New secoiridoids from Ligustrum ovalifolium and their hypotensive activity

Abstract

New Secoiridoid glucosides 1-5; ligustaloside A methyl hemiacetal 1, ligustaloside B methyl hemiacetal 2, ligustaloside A dimethyl acetal 3 ligustaloside A butyl-methyl acetal 4, and ligustaloside B butyl hemiacetal 5 have been isolated from the leaves of Ligustrum ovalifolium L. along with five known secoiridoids; ligustaloside B dimethyl acetal 6, 10-hydroxy oleuropein 7, 10-hydroxy ligstroside 8, oleuropein 9 and ligstroside 10, one known iridoid; loganin 11 and two known phenethyl alcohol glucosides; 3,4-di hydroxyphenylethyl-β-D-glucoside 12 and p-hydroxyphenylethyl-β-D-glucoside 13. The structures have been elucidated by spectroscopic means including 1D NMR (1H, 13C, and DEPT), 2D NMR (COSY, HMQC and HMBC experiments), UV, IR and FAB-MS (positive mode). Both n-BuOH fraction and the isolated new compounds 1-5 were evaluated for their hypotensive activity on experimental animal. The n-BuOH fraction showed good activity; however, the activity of the isolated new compounds 1-5 did not particularly strong.

Keywords: Ligustrum ovalifolium; Oleaceae; Secoiridoid glucosides; Iridoid glucosides and Phenylethanoids