Effect of the water content on the retention and enantioselectivity of albendazole and fenbendazole sulfoxides using amylose-based chiral stationary phases in organic–aqueous conditions

doi:10.1016/j.chroma.2013.12.051

Journal of Chromatography A

Volume 1327, 31 January 2014, Pages 73-79

https://doi.org/10.1016/j.chroma.2013.12.051 Get rights and content

Highlights

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Four immobilized amylose-derived CSPs are used in chiral separation of FBZ-SO and ABZ-SO.
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Good enantioselectivity is achieved in organic–aqueous conditions.
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Two different retention mechanisms operated with water-poor and water-rich eluents modes.
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The retention of sulfoxides and sulfide/sulfone forms can by modulated by changing the water content.

Abstract

Four commercially available immobilized amylose-derived CSPs (Chiralpak IA-3, Chiralpak ID-3, Chiralpak IE-3 and Chiralpak IF-3) were used in the HPLC analysis of the chiral sulfoxides albendazole (ABZ-SO) and fenbendazole (FBZ-SO) and their in vivo sulfide precursor (ABZ and FBZ) and sulfone metabolite (ABZ-SO₂ and FBZ-SO₂) under organic–aqueous mode. U-shape retention maps, established by varying the water content in the acetonitrile- and ethanol–water mobile phases, were indicative of two retention mechanisms operating on the same CSP. The dual retention behavior of polysaccharide-based CSPs was exploited to design greener enantioselective and chemoselective separations in a short time frame. The enantiomers of ABZ-SO and FBZ-SO were baseline resolved with water-rich mobile phases (with the main component usually being 50–65% water in acetonitrile) on the IF-3 CSP and ethanol–water 100:5 mixture on the IA-3 and IE-3 CSPs. A simultaneous separation of ABZ (or FBZ), enantiomers of the corresponding sulfoxide and sulfone was achieved on the IA-3 using ethanol–water 100:60 (acetonitrile–water 100:100 for FBZ) as a mobile phase.

Introduction

Albendazole (ABZ) and fenbendazole (FBZ) are benzimidazole carbamates with a broad spectrum of activity against human and animal helminthe parasites. When administered orally, ABZ and FBZ are quickly biotransformed into the corresponding sulfoxides (ABZ-SO and FBZ-SO, known as ricobendazole and oxfendazole, respectively), which are then further oxidized to sulfones (ABZ-SO₂ and FBZ-SO₂) (Fig. 1) [1]. Because of their affinity for the parasite β-tubulin, both sulfide and sulfoxide forms show pharmacological activity whereas the sulfone is the main inactive metabolite. The biological activity of ABZ and ABZ-SO has been recently extended to include interesting antitumor properties [2], [3], [4].

ABZ-SO and FBZ-SO have a stereogenic sulfur center in their chemical structure and both enantiomers of each sulfoxide have been in vivo identified. Studies have demonstrated that the plasma concentration of the (+)-ABZ-SO-enantiomer in patients treated with ABZ is predominant on the (−)-ABZ-SO-enantiomer [5]. Furthermore, in the neurocysticercosis therapy an accumulation of (+)-ABZ-SO in the cerebrospinal fluid has been observed [6].

On the basis of these biological evidence, it would be appropriate: (i) to monitor the plasma concentration of the three forms of the metabolic pathway of ABZ and FBZ in patient or animals receiving anthelmintic therapy; (ii) to check the biological activity and efficacy of the ABZ-SO and FBZ-SO enantiomers separately by enantioselective studies; (iii) to set synthetic or HPLC methods that allow to obtain single enantiomers at semipreparative level to evaluate the efficacy of each one in vivo experiments and in future clinical trials.

Some authors have already described the HPLC separation of the enantiomers of the anthelmintic chiral sulfoxides [7], [8], [9], [10]. Belaz et al. and Lourenço et al. have reported a good enantioselectivity for ABZ-SO using the amylose-based Chiralpak AD CSP in normal-phase (NP) and polar organic (PO) modes [4], [7]. On the other hand, there have only been a few reports on the separation of ABZ-SO and FBZ-SO enantiomers and their sulfide precursor and sulfone metabolite simultaneously in reversed-phase (RP) mode [8], [11], [12]. This and our current research activity associated with the use of the polysaccharide-based CSPs with aqueous–organic mobile phases [13], [14], [15], [16], prompted us to explore greener and more versatile chromatographic conditions to analyze the enantiomers of two benzimidazole sulfoxides. In this work, the chromatographic data obtained using four commercially available amylose-derived CSPs (Chiralpak IA-3, Chiralpak ID-3, Chiralpak IE-3 and Chiralpak IF-3 CSPs) are presented.

A special attention is dedicated to describe the influence of water content in mobile phase on the retention of the sulfoxide, sulfide and sulfone forms of ABZ and FBZ and on the effect of the mobile phase composition on enantio- and chemoselectivity exhibited by the four immobilized amylose-based CSPs.

Section snippets

Instruments, synthesis, chromatographic conditions and chemicals

ABZ, FBZ and all the other chemicals were purchased by Sigma-Aldrich (Italy) and used without further purification. The corresponding ABZ-SO and FBZ-SO were obtained by adding dropwise hydrogen peroxide (33%, 4.0 eq) to a stirring solution of the proper benzimidazole (1.0 eq) in glacial acetic acid (7 mL) at room temperature. After 2 h the reaction was quenched with NaOH 2 N and extracted with chloroform (3 × 50 mL). The organic phases were reunited, dried over anhydrous sodium sulfate and concentrated

Enantioseparation under organic–aqueous conditions

Chiralpak IA-3, Chiralpak ID-3, Chiralpak IE-3 and Chiralpak IF-3 are commercially available CSPs based on tris(3,5-dimethylphenylcarbamate), tris(3-chlorophenylcarbamate), tris(3,5-dichlorophenylcarbamate) and tris(3-chloro-4-methylphenylcarbamate) of amylose, respectively, chemically immobilized onto 3 μm silica particles. So, they contain the same amylose backbone but different substituents on the aromatic ring. This structural difference leads to peculiar chiral resolving abilities and

Conclusion

The dual retention mechanism operating on the amylose-based Chiralpak IA-3, Chiralpak ID-3, Chiralpak IE-3 and Chiralpak IF-3 CSPs under organic–aqueous mode was exploited: (i) to develop sustainable HPLC conditions based on the use of ethanol–water mixtures or ACN–water rich mobile phases to resolve the enantiomers of FBZ-SO and ABZ-SO; (ii) to set chemo- and enantioselective HPLC methods capable to simultaneously separate the chiral forms of sulfoxides from the achiral precursor sulfide and

Acknowledgment

We are grateful to Mrs. A. Mosca and Mr. L. Zanitti for their helpful technical collaboration.

References (24)

B.P.S. Capece et al.
Vet. J.
(2009)
K.R.A. Belaz et al.
J. Pharm. Biomed. Anal.
(2012)
V.L. Lanchote et al.
J. Chromatogr. B
(1998)
T.C. Lourenço et al.
J. Chromatogr. A
(2012)
K.R.A. Belaz et al.
Talanta
(2008)
V.C. Hilário et al.
J. Pharm. Biomed. Anal.
(2012)
J.J. Garcia et al.
J. Chromatogr. B
(1999)
K.R.A. Belaz et al.
J. Chromatogr. B
(2013)
R. Cirilli et al.
J. Chromatogr. A
(2013)
R. Cirilli et al.
J. Chromatogr. A
(2008)

R. Ferretti et al.

J. Chromatogr. A

(2009)

T. Zhang et al.

J. Chromatogr. A

(2012)

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Citation Excerpt :
These immobilized PS-based CSPs have further expanded the application range through their extended choice of mobile phases, which provides great flexibility for method development. Dipole–dipole interactions between chiral solutes and PS-based chiral selectors have been suggested to be the key to achieving chiral recognition, and these interactions may be weakened in reversed-phase mode; however, several recent studies have demonstrated that PS-based CSPs are also highly useful for separating enantiomers using an aqueous–organic mobile phase [5,11–15]. Mitchell et al. used a linear solvation energy relationship to characterize PS-based CSPs [16].
The electrostatic interactions between chiral solutes and polysaccharide (PS)-based chiral selectors are the key to achieving chiral recognition; however, PS-based sorbents, derivatized of phenyl moieties, can exhibit considerably non-polar characteristics, and they are also useful for the separation of enantiomers in the reversed-phase mode. In this study, an immobilized amylose 3,5-dimethylphenylcarbamate-based sorbent was used to investigate the balance between electrostatic interactions and solvophobic interactions, with complementary effects on solute retention behavior when the isopropanol (IPA) concentration was altered. It was proposed that in both normal- and reversed-phase modes, information on the retention mechanisms could be obtained by observing the curvature of the logarithm of the retention factor versus the logarithm of the IPA concentration, and the slope values of the curves were related to the number of displaced IPA molecules upon solute adsorption. Using the proposed model and the two-site adsorption model, the retention behaviors of pantolactone (PL) enantiomers in both normal- and reversed-phase modes were investigated. The PL−sorbent interactions were classified into four types: electrostatic/enantioselective, electrostatic/nonselective, solvophobic/enantioselective, and solvophobic/nonselective. At IPA concentrations below 50 vol.% in n-hexane, the retention behaviors of PL were dominated by electrostatic/enantioselective sites, whereas at IPA concentrations beyond 50 vol.%, the solvophobic interactions of PL−sorbent were strengthened and mostly nonselective. By contrast, in the reversed-phase mode, a reverse in the enantiomeric elution order of PL was observed at 10 vol.% IPA, and considerably different enantioselectivity behaviors were found below and above 20 vol.%, indicating an abrupt change in the sorbent molecular environment. At IPA concentrations beyond 40 vol.%, the presence of PL-sorbent electrostatic interactions enhanced chiral recognition.

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Effect of the water content on the retention and enantioselectivity of albendazole and fenbendazole sulfoxides using amylose-based chiral stationary phases in organic–aqueous conditions

Highlights

Abstract

Introduction

Section snippets

Instruments, synthesis, chromatographic conditions and chemicals

Enantioseparation under organic–aqueous conditions

Conclusion

Acknowledgment

Vet. J.

J. Pharm. Biomed. Anal.

J. Chromatogr. B

J. Chromatogr. A

Talanta

J. Pharm. Biomed. Anal.

J. Chromatogr. B

J. Chromatogr. B

J. Chromatogr. A

J. Chromatogr. A

J. Chromatogr. A

J. Chromatogr. A