DFT study of the radical scavenging activity of isoxanthohumol, humulones (α-acids), and iso-α-acids from beer

Humulones and iso-humulones are potent natural antioxidants found in beer. In this study, density functional theory (DFT) method was applied for elucidating the structure-antioxidant activity relationship and molecular mechanism of antioxidant activity of eight bioactive humulones previously identified in different beer samples: isoxanthohumol, (R)- and (S)-adhumulone, cis- and trans-iso-adhumulone, cis- and trans-iso-n-humulone, and desdimethyl-octahydro-iso-cohumulone. The calculated bond dissociation enthalpies (BDEs) suggest that desdimethyl-octahydro-iso-cohumulone was the most potent compound with BDEs 5.1 and 23.9 kJ/mol lower compared to the values for resveratrol in gas phase and water, respectively. The enolic –OH is the most reactive site for hydrogen atom transfer (HAT). The presence of β-keto group with respect to enolic –OH diminishes the HAT potency via the formation of a strong intramolecular hydrogen bond. Another common antioxidant mechanism, single electron transfer followed by proton transfer (SET-PT), is only feasible for isoxanthohumol. The results of this study indicate a strong correlation between the increased antioxidant activity of beer products and the higher content of reduced iso-α-acids

A prospective, randomized, double-blind, placebo-controlled trial of polyphenols on the outcomes of inflammatory factors and oxidative stress in patients with type 2 diabetes mellitus

Type 2 diabetes mellitus (T2DM) is commonly associated with hyperglycemia, dyslipidemia, oxidative stress and inflammation which are well known cardiovascular risk factors. Pomegranate peel polyphenols have a proven hypolipemic, antioxidant and anti-inflammatory activity. However, there is a lack of clinical studies that would confirm its antioxidant and anti-inflammatory effects in diabetic patients. The potential of pomegranate peel extract (PoPEx) to counteract inflammation and oxidative stress in T2DM patients was investigated. For this purpose, a randomized, double-blind placebo-controlled study involving adult T2DM patients treated with PoPEx or placebo for eight-weeks was conducted. Methods: Patients were randomly divided into two groups: the first group (n = 30) received capsules containing PoPEx 250 mg twice daily, while the placebo group (n = 30) received placebo capsules twice daily. Plasma concentration of inflammatory factors (interleukin 6 (IL-6), tumor necrosis factor α (TNF-α) and high sensitivity C reactive protein (hsCRP)), oxidative stress biomarkers (thiobarbituric acid reactive substances (TBARS), nitrites (NO2−), superoxide anion radical (O2−), hydrogen peroxide (H2O2), total antioxidant capacity (TAC)), homocysteine and lipid profile were analyzed. Results: The PoPEx treatment showed a significant reduction of inflammatory factors (IL-6, TNF-α, hsCRP), oxidative stress biomarkers (TBARS, NO2−, O2−) and homocysteine, while the TAC was increased. Moreover, a significant improvement in lipid profile was observed in the PoPEx group. Additional analysis showed a significant inverse correlation between the decrements of all measured inflammatory markers and TAC in the PoPEx group. Conclusions: The study demonstrated that eight-week-long PoPEx administration had favorable effects on inflammatory status and oxidative stress biomarkers in diabetic patients

Supplementary data for article: Narančić, T.; Kadivojevic, J.; Jovanovic, P.; Francuski, D.; Bigović, M.; Maslak, V.; Savić, V.; Vasiljević, B.; O’Connor, K. E.; Nikodinović-Runić, J. Highly Efficient Michael-Type Addition of Acetaldehyde to Beta-Nitrostyrenes by Whole Resting Cells of Escherichia Coli Expressing 4-Oxalocrotonate Tautomerase. Bioresource Technology 2013, 142, 462–468. https://doi.org/10.1016/j.biortech.2013.05.074

Supplementary material for: [https://doi.org/10.1016/j.biortech.2013.05.074]Related to published version: [http://cherry.chem.bg.ac.rs/handle/123456789/1377

Supplementary data for article: Narančić, T.; Kadivojevic, J.; Jovanovic, P.; Francuski, D.; Bigović, M.; Maslak, V.; Savić, V.; Vasiljević, B.; O’Connor, K. E.; Nikodinović-Runić, J. Highly Efficient Michael-Type Addition of Acetaldehyde to Beta-Nitrostyrenes by Whole Resting Cells of Escherichia Coli Expressing 4-Oxalocrotonate Tautomerase. Bioresource Technology 2013, 142, 462–468. https://doi.org/10.1016/j.biortech.2013.05.074

Supplementary material for: [https://doi.org/10.1016/j.biortech.2013.05.074]Related to published version: [http://cherry.chem.bg.ac.rs/handle/123456789/1377

Highly efficient Michael-type addition of acetaldehyde to beta-nitrostyrenes by whole resting cells of Escherichia coli expressing 4-oxalocrotonate tautomerase

A novel whole cell system based on recombinantly expressed 4-oxalocrotonate tautomerase (4-OT) was developed and shown to be an effective biocatalyst for the asymmetric Michael addition of acetaldehyde to beta-nitrostyrenes. Optimal ratio of substrates (2 mM beta-nitrostyrenes and 20 mM acetaldehyde) and biocatalyst of 5 g of cell dry weight of biocatalyst per liter was determined. Through further bioprocess improvement by sequential addition of substrate 10 mM nitrostyrene biotransformation was achieved within 150 min. Excellent enantioselectivity ( gt 99% ee) and product yields of up to 60% were obtained with beta-nitrostyrene substrate. The biotransformation product, 4-nitro-3-phenyl-butanal, was isolated from aqueous media and further transformed into the corresponding amino alcohol. The biocatalyst exhibited lower reaction rates with p-Cl-, o-Cl- and p-F-beta-nitrostyrenes with product yields of 38%, 51%, 31% and ee values of 84%, 88% and 94% respectively. The importance of the terminal,proline of 4-UT was confirmed by two proline enriched variants and homology modeling.Supplementary material: [http://cherry.chem.bg.ac.rs/handle/123456789/3499