STEROID
A steroid is a type of organic
compound that contains a characteristic arrangement of four cycloalkane
rings that are joined to each other. Examples of steroids include the dietary
fat cholesterol,
the sex hormones estradiol and testosteron,
and the anti-inflammatory drug dexamethasone.
The core of steroids is composed of twenty carbon atoms
bonded together that take the form of four fused rings: three cyclohexane
rings (designated as rings A, B, and C in the figure to the right) and one cyclopentane
ring (the D ring). The steroids vary by the functional groups attached to this
four-ring core and by the oxidation state of the rings. Sterols are
special forms of steroids, with a hydroxyl
group at position-3 and a skeleton derived from cholestane.
Cholesterol, from the Greek
chole- (bile)
and stereos (solid) followed by the chemical
suffix
-ol for an alcohol, is an organic
chemical substance classified as a waxy steroid
of fat. It is an essential structural component of mammalian cell membranes and
is required to establish proper membrane permeability and fluidity.
BIOSYNTHESIS of CHOLESTEROL
formation of cholesterol can be prevented by inhibitor such as statin
BalasHapushow much inhibitor should be use?