ISSN print edition: 0366-6352 ISSN electronic edition: 1336-9075 Registr. No.: MK SR 9/7 Published monthly

Mangiferin/β-cyclodextrin complex: determination of the Inclusion constant in aqueous solution by Higuchi–Connors method and molecular absorption and photoluminescence UV spectroscopies at pH 3.4

Lucero Hernández-García, Alberto Rojas-Hernández, and Annia Galano

Departamento de Química, Área de Química Analítica, Universidad Autónoma Metropolitana-Iztapalapa, Iztapalapa, Ciudad de México, México

E-mail: suemi918@xanum.uam.mx

Received: 22 February 2022  Accepted: 16 July 2022

Abstract:

The purpose of this paper was to determine the inclusion constant of the complex formed between mangiferin and β-cyclodextrin (βCD) at pH 3.4, by Higuchi–Connors and absorption and fluorescence spectroscopies methods, as well as to elucidate whether mangiferin molecule enters to the cavity of βCD by the glucosidic or by the xanthone end of the molecule, using computational chemistry calculations of density functional theory (DFT). The phase-solubility diagram showed that H₄MGF was included in the cavity of βCD to form a complex with the stoichiometric ratio 1:1 (H₄MGF/βCD) with the inclusion constant: K_1:1 = 344 ± 32 (logK_1:1 = 2.54 ± 0.04) at pH 3.4. The inclusion constant obtained using the program SQUAD by the fitting of absorption and fluorescence spectra is in good agreement with that value. Finally, the DFT calculations have shown that mangiferin molecule enters by its xanthone group—to the cavity—through the wider rim of the βCD molecule.

Keywords: Cyclodextrins; Higuchi–Connors method; Inclusion complexes

Full paper is available at www.springerlink.com.

DOI: 10.1007/s11696-022-02381-z

Chemical Papers 76 (11) 7123–7132 (2022)