Chemical and Biological Investigation of the Root Bark of Clerodendrum mandarinorum

Abstract

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, α2-adrenergic, 5HT-1, 5HT-2, dopamine-2, histamine-1, GABA_A, and GABA_B receptors. Fourteen compounds were isolated and identified by EI-MS, ¹H-NMR and ¹³C-NMR spectra as known triterpenoids (friedelanone, lupeol, betulinic acid), steroids (24S-stigmata-5,25-dien-3β-ol, 22E,24S-stigmata-5,22,25-trien-3β-ol), flavonoids (cirsimaritin, cirsimaritin-4′-glucoside, quercetin-3-methyl ether), tetrahydro-α-pyrone and saccharides (sucrose, α-D- and β-D-glucopyranose, ethyl-α-D-glucopyranoside, 2-ethyl-β-D-fructofuranoside). The isolated compounds were assessed for activity by the radioligand receptor binding assays. Betulinic acid and ethyl-α-D-glucopyranoside showed weak activities against sulphonylureas(IC₅₀ = 7.5 µM)and muscarinic receptors (IC₅₀ = 5.5 µM), respectively. Cirsimaritin-4′-glucoside was weakly active in the adenosine-1 binding assay (IC₅₀ = 3.0 µM), whereas seven structurally related flavonoids, not isolated from C. mandarinorum, were inactive.

Key words

Clerodendrum mandarinorum - Verbenaceae - terpenoids - flavonoids - saccharides - radioligand receptor binding assays