A 70% EtOH extract of Clerodendrum mandarinorum root bark was assessed
for CNS activity against 18 radioligand receptor binding assays. The
results showed that the extract was able to bind to opiate, adenosine-
1, alpha 2-adrenergic, 5HT-1, 5HT-2, dopamine-2, histamine-1, GABA(A),
and GABA(B) receptors. Fourteen compounds were isolated and identifie
d by EI-MS, H-1-NMR and C-13-NMR spectra as known triterpenoids (fried
elanone, lupeol, betulinic acid), steroids (245-stigmata-5,25-dien-3 b
eta-ol, 22E,245-stigmata-5,22,25-trien-3 beta-ol), flavonoids (cirsima
ritin, cirsimaritin-4'-glucoside, quercetin-3-methyl ether), tetrahydr
o-alpha-pyrone and saccharides (sucrose, alpha-D- and beta-D-glucopyra
nose, ethyl-alpha-D-glucopyranoside, 2-ethyl-beta-D-fructofuranoside).
The isolated compounds were assessed for activity by the radioligand
receptor binding assays. Betulinic acid and ethyl-alpha-D-glucopyranos
ide showed weak activities against sulphonylureas (IC50 = 7.5 mu M) an
d muscarinic receptors (IC50 = 5.5 mu M), respectively. Cirsimaritin-4
'-glucoside was weakly active in the adenosine-l binding assay (IC50 =
3.0 mu M), whereas seven structurally related flavonoids, not isolate
d from C. mandarinorum, were inactive.