5-lipoxygenase-inhibitory constituents from Schizandra fructus and Magnolia flos.

In order to establish the antiallergic properties of Schisandra fructus and Magnolia flos, several compounds isolated from these plants were tested for 5-lipoxygenase (5-LOX) inhibitory activity in vitro, for the first time. The compounds including schizandrins, schisandrols, gomisins, fargesin, eudesmin and lirioresinol B dimethyl ether, inhibited 5-LOX-catalysed leukotriene production from A23187-treated rat basophilic leukemia (RBL-1) cells at concentrations of 1-100 microm. In particular, constituents such as schisandrol A and gomisins showed potent inhibitory activity (IC(50)s < 10 microm) on 5-LOX-catalysed leukotriene production, but were much less active on cyclooxygenase-2-catalysed prostaglandin E(2) and inducible nitric oxide-catalysed NO production. These compounds have the potential to be developed as novel antiallergic agents and may contribute to the antiallergic pharmacological use of these plant materials in Chinese medicine.