What is the concensus of the efficacy of anthocyanidins as antioxidants? Chokeberry, elderberry, and black currant as sources?
I'm not sure what the consensus is but I'm sure a literature search would reveal that they are valuable. As a general rule of thumb, just about any of these compounds in fruits, plants, vegetables, which have those phenol rings or phenolic groups, are, in a great deal of the times, very good antioxidative molecules. Those very stable phenolic groups are very good at acting as electron "traps" so to speak, in turn scavenging hydroxyl radicals, peroxy radicals, superoxide anions, etc.
Hope this helps.