Quantum Mechanical Modelling of Tannin-Iron Interactions in Fermented Maize Enriched with Ficus Sur Leaves and Implications for Non-Haem Iron Bioavailability

Summary

This computational study applies quantum mechanical modelling to investigate how tannin compounds from Ficus sur leaves interact with non-haem iron in fermented maize, a staple food enrichment strategy in developing regions. Using density functional theory at the B3LYP/6-311+G(d,p)/SDD(Fe) level, the authors modelled catechol- and galloyl-type tannin motifs and found that galloyl-type tannins exhibit greater iron-binding capacity than catechol-type, with Fe(III) forming more stable complexes than Fe(II). The findings suggest that whilst Ficus sur enrichment may enhance functional properties, stable tannin–iron complexation could substantially limit iron bioavailability under physiologically relevant digestive conditions.

Regional applicability

The study is a computational model with no explicit geographic focus, though Ficus sur is an African plant and fermented maize is relevant to Sub-Saharan nutrition contexts. The findings would be directly applicable to food fortification and enrichment strategies in developing regions where maize-based foods dominate and plant-based iron sources are important; transferability to United Kingdom contexts would be limited unless similar plant enrichments were adopted in functional food formulations.

Key measures

Fe–O equilibrium distance (Å), binding energies, spin-state effects, electronic descriptors, pH-dependent ligand deprotonation, thermal stability of tannin–iron complexes

Outcomes reported

The study modelled tannin–iron coordination chemistry in Ficus sur-enriched fermented maize using quantum mechanical methods to predict non-haem iron bioavailability. DFT calculations identified stable Fe–O coordination distances and binding energies, demonstrating that galloyl-type tannins form more stable complexes with iron than catechol-type tannins, potentially reducing dietary iron bioavailability.

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