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The present study investigates the effect of strawberry antioxidants in beverage form on meal-induced postprandial inflammatory and insulin responses in human subjects. Overweight adults (n 24) consumed a high-carbohydrate, moderate-fat meal (HCFM) accompanied by either a strawberry or a placebo beverage in a cross-over design. Postprandial changes in plasma anthocyanins, their metabolites, insulin, glucose and inflammatory markers were assessed for 6 h. The postprandial concentrations of pelargonidin sulfate and pelargonidin-3-O-glucoside were significantly increased when the strawberry beverage was consumed concurrently with the HCFM compared with the placebo beverage (P < 0·001). The strawberry beverage significantly attenuated the postprandial inflammatory response as measured by high-sensitivity C-reactive protein and IL-6 (P < 0·05) induced by the HCFM. It was also associated with a reduction in postprandial insulin response (P < 0·05). Collectively, these data provide evidence for favourable effects of strawberry antioxidants on postprandial inflammation and insulin sensitivity.

Background Exposures to ambient particulate matter (PM) are associated with increased morbidity and mortality. PM 2.5 (<2.5 μm) and ozone exposures have been shown to associate with carotid intima media thickness in humans. Animal studies support a causal relationship between air pollution and atherosclerosis and identified adverse PM effects on HDL functionality. We aimed to determine whether brief exposures to PM 2.5 and/or ozone could induce effects on HDL anti-oxidant and anti-inflammatory capacity in humans. Methods Subjects were exposed to fine concentrated ambient fine particles (CAP) with PM 2.5 targeted at 150 μg/m 3 , ozone targeted at 240 μg/m 3 (120 ppb) , PM 2.5 plus ozone targeted at similar concentrations, and filtered air (FA) for 2 h, on 4 different occasions, at least two weeks apart, in a randomized, crossover study. Blood was obtained before exposures (baseline), 1 h after and 20 h after exposures. Plasma HDL anti-oxidant/anti-inflammatory capacity and paraoxonase activity were determined. HDL anti-oxidant/anti-inflammatory capacity was assessed by a cell-free fluorescent assay and expressed in units of a HDL oxidant index (HOI). Changes in HOI (ΔHOI) were calculated as the difference in HOI from baseline to 1 h after or 20 h after exposures. Results There was a trend towards bigger ΔHOI between PM 2.5 and FA 1 h after exposures ( p  = 0.18) but not 20 h after. This trend became significant ( p  <0.05) when baseline HOI was lower (<1.5 or <2.0), indicating decreased HDL anti-oxidant/anti-inflammatory capacity shortly after the exposures. There were no significant effects of ozone alone or in combination with PM 2.5 on the change in HOI at both time points. The change in HOI due to PM 2.5 showed a positive trend with particle mass concentration ( p  = 0.078) and significantly associated with the slope of systolic blood pressure during exposures ( p  = 0.005). Conclusions Brief exposures to concentrated PM 2.5 elicited swift effects on HDL anti-oxidant/anti-inflammatory functionality, which could indicate a potential mechanism for how particulate air pollution induces harmful cardiovascular effects.

Photoenzymes are light-powered biocatalysts that typically rely on the excitation of cofactors or unnatural amino acids for their catalytic activities 1 , 2 . A notable natural example is the fatty acid photodecarboxylase, which uses light energy to convert aliphatic carboxylic acids to achiral hydrocarbons 3 . Here we report a method for the design of a non-natural photodecarboxylase based on the excitation of enzyme-bound catalytic intermediates, rather than reliance on cofactor excitation 4 . Iminium ions 5 , transiently generated from enals within the active site of an engineered class I aldolase 6 , can absorb violet light and function as single-electron oxidants. Activation of chiral carboxylic acids, followed by decarboxylation, generates two radicals that undergo stereospecific cross-coupling, yielding products with two stereocentres. Using the appropriate enantiopure chiral substrate, the desired diastereoisomeric product is selectively obtained with complete enantiocontrol. This finding underscores the ability of the active site to transfer stereochemical information from the chiral radical precursor into the product, effectively addressing the long-standing problem of rapid racemization of chiral radicals. The resulting ‘memory of chirality’ scenario 7 is a rarity in enantioselective radical chemistry. We report a method for the design of a non-natural photodecarboxylase based on the excitation of enzyme-bound catalytic intermediates, rather than reliance on cofactor excitation.

Cytochrome P450 enzymes are known to catalyse bimodal oxidation of aliphatic acids via radical intermediates, which partition between pathways of hydroxylation and desaturation 1 , 2 . Developing analogous catalytic systems for remote C–H functionalization remains a significant challenge 3 – 5 . Here, we report the development of Cu(I)-catalysed bimodal dehydrogenation/lactonization reactions of synthetically common N -methoxyamides through radical abstractions of the γ-aliphatic C–H bonds. The feasibility of switching from dehydrogenation to lactonization is also demonstrated by altering reaction conditions. The use of a readily available amide as both radical precursor and internal oxidant allows for the development of redox-neutral C–H functionalization reactions with methanol as the sole side product. These C–H functionalization reactions using a Cu(I) catalyst with loading as low as 0.5 mol.% is applied to the diversification of a wide range of aliphatic acids including drug molecules and natural products. The exceptional compatibility of this catalytic system with a wide range of oxidatively sensitive functionality demonstrates the unique advantage of using a simple amide substrate as a mild internal oxidant. Use of N -methoxyamides as oxidants enables controllable, redox-neutral, green catalysis of bimodal dehydrogenation/lactonization reactions with methanol as the only by-product.

Flavonoids, a large group of secondary plant phenolic metabolites, are important natural antioxidants and regulators of cellular redox balance. The present study addressed evaluation of the electronic properties of some flavonoids belonging to different classes such as quercetin (flavonols), catechin (flavanols), and naringenin (flavanones) and their interactions with oxidants in model systems of DPPH reduction, flavonoid autoxidation, and chlorination. According to our ab initio calculations, the high net negative excess charges of the C rings and the small positive excess charges of the B rings of quercetin, catechin, and naringenin make these parts of flavonoid molecules attractive for electrophilic attack. The 3′-OH group of the B ring of quercetin has the highest excess negative charge and the lowest energy of hydrogen atom abstraction for the flavonoids studied. The apparent reaction rate constants (s−1, 20 °C) and the activation energies (kJ/mol) of DPPH reduction were 0.34 ± 0.06 and 23.0 ± 2.5 in the case of quercetin, 0.09 ± 0.02 and 32.5 ± 2.5 in the case of catechin, respectively. The stoichiometry of the DPPH–flavonoid reaction was 1:1. The activation energies (kJ/mol) of quercetin and catechin autoxidations were 50.8 ± 6.1 and 58.1 ± 7.2, respectively. Naringenin was not oxidized by the DPPH radical and air oxygen (autoxidation) and the flavonoids studied effectively prevented HOCl-induced hemolysis due to direct scavenging of hypochlorous acid (flavonoid chlorination). The best antioxidant quercetin had the highest value of HOMO energy, a planar structure and optimal electron orbital delocalization on all the phenolic rings due to the C2=C3 double bond in the C ring (absent in catechin and naringenin).

Functionalization of the β-C–H bonds of aliphatic acids is emerging as a valuable synthetic disconnection that complements a wide range of conjugate addition reactions 1 – 5 . Despite efforts for β-C–H functionalization in carbon–carbon and carbon–heteroatom bond-forming reactions, these have numerous crucial limitations, especially for industrial-scale applications, including lack of mono-selectivity, use of expensive oxidants and limited scope 6 – 13 . Notably, the majority of these reactions are incompatible with free aliphatic acids without exogenous directing groups. Considering the challenge of developing C–H activation reactions, it is not surprising that achieving different transformations requires independent catalyst design and directing group optimizations in each case. Here we report a Pd-catalysed β-C( sp 3 )–H lactonization of aliphatic acids enabled by a mono- N -protected β-amino acid ligand. The highly strained and reactive β-lactone products are versatile linchpins for the mono-selective installation of diverse alkyl, alkenyl, aryl, alkynyl, fluoro, hydroxyl and amino groups at the β position of the parent acid, thus providing a route to many carboxylic acids. The use of inexpensive tert -butyl hydrogen peroxide as the oxidant to promote the desired selective reductive elimination from the Pd( iv ) centre, as well as the ease of product purification without column chromatography, render this reaction amenable to tonne-scale manufacturing. Pd-catalysed β-C( sp 3 )–H lactonization of aliphatic acids enabled by a mono- N -protected β-amino acid and tert -butyl hydrogen peroxide is reported, achieving high β-position selectivity without the use of a directing group.

The link between mucus plugs and airflow obstruction has not been established in chronic severe asthma, and the role of eosinophils and their products in mucus plug formation is unknown. In clinical studies, we developed and applied a bronchopulmonary segment-based scoring system to quantify mucus plugs on multidetector computed tomography (MDCT) lung scans from 146 subjects with asthma and 22 controls, and analyzed relationships among mucus plug scores, forced expiratory volume in 1 second (FEV1), and airway eosinophils. Additionally, we used airway mucus gel models to explore whether oxidants generated by eosinophil peroxidase (EPO) oxidize cysteine thiol groups to promote mucus plug formation. Mucus plugs occurred in at least 1 of 20 lung segments in 58% of subjects with asthma and in only 4.5% of controls, and the plugs in subjects with asthma persisted in the same segment for years. A high mucus score (plugs in ≥ 4 segments) occurred in 67% of subjects with asthma with FEV1 of less than 60% of predicted volume, 19% with FEV1 of 60%-80%, and 6% with FEV1 greater than 80% (P < 0.001) and was associated with marked increases in sputum eosinophils and EPO. EPO catalyzed oxidation of thiocyanate and bromide by H2O2 to generate oxidants that crosslink cysteine thiol groups and stiffen thiolated hydrogels. Mucus plugs are a plausible mechanism of chronic airflow obstruction in severe asthma, and EPO-generated oxidants may mediate mucus plug formation. We propose an approach for quantifying airway mucus plugging using MDCT lung scans and suggest that treating mucus plugs may improve airflow in chronic severe asthma. Clinicaltrials.gov NCT01718197, NCT01606826, NCT01750411, NCT01761058, NCT01761630, NCT01759186, NCT01716494, and NCT01760915. NIH grants P01 HL107201, R01 HL080414, U10 HL109146, U10 HL109164, U10 HL109172, U10 HL109086, U10 HL109250, U10 HL109168, U10 HL109257, U10 HL109152, and P01 HL107202 and National Center for Advancing Translational Sciences grants UL1TR0000427, UL1TR000448, and KL2TR000428.

Ascorbic acid (AscH2) is one of the most important vitamins found in the human diet, with many biological functions including antioxidant, chelating, and coenzyme activities. Ascorbic acid is also widely used in medical practice especially for increasing iron absorption and as an adjuvant therapeutic in iron chelation therapy, but its mode of action and implications in iron metabolism and toxicity are not yet clear. In this study, we used UV–Vis spectrophotometry, NMR spectroscopy, and EPR spin trapping spectroscopy to investigate the antioxidant/pro-oxidant effects of ascorbic acid in reactions involving iron and the iron chelator deferiprone (L1). The experiments were carried out in a weak acidic (pH from 3 to 5) and neutral (pH 7.4) medium. Ascorbic acid exhibits predominantly pro-oxidant activity by reducing Fe3+ to Fe2+, followed by the formation of dehydroascorbic acid. As a result, ascorbic acid accelerates the redox cycle Fe3+ ↔ Fe2+ in the Fenton reaction, which leads to a significant increase in the yield of toxic hydroxyl radicals. The analysis of the experimental data suggests that despite a much lower stability constant of the iron–ascorbate complex compared to the FeL13 complex, ascorbic acid at high concentrations is able to substitute L1 in the FeL13 chelate complex resulting in the formation of mixed L12AscFe complex. This mixed chelate complex is redox stable at neutral pH = 7.4, but decomposes at pH = 4–5 during several minutes at sub-millimolar concentrations of ascorbic acid. The proposed mechanisms play a significant role in understanding the mechanism of action, pharmacological, therapeutic, and toxic effects of the interaction of ascorbic acid, iron, and L1.

An electrochemical C–H oxidation strategy that exhibits broad substrate scope, operational simplicity and high chemoselectivity is described; it uses inexpensive and readily available materials and represents a scalable allylic C–H oxidation that could be adopted in large-scale industrial settings without substantial environmental impact. Electrical allylic C–H oxidation Allylic C–H oxidation has been used widely in the syntheses of natural product variants, medicines and new materials. One disadvantage of the reaction is that it requires highly toxic reagents or expensive catalysts. In this manuscript, the authors describe an electrochemical alternative to conventional allylic oxidation. The new method utilizes inexpensive and readily available materials, has broad substrate scope, operational simplicity, and high chemoselectivity, all with minimal environmental impact. New methods and strategies for the direct functionalization of C–H bonds are beginning to reshape the field of retrosynthetic analysis, affecting the synthesis of natural products, medicines and materials 1 . The oxidation of allylic systems has played a prominent role in this context as possibly the most widely applied C–H functionalization, owing to the utility of enones and allylic alcohols as versatile intermediates, and their prevalence in natural and unnatural materials 2 . Allylic oxidations have featured in hundreds of syntheses, including some natural product syntheses regarded as “classics” 3 . Despite many attempts to improve the efficiency and practicality of this transformation, the majority of conditions still use highly toxic reagents (based around toxic elements such as chromium or selenium) or expensive catalysts (such as palladium or rhodium) 2 . These requirements are problematic in industrial settings; currently, no scalable and sustainable solution to allylic oxidation exists. This oxidation strategy is therefore rarely used for large-scale synthetic applications, limiting the adoption of this retrosynthetic strategy by industrial scientists. Here we describe an electrochemical C–H oxidation strategy that exhibits broad substrate scope, operational simplicity and high chemoselectivity. It uses inexpensive and readily available materials, and represents a scalable allylic C–H oxidation (demonstrated on 100 grams), enabling the adoption of this C–H oxidation strategy in large-scale industrial settings without substantial environmental impact.

The direct hydroxylation of arene C–H bonds is a highly sought-after transformation but remains an unsolved challenge due to the difficulty in efficient and regioselective C–H oxygenation and high reactivity of the phenolic products leading to overoxidation. Herein we report electrochemical C–H hydroxylation of arenes in continuous flow for the synthesis of phenols. The method is characterized by broad scope (compatible with arenes of diverse electronic properties), mild conditions without any catalysts or chemical oxidants, and excellent scalability as demonstrated by the continuous production of 1 mol (204 grams) of one of the phenol products. The direct hydroxylation of arene C–H bonds is a highly sought-after transformation but with little literature precedent. Herein the authors report a scalable electrochemical C–H hydroxylation of arenes in continuous flow for the synthesis of phenols.