How is it a polyphenol if it doesn't have a hydroxyl group?
If it isn't which subclass would you put it in, and which functional groups does it contain?
How is rotenone a polyphenol?
It is not. Wikipedia says: Polyphenols are $\ldots$ characterized by the presence of large multiples of phenol structural units.
And if you're to pull up an image which gives you the structural formula of rotenone you get (Image source: https://upload.wikimedia.org/wikipedi...)
Do you see any phenols in this structure?
If it isn't which subclass would you put it in
According to this article I've found:
In the late $1920$’s, the chemical structure of rotenone was determined. Rotenone is a member of a class of compounds of related molecular structure referred to as isoflavones.
which functional groups does it contain?
With a keen eye, if you look at the structure carefully, you'll at least be able to spot a ketone.