[Dolphinsiu]

This website says anthocyanin has OH groups appearing in 4',5',5 and 7 while sugar will attack 3 and 5
http://www.herbalchem.net/PhenolicsInterm.htm

For wiki,
there is no specific speaking that 4' has OH group.

For my lecture,

OH groups appears in 5 and 7 only while say 3' and 5' is R group but leaving 4' as H group rather than OH group.

Actually, anyone can be sure which version is the correct one for the structure of anthocyanins???

[Dolphinsiu]

No need to answer. I have checked that OH groups appears in 5,7,4'