Evaluation of Verbascum species and harpagoside in models of acute and chronic inflammation

Verbascum species are widely used in folk medicine because of their broad range of biological activities. Harpagoside, an iridoid glycoside isolated from some Verbascum plants is known for its anti-inflammatory properties. In the present study, the effect of five extracts of Verbascum species and harpagosides were evaluated in mouse models of acute and chronic inflammation. The results demonstrate that Verbascum phoeniceum extract strongly inhibits COX-1 (60.2% inhibition vs PMA-stimulated cells) and COX-2 (44.8% inhibition) expression stimulated peritoneal macrophages resulting in reduced paw swelling in carrageenan-induced oedema (55.5% inhibition vs PBS-treated mice). Harpagoside ameliorated the development of zymosaninduced arthritis and reduced pathological changes in joints as shown by the decreased histological score for cell infiltration in synovial cavity (3.5±0.2 in vs 2.0±0.16), cartilage loss (2.5±0.3 vs 1.8±0.5) and bone resorption (2.4±0.2 vs 1.8±0.4). Molecular docking simulations of harpagoside suggest that it may function with increased specific affinity towards COX-1 than COX-2. The potential of harpagoside to be applied as an effective agent for treating joint-related disorders is discussed.