Analytical Separation of Closantel Enantiomers by HPLC.

Basma Saleh,Rong Liu,Yuwei Wang,Tongyan Ding,Xiantong Zheng,Limin He

doi:10.3390/molecules26237288

Abstract

Closantel is an antiparasitic drug marketed in a racemic form with one chiral center. It is meaningful to develop a method for separating and analyzing the closantel enantiomers. In this work, two enantiomeric separation methods of closantel were explored by normal-phase high-performance liquid chromatography. The influences of the chiral stationary phase (CSP) structure, the mobile phase composition, the nature and proportion of different mobile phase modifiers (alcohols and acids), and the column temperature on the enantiomeric separation of closantel were investigated in detail. The two enantiomers were successfully separated on the novel CSP of isopropyl derivatives of cyclofructan 6 and n-hexane-isopropanol-trifluoroacetic acid (97:3:0.1, v/v/v) as a mobile phase with a resolution (Rs) of about 2.48. The enantiomers were also well separated on the CSP of tris-carbamates of amylose with a higher Rs (about 3.79) when a mixture of n-hexane-isopropanol-trifluoroacetic acid (55:45:0.1, v/v/v) was used as mobile phase. Thus, the proposed separation methods can facilitate molecular pharmacological and biological research on closantel and its enantiomers.

Highlights

Chiral recognition occurs mainly in natural and chemical systems, and this phenomenon has had a fundamental impact in various fields [1]
The factors affecting the chiral separation of closantel enantiomers are described in detail
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Summary

Introduction

Chiral recognition occurs mainly in natural and chemical systems, and this phenomenon has had a fundamental impact in various fields [1]. Numerous scientific research has focused on developing effective chromatographic methods for separating the racemic drugs [6,7,8,9]. The optimization process of the chromatographic condition is time-consuming, owing to the influences of many factors such as the composition of the mobile phase [10], structure of the chiral stationary phase (CSP) [11], and the column temperature [12]. Numerous CSPs have been modified with various chiral selectors for effective chiral separations. The proper choice of CSP and the optimization of mobile phase modifiers are needed to achieve higher enantioselectivity, which is realized through improving the complementary interactions between the analyte and functional groups on the chiral selector [13]

Objectives

Methods

Results

Conclusion