PTGS2 and rheumatoid arthritis: The phenolic compound 5-hydroxyconiferaldehyde, isolated from Campanula takesimana, revealed its anti-RA potential by inhibiting the inflammatory response in vitro (inhibition of PGE2, iNOS, TNF-α, COX-2, IL-6, and -1β) through the suppression of several signaling pathways, such as MAPK, NF-κB, and Nrf-2 [311].