In vivo anti-inflammatory activity, safety and gene expression profiles of Carissa edulis, Withania somnifera, Prunus africana and Rhamnus prinoides for potential management of rheumatoid arthritis

Rheumatoid arthritis (RA) is a chronic, inflammatory and systemic autoimmune disease. Treatment for RA is aimed at eliminating symptoms, slowing disease progression, and optimizing quality of life. However, drugs currently in use are associated with adverse side effects. Search for alternative treatment for rheumatoid arthritis involves traditional herbal plants owing to the fewer side effects and more compatibility with long-term usage compared to the conventional drugs. The use of the selected medicinal plants to manage RA among local communities in Kenya is rife. This study sought to establish the safety and effectiveness of Carissa edulis, Withania somnifera, Prunus africana and Rhamnus prinoides aqueous extracts in the management and treatment of RA. Lambda IV Carrageenan was used to induce inflammation and the percentage inhibition calculated, gene expression of IL-6, TNF-α and IL-4 was evaluated using Real Time Polymerase Chain Reaction and acute oral and sub-acute toxicity was assessed in Swiss albino mice. C. edulis, W. somnifera, P. africana and R. prinoides showed a dose dependent anti-inflammatory activity, there was also a downregulation of TNF-α and IL-6 and upregulation expression of IL-4. Acute toxicity showed no mortality or significant changes in body weight and behavioral parameters at a cut-off dosage of 2000 mg/kg of the plant's extracts. The sub-acute toxicity also confirmed no toxic effects as evidenced by the hematological parameters and weekly change in body weights of mice. This study confirms potential application of these medicinal plants in RA management and act as a lead in drug development.