Abstract
Maillard reaction products (MRPs) of protein, amino acids, and reducing sugars from many foods and aqueous extracts of herbs are found to have various bioactivities, including antiviral effects. A hypothesis was proposed that their antiviral activity is due to the interaction with the cellular membrane. Aiming to estimate the possible actions of MRPs on phospholipid bilayers, the Arg-Glc MRPs were prepared by boiling the pre-mixed solution of arginine and glucose for 60 min at 100°C and then examined at a series of concentrations for their effects on the phase transition of MeDOPE multilamellar vesicles (MLVs), for the first time, by using differential scanning calorimetry (DSC) and temperature-resolved small-angle X-ray scattering (SAXS). Arg-Glc MRPs inhibited the lamellar gel–liquid crystal (Lβ-Lα), lamellar liquid crystal–cubic (Lα-QII), and lamellar liquid crystal–inverted hexagonal (Lα-HII) phase transitions at low concentration (molar ratio of lipid vs. MRPs was 100:1 or 100:2), but promoted all three transitions at medium concentration (100:5). At high concentration (10:1), the MRPs exhibited inhibitory effect again. The fusion peptide from simian immunodeficiency virus (SIV) induces membrane fusion by promoting the formation of a non-lamellar phase, e.g., cubic (QII) phase, and inhibiting the transition to HII. Arg-Glc MRPs, at low concentration, stabilized the lamellar structure of SIV peptide containing lipid bilayers, but facilitated the formation of non-lamellar phases at medium concentration (100:5). The concentration-dependent activity of MRPs upon lipid phase transition indiciates a potential role in modulating some membrane-related biological events, e.g., viral membrane fusion.
Highlights
The Maillard reaction is a non-enzymatic browning chemistry reaction between amino acids and a reducing sugar, usually requiring heat
Lipids with smaller head groups and bigger tail groups present a cone shape. This type of lipids, e.g., MeDOPE, forms nonlamellar phases and allows us to monitor the influence of Maillard reaction products (MRPs) on the lamellar to non-lamellar phase transition
The nonlamellar structures are believed to relate to the initiation of peptide-induced membrane fusion
Summary
The Maillard reaction is a non-enzymatic browning chemistry reaction between amino acids (or peptides, or proteins) and a reducing sugar, usually requiring heat. As a major chemical change that occurs during food processing, herb decocting, and physiological aging, Maillard reaction products (MRPs) have been associated with a number of functions and bioactivities, such as flavoring, coloring, modification of proteins and lipids with glycation, and formation of antioxidant or mutagenic compounds Both positive and negative influences of MRPs on cell reproduction have been reported (Einarsson et al, 1983; Harris and Tan, 1999; Kundinger, 2004; Rufián-Henares and Morales, 2006). MRPs from amino acids and glucose showed significant impacts on the growth of the microorganisms (Harris and Tan, 1999). MRPs derived from reaction of arginine, glycine, and histidine with glucose promoted the growth of Staphylococcus aureus and Salmonella enteritidis, while MRPs of cysteine and glucose inhibited the growth of both germs
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