Isolation and structure elucidation of cyclopeptide alkaloids from Ziziphus nummularia and Ziziphus spina-christi by HPLC-DAD-MS and HPLC-PDA-(HRMS)-SPE-NMR

Abstract

Seven cyclopeptide alkaloids were isolated from the stem bark of Ziziphus nummularia and Ziziphus spina-christi. Three previously undescribed compounds were identified: nummularine-U, spinanine-B and spinanine-C, together with the known compounds mauritine-F, nummularine-D, nummularine-E and amphibine-D. For their purification either semi-preparative HPLC with DAD and ESIMS detection or HPLC-PDA-(HRMS)-SPE-NMR was applied, together with conventional separation methods. Their structures were elucidated by spectroscopic means.

Keywords: Cyclopeptide alkaloids; Rhamnaceae; Ziziphus nummularia; Ziziphus spina-christi.