Steroid chemistry Flashcards
Basic info about steroid structure?
They are small organic molecules with a rigid structure. A small structural difference can result in massive differences in biological activity
Give examples of endogenous steroids
- sex hormones
- corticosteroids
- steroid lipids
Steroids are important for what?
They are essential structure components in cell membranes:
mammals - cholesterol
plants - beta-sitosterol
fungi - Ergosterol
Corticosteroids are hormones released from _____ _____. There are two types:
mineralocorticoids
glucocorticoids
What are the female and male sex hormones? Give examples
FEMALES: progestogen e.g. progesterone, oestrogen e.g. estrone, estradiol and estriol
MALES: androgens e.g. testosterone
Why is it beneficial if we establish a SAR (structure activity relationship) for a particular activity?
So that we can:
- design new drugs with improved properties
- predict the activity for a known structure
What groups added to a parent nucleus will provide additional functionality?
- alkene/alkyl
- hydroxy
- aldehyde
- ketone
- methyl
- halogen
What is the most important corticosteroid?
Aldosterone
What does aldosterone control?
Homeostasis of blood electrolyte levels and blood volume.
What is aldosterone a major component of?
The renin angiotensin system
What kinda of steroid is cortisol?
Glucocorticoid
What is cortisol involved in?
- stress response
- inflammatory response
- protein, carbohydrate and lipid metabolism
Substituents above the plane of a steroid are described as? How are they drawn?
beta solid line (or wedge)
Substituents below the plane of a steroid are described as? How are they drawn?
alpha broken line (or broken wedge)
Which is the most potent steroid?
Betamethasone
Which is the least potent steroid?
Hydrocortisone
The weaker the potency, the ______ lower the half life
slower
What are the structure requirements for corticosteroid activity?
- A pregnane steroid nucleus
- A hydroxyl functional group at position 11β
- An a-β unsaturated ketone at position 3; i.e double bond at 4-5
- A ketone functional group at position 20
What is oestrogen?
a primary female sex hormone
What is the role of oestrogen
- regulates menstruation cycle
- promotes development of secondary sex characteristics
Name a non-steroidal oestrogen
Stilboestrol (DES)
What was DES (stilboestrol) used for back n 1950s?
Prophylactic treatment to prevent miscarriage in first trimester
Why was DES discontinued?
Daughters at increased risk of clear cell adenocarcinoma of vagina and cervix, post puberty
What is Tamoxifen?
Oestrogen receptor antagonist in breast tissue. Has agonist actions in liver, bones and CV system.
Progesterone is critical for maintenance of _______, but also has activity in maintaining the ______
pregnancy
uterus
what does the prefix ‘nor’ indicate?
removal of methylene group.
What sex is testosterone found in?
male AND female
What is testosterone responsible for?
- anabolic activity
- promoting male sex characteristics
Introduction of unsaturation into ring makes it more or less planar?
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