5-Hydroxytryptamine2A Receptor Binding Activity of Compounds from Litsea sessilis

A 96-well microplate filtration based 5-HT2A receptor-radioligand binding assay was optimized and adopted to carry out a bioassay-guided fractionation of the methanol extract of the leaves of Litsea sessilis. This purification led to the isolation of two compounds identified as (+)-boldine (1) and (+)-dehydrovomifoliol (2). (+)-Boldine binds to 5-HT2A receptors at high concentrations with a K-i value of 2.16 mu m. However, (+)-dehydrovomifoliol showed minimal competitive inhibition on the binding of [H-3]ketanserin to the same receptor with a K-i value of 2.06 mM. These results suggest that (+)-boldine influences the activity of 5-HT2A receptors through competitive binding as an agonist or antagonist. Copyright (C) 2008 John Wiley & Sons, Ltd.