Objective: To study the effects and mechanism of chromones from Saposhnikovia divaricata on collagen-induced arthritis(CIA) in rats.Method: Wistar rats were intradermally injected with type II bovine collagen at the base of the tail.Rats were treated daily with oral administration of different doses of chromones from Saposhnikovia divaricata from day 3 before the day of the induction of arthritis to day 35

Clinical symptoms as well as clinical scores and incidence were observed.All rats were sacrificed on day 35 after immunization to observe radiologic and histopathologic changes.Antibody to type II collagen was measured by enzyme-linked immunosorbent assay

the serum levels of pro-inflammatory cytokines tumor necrosis factor-α(TNF-α)

interleukin-1β(IL-1β)

and IL-6 were determined using radioimmunoassay.Result: Treatment with chromones resulted in significant delay of onset of arthritis

as well as significant decrease in arthritis incidence

clinical arthritis severity score

radiographic and histopathological arthritis severity scores

Histopathological examination demonstrated that chromones significantly reduced the inflammatory responses

cartilage damage and bone erosion in the joint tissues.Radiologic changes in the arthritic joints were also significantly reduced in the chromones-treated versus vehicle-treated rats.Chromones inhibited the serum levels of IgG and IgM

TNF-α

IL-1β and IL-6.Conclusion:These results suggest that chromones from Saposhnikovia divaricata contribute to an amelioration of arthritis severity in CIA and the mechanisms of chromones on RA might be in part

related to the inhibited activities of the pro-inflammatory cytokines.