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Samwirin A (SW), a natural compound isolated from Sambucus williamsii or Rourea harmandiana, is known to exhibit potent antiosteoporosis activity and promote cell proliferation in rat osteoblast-like UMR 106 cells. Antiosteoporosis activity suggests that the compound must also exhibit antioxidant activity but this has not been studied thus far. In the present study, the antioxidant activity of SW was examined by experimental and computational studies. It was found that SW exhibits good hydroperoxyl scavenging activity, particularly in water at physiological pH (koverall = 1.01 × 107 M–1 s–1). The single-electron transfer mechanism defines the HOO• + SW reaction in water, while the activity in the lipid medium is moderate and it follows the formal hydrogen transfer mechanism. The rate constant of the HOO• scavenging reaction in the aqueous solution is about 78 times higher than the reference compound Trolox. The computational results are in line with experimental data underscoring that SW is a promising radical scavenger in aqueous media at physiological pH.

Muriolide (MO) is a natural lactone that was isolated from Ranunculus muricatus. This compound exhibited good antioxidant activity in some experiments; however, the radical scavenging activity of MO in physiological environments has not been studied yet. In this study, the reaction between hydroperoxyl radical and MO was investigated in physiological environments by using density functional theory (DFT) calculations. It was found that MO exhibits excellent antiradical activity in water at physiological pH (k = 1.05 × 108 M−1 s−1) by the single electron transfer mechanism of the anion state. However, the activity in lipid media is moderate with k = 2.54 × 104 M−1 s−1 and is defined by the formal hydrogen transfer pathway. The antiradical reactions can occur in double processes; however, the first reaction may define the HOO˙ radical scavenging activity of MO. Compared with typical natural antioxidants, the antiradical activity of MO against HOO˙ radicals is slightly lower than Trolox in pentyl ethanoate. However, the activity of MO is approximately 808 times faster than that of the reference in aqueous solution. Thus, the data suggest that MO is a promising natural radical scavenger in the physiological environment.

Coumarins are important chemical precursors for the synthesis of anticoagulants used as human medicines as well as rodenticides. Environmental discharge of these coumarin derivatives, commonly known as 4-hydroxycoumarins, is therefore a major concern. Advanced oxidative processes (AOP) are radical reactions of toxic contaminants with environmental free radicals, ideally leading to less toxic products. Therefore, the study of these processes is of key importance for a better understanding of the chemical transformations and long term environmental effect of toxic discharges. Here the AOP of the unsubstituted 4-Hydroxycoumarin (4HC), the parent compound of the drugs and pesticides, is studied with HO˙ radical in aqueous and lipidic environments, using quantum chemical methods. Two reaction steps were modelled by considering the fundamental radical reactions of phenolic compounds as established before. Particular attention is paid to the reactions in aqueous environment. Thermodynamic and kinetic calculations were performed, assessing the likelihood and contribution of each possible reaction path to yield the most likely products. Previous works on AOP of 4HC neglected the deprotonation of the acidic moiety and the diffusion limits of the solvent. Here these points are addressed, predicting a different set of intermediate and final products. Toxicity tests predict that the main products are less toxic than 4HC. Our results demonstrate the importance of aqueous environment in the chemical fate of toxins in the environment.

Artepillin C (AC) is a natural prenylated phenolic compound present in propolis produced by honey bees in Brazil, which was reported to exhibit a variety of biological activities. In the present study we report a systematic thermodynamic and kinetic investigation on the hydroperoxyl (HOO˙) scavenging activity and mechanism of AC using DFT calculations. Different reaction mechanisms have been investigated at all the possible active sites of AC in the gas phase and in physiological environments. Based on the results, AC is predicted to exhibit excellent HOO˙ radical scavenging in aqueous solution with koverall = 7.44 × 107 M−1 s−1. Its activity is significantly lower in the gas phase and lipid environment. Single electron transfer was found to be the main antiradical mechanism in the aqueous solution at pH = 7.4, dominated by the dianion state of AC. The overall rate coefficient of HOO˙ radical scavenging of AC in water is about 572 times higher than that of Trolox. This suggests that AC is a potent HOO˙ radical scavenger in water.

Conjugated linoleic acid (CLA) have been shown to exert numerous health benefits, including anti-carcinogenic, anti-atherogenic, anti-diabetic, antiobesity, cholesterol reducing, antioxidant, anti-microbial, immune system modulator and growth-stimulating properties. In human, CLA is produced from Linoleic acid (LA) by gut bacteria. In this study, nineteen Lactobacillus (Lac.) strains isolated from human feces were studied to determine their ability to metabolize LA. The bacteria were grown in the liquid form of anaerobic MRS medium supplemented with 0.5 mg/mL LA. The linoleate isomerase activity in bacteria grown on MRS medium was determined by Gas chromatograpy. The results indicated that 4 out of 19 strains, including strains Lac.02, Lac.05, Lac.14 and Lac.16 are capable of producing about 40-50 μg/mL CLA from LA. Among them, the highest ability to produce CLA from LA is Lac.02 strain. In the production of CLA from LA, enzymes involved in this metabolism in Lactobacillus act as catalysts of hydration/dehydration (CLA-HY), oxidation of hydroxy groups/reduction of oxo groups (CLA-DH), migration of carbon-carbon double bonds (CLA-DC), and saturation of carbon-carbon double bonds (CLA-ER). The cla-dh, cla-dc, cla-hy and cla-er genes that encode enzymes CLA-DH, CLA-DC, and CLA-ER had been found in all Lac.02, Lac.05, Lac.14 and Lac.16 strains. Gas chromatography traces indicated that these strains produced the same compounds, which was subsequently identified as cis-9, trans-11, and trans-10, cis-12 CLA. In the next study, we will optimize the conditions such as substrate concentrations, pH values, temperature and culture time of each strain to obtain the best rerults.

Usnic acid (UA) is a natural product found in the lichen genera. Because of the phenolic groups in its structure, UA is suspected to be an antioxidant. Therefore, in this study, the radical scavenging of UA was investigated in physiological environments in silico by using kinetic calculations. It was found that the overall rate constant for the hydroxyl radical scavenging activity was approximately 109 M–1 s–1 in all environments, whereas the HOO• and CH3OO• radical scavenging activities were only significant in the polar environments with k in the range of 103–104 M–1 s–1. The results also revealed that the HO• scavenging activity followed the single electron transfer (SET) and radical adduct formation mechanisms; however, the SET pathway (for the dianion HU2–) played a dominant role in the scavenging of other studied radicals, including CH3O•, CCl3O•, CCl3OO•, NO2, SO4•–, and N3•. The activity of UA against these radicals was as high as that of typical phenolic acids such as ferulic acid, p-coumaric acid, caffeic acid, dihydrocaffeic acid, and sinapinic acid (kf ∼ 108 M–1 s–1) in polar solvents. Thus, UA is a promising natural antioxidant in aqueous environments.

Depsidones are secondary metabolites in lichens with a range of potential health benefits. Among others, these compounds are believed to exhibit high hydroxyl radical and superoxide scavenging abilities, warranting a detailed investigation of their antioxidant properties. In this study, the radical scavenging activity of natural depsidones from Ramalina lichenized fungi was investigated in silico. Calculations of the thermodynamic parameters suggested that the main radical scavenging pathway follows the formal hydrogen transfer (FHT) mechanism; however, unexpectedly low rate constants were found in the CH3OO• scavenging reaction. Establishing that the depsidones are mostly ionized in an aqueous environment suggested that the single-electron transfer (SET) mechanism should not be ruled out. Consistently, depsidones were revealed to be excellent HO• and O2•– scavengers in aqueous solutions (k = 4.60 × 105 – 8.60 × 109 M–1 s–1 and k = 2.60 × 108 – 8.30 × 109 M–1 s–1, respectively) following the sequential proton loss electron transfer (SPLET) mechanism. These results suggest that natural fungal depsidones are potent hydroxyl and superoxide radical scavengers in aqueous solutions.

5-Hydroxymethylfurfural (HMF) is a natural product derived from the degradation of sugars in e.g. milk, honey and raisins. Recent studies have shown that this compound has several beneficial physiological effects including antioxidant activity. In the present paper, the antiradical properties of 5-HMF were systematically investigated by using the M06-2X/6-311++G(d,p) model chemistry in the gas phase, in water solution and, for a lipid-mimetic environment, in pentyl ethanoate solvent. The thermodynamic and kinetic modelling of the reactions of 5-HMF with a range of reactive oxidative species revealed that 5-HMF scavenges HO˙ and HOO˙ radicals. The overall rate constants for the HO˙ radical scavenging in the gas phase and water and pentyl ethanoate solvents are 2.39 × 1012, 5.92 × 109 and 5.28 × 109 M−1 s−1, respectively, whereas those for the HOO˙ radical scavenging in these environments are low with k = 1.27 × 102, 12.1 and 5.48 M−1 s−1, respectively. The radical adduct formation mechanism plays an important role in the reactions of 5-HMF with HO˙ radicals in all of the studied media.

Diterpenes that were isolated from Crossopetalum gaumeri (Loes.) Lundell (Celastraceae) plants are reported to exhibit a range of biological activities, in particular as radical scavengers. Thus further insight into the antioxidant activity of diterpenes in physiological environments is much needed but not studied yet. In this study, the antioxidant activity of nine natural diterpenes was evaluated using kinetic and thermodynamic calculations. It was found that the sequential proton loss electron transfer (SPLET) mechanism is favored in polar environments, whereas formal hydrogen transfer (FHT) is the main pathway for the radical scavenging of these diterpenes in the gas phase as well as in lipid media. The rate constants for the HOO˙ radical scavenging of these compounds in the gas phase, polar and nonpolar solvents are in the range of 2.29 × 10−2 to 4.58 × 107, 9.74 × 10−3 to 1.67 × 108 and 3.54 × 10−5 to 1.31 × 105 M−1 s−1, respectively. 7-Deoxynimbidiol (6), exhibits the highest HOO˙ radical scavenging with koverall = 1.69 × 108 M−1 s−1 and 9.10 × 104 M−1 s−1 in water and pentyl ethanoate solvents, respectively, that is about 1300 times higher than that of Trolox in polar environments. It is thus a promising natural antioxidant in physiological environments.

The HOO• and O2•− scavenging activities of 12 natural anthocyanidins were investigated in physiological environments by using DFT calculations. The results suggest high HOO• scavenging activity in aqueous medium with overall rate constants in the range of koverall = 1.58 × 108 − 7.59 × 109 M−1 s−1, whereas in lipid medium only weak activity is predicted. O2•− scavenging is also fast in water with kapp = ∼109 M−1 s−1. Like in the case of many other antioxidants that contain acidic moieties, the anion states (H3A− and H2A2−) and the single electron transfer mechanism play a dominant role in the HOO• scavenging activity of anthocyanidins in water at pH = 7.4. Analysis of the mechanism suggests that the O2•− and HOO• radical scavenging can occur as a regeneration cycle that might increase the protective efficiency of anthocyanidins against oxidative stress.

Sulfuretin (SFR), which is isolated fromRhus verniciflua,Toxicodendron vernicifluum, Dahlia, Bidens tripartiteandDipterx lacunifera, is one of the most important natural flavonoids. This compound is known to have numerous biological activities; among these, the antioxidant activity has not been thoroughly studied yet. In this study, the hydroperoxyl scavenging activity of SFR was examined by using density functional theory calculations. SFR is predicted to be an excellent HOO•scavenger in water at pH = 7.40 withkoverall= 4.75 × 107M−1s−1, principally due to an increase in the activity of the anionic form following the single-electron transfer mechanism. Consistently, the activity of the neutral form is more prominent in the non-polar environment withkoverall= 1.79 × 104M−1s−1following the formal hydrogen transfer mechanism. Thus, it is predicted that SFR exhibits better HOO•antiradical activity than typical antioxidants such as resveratrol, ascorbic acid or Trolox in the lipid medium. The hydroperoxyl radical scavenging of SFR in the aqueous solution is approximately 530 times faster than that of Trolox and similar to ascorbic acid or resveratrol. This suggests that SFR is a promising radical scavenger in physiological environments.

Fraxin (FX) (7-hydroxy-6-methoxycoumarin 8-glucoside) is a typical natural product of the coumarin family. This compound was shown to protect endothelial cells from oxidative stress; however, the nature of its antioxidant properties is still ambiguous. In this study, we report on a systematic evaluation of the radical scavenging activity of FX using a two-tier protocol based on thermodynamic and kinetic calculations. The results show that FX has moderate activity in the aqueous physiological environment against a range of radicals including HO˙, CCl3O˙, CCl3OO˙, NO2, , and HOO˙. The latter was examined in detail due to the prevalence of HOO˙ as a source of oxidative stress in biological systems. HOO˙ scavenging activity was promising in the gas phase but low in physiological environments with koverall = 1.57 × 106, 3.13 × 102 and 2.68 × 103 M−1 s−1 in the gas phase, pentyl ethanoate and water solvents, respectively. The formal hydrogen transfer mechanism at the O7–H bond dominates the hydroperoxyl radical scavenging of FX in the nonpolar media, whereas, in the polar environment, the activity is exerted by the single electron transfer mechanism of the anion state. This activity falls behind typical antioxidants such as Trolox, ascorbic acid, and trans-resveratrol under the studied conditions. Thus FX may have multiple health benefits, but it is not an outstanding natural antioxidant.

Syringic acid (SA) is a natural phenolic acid found in vegetables, fruits, and other plant-based foods. A range of biological activities were proposed for this compound including anticancer, antimicrobial, anti-inflammation, and anti-diabetic activities, as well as antioxidant and antinitrosant properties. In this study, the focus is on the latter two. The HO•, HOO•, NO, and NO2 scavenging activities of SA were evaluated in physiological environments by kinetic and thermodynamic calculations. The computed rate constants of the HO• radical scavenging of SA were 4.63 × 109 and 9.77 × 107 M-1 s-1 in polar and nonpolar solvents, respectively. A comparison with the experimentally determined rate constant in aqueous solution yields a kcalculated/kexperimental ratio of 0.3, thus the computed kinetic data are reasonably accurate. SA exhibited excellent HOO• and NO2 scavenging activity in water (koverall(HOO•) = 1.53 × 108 M-1 s-1 and koverall(NO2) = 1.98 × 108 M-1 s-1), whereas it did not show NO scavenging activity in any of the studied environments. In lipid medium, SA exhibited weak activity. Thus, in polar environments, the HOO• radical scavenging of SA is 1.53 times higher than that of ascorbic acid. Consistently, SA is a promising antioxidant and antinitrosant agent in polar environments.

Moracins are natural products that have been isolated from different plants such as Artocarpus heterophyllus, Cassia fistula, Morus alba, and Morus mesozygia. Studies showed that moracins may have various advantageous physiological effects such as anticancer, anti-inflammatory, anticholinesterase and particularly antioxidant activities. Most of these bioactivities have not been studied systematically. In this study, the radical scavenging of a typical moracin (moracin M, MM) against HO˙ and HOO˙ radicals was evaluated by thermodynamic and kinetic calculations in the gas phase as well as in water and pentyl ethanoate solvents. It was found that the overall rate constants for the HO˙ radical scavenging in the gas phase and the physiological environments are in the range of 1011 to 1010 M−1 s−1, respectively. For the HOO˙ + MM reaction the rate constants are 4.10 × 107 and 3.80 × 104 M−1 s−1 in the polar and lipid media, respectively. It is important to notice that the single electron transfer pathway of the anion state (MM–O6′−) dominated the HOO˙ radical scavenging in the aqueous solution, whereas in lipid medium the neutral MM exerted its activity by the formal hydrogen transfer mechanism. The HOO˙ radical scavenging of MM is comparable to that of Trolox in lipid medium, whereas it is 315.4 times more active in the polar environment.

Novel hydroanthraquinones isolated from marine algal-derived endophytic fungus Talaromyces islandicus EN-501 exhibited promising antioxidant properties in preliminary studies, raising the prospect of adapting these compounds for therapeutic use in diseases caused by oxidative stress. For medicinal applications it is beneficial to develop a full understanding of the antioxidant activity of these compounds. In this study, the hydroperoxide radical scavenging activity of five natural hydroanthraquinones was evaluated by kinetic and thermodynamic calculations. The results showed that the radical scavenging of these hydroanthraquinones in the gas phase and in lipid solvents was defined by the formal hydrogen transfer mechanism, that for the polar environments was decided by the sequential proton loss electron transfer pathway. The hydroanthraquinones exhibited good hydroperoxide scavenging activity in both polar and non-polar media. The overall rate constant values for the radical scavenging reaction were in the range of 3.42 × 101 to 2.60 × 105 M−1 s−1 and 3.80 × 106 to 5.87 × 107 M−1 s−1 in pentyl ethanoate and water solvents, respectively. Thus the activity of 8-hydroxyconiothyrinone B (1) is about 2.6 and 444.6 times higher than that of Trolox in the studied solvents, identifying 8-hydroxyconiothyrinone B as a promising antioxidant.

In this study, cobalt ferrite coated carbon felt (CoFe2O4/CF) was synthesized by solvothermal method and applied as cathode for electro-Fenton (EF) treatment of tartrazine (TTZ) in water. The materials were characterized by SEM, XRD, FTIR, CV, and EIS to explore their physical, chemical, and electrical properties. The effects of solvothermal temperature and metal content on the TTZ removal were examined, showing that 220 °C with 2 mM of Co and 4 mM of Fe precursors were the best synthesis condition. Various influencing factors such as applied current density, pH, TTZ concentration, and electrolytes were investigated, and the optimal condition was found at 8.33 mA cm−2, pH 3, 50 mgTTZ L−1, and 50 mM of Na2SO4, respectively. By radical quenching test, , 1O2, and HO were recognized as the key reactive oxygen species and the reaction mechanism was proposed for the EF decolorization of TTZ using CoFe2O4/CF cathode. The reusability and stability test showed that the highly efficient CoFe2O4/CF cathode is very promising for practical application in wastewater treatment, especially for dyes and other recalcitrant organic compounds to improve its biodegradability.

Iminostilbene (IS) (5H‐dibenz[b,f]azepine) is a common polymerization inhibitor used in industrial processes to control radical polymerization reactions. Here a library of 90 monosubstituted IS derivatives was screened in silico to establish an activity scale for radical scavenging. Substituents on the aromatic rings had only weak effect on bond dissociation energies of the N-H moiety; however, ionization energies were much more affected. Thus the IS derivatives 3-NMe2-IS, 1-OH-IS, and 10-OH-IS are predicted to be potent radical scavengers in organic solvents suitable for capturing radicals in polymerization reactions and improving polymer stability.

Abietanes are natural products that were isolated from Salvia clinopodioides. In this work, the HOO scavenging activity of ten abietanes was thoroughly evaluated by using computational methods for the first time. It was found that the studied abietanes could exhibit moderate HOO scavenging activity. Considerable antioxidant activity of the abietanes was only predicted in the aqueous solution and not in lipidic environments. Among the studied compounds, aldehyde (10) exhibited the highest HOO radical scavenging activity in the aqueous solution (koverall = 3.72 × 108 M−1s−1) that is higher than the reference natural antioxidants Trolox, trans-resveratrol, and ascorbic acid.

Iminostilbene (IS) (5H‐dibenz[b,f]azepine) is frequently used as a polymerization inhibitor to stop the reactions of radical polymerization. The compound itself is considered an antioxidant; however, little is known about the mechanism and kinetics of its activity. In this study, the antiradical activity of IS against typical radicals i.e. HO•, HOO• and TBO• (tert-butoxy radical) has been evaluated by computational methods. It was found that IS exhibits excellent HO• and TBO• scavenging activity in gas phase and in lipid-mimetic environment (benzene), whereas its activity against HOO• is moderate with koverall = ~ 104 M−1 s−1. The overall rate constants of the HO• antiradical activity are koverall = 7.06 × 1011 and 7.20 × 109 M−1 s−1 in gas phase and benzene, respectively, whereas for the TBO• antiradical activity in benzene it is 2.10 × 108 M−1 s−1. Comparison with the experimentally determined rate constant in benzene (k(BTO•) = 7.8 × 108 M−1s−1) yields the kcalculated/kexperimetal ratio of 0.3; thus, the computed kinetic data are reasonably accurate. It was shown that the TBO• and HOO• radicals scavenging of IS mostly follows the FHT mechanism at the N H bond; however, in case of the HO• radical both FHT (at N H bond) and RAF (at C10 position) mechanisms contribute to the observable activity.

Bacillus thuringiensis strains were isolated from sugarcane farming soil in three provinces of northern Vietnam. Of these, 24 strains were identified as serotype H5a, 5b, B. thuringiensis serovar galleriae. A strain, namely MHB11.3 (deposited in GenBank: FN796428) belonging to the serovar galleriae, was highly toxic to larvae of the scarab beetles, Anomala cuprea and Cotinis nitida (Coleoptera: Scarabaeidae). A 2-kb DNA fragment, obtained by PCR from the strain MHB11.3 using cry8 specific primers, namelycry8Dat (truncated cry8Da gene), was cloned and expressed in Escherichia coli. The sequence of the cry8Dat from B. thuringiensis serovar galleriae MHB11.3 showed almost complete identity (99%) to that of B. thuringiensis serovar galleriae SDS502 (GenBank: AB089299), differs only by two nucleotides (positions A26G; A1493T), leading to 2 amino acid changes (Y9C and N498I). The recombinant protein pET32a(+)-Cry8Dat of 96 kDa molecular weight was purified by Ni(2+) affinity chromatography. This polypeptide was tested to be toxic to A. cuprea and C. nitida. The amino acid change (Y9C) is located in a region responsible for the host specificity of the Cry8Da toxin. The strain B. thuringiensisserovar galleriae MHB11.3 harboring cry8Da gene as characterized in this study is a promising candidate as a biopesticide and suggested as an important genetic material for gene transfer into sugarcane for scarab beetle control. Key words: Bacillus thuringiensis serovar galleriae, Coleoptera, cry8Da gene, Anomala cuprea, Cotinis nitida.

A glucomannan has been isolated from the tuber of amorphophallus panomensis by a simple method without using toxic chemicals. The weight content of the glucomannan was about 4% of original amorphophallus tuber. The structure of the glucomannan was investigated by infrared (IR) and nuclear magnetic resonance spectroscopy (NMR). The results showed that the structural component of the glucomannan was consisted of mannose and glucose units with the mannose/glucose ratio was about 1.00/0.13. The degree of crystalation and molecular weight of the glucomannan were also investigated by XRD diffraction and viscosimetry, respectively. The results indicated that the glucomannan was amorphous and molecular weight was Mv = 1.2´106Da.

Antimicrobials are extensively used as growth promoters in animal feeds worldwide, but reliable estimates are lacking. We conducted an internet-based survey of commercial chicken and pig feed products officially approved for sale in Vietnam over the period March-June 2015. Information on the antimicrobial contents in feed products, alongside animal production data, was used to estimate in-feed antimicrobial consumption to produce one kilogram of live animal (chicken, pig), as well as to estimate country-wide antimicrobial consumption through animal feeds. A total of 1462 commercial feed formulations were examined. The survey-adjusted estimated antimicrobial contents were 25.7 and 62.3 mg/kg in chicken and pig feeds, respectively. Overall, it was estimated that 77.4 mg [95% CI 48.1-106.8] and 286.6 mg [95% CI 191.6-418.3] of in-feed antimicrobials were used to raise 1 kg of live chicken and pig, respectively. Bacitracin (15.5% feeds), chlortetracycline (11.4%), and enramycin (10.8%) were the most common antimicrobials present in chicken feed formulations, whereas bacitracin (24.8%), chlortetracycline (23.9%), and florfenicol (17.4%) were the most common in pig feed formulations. Overall, 57% of the total quantitative usage consisted of antimicrobials regarded by WHO of importance for human medicine, including amoxicillin, colistin, tetracyclines, neomycin, lincomycin, and bacitracin. These figures confirm a very high magnitude of in-feed consumption of antimicrobials, especially in pig production. Results from this study should encourage further monitoring of antimicrobials used in animal production, and foster discussion about existing policies on inclusion of antimicrobials in animal feed rations.