NOS2 and rheumatoid arthritis: The natural polyphenol N-feruloylserotonin (N-f-5HT), extracted from Leuzea carthamoides, had RA-inhibitory effects via suppressing c-reactive protein (CRP), 12/15-lipoxygenase (LOX), TNF-α, inducible nitric oxide synthase (iNOS), IL-1β in liver and spleen cells of arthritic rats.