Abstract
Proteins undergo continuous changes under the action of various intrinsic and extrinsic factors, leading to alteration of several intracellular metabolic pathways and the development of various clinical disorders. Non-enzymatic glycosylation is one of the main factors responsible for the progression of diabetic complications and the aging process. Although there are currently many effective therapies in the prevention and treatment of these diseases, in the last decade, there has been an increasing trend of replacing synthetic drugs by natural compounds, in order to reduce the side effects that may occur and the production costs. It is well known that aspirin (acetylsalicylic acid) inhibits the glycation process of serum proteins by acetylating N-terminal amino groups and lysine residues in their structure. Therefore, the main purpose of our research was to analyze the non-enzymatic glycation and fructation process of hemoglobin through spectrometric and electrophoretic techniques, in order to reveal how this process could influence the three-dimensional structure and biological function of the protein, and the effect of some natural aspirin-like compounds on the peroxidase and esterase activity of hemoglobin during fructose and glucose binding. In this way, a preliminary phytochemical characterization of a bark extract of white willow (Salix alba) was performed in order to evaluate the content of total phenolics, flavonoids, and salicylic derivatives, as well as the antioxidant activity. Then, human erythrocytes isolated from whole peripheral blood were incubated with different concentrations of fructose/glucose (10, 50, 100 mM) and S. alba extract for 5, 7, 10 and 14 days. The results obtained from the THz spectra confirmed that fructose was more reactive than glucose, so the glycation process took place more slowly than fructation. Also, the presence of S. alba extract showed an antiglycosylating effect, but not a total inhibition of the glycation process. In addition, enzymatic determinations proved that willow bark extract restored the peroxidase and esterase activities to the control levels. Our data indicated that salicylic compounds can be successfully used as substitutes for aspirin, one of the main synthetic compounds with anti-inflammatory and anti-glycosylating roles. Salicin, salicylic acid and other salicylic compounds possess strong antioxidant properties, which give them the ability to participate in the glycosylation process to block the formation of advanced glycation end products (AGEs).
Highlights
Protein glycation is a complex cascade of condensation, rearrangement, fragmentation, and oxidative changes; non-enzymatic glycation is a natural phenomenon, which consists in the attachment of free carbohydrate molecules to certain amino acid residues in the structure of proteins, leading to the formation of products with major alterations in secondary and tertiary structure, which affects their functional properties
high pressure liquid chromatography (HPLC) analysis of the willow bark extract obtained in our study resulted in a content of 0.011 mg/mL salicylic derivatives, expressed as salicin
The potential antiglycosylating effect of willow bark extract is due to significant concentrations of polyphenols and flavonoid compounds which provide a high antioxidant activity (Table 1), salicylates having the role of maintaining oxidative stress at a low level that does not disrupt the physiological processes at the cellular level
Summary
Protein glycation is a complex cascade of condensation, rearrangement, fragmentation, and oxidative changes; non-enzymatic glycation is a natural phenomenon, which consists in the attachment of free carbohydrate molecules to certain amino acid residues in the structure of proteins, leading to the formation of products with major alterations in secondary and tertiary structure, which affects their functional properties. Synthetic inhibitors of AGEs formation tested clinically so far have shown low efficacy, reduced pharmacokinetic properties and generated a number of side effects incompatible with patient safety, so in recent decades there has been an increasing emphasis on natural products based on plant extracts with antiglycosylating effect and safe for human consumption In addition to their hypoglycemic properties, they have hypolipidemic and antioxidant potential [2]. Salicylates are well known as hydroxyl radical scavengers, their mechanism of action being based on the chelation of transition metals, regulation of nitric oxide levels, increased lipoxin synthesis with an important role in maintaining a balance of oxidative stress, and inhibition of protein kinases NF-kB and AP-1 These compounds protect against oxidation of low-density lipoproteins (LDL) and have an inhibitory effect on the expression of lectin-like receptors for oxidized LDL on the surface of endothelial cells [3]
Sign-in/Register to view highlights & summary 
Published Version (
Free)
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a call