What is the significance of it being phenolic?
Most phenolics are extensively metabolized iinto unabsorbable and/or biologically inactive metabolites in the intestines and liver. Depending on how much they are subject to enterohepatic circulation, i.p. injection can artificially inflate bioactivity by bypassing such metabolism (more enterohepatic ciculation implies a more realistic reflection of oral dosing). We only discovered relatively late that curcumin is probably not subject to much enterohepatic circulation, contrary to exectations based on its lipophilicity, which helps explain its miserably low oral bioavailabilty (particularly for the free/parent compound). And rodents (mice and possibly even more so rats) metabolize phenolics less than humans, even after accounting for biometric scaling.
I give up, unless there's a human study, I'm not even bothering with anything. Mice are such a waste of time except where toxicity studies are concerned, then again even that may not translate well.
I think that's taking it too far in the other direction — but certainly, you want a study that reflects the actual use case (for most of us, basically healthy except for aging) and that isn't specifically known to have a translation problem (phenolics) unless there's some specific reason to expect translation anyway.
Does anyone have a copy of this new paper (especially the extended version) they could PM me (or if it's too big, send me via email, which I'll communicate via PM)?