Kinetics of conversion of dihydroxyacetone to methylglyoxal in New Zealand mānuka honey: Part V – The rate determining step

TY - JOUR

T1 - Kinetics of conversion of dihydroxyacetone to methylglyoxal in New Zealand mānuka honey

T2 - Part V – The rate determining step

AU - Owens, Adrian

AU - Lane, Joseph R.

AU - Manley-harris, Merilyn

AU - Marie Jensen, Annesofie

AU - Jørgensen, Solvejg

PY - 2019/3/15

Y1 - 2019/3/15

N2 - Monomer formation from dimeric DHA has previously been suggested as the rate-determining step in formation of methylglyoxal, the bioactive component in mānuka honey. This step was studied by 1H NMR in DMSO‑d6. First order reaction rate was 3.31 × 10−3 ± 9.1 × 10−4 min−1. Upon titration with D2O, little change was observed until ∼15 mass% whereupon an exponential increase in rate occurred until indistinguishable from the rate observed in water. Acid or base caused rate accelerations. Theoretical modelling confirmed the existence of acid and base-catalysed mechanisms for dimer decomposition and the structures of two intermediates observed. In honey it is likely the base-catalysed decomposition predominates with water as catalyst but there is little rate acceleration at the levels of water present normally in honey however a small increase in the mass% of water in the honey could cause significant rate acceleration of dimer decomposition and hence formation of methylglyoxal.

AB - Monomer formation from dimeric DHA has previously been suggested as the rate-determining step in formation of methylglyoxal, the bioactive component in mānuka honey. This step was studied by 1H NMR in DMSO‑d6. First order reaction rate was 3.31 × 10−3 ± 9.1 × 10−4 min−1. Upon titration with D2O, little change was observed until ∼15 mass% whereupon an exponential increase in rate occurred until indistinguishable from the rate observed in water. Acid or base caused rate accelerations. Theoretical modelling confirmed the existence of acid and base-catalysed mechanisms for dimer decomposition and the structures of two intermediates observed. In honey it is likely the base-catalysed decomposition predominates with water as catalyst but there is little rate acceleration at the levels of water present normally in honey however a small increase in the mass% of water in the honey could cause significant rate acceleration of dimer decomposition and hence formation of methylglyoxal.

U2 - 10.1016/j.foodchem.2018.10.039

DO - 10.1016/j.foodchem.2018.10.039

M3 - Journal article

C2 - 30409643

SN - 0308-8146

VL - 276

SP - 636

EP - 642

JO - Food Chemistry

JF - Food Chemistry

ER -