 6/7/11 reduces activity

removal of oxygen function from 3/17 or epimerization 17b-OH = decrease activity

distance between 2 OH groups, 17B-OH group important for full estrogenic activity

11b sub well tolerated, 11b-methoxy/ethyl analog sig greater activity for receptor

38
Q

Impeded estrogens

A

interact with ER in target tissue but dissociate from receptor too rapidly to produce any strong estrogenic effect

classical impeded estrogen is estriol

39
Q

Antiestrogens

A

Triphenylethylene analogs exhibit strong and persistent binding to the estrogen receptor, producing antiestrogen-receptor complex which is unable to produce an estrogenic response.

40
Q

Clomiphene citrate

A

has both esterogenic and antiesterogenic properties (partial agonist) and is used to induce ovulation for the treatment of infertility.

41
Q

Tamoxifen

A

is an estrogen agonist-antagonist (partial agonist) that is used in the treatment of estrogen-dependent breast cancer. Metabolism of tamoxifen produces active metabolite 4-hydroxytamoxifen

42
Q

Inhibitors of aromatase will….

A

block the conversion of androgens to estrogens and thus have therapeutic potential in the control of reproductive functions and in the treatment of estrogen dependent cancers such as breast cancer.

43
Q

competitive inhibitors of aromatase will….

A

selectively inhibit the conversion of testosterone to estrogens in all tissues.

44
Q

Anastrazole and other triazoles inhibit the aromatase enzyme by binding of the

A

N-4 nitrogen of the triazole ring with the heme iron atom of the CYP19 enzyme complex.

Anastrazole and letrozole are used for the treatment of advanced breast cancer in postmenopausal woman with disease progression following tamoxifen therapy.

45
Q

Progesterone Metabolism

A

rapidly metabolized by liver and mainly excreted as glucuronide and sulfate conjugates of 5b-pregnanediol.

also 6a-hydroxylation (CYP3A4)
and reduction of 20-ketone to alcohol by dehydrogenase

46
Q

premature drop of what may be a warning of possible miscarriage

A

glucuronide conjugate of 5b-preganediol

47
Q

Substituents at what position hinder 6-hydroxylation of progestins, increase their lipohilicity and result in enhanced biologic effect?

A

C6

further enhanced when double bond introduced between position 6-7

48
Q

Removal of what group on steroids results in activity equal to or greater than that of parenterally admin progesterone

A

C19 methyl

49
Q

antiprogestin

A

is a compound that antagonizes the actions of progesterone by competing for its receptor, would be an important agent for interfering with the early phases of pregnancy.

Mefepristone

Pharmacology & Medical Chemistry II (43 decks)

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