Identification of new inhibitors for human hematopoietic prostaglandin D2 synthase among FDA-approved drugs and other compounds

- FDA-approved drugs were tested as prostaglandin D2 synthase (HPGDS) inhibitors.
- 23 compounds were effective inhibitors of HPGDS with low µM IC50 values.
- Erythrosine, suramin, tannic acid and sanguinarine sulphate were potent inhibitors.
- Some compounds have potential to reduce excessive PGD synthesis in allergic asthma.
- These compounds may serve as leads for synthesis of more efficient HPGDS inhibitors.

ObjectiveHematopoietic prostaglandin D2 synthase (HPGDS) is a member of the Sigma class glutathione transferases (GSTs) catalyzing the isomerization of prostaglandin H2 to prostaglandin D2, a mediator of allergy and inflammation responses. Selective inhibitors of human HPGDS are expected to be of therapeutic importance in relieving symptoms related to allergy and asthma. Hence, a collection of diverse FDA-approved compounds was screened for potential novel applications as inhibitors of HPGDS.MethodsThe catalytic activity of purified HPGDS was used for inhibition studies in vitro.ResultsOur inhibition studies revealed 23 compounds as effective inhibitors of HPGDS with IC50 values in the low micromolar range. Erythrosine sodium, suramin, tannic acid and sanguinarine sulfate were characterized with IC50 values of 0.2, 0.3, 0.4, and 0.6 μM, respectively. Kinetic inhibition analysis showed that erythrosine sodium is a nonlinear competitive inhibitor of HPGDS, while suramin, tannic acid and sanguinarine sulfate are linear competitive inhibitors.ConclusionThe results show that certain FDA-approved compounds may have pharmacological effects not previously realized that warrant further consideration in their clinical use.