A Proposed Molecular Mechanism of High-Dose Vitamin D3 Supplementation in Prevention and Treatment of Preeclampsia

A randomized prospective clinical study performed on a group of 74 pregnant women (43 presenting with severe preeclampsia) proved that urinary levels of 15-F_2t-isoprostane were significantly higher in preeclamptic patients relative to the control (3.05 vs. 2.00 ng/mg creatinine). Surprisingly enough, plasma levels of 25-hydroxyvitamin D₃ in both study groups were below the clinical reference range with no significant difference between the groups. In vitro study performed on isolated placental mitochondria and placental cell line showed that suicidal self-oxidation of cytochrome P450scc may lead to structural disintegration of heme, potentially contributing to enhancement of oxidative stress phenomena in the course of preeclampsia. As placental cytochrome P450scc pleiotropic activity is implicated in the metabolism of free radical mediated arachidonic acid derivatives as well as multiple Vitamin D₃ hydroxylations and progesterone synthesis, we propose that Vitamin D₃ might act as a competitive inhibitor of placental cytochrome P450scc preventing the production of lipid peroxides or excess progesterone synthesis, both of which may contribute to the etiopathogenesis of preeclampsia. The proposed molecular mechanism is in accord with the preliminary clinical observations on the surprisingly high efficacy of high-dose Vitamin D₃ supplementation in prevention and treatment of preeclampsia.     

Determination of lipid and protein hydroperoxides using the fluorescent probe diphenyl-1-pyrenylphosphine

By means of two alternative methods lipid and protein hydroperoxides (HP) were determined by fluorometry using the diphenyl-1-pyrenylphosphine (DPPP) probe. It has been shown that the formation of the fluorescence was influenced by the type of solvent and HP whereas the presence in the media of antioxidants such tocopherol and butylated hydroxytoluene had no effect. The combination of the chloroform:methanol (2:1, v/v) solvent mixture that is widely used for lipid extraction was combined with suitable solvents to develop a method with the maximum performance in determining HP in lipid extracts. Using a variety of lipids and lipid extracts, the final method proposed agreed well with the thiocyanate method for HP determination. In addition, the DPPP method was very sensitive, precise, accurate, free of interferences and specific for the determination of lipid soluble HP. DPPP can be also used to measure HP soluble in hydroalcoholic media. This alternative procedure showed a similar performance to its lipid soluble equivalent and was able to measure hydrogen peroxide promoted peroxidation of bovine serum albumin and water soluble HP in protein extracts. With the addition of triphenylphosphine the hydroalcoholic method is specific for the determination of protein HP.     

含铬分子筛催化环己基过氧化氢分解反应研究

研究了含铬分子筛催化环己基过氧化氢分解制备环己酮（醇）的反应。结果表明，在分子筛质量分数为1％、常压、80℃、反应1h的条件下，Cr-Silicalite-1和Cr-APO-5分子筛催化分解转化率分别达到96．7％和86．8％，环己酮和环己醇总选择性分别为113．4％和117．9％。铬流失是造成含铬分子筛不可逆失活的原因，分子筛骨架中高度分散的六配位铬原子具有较好的催化活性和稳定性。     

环己基过氧化氢分解法合成环己酮的研究

研究了环己烷工业生产环己酮中,无催化氧化低温分解工艺中碱度、反应时间、反应温度、Co源浓度等条件对环己基过氧化氢分解转化率和总收率的影响.结果表明,在碱度为1.0 mol/L、反应时间为1.4h、反应温度为95～105℃、Co源含量1.0～1.2 μg/g条件下,该反应的转化率和总收率可以达到最优,分别为95.4％和8...     

Oxidative Coupling between Methylarenes and Ammonia: A Direct Approach to Aromatic Primary Amides

A direct oxidative amidation between methylarenes and aqueous ammonia using a tert‐butyl hydroperoxide and tetrabutylammonium iodide (TBHP/TBAI) oxidation system with co‐catalysis of iron(III) chloride has been developed. Both coupling partners were used in their native form to render prior functionalization unnecessary and afford a facile approach to aromatic primary amides.

     

Oxidation reactions of steryl esters in a saturated lipid matrix

In the present study, the formation and further reactions of intact steryl ester hydroperoxides were followed in a tripalmitin matrix maintained at 100 °C. The effects of the acyl moiety and its unsaturation degree, and of the sterol structure were investigated. Intact steryl ester hydroperoxides were isolated from the lipid matrix by a developed solid-phase extraction (SPE) method and were determined by HPLC–ELSD. Further reactions of hydroperoxides were followed by determining secondary oxidation products of sterol by GC-FID/MS and oligomers by HPSEC-RI. The oxidation of sterol decreased when its solubility in the lipid medium was increased by introduction of acyl moiety. Increased unsaturation of the acyl or steryl moiety of steryl ester shortened the induction period and increased the oxidation of both steryl and acyl moieties. Thus, by changing the chemical and physical properties of sterols, their oxidation may be greatly affected.     

苦菊提取物的肝保护作用研究

目的 研究苦菊提取物在体内外的肝保护作用.方法 苦菊经95％乙醇加热回流、石油醚脱脂、乙酸乙酯提取、大孔树脂20％乙醇洗脱获得提取物.通过检测其对HepG2细胞的氧化损伤模型及氧化剂叔丁基过氧化氢(tert-buty1hydroperoxide,t-BHP)诱导的体内小鼠肝损伤模型的影响,评价其对肝脏的保护作用.结果 苦菊提取物能够有效抑制细胞氧化损伤导致的死亡,对细胞产生的炎症因子也有很好的抑制作用.体内试验结果表明,该提取物也对t-BHP诱导的小鼠肝损伤有一定的保护作用.结论 体外和体内试验均表明,苦菊提取物具有很好的肝保护作用,可作为食品和药品进行开发利用.     

Cytoprotective effects of pu-erh tea on hepatotoxicity in vitro and in vivo induced by tert-butyl-hydroperoxide

The in vitro and in vivo protective effects of water extract of pu-erh tea (WEPT) on tert-butyl-hydroperoxide (t-BHP)-induced oxidative damage in hepatocytes of HepG2 cells and in rat livers were investigated. After treatment with 200 μg/ml of samples, the survival rate of HepG2 cells induced by t-BHP increased. WEPT concentration-dependently inhibited reactive oxygen species (ROS) generation in HepG2 cells in response to the oxidative challenge induced by t-BHP. Administration of WEPT (0.2, 0.5 and 1.0 g/kg of body weigh) to rats for 56 consecutive days before a single dose of t-BHP (0.5 mmol/kg, i.p.) exhibited a significant (p < 0.01) protective effect by lowering serum levels of glutamate oxaloacetate transaminase (GOT) and glutamate pyruvate transaminase (GPT), as well as reducing the formation of malondialdehyde. Taken together, these results demonstrate that WEPT is able to protect against hepatic damage in vitro and in vivo, suggesting that the drinking of pu-erh tea may protect liver tissue from oxidative damage.     

草苁蓉多糖对氧化应激所致血管内皮细胞凋亡的抑制作用

目的：研究草苁蓉多糖（Boschniakia rossica polysaccharides,BRPS）对氧化应激所致血管内皮细胞凋亡 的抑制作用。方法：利用叔丁基过氧化氢（tert-butyl hydroperoxide,tBHP）损伤人脐静脉血管内皮细胞制备细胞 氧化应激损伤模型,采用四甲基偶氮唑盐（methylthiazolyldiphenyl-tetrazolium bromide,MTT）比色法检测细胞存 活率,分光光度法检测细胞内丙二醛（malondialdelyde,MDA）水平、超氧化物歧化酶（superoxide dismutase, SOD）活力和还原型谷胱甘肽（reduced glutathione,GSH）水平。采用二氯荧光乙酰乙酸盐（dichlorofluorescein diacetate,DCFH-DA）法检测细胞内活性氧（reactive oxygen species,ROS）水平,采用JC-1荧光染色法观察 细胞线粒体跨膜电位（mitochondrial membrane potentials,ΔΨm）水平,采用Hoechst染色和原位末端标记（TdTmediated dUTP nick end labeling,TUNEL）法观察细胞凋亡情况。Western blot法检测细胞Bax、Bcl-2、细胞色素c （cytochrome c,Cyt c）、Bid片段（truncated Bid,tBid）、Caspase-3、Caspase-8和Caspase-9蛋白的表达情况。 结果：BRPS提高tBHP损伤的内皮细胞存活率,降低细胞ROS水平,减少MDA生成,提高SOD活性与GSH水 平,升高ΔΨm水平,抑制细胞凋亡。Western blot结果显示,BRPS降低胞浆Cyt c、线粒体tBid水平,减小细胞 Bax/Bcl-2比值,抑制Caspase-3、Caspase-8和Caspase-9的活化。结论：BRPS对氧化应激所致血管内皮细胞凋亡具有 抑制作用,机制可能与线粒体凋亡途径和死亡受体途径均有关。     

Purification and characterisation of a novel antioxidant protein molecule from Phyllanthus niruri

The herb Phyllanthus niruri is known to possess antioxidant activity, but the nature of the responsible active principle(s) is not well defined. The present study reports the purification and characterisation of a 35 kDa antioxidant protein molecule from this herb using a bioassay in which oxidative stress was introduced in hepatocytes with the help of a suitable free radical inducer, tertiary butyl hydroperoxide (TBHP), and the prevention of that stress was monitored using the protein fraction(s) obtained at each step of the purification. Partial amino acid sequence of this protein revealed its unique structural features. The purified protein possesses potent radical-scavenging activity, enhances intracellular antioxidant power and protects the TBHP-induced alterations of the cytoprotective and antioxidant molecules, as well as other parameters used in this particular study. Combining, data suggest that the antioxidant activity of Phyllanthus niruri is at least partly due to this unique protein molecule.