This paper describes the guest-host complex formation of anthranilic acid (2-aminobenzoic acid, AA) and different natural and modified cyclodextrins (CDs), using steady state fluorescence. The experimental data point to the formation of 1:1 inclusion complexes with natural (ß and ɣ-CD) and modified (HP-ß HE-ß and M-ß-CD) CDs. Of the natural CDs, the ß-CD complex showed the highest encapsulation constant (KF) value (14056 ± 1241 M−1). However, modified ß-CDs showed higher binding constants than ß-CDs. Of the modified CDs, M-β-CD showed the highest KF (18622 ± 897 M−1). To gain information on the encapsulation process of M-ß-CD/AA, the thermodynamic parameters of the complexation (ΔH, ΔS and ΔG), were studied. The results showed positive entropy (66 ± 7.9 J mol−1 K−1), negative enthalpy (−5.74 ± 2.96 kJ mol−1) and a change in Gibbs free energy at 25 °C (−24.30 ± 0.27 kJ mol−1). Finally, a computational study carried out using molecular docking simulations showed the high correlation between experimental values and computed scores. The complexation of M-ß-CD/AA depends on several physicochemical factors including temperature and pH. The values of KF exhibited a strong negative relation with temperature and pH. Moreover, the interaction of AA and M-ß-CD was most effective in the pH region where the molecule presents intramolecular hydrogen bonds that neutralize the charge of the protonated species of AA.
Nanoencapsulation as fluorescence enhancer of vitamin L1 (anthranilic acid). An exhaustive study
Matencio Duran A.;
2019-01-01
Abstract
This paper describes the guest-host complex formation of anthranilic acid (2-aminobenzoic acid, AA) and different natural and modified cyclodextrins (CDs), using steady state fluorescence. The experimental data point to the formation of 1:1 inclusion complexes with natural (ß and ɣ-CD) and modified (HP-ß HE-ß and M-ß-CD) CDs. Of the natural CDs, the ß-CD complex showed the highest encapsulation constant (KF) value (14056 ± 1241 M−1). However, modified ß-CDs showed higher binding constants than ß-CDs. Of the modified CDs, M-β-CD showed the highest KF (18622 ± 897 M−1). To gain information on the encapsulation process of M-ß-CD/AA, the thermodynamic parameters of the complexation (ΔH, ΔS and ΔG), were studied. The results showed positive entropy (66 ± 7.9 J mol−1 K−1), negative enthalpy (−5.74 ± 2.96 kJ mol−1) and a change in Gibbs free energy at 25 °C (−24.30 ± 0.27 kJ mol−1). Finally, a computational study carried out using molecular docking simulations showed the high correlation between experimental values and computed scores. The complexation of M-ß-CD/AA depends on several physicochemical factors including temperature and pH. The values of KF exhibited a strong negative relation with temperature and pH. Moreover, the interaction of AA and M-ß-CD was most effective in the pH region where the molecule presents intramolecular hydrogen bonds that neutralize the charge of the protonated species of AA.
I documenti in IRIS sono protetti da copyright e tutti i diritti sono riservati, salvo diversa indicazione.
