Xiao Pei-gen

Triterpenoid glucuronide saponins from root bark of Aralia armata

Abstract Seventeen oleanane-type saponins were isolated from the root bark of Aralia armata . Their structures were elucidated by chemical and spectral evidence. Except for oleanolic acid 28-O-β- d -glucopyranoside all the saponins have a glucuronopyranosyl residue at the C-3 position of the aglycones and other sugar substitutes bind to glucuronic acid at positions C-3 and/or C-4. A comparison of saponin constituents of this plant with other araliaceous plants is provided.

Beesioside III, a cyclolanostanol xyloside from the rhizomes of Beesia calthaefolia and Souliea vaginata

Abstract The chemical constituents of Beesia calthaefolia and Souliea vaginata were examined. From the rhizomes of B. calthaefolia, four new 9,19-cyclolanostanol xylosides, named beesiosides I–IV were isolated. Beesiosides 111 and IV were found also in the rhizomes of S. vaginata. On the basis of chemical and spectral evidence the structure of beesioside III was established as 15α-acetoxy-20ξ1,24ξ2-epoxy-9,19-cyclolanostane-3β,12β,16β,25-tetraol-3-O-β- D -xylopyranoside.

Mechanism of Selective Inhibition of Yohimbine and Its Derivatives in Adrenoceptor α2 Subtypes

Some natural alkaloids from medicinal plants, such as yohimbine and its derivatives, have been reported with adrenoceptor (AR) α2 subtypes inhibiting activity. In trying to address the possible mechanism of the action, a set of homology models of AR α2 was built based on MOE. After that, docking and molecular dynamics methods were used to investigate the binding modes of yohimbine and its 2 derivatives in the active pocket of adrenoceptor α2 subtype A, B, and C. The key interactions between the 3 ligands and the 3 receptors were mapped. Binding mode analysis presents a strong identity in the key residues in each subtype. Only a few differences play the key role in modulating selectivity of yohimbine and its derivatives. These results can guide the design of new selective AR α2 inhibitors.