Category:TP3V

The backbone of estrogens, the hormones responsible for female reproductive organs and secondary sex characteristics. The original spelling was 'oestrogen'. Major namings are:

• estrogen ... estra-1,3,5(10)-triene
• estrone ... 3-hydroxyestra-1,3,5(10)-triene-17-one
• estradiol ... estra-1,3,5(10)-triene-3,17β-diol
• estriol ... estra-1,3,5(10)-triene-3,16α,17β-triol
• equine estrogens ... estra-1,3,5(10),7-tetraene and estra-1,3,5,7,9-pentaene series

The backbone of male hormone testosterones. Major namings are:

• etianic acids (C20) ... androstane-17-carboxylic acids and their derivatives
• D-homoandrostanes (C20) ... ring D is expanded by including C-17a carbon.

The backbone of pregnancy hormone progesterone and the majority of corticosteroids. It is the largest single group of steroids. Major namings are:

• progesterone ... pregn-4-ene-3,20-dione
• 17α-ethynylandrostane ... 17α-pregn-20-yne
• 19-norpregnane (C20) ... 17α-ethynylestrane, 19-nor-17α-pregn-20-yne

The backbone of bile acids, i.e., 5β-cholan-24-oic acids with hydroxyl substitution at C-3.

• primary bile acids ... cholic acid and chenodeoxycholic acid are biosynthesized directly from cholesterol.
• secondary bile acids ... deoxycholic acid and lithocholic acid are generated by intestinal bacteria.
• 24-norcholan-23-oic acids ... loss of one carbon side chain
• 23,24-dinorcholan-22-oic acids ... loss of two carbon side chains

The sterol backbone contains a β hydroxyl group at C-3 and side chains of 8-10 carbons at C-17. They are important membrane constituents in addition to their biologically activity.
Major categories are:

• cholestane ... androstane structure with a branched C8 chain at the 17β-position
• norcholestane ... cholestane lacking one of 27 carbons
• ergostane and campestane ... 24β- and 24α-methylcholestane
• poriferastane and stigmastane ... 24β- and 24α-ethylcholestane
• vitamin D2 ... 9,10-secoergonstane derivatives
• vitamin D3 ... 9,10-secocholestane derivatives
• lumistane ... 9β,10α-ergosta-5,7-diene

Furostan has the additional epoxy ring E. Spirostan has another epoxy ring F, which is perpendicular to the planar orientation of rings A-E. The omission of a terminal 'e' from spirostans and furostans indicates that they are not hydrocarbons. (However, the last 'e' is needed if a consonant follows.)
Major categories are:

• furostan ... 16β,22-epoxycholestane
• spirostan ... 22,26-epoxyfurostan