Attenuation of oxidative stress by Allylpyrocatechol in synovial cellular infiltrate of patients with Rheumatoid Arthritis

Abstract

Free radicals are involved in the pathogenesis of Rheumatoid arthritis, a systemic autoimmune disorder characterized by unchecked synovial inflammation. Allylpyrocatechol, a phytoconstituent of Piper betle leaves, has potent anti-inflammatory activity and this study evaluated its anti-oxidant effect on the synovial infiltrate of patients with Rheumatoid arthritis. The ex vivo effect of allylpyrocatechol upon generation of reactive oxygen species in neutrophils, macrophages and lymphocytes was measured by flow cytometry using dichlorodihydrofluorescein diacetate, wherein it significantly decreased basal levels as also scavenged phorbol myristate acetate generated reactive oxygen species. Furthermore, its effect on generation of superoxide and hydroxyl radicals produced within infiltrated neutrophils was measured by cytochrome c and deoxyribose assay, respectively. Allylpyrocatechol significantly scavenged superoxide and hydroxyl radicals in infiltrated neutrophils. The effect of allylpyrocatechol on nitric oxide was measured in macrophages using 4,5-diaminofluorescein diacetate by flow cytometry wherein it decreased production of nitric oxide in infiltrated macrophages, which correlated with its in vitro nitric oxide scavenging activity. Taken together, this ex vivo study has established that allylpyrocatechol has potent scavenging activity and could be considered as an add-on therapy in the treatment of inflammation-associated disorders like Rheumatoid Arthritis.