Page 235 - 2025中醫藥與天然藥物聯合學術研討會-中醫藥與天然藥物的挑戰Ｘ機遇與未來大會手冊

PP-52

Investigation of 3,4-dimethoxycinnamic acid as a novel therapeutic agent for

rheumatoid arthritis

,1
1
Wan-Ling Chang, Shan-Chi Liu*

1 Institute of Biomedical Sciences, Mackay Medical University, New Taipei City 252005,
Taiwan
* E-mail: shanchiliu@mmu.edu.tw

Abstract
Rheumatoid arthritis (RA) is a chronic autoimmune disease whose pathogenesis is not fully
understood but is known to involve inflammatory cell infiltration into joints, leading to swelling,
synovial hyperplasia, cartilage damage, and bone erosion. Synovial fibroblasts and
chondrocytes within the joint capsule secrete numerous pro-inflammatory factors, disrupting
the microenvironment that maintains bone homeostasis, including interleukin-1β (IL-1β),
interleukin-8 (IL-8), and interleukin-6 (IL-6). Current RA treatments primarily aim to alleviate
pain with nonsteroidal anti-inflammatory drugs (NSAIDs) and steroids and to suppress disease
progression early on with disease-modifying antirheumatic drugs (DMARDs). However, to date,
a definitive cure for RA remains elusive, and these medications still carry side effects. Therefore,
the quest for new, safer alternative therapies to complement RA treatment is an area of interest.
We aim to explore the potential of five compounds extracted from water bamboo shoots
(Zizania latifolia; WBS)—Naringenin, Sinensetin, Ferulic Acid methyl ester, Nobiletin, and
3,4-Dimethoxycinnamic acid—in the treatment of rheumatoid arthritis. While these compounds
have been shown in previous studies to possess anti-inflammatory and antioxidant activities,
their efficacy in treating rheumatoid arthritis remains unknown. Thus, we investigate their anti-
inflammatory effects on synovial fibroblasts and elucidate their inhibition of inflammatory
signaling pathways, hoping to offer new therapeutic avenues for RA treatment. Our preliminary
data reveal significant expression of IL-1β and IL-8 in the synovial tissues of RA patients,
contributing to synovial inflammation and arthritis formation. Treatment with 3,4-
Dimethoxycinnamic acid inhibits the pro-inflammatory cytokines IL-1β and IL-8 expression
levels in MH7A. Additionally, treatment with 3,4-Dimethoxycinnamic acid suppresses the
inflammatory pathway (MAPK pathway), leading to reduced expression of IL-1β and IL-8. Our
data support clinical investigations using 3,4-Dimethoxycinnamic acid in RA disease

Keywords: Rheumatoid arthritis; 3,4-Dimethoxycinnamic acid; Interleukin-1β (IL-1β);
Interleukin-8 (IL-8)