A 70% EtOH extract of root bark of Alangium plantanifolium showed binding activities to nine receptors in the central nervous system (CNS). In an attempt to search for CNS active ingredients, the extract was isolated and five compounds were identified as beta-sitosterol, stigmasterol, sitosterol 3- O-beta- D-gluco-pyranoside, beta- D-fructofuranosyl(1-->4)-alpha- D-fructopyranoside and 5beta,6beta-dihydroxycyclohex-2-en-1-ol 1-beta-glucoside, a possibly new compound, by El-mass, (1)H-NMR, and (13)C-NMR spectra. Stigmasterol and 5beta,6beta-dihydroxycyclohexa-2-en-1-ol 1-beta-glucoside were able to bind to muscarinic receptors with IC (50) values of 8.52 microM and 6.74 microM, respectively. In addition, beta-sitosterol, sitosterol 3- O-beta- D-glucopyranoside and 5beta,6beta-dihydroxy-cyclohex-2-en-1-ol 1-beta-glucoside were found to affect the binding of other compounds to the receptors.