Redox properties of catechins and enriched green tea extracts effectively preserve L-5-methyltetrahydrofolate: Assessment using cyclic voltammetry analysis

摘要

A cyclic voltammetry (CV) study was performed in pH 5.5 Britton-Robinson buffer at room temperature to study the stability of 1 mM L-5-methyltetrahydrofolate (L-5-MTHF) in combination with epigallocate-chin-gallate-enriched extract (EGCGe) and epigallocatechin-enriched extract (EGCe). The combination of L-5-MTHF with enriched catechin extracts provided enhanced stability of L-5-MTHF over a period of 12 h under ambient air conditions at pH 5.5. CV experiments showed that increasing the concentrations of EGCGe or EGCe extracts from 80 to 400 mg/L produced a decrease in the second oxidation peak of L-5-MTHF. Thus, we calculated that L-5-MTHF remained at nearly 90% when in the presence of enriched tea extracts, compared to 74% without the tea antioxidants. The catechins responsible for this preservation were EGCG and C, confirmed by LC-MS. Compared to covalent link only low interaction (hydrogen bonds) between the different catechins present in the tea extract would stabilise L-5-MTHF. Rather, it was hypothesised that EGCGe and EGCe were effective agents to preserve L-5-MTHF, through a mechanism that also involved the redox potential of catechins to maintain L-5-MTHF in its reduced form.