Please Scroll Down to See Forums Below 
I'm sure most folks here know this, but in case you ever wondered where they come up the description "17-alpha alkylated" comes from. It simply means that if you start on the carbon labeled number "17" and go exactly one carbon away, that bond that is sticking up (-CH3) is a methyl. That's also known as an "alkyl" group. So whether you have an "ethyl", "propyl", or "butyl" group on carbons 13 or 16, it can be classified as "17-alpha alkylated" because "methyl", "ethyl", "propyl", and "butyl" et cetera are all "alkyl" groups. "Alkyl" is just a general term to describe these groups.
In general though, when they refer to the molecule as "17-alpha alkylated" it's generally on carbon 13 that they are referring to.
The molecule in the picture is "progesterone" and although body builders don't take progesterone, it is a 17-aa steroid and by that definition would be toxic.
The scheme for numbering steroids is the same no matter what. The rings "A", "B", and "C" are 6 membered rings and ring "D" is five membered. This is the template that constitutes the basic structure that makes up what we know as "steroid."
-SWOLNUTZ
In general though, when they refer to the molecule as "17-alpha alkylated" it's generally on carbon 13 that they are referring to.
The molecule in the picture is "progesterone" and although body builders don't take progesterone, it is a 17-aa steroid and by that definition would be toxic.
The scheme for numbering steroids is the same no matter what. The rings "A", "B", and "C" are 6 membered rings and ring "D" is five membered. This is the template that constitutes the basic structure that makes up what we know as "steroid."
-SWOLNUTZ
