Is Iron Chelation Important in Preventing Glycation of Bovine Serum Albumin in Vitro?

A comparative study on the antioxidant and antiglycation properties of different vitamin D forms

Vitamin D plays multiple roles in the body. Recently, there has been an increase in its popularity and growing interest in vitamin D supplementation. However, the mechanisms of vitamin D action have not yet been sufficiently explored. Our study focused on the antioxidant and antiglycation properties of the four primary forms of vitamin D such as cholecalciferol, calcifediol, alfacalcidol, and calcitriol. For this purpose, we used an in vitro bovine serum albumin model. Glucose, fructose, ribose, galactose, glyoxal, and methylglyoxal were glycation factors. The antiglycative mechanism of vitamin D was evaluated through in silico docking. We showed that all forms of vitamin D exhibit antioxidant and antiglycation activity, although calcitriol demonstrated the most potent effect. We observed decreased levels of advanced glycation end products and advanced oxidation protein products in samples with the addition of different vitamin D forms compared to positive control. Notably, the antioxidant and antiglycation activity is similar to routinely used antioxidants (reduced glutathione) and protein glycation inhibitors (aminoguanidine). Molecular docking analyses revealed that calcitriol demonstrated strong binding affinities with human and bovine serum albumin forming polar contacts with lysine residues highly susceptible to glycation. Calcitriol also exhibited significant interactions with the receptor for advanced glycation endproducts (RAGE). The pleiotropic action of vitamin D, especially calcitriol, may indicate a high therapeutic potential of vitamin D supplementation in various diseases with carbonyl stress etiology. Further research is needed to fully understand the underlying mechanisms of vitamin D pleiotropic effects and determine the optimal dosages for clinical use.

Antiglycoxidative properties of amantadine – a systematic review and comprehensive in vitro study

An important drug used in the treatment of Parkinson’s disease is amantadine. We are the first to perform a comprehensive study based on various glycation and oxidation factors, determining the impact of amantadine on protein glycoxidation. Sugars (glucose, fructose, galactose) and aldehydes (glyoxal, methylglyoxal) were used as glycation agents, and chloramine T was used as an oxidant. Glycoxidation biomarkers in albumin treated with amantadine were generally not different from the control group (glycation/oxidation factors), indicating that the drug did not affect oxidation and glycation processes. Molecular docking analysis did not reveal strong binding sites of amantadine on the bovine serum albumin structure. Although amantadine poorly scavenged hydroxyl radical and hydrogen peroxide, it had significantly lower antioxidant and antiglycation effect than all protein oxidation and glycation inhibitors. In some cases, amantadine even demonstrated glycoxidant, proglycation, and prooxidant properties. In summary, amantadine exhibited weak antioxidant properties and a lack of antiglycation activity.

Pleiotropic Properties of Valsartan: Do They Result from the Antiglycooxidant Activity? Literature Review and In Vitro Study

Valsartan belongs to angiotensin II type 1 (AT1) receptor blockers (ARB) used in cardiovascular diseases like heart failure and hypertension. Except for its AT1-antagonism, another mechanism of drug action has been suggested in recent research. One of the supposed actions refers to the positive impact on redox balance and reducing protein glycation. Our study is aimed at assessing the antiglycooxidant properties of valsartan in an in vitro model of oxidized bovine serum albumin (BSA). Glucose, fructose, ribose, glyoxal (GO), methylglyoxal (MGO), and chloramine T were used as glycation or oxidation agents. Protein oxidation products (total thiols, protein carbonyls (PC), and advanced oxidation protein products (AOPP)), glycooxidation products (tryptophan, kynurenine, N-formylkynurenine, and dityrosine), glycation products (amyloid-β structure, fructosamine, and advanced glycation end products (AGE)), and albumin antioxidant activity (total antioxidant capacity (TAC), DPPH assay, and ferric reducing antioxidant power (FRAP)) were measured in each sample. In the presence of valsartan, concentrations of protein oxidation and glycation products were significantly lower comparing to control. Moreover, albumin antioxidant activity was significantly higher in those samples. The drug's action was comparable to renowned antiglycation agents and antioxidants, e.g., aminoguanidine, metformin, Trolox, N-acetylcysteine, or alpha-lipoic acid. The conducted experiment proves that valsartan can ameliorate protein glycation and oxidation in vitro in various conditions. Available animal and clinical studies uphold this statement, but further research is needed to confirm it, as reduction of protein oxidation and glycation may prevent cardiovascular disease development.

A New Insight into Meloxicam: Assessment of Antioxidant and Anti-Glycating Activity in In Vitro Studies

Meloxicam is a non-steroidal anti-inflammatory drug, which has a preferential inhibitory effect to cyclooxyganase-2 (COX-2). Although the drug inhibits prostaglandin synthesis, the exact mechanism of meloxicam is still unknown. This is the first study to assess the effect of meloxicam on protein glyco-oxidation as well as antioxidant activity. For this purpose, we used an in vitro model of oxidized bovine serum albumin (BSA). Glucose, fructose, ribose, glyoxal and methylglyoxal were used as glycating agents, while chloramine T was used as an oxidant. We evaluated the antioxidant properties of albumin (2,2-di-phenyl-1-picrylhydrazyl radical scavenging capacity, total antioxidant capacity and ferric reducing antioxidant power), the intensity of protein glycation (Amadori products, advanced glycation end products) and glyco-oxidation (dityrosine, kynurenine, N-formylkynurenine, tryptophan and amyloid-β) as well as the content of protein oxidation products (advanced oxidation protein products, carbonyl groups and thiol groups). We have demonstrated that meloxicam enhances the antioxidant properties of albumin and prevents the protein oxidation and glycation under the influence of various factors such as sugars, aldehydes and oxidants. Importantly, the antioxidant and anti-glycating activity is similar to that of routinely used antioxidants such as captopril, Trolox, reduced glutathione and lipoic acid as well as protein glycation inhibitors (aminoguanidine). Pleiotropic action of meloxicam may increase the effectiveness of anti-inflammatory treatment in diseases with oxidative stress etiology.