Inhibition of lipoxygenase of rat dental pulp and human platelets by phenolic dental medicaments

The effects of phenolic dental medicaments on lipoxygenase activities of rat dental pulp and human platelets were studied. The major product derived from [14C] arachidonic acid by the homogenate of rat dental pulp was 12-HETE (15-HETE). Eugenol and p-chlorophenol dose-dependently inhibited HETEs formation. The IC50 values of eugenol and p-chlorophenol were 0.62 and 0.34 mM respectively. The concentrations of these compounds that inhibit lipoxygenase were similar to those required to inhibit cyclooxygenase. These compounds also inhibited 12-lipoxygenase of human platelets with a similar range of concentrations. The results show that phenolic dental medicaments inhibit pulpal and platelet lipoxygenase. Thus, inhibition of arachidonic acid metabolism by phenolic dental medicaments via the lipoxygenase pathway may be involved in the analgesic and anti-inflammatory effects of the medicaments in endodontic therapy.