COMPUTATIONAL STUDY OF THE INFLUENCE OF THE ABILITY OF LAPACHOL AND ITS DERIVATIVES TO CHELATE IRON (II) CATION ON THEIR ANTIOXIDANT PROPERTIES

Djafarou NGOUH PAJOUDORO, BIKELE MAMA Désiré^*

University of Douala, Cameroon

1-ABSTRACT

The computational elucidation of the influence of the complexation of Lapachol and its derivatives with Fe²⁺ cation on their antioxidant power has been performed at B3LYP/6-311++G (d,p)//B3LYP/6-31+G(d,p) level of theory in gas phase, water, acetonitrile, benzene and toluene.  Only bi-dentate and tri-dentate binding of  Fe²⁺ to ligands have been taken into account. The results indicated   proportionality between the metal ion affinity (MIA) values and the retained charge on Fe²⁺ cation and an inverse one between the two respectively for  k²-(O₁,O₂) and k³-(O₂, C=C) modes. In addition, the higher stability obtained for a tri-dentate coordination mode in which the Fe²⁺ cation is simultaneously attached to the two carbon atoms of the ethylenic bond (C=C) and sp²O₃ oxygen atom. The topological analysis of complexes exhibits the localization of concentration of electron density between the oxygen atom of the ligand attached to Fe²⁺ and this metal cation for this latter mode in gas phase. Our results also indicate that the electron extraction in Fe²⁺...La_i complexes is more difficult than in the one in free ligand. This tight binding of electron in cationic Fe²⁺complex system is similar to the  previous computational prediction done for Fe²⁺-caffeic acid phenethyl ester derivative complexes and  Fe²⁺-curcumin complexes

2- MOLECULAR LIBRARY BUILT AROUND  LAPACHOL AND ITS DERIVATIVES

3-RESULTS

I- VARIOUS COORDINATION MODES OF Fe²⁺...La_i COMPLEXES

II-INTRAMOLECULAR INTERACTIONS

III-METAL ION AFFINITY AND RETAINED  CHARGE ON THE Fe(II) CATION

IV-INFLUENCE ON Fe²⁺ CHELATION ON ANTIOXIDANT POWER

4-Conclusion

This work is focused on the impact of the complexation of Lapachol and its derivatives to Fe²⁺ cation  on their antioxidant powers by the means of computational tools. Our results have indicated that the electron extraction from Fe²⁺...La_i complexes is more difficult compared to that from free ligands. 

5-Aknowledgements

This work was supported by the Ministry of  Higher Education of Cameroon

Autor courriel:bikelemama@yahoo.fr

5- References

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