Corymbones A and B, phloroglucinols with thyrotropin releasing hormone receptor 2 binding affinity from the flowers of Corymbia peltata

High-throughput screeing of a plant and marine invertebrate extract library to find natural products with rat thytotropin releasing hormone receptor 2 binding affinity led to the isolation of two new active acylphloroglucinols, corymbones A and B (1 and 2) from flowers of the Queensland tree Corymbia peltata. Their structures were assigned from interpretation of 2D NMR and high-resolution ESIMS data. Compounds 1 and 2 showed rat TRH receptor 2 binding affinity with IC(50) values of 23 and 19 mu M, respectively.