Redox imbalance occurs when the factors of oxidative stress, known as prooxidants, outweigh the mechanisms of antioxidant protection. In a healthy state, homeostatic mechanisms ensure the balanced production of free radicals and a complete series of antioxidants responsible for their safe removal. The generation of free radicals is a part of physiological processes in a healthy organism, some of which act as specific signaling molecules, and their presence and activity are necessary in these processes. In various diseases such as cancer, cardiovascular disease, diabetes, autoimmune diseases, rheumatic diseases, systemic lupus, and skin diseases, the generation of free radicals overwhelms the protective mechanisms, leading to the development of "oxidative stress" that damages cells and tissues. To prevent the harmful effects of free radicals within cells, there exists a system of enzymatic antioxidant protection composed of superoxide dismutase (SOD), glutathione peroxidase (GSHPx), glutathione reductase (GR), glutaredoxin, reduced/oxidized glutathione (GSH/GSSG), and thioredoxin (TRX). The examples of non-enzymatic antioxidants are: antioxidant vitamins such as A, C and E, dihydrolypoic acid, metallothioneins, ceruloplasmin, coenzyme Q 10, urea, creatinine, etc. Redox balance is influenced by the circadian rhythm and external factors that constitute the "exposome", including dietary habits and lifestyle. Antioxidant supplementation has become increasingly popular for maintaining optimal body function. However, it is important to note that some antioxidants can exhibit prooxidant activity, emphasizing the need for controlled use. The relationship between the redox status of the body and the action of antioxidants enables the development of multidisciplinary research that connects biochemistry, molecular biology, nutritional science, natural product chemistry, and clinical practice.

Six β-hydroxy-β-aryl propanoic acids were synthesised using a modification of Reformatsky reaction which has already been reported. These acids belong to the aryl propanoic acid class of compounds, structurally similar to the NSAIDs, such as ibuprofen, and an anti-inflammatory activity is thus expected. The aim of this work was to determine anti-inflammatory activity, examine gastric tolerability, and to carry out molecular docking experiments to identify potential COX-2 inhibitors among the β-hydroxy-β-aryl propanoic acids, and to elucidate the effect α-methyl substitution on the anti-inflammatory activity. Anti-inflammatory activity and gastric tolerability were determined on rats using carragenan induced paw oedema method, and docking studies were carried out using Autodock v4.0.1. The range of ED₅₀ values is between 127 µmol/kg and 15 µmol/kg, while the result for ibuprofen is 51.7 µmol/kg. Only slight hyperaemia or few petechiae were spotted on rat’s stomach. The results indicate that all compounds possess significant anti-inflammatory activity after oral administration, and that 2-methyl-3-hydroxy-3,3-diphenyl-propanoic acid has greatest activity, surpassing that of ibuprofen, a standard NSAID. Another compound, 3-hydroxy-3,3-diphenylpropanoic acid, shows activity matching that of ibuprofen, and is non-chiral and is proven to be non-toxic. The most of investigated compounds have interactions with P3 anchor site like COX-2 selective inhibitors. No tested substances or ibuprofen produced any significant gastric lesions.

Background: Nonsteriodal anti-inflammatory drugs (NSAIDs) are numerous and widely used for more than 60 years, but there is still a strong need for developing novel selective NSAIDs. The need is justified by the fact that nonselective NSAIDs can produce serious gastric side effects and that some of the selective NSAID are withdrawn due to their cardiotoxic side effects. Methods: Eight β-hydroxy-β-arylpropanoic acids, which belong to the arylpropanoic acid class of compounds, structurally similar to some nonsteroidal anti-inflammatory drugs (NSAIDs), were docked into 3D catalytic site of both cyclooxygenase-1 (COX-1) and cyclooxygenase-2 (COX-2). Seven out of those eight acids were synthesized using already published modification of Reformatsky reaction additionally optimized by increasing temperature. Synthesized compounds were tested in vivo in order to elucidate anti-inflammatory activity, gastric tolerability and impact on liver function of rats. Results: Results of docking studies have indicated that all compounds have potential to selectively inhibit COX-2 isoform, but that the compounds containing polar substituents on phenyl ring are better inhibitors. Results of carrageenan-induced rat paw oedema test have shown that all compounds exhibit dose dependence and good gastric tolerability and none of the tested compounds have shown negative effect on liver function compared to ibuprofen. Conclusion: The compound containing polar nitro group in para position has shown the best docking results, anti-inflammatory activity, low hepatotoxicity and good gastric tolerability.

Evaluation of pharmacokinetic properties is a significant step at the early stages of drug development. In this study, an in vitro evaluation of the pharmacokinetic properties of five newly synthesized compounds was performed. These compounds belong to N-hydroxyurea and hydroxamic acid derivatives and analogs of NSAIDs indomethacin, flurbiprofen, diclofenac, ibuprofen, and naproxen (compounds 1, 2, 3, 11, and 12, respectively) with dual COX-2 and 5-LOX inhibitory activity. Two in vitro methods (biopartitioning micellar chromatography (BMC) and PAMPA) were used to evaluate passive gastrointestinal absorption, while high-performance affinity chromatography (HPAC) and differential pulse voltammetry (DPV) were used to evaluate binding to human serum albumin (HSA). The introduction of N-hydroxyurea and hydroxamic acid groups into the structure of NSAIDs decreases both expected passive gastrointestinal absorption (BMC k values were from 3.02 to 9.50, while for NSAIDs were from 5.29 to 13.36; PAMPA –logPe values were between 3.81 and 4.76, while for NSAIDs were ≤3.46) and HSA binding (HPAC logk values were from 2.03 to 9.54, while for NSAIDs were ≥11.03; DPV peak potential shifts were between 7 and 34, while for NSAIDs were ≥54). Structural modifications of all tested compounds that increase lipophilicity could be considered to enhance their passive gastrointestinal absorption. Considering lower expected HSA binding and higher lipophilicity of tested compounds compared to corresponding NSAIDs, it can be expected that the volume of distribution of compounds 1, 2, 3, 11, and 12 will be higher. Reduced HSA binding may also decrease interactions with other drugs in comparison to corresponding NSAIDs. All tested compounds showed significant microsomal instability (25.07–58.44% decrease in concentration) in comparison to indomethacin (14.47%) and diclofenac (20.99%).

PKa values of five β-hydroxy-β-arylalkanoic acids and ibuprofen were determined using the RP-HPLC method. Stationary phase was octadecyl modified (C-18) silica gel, and mobile phase was a mixture of methanol and one of nine different buffers (60:40, v/v). wspH values were measured after mixing methanol with an appropriate buffer. The mean retention time of each compound was plotted against wspH of each mobile phase. The inflection point of each sigmoidal curve represented wspK a of the compound. Using wspK a in already known equations for the specific methanol/buffer mixture, wwpK a values were calculated. Obtained pKa values for synthesized compounds were in a narrow range from 3.34-3.81 and pKa for ibuprofen was 4.45. Predicted pKa values for these compounds in SPARC software showed good correlation with experimental pKa values (R2=0.8048).

The pKa values of twelve ?-hydroxy-?-arylalkanoic acids and ibuprofen were determined using a modified RP-HPLC method. The stationary phase was octadecyl modified (C-18) silica gel, and the mobile phases were mixtures of methanol and one of ten different buffers (60:40 volume ratio). The mean retention time of each compound was plotted against the pH of each of the ten used mobile phases. The inflection point of the obtained sigmoidal curve represents the s w pKa of a compound. Using s w pKa in previously established equations for the specific methanol/buffer mixture, the w w pKa values (in pure water) were calculated. The obtained w w pKa values for the synthesized compounds were in a range from 3.40 to 3.74, and the w w pKa for ibuprofen was 4.27. The Predicted pKa values for this type of compounds in the MarvinSketch 5.11.5. Program were in poor correlation with the experimental results, while in ACD/ /I-Labs pKa values were calculated as a wide range.