Preclinical assessment of anti-arthritic activity of methanolic extract from processed Plumbago zeylanica roots

Ayurveda, a traditional Indian system of medicine, advocates the use of processed Plumbago zeylanica L. roots for managing inflammatory and rheumatic conditions. However, scientific evidence supporting its anti-arthritic potential remains unexplored. Our preliminary in vitro and in silico studies demonstrated potent anti-inflammatory activities in the methanolic extract of the processed root. Hence, this study aimed to investigate the pharmacological activities of the methanolic extract of processed roots in Freund's Complete Adjuvant (FCA)-induced rheumatoid arthritis in rats. Rheumatoid arthritis was induced in the rats by intra-articular injection of FCA in right paw on day 0, and treatment of prednisolone and different doses of Plumbago zeylanica methanolic extract (PZME) was given from day 1 to 28. Throughout the study, behavioral and physical arthritis parameters were evaluated, while biochemical serum levels of COX-2, inflammatory markers, and oxidative stress parameters were measured at the study's endpoint, and tibiotarsal joints were subjected to microscopic studies for histological evaluation. PZME treatment significantly attenuated FCA-induced rheumatoid arthritis, evidenced by reduced paw volume, joint diameter, and improved behavioral parameters (gait, weight-bearing). PZME also decreased serum levels of inflammatory markers (TNF-α, IL-6, RF, CRP), oxidative stress parameters (TBARS, catalase), and COX-2 expression. Histological analysis confirmed reduced synovial hyperplasia and cartilage erosion. LC-MS/MS analysis identified several phytoconstituents, which may contribute to the observed effects. In conclusion, the study demonstrates that the methanolic extract of P. zeylanica roots possesses potent anti-arthritic properties. This effect is likely due to its ability to reduce inflammation by inhibiting pro-inflammatory cytokines and oxidative stress, as well as decreasing COX-2 expression. However, further research is needed to elucidate precise molecular mechanisms, identification of bioactive phytoconstituents and assess long-term safety before clinical application.