Phagnalon rupestre as a source of compounds active on contact hypersensitivity

The effect of Phagnalon rupestre MeOH extract on dinitrofluorobenzene- and sheep red blood cells-induced hypersensitivity was investigated. Eight compounds were identified: three dimethylallyl-hydroquinone glucosides (1-3), 3,5- and 4,5-di-O-caffeoylquinic acid methyl esters (4 and 5), their free carboxyl analogues (6 and 7), and luteolin 7-O-beta-glucoside (8). All were tested for dinitrofluorobenzene-induced contact hypersensitivity inhibitory activity. Flavonoid 8 was the most active (49% and 79% inhibition at 24 and 96 h, respectively). The hydroquinones 1, 2 and 3 were effective at 96 h after challenge (62%, 73% and 60% inhibition, respectively), while some of the dicaffeoylquinic derivatives (4 and 7) produced slightly lower reduction of the inflammatory reaction.