Alkaloids from Boophane disticha with affinity to the serotonin transporter in rat brain

Bulbs and leaves of Boophane disticha are used in South African traditional medicine in the treatment of anxiety. Crude extracts of the leaves have shown affinity to the SSRI site on the serotonin transporter in a radioligand binding assay. In this study, two compounds, buphanadrine and buphanamine, were isolated by bioassay-guided fractionation on VLC and preparative TLC. The structures of the compounds were determined by 1H and 13C NMR. Fractions were tested for affinity to the serotonin transporter in a binding assay using [3H]-citalopram as ligand. The IC50 values of buphanidrine and buphanamine were 274 μM (Ki = 132 μM) and 1799 μM (Ki = 868 μM), respectively. The two alkaloids were also tested for affinity to the 5HT1A receptor, but only showed slight affinity.