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5-Hydroxytryptamine2A receptor binding activity of compounds from Litsea sessilis
Lip Yong Chung1, Mee Wah Lo, Muhammad Rais Mustafa
1Department of Pharmacy, Faculty of Medicine, University of Malaya, 50603 Kuala Lumpur, Malaysia. chungly@hotmail.com
Abstract:
A 96-well microplate filtration based 5-HT(2A) 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-HT(2A) receptors at high concentrations with a K(i) value of 2.16 microm. However, (+)-dehydrovomifoliol showed minimal competitive inhibition on the binding of [(3)H]ketanserin to the same receptor with a K(i) value of 2.06 mm. These results suggest that (+)-boldine influences the activity of 5-HT(2A) receptors through competitive binding as an agonist or antagonist.
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