What have they researched using it?
Details of how the brain works, by blocking certain signal receptors, that are control points or sockets for inputs.
Any useful results?
Yes, they can block specific brain “sockets” in a controllable way, what socket, and how much it is blocked. They can then design specific chemical tools.
Why and how would researching a synthetic compound be relevant to the natural compound?
The natural compound is what it is, and does what it does. By modifying the natural molecule you can figure out how it works, and make a better one. In the case of the article I lined, they change the length of a side chain and get more, or less, binding to a specific socket.
Say you have a key that works in a lock. By using a lockpick you can figure out how the lock works, and may either find a “master key” or find out how locks and keys work in detail, or find a better key (not the best analogy but close).
That’s a nice synopsis. Thanks again.