Photostabilising action of Zn and Ni salts of 3,5-DI-t.-butyl-4-hydroxybenzoic acid in polypropylene

The photostabilising action of two metal chelates of the commercial antioxidant Shell acid (3,5-di-t.-butyl-4-hydroxybenzoic acid) viz. its zinc and nickel salts, is examined, using i.r. and derivative u.v.-visible spectroscopy and hydroperoxide analysis. The polymeric matrix was commercial polypropylene. The results show that both salts operate by inhibiting hydroperoxide formation during melt processing and thermo-oxidative conditions. The latter effect is attributed to a chain breaking donor mechanism which terminates, not alkylperoxyl, but macroalkyl radicals. Both salts are relatively efficient photostabilisers when compared with the parent antioxidant, probably because of their good photostability to both polychromatic and monochromatic radiation. The latter also shows that the nickel salt may also operate by scavenging alkoxyl and hydroxyl radicals during photo-oxidation. The addition of calcium stearate in conjunction with the salts produces some interesting effects which are explained in terms of metal exchange.     

Solid-state polymerization of acrylamide and its derivatives complexed with some lewis acids. II. Radiation-induced in-source polymerization

Radiation-induced solid-state polymerizations of complexes of N-tert-butylacrylamide, N-tert-amylacrylamide, and N-tert-hexylacrylamide with zinc chloride and zinc bromide have been studied. An accelerating effect of temperature and an inhibiting effect of oxygen on the polymerization process were observed. The activation energies have been established. The influence of monomer structure as well as the halide used on the polymerization rate have been discussed and some regularities have been pointed out. The polymers obtained show good solubilities in common solvents, which proves that they are not crosslinked.     

Performance of a phenolic antioxidant introduced by different procedures into polyethylene containing dispersed fillers

The performance of Irganox 1010 phenolic antioxidant was studied in relation to the procedure of its introduction into a stock of the polymer and dispersed filler powders. Three procedures were used for introducing the antioxidant: the antioxidant was deposited onto the surface of filler (procedure I) or polymer powder (procedure II) particles prior to mixing the components, or it was deposited after mixing the polymer and filler powders (procedure III). We studied mixtures with an inert filler (aluminum oxide) and with fillers active in polymer oxidation and regeneration of the phenolic antioxidant (dispersed zinc, zinc oxide). The film samples for the studies were prepared from powder stocks by hot pressing. The antioxidant performance was evaluated by the induction period of oxidation, which was determined from the time dependences of accumulation of carbonyl groups in the polymer structure.     

Evaluation of antioxidant and immunity-enhancing activities of Sargassum pallidum aqueous extract in gastric cancer rats

The effect of Sargassum pallidum (brown seaweed) aqueous extract on the immunity function and antioxidant activities in was studied gastric cancer rats. Treatment with Sargassum pallidum aqueous extract at oral doses 400, 600 or 800 mg/kg body weight was found to provide a dose-dependent protection against N-methyl-N′-nitro-Nnitrosoguanidine (MNNG)-induced immunity damage and oxidative injury by enhancing serum interleukin-2 (IL-2), interleukin-4 (IL-4), interleukin-10 (IL-10) levels, decreasing interleukin-6 (IL-6), interleukin-1β (IL-1β), tumor necrosis factor-alpha (TNF-α) levels, preserving normal antioxidant enzymes activities, and by inhibiting lipid peroxidation in gastric mucosa. It can be concluded that Sargassum pallidum aqueous extract may enhance the immunity and antioxidant activities in gastric cancer rats.     

Piperine loaded zinc oxide nanocomposite inhibits the PI3K/AKT/mTOR signaling pathway via attenuating the development of gastric carcinoma: In vitro and in vivo studies

Gastric cancer (GC) is the fifth most cancer type and the third most cause of cancer-associated deaths worldwide along with the 5-year survival rate is less the 30%. This investigation was aimed to synthesis the piperine-loaded zinc oxide nanocomposite (ZnO-Pip-NC) and investigating its anticancer activity against the GC by in vitro and in vivo models by the inhibiting the apoptotic and PI3K/Akt/mTOR signaling pathways. The synthesized ZnO-Pip-NC was characterized by different techniques. The cytotoxicity of zinc oxide, piperine and the formulated ZnO-Pip-NC was tested against the AGS cells by MTT assay. The intracellular ROS level, mitochondrial membrane potential, and apoptotic cell necrosis in the AGS cells was examined by fluorescent staining techniques. The expression of apoptotic and PI3K/Akt/mTOR signaling markers were inspected by western blotting and the expression of pro0inflammatory markers analyzed by RT-PCR technique. The antioxidant levels were examined by standard methods and histopathology of gastric mucosa was analyzed. The ZnO-Pip-NC treatment appreciably inhibited the AGS cell viability. ZnO-Pip-NC treated cells also exhibited excessive intracellular ROS, diminished MMP, nuclear damages, and apoptosis induction in AGS cells. The enhanced expression of pro-apoptotic proteins and inhibition of PI3K/Akt/mTOR signaling pathway was noted in ZnO-Pip-NC treated cells. In vivo studies proved that the ZnO-Pip-NC noticeably restored the antioxidants in the GC animals and also prevented the gastric mucosa and inhibited the GC tumor formation. In conclusion, the findings of this investigation confirmed the anticancer potential of ZnO-Pip-NC against the GC via inhibiting the PI3K/Akt/mTOR signaling pathway.     

Phenolic Acids and Flavonoids in Acetonic Extract from Quince (Cydonia oblonga Mill.): Nutraceuticals with Antioxidant and Anti-Inflammatory Potential

Quince (Cydonia oblonga Mill.) is a potential source of polyphenolic compounds related with beneficial biological processes. In this study polyphenols from quince fruit were extracted with aqueous acetone at different ratios. A polyphenol profile was identified and quantified by LC-ESI-QqQ. The antioxidant capacity (ORAC and DPPH) and anti-inflammatory effect (inhibition of COX-2 cyclooxygenase) were evaluated in vitro. The results indicated an effect of the aqueous acetone ratio on the extraction of polyphenolic compounds. The higher extraction yields of polyphenolic compounds were attained with 60–75% aqueous acetone. However, extracts obtained with 85% aqueous acetone promoted higher antioxidant and anti-inflammatory effects. Optimal scaling analysis indicated that hydroxycinnamic acids (quinic and chlorogenic), hydroxybenzoic acids (vanillic and syringic), flavonoids (quercetin and kaempferol), dihydrochalcones (neohesperidin) and flavones (acacetin) are related to the antioxidant activity of quince. While phenolic acids, flavonols (kaempferol-3-O-glucoside and rutin) and flavanols (epicatechin) generated the anti-inflammatory effect by inhibiting 52.3% of the COX-2 enzyme. Therefore, a selective extraction of phenolic mix can reduce oxidative stress or inflammatory processes. This suggests the use of quince as a natural source with significant nutraceutical potential.     

Activation of CuSi and CuZnSnSi contact masses for the direct synthesis of methylchlorosilanes

The temperature-programmed-activation (TPA) of CuSi, CuSi(H) (prepared using CuCl and CuCl 2H2O, respectively), and CuSi copromoted with zinc and tin have been investigated. The main effect of promotion was to increase the activation temperature suggesting that zinc may inhibit the transfer of chlorine from CuCl to surface silicon atoms. The sample prepared using hydrated cuprous chloride initially exhibited reduced activity for the Direct Reaction relative to CuSi, apparently, due to oxidation of the contact mass surface inhibiting the formation of -Cu₃Si.     

Polyphenolic characterisation and bioactivity of an Oxalis pes-caprae L. leaf extract

The present work is focused on the characterisation of the polyphenolic content of an Oxalis pes-caprae L. leaf extract and on the evaluation of its bioactivity with particular interest on its vascular activity and antioxidant potential. The polyphenolic content was characterised by HPLC-DAD and LC-MS/MS. The vascular activity was evaluated according to the influence on the serotonergic and adrenergic systems of the human internal mammary artery (HIMA). Antioxidant and neuroprotective studies were also conducted. Several luteolin and apigenin derivatives were identified as main constituents of the extract, which did not present any contractile effect nor had any effect on the serotonergic system of HIMA. However, it showed antagonistic effect on the adrenergic system, inhibiting the contraction to noradrenaline (reduction of 58.44% of maximum contraction). The extract showed antioxidant activity and standardised luteolin and apigenin derivatives showed neuroprotective potential, particularly homoorientin.     

锡酸钾对流动锌酸钾碱液中锌沉积/溶解的影响

研究了在流动的高浓度锌酸钾溶液中锡酸钾添加剂对锌负极沉积/溶解行为的影响. 循环伏安测试结果表明, 扫描速度为1 mV/s时, 随着添加锡酸钾浓度的增加, 阴极分支更早出现沉积, 溶解峰的峰值逐渐减小; 随着扫描速度的增加, 这种规律变得不明显. 利用SEM观测电沉积500 s的沉积物形貌发现, 向基础溶液中添加锡酸钾有利于晶种的产生和晶粒的生长. EDS测试结果表明含锡酸钾的锌酸钾溶液中沉积层含有锌和锡. 自放电测试结果表明, 基础电解液加入锡酸钾后自放电现象得到了明显的改善, 充满电静置12 h后加入0.1 mol/L锡酸钾的电池放电库仑效率从基础溶液的60.0%提高到81.1%.     

Structure,surface analysis and bioactivity of Mn doped zinc oxide nanoparticles

Undoped zinc oxide nanoparticles and Mn (5 atomic % & 10 atomic %) doped zinc oxide nanoparticles were prepared by soft chemical method. Antibacterial, antioxidant and anticancer activities in breast cancer cell line MDAMB231 of prepared nanoparticles were investigated. The nanoparticles were characterized using XRD, SEM, EDAX, UV–Vis, FT-IR, and room temperature PL Analysis. Antimicrobial activity was tested against both gram positive and gram negative human pathogens. The antioxidant potential of prepared nanoparticles was estimated using Phosphomolybdate and DPPH assay. The MTT assay was used for cytotoxicity evaluation of prepared nanoparticles against breast cancer cell line MDAMB231. XRD patterns confirmed the nanoparticles were crystallized hexagonal wurtzite structure with an average size of 38.95 ?nm. The absorption wavelength was observed at 361 ?nm in UV–Vis spectrum of Mn (10 atomic %) doped ZnO nanoparticles. The Mn (5 atomic %) doped ZnO nanoparticles exhibited significant antibacterial activity against the gram negative bacteria Escherichia coli, Klebsiella pneumonia at all concentrations. Undoped zinc oxide nanoparticles and Mn doped zinc oxide nanoparticles were effective against the breast cancer cell line MDAMB231.     

Preparation of a Zinc Monocysteine Compound

Both zinc and the amino acid cysteine play important roles in biological function, including antioxidant protection and tissue repair. We attempted to prepare a (1:l) zinc‐cysteine complex using L‐cysteine and zinc metal. Zinc metal was added to a solution of L‐cysteine and refluxed with constant stirring. The product was selected by filtration and, after evaporation precipitation, was subjected to elemental analysis, ¹H NMR, and mass spectroscopy. The novel compound has one molecule of zinc conjugated to one molecule of cysteine.     

Metal-chelating properties of carvedilol: an antihypertensive drug with antioxidant activity

Carvedilol (CarvH) (1-[carbazolyl-(4)-oxyl]-3-[2-methoxyphenoxyethyl)-amino]-2-propanol, an antihypertensive agent with β-blocker function, has been shown to act as an antioxidant. The antioxidative properties can be correlated with metal chelating ability of the drug. Iron(III), zinc(II), and copper(II) complexes of carvedilol were synthesized and characterized with respect to their structural and spectroscopic properties. Metal interaction involves O and N donors from the aliphatic moiety of carvedilol. NMR studies allowed us to obtain the structural information on metal coordination and to suggest that the physiological concentration of carvedilol and free metal ions may be enough for a protective effect by metal chelation.     

Physicochemical,Antioxidant, Microstructural Properties and Bioaccessibility of Dark Chocolate with Plant Extracts

In this study, dark chocolates (DCh) containing zinc lactate (ZnL) were enriched with extracts from elderberries (EFrE), elderflowers (EFlE), and chokeberries (ChFrE) to improve their functional properties. Both dried plant extracts and chocolates were analyzed for antioxidant capacity (AC) using four different analytical methods: 2,2-diphenyl-1-picrylhydrazyl (DPPH), 2,2′-azino-bis(3-ethylbenzothiazoline-6-sulfonic acid) (ABTS), cupric ion-reducing antioxidant capacity (CUPRAC), and ferric-reducing antioxidant power (FRAP), while total phenolic content (TPC) was determined by Folin–Ciocalteu (F–C) assay. An increase in antioxidant properties of fortified chocolates was found, and the bioaccessibility of their antioxidants was evaluated. The highest AC and TPC were found in ChFrE and chocolate with chokeberries (DCh + ChFrE) before and after simulated in vitro digestion. Bioaccessibility studies indicated that during the simulated digestion the AC of all chocolates reduced significantly, whereas insignificant differences in TPC results were observed between chemical and physiological extracts. Moreover, the influence of plant extracts on physicochemical parameters such as moisture content (MC), fat content (FC), and viscosity of chocolates was estimated. Furthermore, scanning electron microscopy with dispersive energy spectroscopy (SEM-EDS) was used to analyze surface properties and differences in the chemical composition of chocolates without and with additives.     

In vitro antioxidative activities of three marine oligosaccharides

The antioxidant activities of three marine oligosaccharides, alginate oligosaccharides (AOs), chitosan oligosaccharides (COs), and fucoidan oligosaccharides (FOs), were investigated in vitro by several antioxidant assays, including hydroxyl radical scavenging, superoxide radical scavenging, erythrocyte hemolysis inhibiting, metal chelating activities, and anti-lipid peroxidation. The results show that these oligosaccharides exhibited different activities in various assays. AOs had the highest scavenging hydroxyl radical activity than FOs and COs at all the tested amounts. COs had the highest scavenging superoxide radical and inhibiting erythrocyte hemolysis activity than AOs and FOs at all the tested amounts. In the assay of chelating Fe2+, COs and FOs indicated good chelation while AOs hardly had any activity. In the assay of anti-lipid peroxidation, only COs had significantly high antioxidant activity.     

Role of the flavonoid-rich fraction in the antioxidant and cytotoxic activities of Bauhinia forficata Link. (Fabaceae) leaves extract

Bauhinia forficata Link. is utilised as an antidiabetic in Brazilian folk-medicine; furthermore, its antioxidant properties suggest a potential usefulness in the prevention of diabetes complications associated with oxidative stress. The contribution of a flavonoid-rich fraction (FRF), HPLC-PDA-ESI-MS characterised, to the antioxidant and cytotoxic properties of B. forficata hydro-alcoholic leaves extract was evaluated for the first time. Both extract and FRF showed radical-scavenging activity and reducing power with a strong relationship with the flavonoid content found; hence, flavonoids are mainly responsible for the primary antioxidant activity of B. forficata extract. The extract significantly decreased FO-1 cell viability at the higher concentrations. FRF did not exert any effect; thus, flavonoids do not appear to be responsible for the cytotoxicity of the extract. The extract resulted virtually non-toxic against both Artemia salina and normal human lymphocytes, demonstrating potential selectivity in inhibiting cancer cell growth. Finally, no antimicrobial activity was observed against the bacteria and yeasts tested.     

Stilbazulenyl nitrone (STAZN): a nitronyl-substituted hydrocarbon with the potency of classical phenolic chain-breaking antioxidants

Stilbazulenyl nitrone (STAZN), 8, a nitronyl-substituted hydrocarbon, is a novel second-generation azulenyl nitrone with significantly enhanced potency as a chain-breaking antioxidant vs conventional alpha-phenyl nitrones previously investigated as antioxidant therapeutics. A convenient (1)H NMR-based assay for assessing the potency of chain-breaking antioxidants has shown that STAZN is ca. 300 times more potent in inhibiting the free radical-mediated aerobic peroxidation of cumene than is PBN and the experimental stroke drug NXY-059. Such levels of antioxidant efficacy are unprecedented among archetypal alpha-phenyl nitrone spin traps. Furthermore, STAZN outperforms such classical phenolic antioxidants as BHT and probucol and rivals the antioxidant potency of Vitamin E in a polar medium comprised of 80% cumene and 20% methanol. The Volodarskii electron-transfer mechanism involving the intermediacy of the STAZN radical cation has been implicated in attempts to ascertain the basis for the increased potency of STAZN over the three alpha-phenyl nitrones PBN, S-PBN, and NXY-059.     

Synergistic Effects in SO-3 Antioxidant and Its Structural Analogs,as Compared to Trialkylphenol-Dialkyl Sulfide Mixtures

The inhibiting activity of SO-3 antioxidant and its structural analogs in the model reaction of autooxidation of Vaseline oil was compared to that of synergistic mixtures of 2,4,6-trialkylphenols and didodecyl sulfide.     

124例缺锌儿童补锌疗效观察

对１２４例１￣５岁缺锌儿童进行补锌疗效观察，结果表明，患儿身高、体重及症状体征均有明显改善，治疗总有效率达７８．１％，提示补锌４￣６周并配合饮食治疗，即可对缺锌引起的一系列病变有非常明显的疗效。     

Antioxidant and Protective Effects of <Emphasis Type="Italic">Schinus terebinthifolius</Emphasis> Raddi Against Doxorubicin-Induced Toxicity

Doxorubicin is an anticancer drug whose toxic effects on non-cancer cells are associated with increased oxidative stress. This study investigated the chemical composition, antioxidant activity of the methanolic extract of Schinus terebinthifolius Raddi leaves (MESL) as well as effects against doxorubicin-induced toxicity in human erythrocytes, K562 human erythroleukemia cells, and mouse hearts. The chemical composition indicated the presence of phenolic compounds, flavonoids, tannins, and ascorbic acid. MESL showed antioxidant activity by scavenging free radicals and inhibiting hemolysis and lipid peroxidation in human erythrocytes incubated with an oxidizing agent, and was able to increase the enzymatic activity of superoxide dismutase and glutathione peroxidase in human erythrocytes, without influencing the activity of enzyme catalase. The increase of oxidative hemolysis and malondialdehyde levels in erythrocytes incubated with doxorubicin was reduced by treatment with MESL. The cytotoxic activity of doxorubicin in erythroleukemia cells treated with MESL was unmodified. Additionally, the extract protected mice against the doxorubicin-induced cardiotoxicity. In conclusion, the MESL exhibits antioxidant activity, reducing doxorubicin-induced oxidative stress without changing the anticancer action of the drug, and protects against doxorubicin-induced cardiotoxicity. Hence, these findings suggest that these effects are via anti-oxidative by inhibiting free radicals, decreased oxidative stress, and increased antioxidant enzyme activity.     

Metal Complexes of the Tetraethyl Ester of 4-(2-Hydroxyphenylamino)-1,3-butadiene-1,3-diphosphonic Acid and the Liquid Phase Oxidation of Cumene in their Presence

Abstract

The tetraethylester of 4-(2-hydroxy-phenylamino)-1,3-butadiene-1,3-diphosphonic acid 3 and its zinc and cobalt complexes (3-Zn, 3-Co) have been synthesized and their structures were determined by IR, ¹-NMR, ³¹P{¹H}-NMR and ¹³C-NMR spectral investigations. The affect of these compounds on the liquid phase oxidation of cumene is studied and compared with that of 2-aminophenol 2 and its metal complexes 2-M. It is found that the ligand 3 shows the strongest inhibiting effect, while 3-Co,3-Zn and 2-Co accelerate the oxidation process. The strong inhibiting effect of the ligand 3 is due to its possibility to react with cumeneperoxide radicals. The disappearance of inhibiting properties in the complexes 3-Zn and 3-Co shows that eleKtrophilic attack of cumeneperoxide radicals is directed to OH or NH groups of 3. Most probably the OH group is affected becouse a similar absence of inhibiting properties is inherent to the 2-Co. The presence of inhibiting properties of the 2-Zn as opposed to 2-Co could mean that this complex (2-Zn) has a more complicated, still unknown structure, possibly a polymeric one.