Purification of pyrethrins from flowers of Chrysanthemum cineraraeflium by high-speed counter-current chromatography based on coordination reaction with silver nitrate

Abstract

Pyrethrum extract is a natural insecticide that has been used worldwide for centuries, with pyrethrins being considered active ingredients. Their purification is difficult due to their chemical structural similarity and instability to light. In the present study, a coordination complex high-speed counter-current chromatography was used to separate pyrethrins from pyrethrum extract. The two-phase solvent system composed of petroleum ether-ethyl acetate-methanol-water (10:2:10:2, v/v/v/v) with 0.30 mol/L silver nitrate was selected for separation. As a result, five pyrethrins including cinerin II (31.2 mg), pyrethrin II (43.9 mg), jasmalin II (39.1 mg), pyrethrin I (32.4 mg), and jasmalin I (16.0 mg) were obtained from 400 mg crude extract in 6 h by one-step HSCCC separation, with purities over 95%. The isolated compounds were identified by MS, ¹H-NMR and ¹³C-NMR spectroscopy. The results demonstrated that the addition of silver nitrate in the two-phase solvent system of HSCCC significantly increased the HSCCC separation factor of pyrethrins. HSCCC is a rapid method for purification of pyrenthrins from pyrethrum extract. The established method may also be applied to separate analogous compounds from natural products in which the chemical structure differs in the position or numbers of alkenes.

Keywords: Chrysanthemum cineraraeflium; Coordination complexation; High-speed counter-current chromatography; Pyrethrins; Silver nitrate.