DCB-3503 was shown to inhibit the carrageenan-induced paw edema; similarly, synthetic dibenzoquinoline DBQ 33b (Figure 2B) significantly reduced carrageenan-induced rat paw edema along with the incidence and severity of collagen type II antibody-induced arthritis (CAIA), the gene expression of the arthritis inflammatory factors (such as iNOS, cyclooxygenase 2 or COX2, TNFα, and IL-17A), and the levels of iNOS, c-Myc (human homolog of the avian myelocytomatosis viral oncogene), and HIF-1α (hypoxia-inducible factor 1α). Here, NOS2 is linked to arthritic joint disease.