Chiral Hydroxy Metabolite of Mebendazole: Analytical and Semi-Preparative High-Performance Liquid Chromatography Resolution and Chiroptical Properties

• Main Authors: Paolo Guglielmi (Author), Gaia Pulitelli (Author), Francesca Arrighi (Author), Daniela Secci (Author), Marco Pierini (Author), Roberto Cirilli (Author)
• Format: Book
• Published: MDPI AG, 2024-05-01T00:00:00Z.
• Subjects: article
• Online Access: Connect to this object online.
• Notes: 10.3390/ph17060696; 1424-8247
• Keywords: hydroxy mebendazole; Chiralpak IG; enantioselective HPLC; chiroptical properties; theoretical calculations; Medicine; R; Pharmacy and materia medica; RS1-441
• Source: Pharmaceuticals, Vol 17, Iss 6, p 696 (2024)

Mebendazole (<b>MBZ</b>) is a benzimidazole carbamate anthelmintic used worldwide for the treatment and prevention of parasitic disorders in animals and humans. A large number of in vivo and in vitro studies have demonstrated that <b>MBZ</b> also has anticancer activity in multiple types of cancers. After oral administration, the phenylketone moiety of <b>MBZ</b> is rapidly reduced to the hydroxyl group to form the chiral hydroxy metabolite (<b>MBZ-OH</b>). To the best of our knowledge, there is no information in the literature on the stereochemical course of transformation and the anthelmintic and antitumor activity of individual enantiomers of <b>MBZ-OH</b>. In the present study, we describe in detail the direct HPLC resolution of <b>MBZ-OH</b> on a 100 mm × 4.6 mm Chirapak IG-3 column packed with 3 μm silica particles containing amylose (3-chloro-5-methylphenylcarbamate) as a selector. At 25 °C and using pure methanol as the mobile phase, the enantioseparation and resolution factors were 2.38 and 6.13, respectively. These conditions were scaled up at a semi-preparative scale using a 250 mm × 10 mm Chiralpak IG column to isolate multi-milligram amounts of both enantiomeric forms of the chiral metabolite. The chiroptical properties of the collected enantiomers were determined and, through a theoretical study, were related to the more stable conformations of MBZ-OH. The first and second eluted enantiomers were dextrorotatory and levorotatory, respectively, in dimethylformamide solution. Finally, by recording the retention factors of the enantiomers as the water content in the water-acetonitrile mobile phases was progressively varied, U-shaped retention maps were generated, indicating a dual and competitive hydrophilic interaction liquid chromatography and reversed-phase liquid chromatography retention mechanism on the Chirapak IG-3 chiral stationary phase.