Alkaloids from Boophone disticha with affinity for the serotonin transporter

Boophone disticha L. Herb (Amaryllidaceae) is used in traditional medicine for treatment of painful wounds, headaches, skin disorders, inflammatory conditions, rheumatic pains and anxiety [1]. At least eight alkaloids have been characterized and reported in literature [1] of which buphanidrine and buphanamine have been reported to have affinity to the serotonin reuptake transport protein (SERT) [2]. Alkaloids from other Amaryllidaceae species have also shown affinity to SERT [3]. In this study, an ethanol extract was prepared from dry bulbs. The residue was dissolved in ethyl acetate and extracted with water by a liquid-liquid partitioning. Through HPLC-UV separation five fractions were collected and characterized by LC-MS and ¹H-NMR and led to the identification of buphanamine, powelline, buphanidrine, distichamine and buphanisine. The activity of these compounds were tested in a functional SERT inhibition assay utilizing COS-7 cells expressing hSERT [4], and a binding assay using [³H]-citalopram as ligand [5]. The two most active compounds, buphanidrine and distichamine, had IC₅₀-values of 0.6 mM and 0.5 mM respectively, both in the binding assay and in the functional assay. The alkaloids also showed activity in the functional assay, again with buphanidrine and distichamine being the most active with IC₅₀-values of 0.5 and 0.6 mM, respectively. These results provide a rationale for the use of B. disticha against anxiety and other central nervous system diseases in traditional medicine.

References: 1. Steenkamp, P.A. (2005) Chemical Analysis of Medicinal and Poisonous Plants of Forensic Importance In South Africa. 2. Sandager, M. et al. (2005)J Ethnopharm 98:367–70. 3. Elgorashi, EE. et al. (2006) Planta Med 72:470–73. 4. Kristensen, A.S., et al. (2004) Eur J Neurosci 19:1512–1523. 5. Nielsen, N.D. et al. (2004)J. Ethnopharm. 70:664–666.