Abstract:
Maillard reaction products are generated during heat processing of foods but with little information on their health impact. Hence, this study sought to investigate the effect of tyrosine-derived Maillard reaction products (MRPs) on key enzymes linked to type-2 diabetes (α-amylase and α-glucosidase) and hypertension (Angiotensin-I converting enzyme, ACE) in vitro. MRPs were produced from the reaction between equimolar (5mM) solutions of tyrosine and four different saccharides each, namely; glucose, sucrose, fructose and maltose at 135 oC for 90 min to give products designated glucose-tyrosine MRPs, sucrose-tyrosine MRPs, fructose-tyrosine MRPs and maltose-tyrosine MRPs respectively. The MRPs inhibited α-amylase and α-glucosidase (0 – 24 μg/mL) and ACE (0 – 7.5 μg/mL) activities in a dose-dependent manner. Furthermore, the MRPs significantly (P<0.05) inhibited pro-oxidants (sodium nitroprusside and FeSO4) -induced lipid peroxidation in isolated tissue (pancreas, liver and heart) homogenates, and also demonstrated strong antioxidant properties as evident by their radical (DPPH and ˙OH) scavenging abilities. The melanoidin content of the MRPs determined by Gas Chromatography (GC) analysis ranged from 33.98 (glucose-tyrosine MPRs) to 47.18 mg/100 g (fructose-tyrosine MRPs). However, the melanoidin content agreed with the α-amylase and ACE inhibition. Nevertheless, the bioactivities of the MRPs is suggested to be a synergistic effect between the melanoidins and other compounds in the MRPs. Hence, tyrosine-derived MRPs could be relevant in the management of postprandial hyperglycaemia (major risk factor of type-2 diabetes) and its complications due to their modulatory effect on α-amylase, α-glucosidase and ACE activities, as well as their antioxidant properties.
