Anti-inflammatory activity in rats and mice of phenolic acids isolated from Scrophularia frutescens

Different species of the Scrophularia genus (Scrophulariaceae) have been reported to have bacteriostatic and anti-inflammatory properties. In previous studies the anti-inflammatory and antibacterial activity of different extracts from Scrophularia frutescens were investigated and p-coumaric, caffeic, ferulic gentisic, protocatechuic, syringic and isovanillic acids were isolated and identified. In this work the anti-inflammatory activity of these compounds, administered orally, has been studied against carrageenan-induced rat paw oedema and, administered topically, against tetradecanoylphorbol acetate (TPA)-induced mouse ear oedema. The compounds' myeloperoxidase activity in inflamed ear was also investigated. Some of the phenolic acids were remarkably active in the TPA test (protocatechuic 71.59% inhibition, P < 0.001; syringic 74.43%, P < 0.001; ferulic 71.02% P < 0.001) and all significantly inhibited mouse ear oedema. They were only moderately active, or were without activity, in the carrageenan test. These results imply that the phenolic acids assayed are more effective topically than as oral anti-inflammatory agents and that their action is markedly influenced by the inhibition of neutrophil migration into inflamed tissue. This study has also enabled us to make some observations on the possible relationship between the chemical structure and anti-inflammatory activity of the compounds assayed.