GUSB and rheumatoid arthritis: Lastly, because curcuminoids, like many other dietary polyphenols, circulate in vivo as inactive glucuronidated “pro-drugs” [68], medicinal effects of this secondary turmeric metabolite are also likely host-dependent, requiring enzymatic bioactivation by β-glucuronidase (GUSB) [40], which interestingly is present at very high levels in bone [40] and in RA (vs. normal) joints [69], and, conversely, whose absence is associated with increased joint inflammation [70].