Evaluation of the Water Extract and Some Pure Principles of Evodiae Fructus on 1, 4-Dihydropyridine Binding Site of L-Type Calcium Channels

Abstract

The interactions of the water extract of Evodiae Fructus (EF, the unripe fruit of Evodia rutaecarpa) and its pure principles, such as dehydroevodiamine (DeHE), evodiamine, rutaecarpine, rhetsinine, limonin, isorhamnetin-3-o-galactosidc, quercetin-3-o-galactoside, and synephrine, with the dihydropyridine (DHP) binding site of L-type calcium channels were studied by radioligand binding assay. The results showed that HF (5-100 mg/mi) significantly competed with [3H] nimodipine for specific binding to DHP binding sites in the ICR mice cortex and heart membrane preparations with a K value of 17.3 and 7.9 mg/ml, respectively. However, all pure principles of EF (except DeHE) tested in the present study had no significant interactions with DHP binding sites even at the concentration of 100 μM in both membrane preparations. The K(subscript i) value of DeHE for DHP binding sites in the heart membrane preparations was 403 μM, which was 100-fold less potent than EF when the content of DeHE in EF was taken into account. Therefore, HF must contain the principles other than the pure compounds tested, which act on the DHP binding site of L-type calcium channels.