Investigating the Anti-Arthritic Potential of Gallic Acid from Tecoma stans Leaves via Phytosome Based Formulation and Examining Physical, Hematological Effects, and Molecular Dynamics Simulations

Background: Rheumatoid arthritis is a chronic inflammatory autoimmune disorder characterized with destruction and degradation of synovial joints. The current study aims to evaluate the physical and hematological effects of gallic acid (GA) isolated from Tecoma stans leaf extract and further synthesis of its gallic acid phytosome (GAP) to evaluate antiarthritic activity in Complete Freund's Adjuvant induced rheumatoid arthritis in Wistar rats. Methods: The experimental rats were categorized into nine groups (n = 6 each group) namely normal control, disease control, methotrexate (0.75 mg/kg) treated group, GA 50 mg/kg treated group, GA 100 mg/kg treated group, GAP 50 mg/kg treated group, GAP 100 mg/kg treated group, GA 100 mg/kg treated group + methotrexate (0.75 mg/kg), GAP 100 mg/kg treated group + methotrexate (0.75 mg/kg) for 21 days. All the parameters were assessed at the end of the study. To assess the role of GA in mediating anti-arthritic activity through inhibition of NLR family pyrin domain containing 3 (NLRP3) inflammasome, an additional Molecular Dynamics (MD) simulation was also conducted. Results: GA and GAP significantly decreased arthritic score (p < 0.01, p < 0.05, and p < 0.001), paw volume, pain latency (p < 0.01, p < 0.05, and p < 0.001) and increased body weight (p < 0.01, p < 0.05, and p < 0.001) in a dose-dependent manner in arthritic rats. The level of Haemoglobin (Hb) and number of red blood cells (RBCs) were significantly increased while the levels of white blood cell (WBC), platelet count and erythrocyte sedimentation rate (ESR) were drastically dropped in treatment groups compared to disease control group (p < 0.001, p < 0.01 and p < 0.05). During the MD simulation, GA demonstrated the formation of 2-3 stable hydrogen bond contacts with the NLR family pyrin domain containing 3 (NLRP3, previously known as NACHT domain), primarily involving the residues Threonine439 (THR439), Single Amino Acid of G alpha 16 Alanine228 (ALA228), and Arginine578 (ARG578). Conclusion: The results produced by GAP were higher than GA indicating the benefit of formulation in providing better efficacy and suggesting its potential role in rheumatoid arthritis. The MD simulation result also suggested that GA has the potential to function as an inhibitor of NLRP3 protein and thus expressing anti-arthritic activity.