DISCUSSION
Human serum albumin (HSA) is the most abundant protein in
human plasma or serum and is normally present at
concentrations ranging from 30 to 50 g/L.37 HSA is a
polypeptide consisting of 585 residues, with 24 arginine
residues, 59 lysine residues, and an N-terminus that can act
as potential sites for the formation of early stage glycation
products and AGEs.37−39 It has been reported that the level of
glycated albumin in diabetic patients is 2−3-fold higher than in
a healthy individual.40 HSA-imposed glycation has been
proposed as a tool not only for diagnosing diabetes but also
for its potential in assessing diabetes-associated complications.
41 The reactive dicarbonyl species, such as MGO and GO,
in humans may account for the formation of HSA-related
AGEs, according to the literature about the glycation of HSA by
MGO in vitro.42 Therefore, inhibiting glycation of HSA by
trapping MGO may prevent or alleviate the development of the
related diabetic complications in diabetic patients.
In this study, we reveal for the first time that both 6S and 6G,
the major active components of ginger, markedly trap MGO in
PBS (pH 7.4, 37 °C) (Figure 1A) and inhibit the formation of
MGO-induced AGEs in the HSA−MGO system (Figure 1B).
To gain deeper insights into the plausible mechanism of actions
underlying the trapping of MGO by 6S and 6G, we investigated
the formation of MGO adducts of 6S and 6G by treating MGO
with 6S and 6G, respectively. We found evidence of the
formation of MGO adducts from both treatments under slightly
basic condition after incubation for 8 h (Figure 2). Two mono-
MGO adducts, 6S-MGO and 6G-MGO, were purified and
identified from the corresponding reaction mixture (Figure 3).
Unlike the MGO conjugates of dietary flavonoids in our