Synthesized diterpene lactone derivative attenuated Freund's complete adjuvant-induced arthritis in Wistar rats.

Objectives: In this study, the SP-38 (Diterpene Lactone derivative) was designed, synthesized from clerodane diterpene (lactone) isolated from Polyanthia longifolia var. pendula, and tested for anti-arthritic activity using the FCA-induced arthritic rat model.

Materials and methods: This study examined the in vivo effects of SP-38 using three different doses (20, 10, and 5 mg/kg) by oral administration for 21 days from day 8 after 0.1 ml FCA sub-planter injection until day 28. Arthritis index, paw swelling, ankle diameter, body weight as well as biochemical, hematological, histopathological, and radiological parameters were examined.

Results: Administered SP-38 reduced arthritis index, paw volume, and joint swelling compared to the arthritic control group. Accordingly, rats treated with SP-38 showed a remarkable increase in body weight and improved biochemical, hematological, histopathological, and radiological parameters. Furthermore, it reduced the increased production of CRP and RF while simultaneously decreasing ESR in all SP-38-treated rats. However, SP-38 showed promising liver protection by reducing elevated serum levels of liver and kidney function markers SGOT, SGPT, and ALP. Furthermore, splenic index, TNF-α, and IL-6 levels were significantly reduced compared to arthritic control rats at certain doses.

Conclusion: The result of the present study concludes that SP-38 has significant anti-arthritic potential in FCA-induced arthritis in Wistar rats. SP-38 therefore showed promising anti-arthritic activity, as evidenced by attenuation of inflammation, inflammatory markers, and pro-inflammatory cytokine levels.