Enhancement of sterol synthesis by the monoterpene perillyl alcohol is unaffected by competitive 3-hydroxy-3-methylglutaryl-CoA reductase inhibition

Monoterpenes such as limonene and perillyl alcohol (PA) are currently under investigation for their chemotherapeutic properties which have been tied to their ability to affect protein isoprenylation. Because PA affects the synthesis of isoprenoids’ such as ubiquinone’ and cholesterol is the end product of the synthetic pathway from which this isoprenoid pathway branches’ we investigated the effects of this compound upon cholesterol metabolism in the colonic adenocarcinoma cell line SW480. PA (1 mM) inhibited incorporation of ¹⁴C-mevalonate into 21–26 kDa proteins by 25% in SW480 cells. Cholesterol (CH) biosynthesis was assessed by measuring the incorporation of ¹⁴C-acetate and ¹⁴C-mevalonate into 27-carbon-sterols. Cells treated with PA (1 mM) exhibited a fourfold increase in the incorporation of ¹⁴C-acetate but not ¹⁴C-mevalonate into cholesterol. Mevinolin (lovastatin)’ an inhibitor of 3-hydroxy-3-methylglutaryl-CoA (HMG-CoA) reductase’ at 2 μM concentration’ inhibited CH synthesis from ¹⁴C-acetate by 80%. Surprisingly’ concurrent addition of mevinolin and PA did not significantly alter the stimulatory effects of PA. As observed differences in ¹⁴C-acetate and ¹⁴C-mevalonate precursor labeling could indicate PA affects early pathway events’ the effects of this monoterpene on HMG-CoA reductase activity were evaluated. Unexpectedly’ 1 mM PA did not stimulate activity of this enzyme. Consistent with its action as a reversibly bound inhibitor’ in washed microsomes’ 2 μM mevinolin pretreatment increased reductase protein expression causing a 12.7 (±2.4)-fold compensatory HMG-CoA reductase activity increase; concurrent treatment with 1 mM PA attenuated this to a 5.3 (±0.03)-fold increase. Gas chromatographic analysis confirmed CH was the major lipid present in the measured thin-layer chromatography spot. Since ¹⁴C-acetate incorporation into free fatty acid and phospholipid pools was not significantly affected by PA treatment’ nonspecific changes in whole acetate pool sizes were not indicated. Because increases in endogenous CH synthesis should result in compensatory changes in exogenous sterol utilization’ the effects of PA upon low density lipoprotein (LDL) receptor activity were evaluated. Consistent with the observed increases in CH synthesis’ 1 mM PA decreased ¹²⁵I-LDL internalization to 50% of the fetal bovine serum control; concurrent addition of 2 μM mevinolin attenuated this effect to a reduction of 80% of the control value. Data suggest that in certain colonic tumor cells PA strongly affects cholesterol metabolism via a mechanism of action that is insensitive to the HMG-CoA reductase inhibitor mevinolin.     

A single oral administration of conjugated linoleic acid enhanced energy metabolism in mice

We investigated the effect of a single oral administration of conjugated linoleic acid (CLA) on energy metabolism in mice. Male Std ddY mice were orally administered CLA (5 mL/kg weight) or linoleic acid (5 mL/kg weight) (both solutions at concentrations of 73.5%) as a control. Oxygen consumption was significantly greater in the CLA-administered mice than in the control mice. Respiratory quotient was slightly lower in the CLA-administered mice than in the control mice. We calculated fat and carbohydrate oxidation from oxygen consumption and respiratory quotient. Fat oxidation in the CLA-administered mice was significantly higher than in the control mice, and there was no difference in carbohydrate oxidation. Serum concentrations of noradrenalin and adrenalin in the CLA administered mice were significantly higher than in the control mice. These results suggested that CLA enhanced sympathetic nervous activity and energy metabolism.     

Inhibition of cholesterol synthesis and hepatic 3-hydroxy-3-methylglutaryl-CoA reductase in rats by simvastatin and pravastatin

In this communication we attempt to provide one possible explanation for the observed differences regarding kinetics and distribution between simvastatin and pravastatin. Rats treated with simvastatin or pravastatin exhibited a reduction in the incorporation of [2-¹⁴C]acetate into liver cholesterol and displayed lower plasma mevalonate levels as compared to control animals. Moreover, both the total and dephosphorylated 3-hydroxy-3-methylglutaryl-CoA (HMG-CoA) reductase (EC 1.1.1.34) activities, particularly 1 h after treatment, were greatly reduced in liver microsomes obtained from simvastatin-treated as compared to control rats. During the same time frame, these parameters were actually elevated with pravastatin treatment. It is known that HMG-CoA reductase synthesis and activity increase following their competitive inhibition. Our results suggest that pravastatin, at 1 h following treatment, was no longer bound to the enzyme; however, it had entered the liver because its inhibitory effect on cholesterol synthesis was manifest at early times after administration. These data provide a plausible rationale for the earlier observation that activity of simvastatin persists longer in plasma than does that of pravastatin.     

Comparison of bile acid synthesis determined by isotope dilution versus fecal acidic sterol output in human subjects

Fecal acidic sterol output has been found to be much lower than bile acid synthesis determined by isotope dilution (J. Lipid Res. 17: 77, 1976). Because of this confusing discrepancy, we compared these 2 measurements done simultaneously on 13 occasions in 5 normal volunteers. In contrast to previous findings, bile acid synthesis by the Lindstedt isotope dilution method averaged 16.3% lower than synthesis simultaneously determined by fecal acidic sterol output (95% confidence limit for the difference −22.2 to −10.4%). When one-sample determinations of bile acid pools were substituted for Lindstedt pools, bile acid synthesis by isotope dilution averaged 5.6% higher than synthesis by fecal acidic sterol output (95% confidence limits −4.9 to 16.1%). These data indicate that the 2 methods yield values in reasonably close agreement with one another. If anything, fecal acidic sterol outputs are slightly higher than synthesis by isotope dilution.     

Corrosion inhibition of mild steel by Calotropis procera leaves extract in a CO2 saturated sodium chloride solution

The Calotropis procera leaves extract (CPLE) was investigated as a corrosion inhibitor for mild steel in a CO₂-saturated 3.5 wt% NaCl solution using various electrochemical techniques. The results show that the CPLE is an effective inhibitor with inhibition efficiency of 80% using 50 ppm. Polarization studies show that the CPLE acts as a mixed inhibitor, and the adsorption of CPLE follows Langmuir adsorption isotherm. Molecular dynamics simulations reveal that the presence of N, O in the CPLE as well as π-electron systems coupled with high adsorption energies of interaction of the CPLE with steel are responsible for corrosion inhibition performance.     

Corrosion inhibition of steel in sodium chloride solution by undoped polyaniline epoxy blend coating

In this study an undoped polyaniline (PAni) was synthesized by chemical oxidative polymerization with ammonium persulfate as an oxidizing reagent. The synthesized PAni was used as a corrosion inhibitive pigment in an epoxy matrix. The corrosion protection performance of steel coated panels in 3.5% sodium chloride solution was evaluated via determination of open circuit potential (OCP) and electrochemical impedance spectroscopy (EIS). It was found that after 300 days of immersing the resistance of coating was about 4 × 10⁵ Ω cm². The OCP was shifted to the noble region due to the passivation effect of PAni pigment. Besides, the phase angle (theta) at 10 kHz was stable around 87 ± 1° during immersion period. Results revealed that PAni pigmented paint showed acceptable protection against the corrosion of carbon steel in 3.5% sodium chloride solution.     

Synthesis of plant sterol esters catalyzed by heteropolyacid in a solvent‐free system

The synthesis of phytosteryl esters is of importance due to their recent recognition and application as cholesterol‐lowering agents in the food and nutraceutical industries. In this study, a synthetic route potentially useful for the large‐scale production of food‐grade phytosteryl esters with high yield and purity in a solvent‐free system was investigated. To examine the feasibility of replacing sodium methylate by heteropolyacid, four heteropolyacids, tungstosilicic acid, tungstophosphoric acid, molybdosilicic acid and molybdophosphoric acid, were evaluated to determine the best catalyst and the optimum conditions for the esterification reaction between various fatty acids and phytosterols. The results suggested that tungstosilicic acid was more selective towards butyric acid and caprylic acid than towards lauric acid, palmitic acid, and oleic acid. However, there was no significant discrimination in terms of the tungstosilicic acid catalyst's selectivity to stearic acid, oleic acid, linoleic acid and alpha‐linolenic acid, all with C18 chains, in the esterification reaction. The yield of phytosteryl ester was higher than 90% when the esterification reaction was carried out at 150 °C, with phytosterols and fatty acids in a molar ratio of 1 : 1.5, and catalyzed by 0.2% tungstosilicic acid in silica gel. The catalysts recovery experiments suggested that the immobilized tungstosilicic acid did not significantly lose its activity in six operation runs. As a result, the immobilized tungstosilicic acid would be a promising catalyst for replacing sodium methylate, to synthesize phytosteryl esters with fatty acids and phytosterols as the starting materials in a commercial production.     

Chemical synthesis of cross-linked polyaniline by a novel solvothermal metathesis reaction of p-dichlorobenzene with sodium amide

We reported the chemical synthesis of cross-linked polyaniline (PANI) by a novel solvothermal metathesis reaction of p-dichlorobenzene (C₆H₄Cl₂) with sodium amide (NaNH₂) in benzene at 220 °C. In this method, the aniline monomer and complicated treatment were needless and the yield of final products was over 50%. The as-synthesized brown samples were NMP-soluble but water-insoluble; and they were characterized by XRD, FT-IR, UV-vis absorption, XPS, elemental analysis, TGA, and TEM. It was found that solvents have significant influence on the final product. The predominant mechanism of chain growth in PANI polymerizations was proposed as the ionic S_NAr process; however, further theoretical and experimental investigations are needed to obtain the undoubted evidences. We believe that this novel solvothermal metathesis reaction will give us a new guideline for the synthesis of some polymers.     

Ⅱa型宝石级金刚石大单晶研究最新进展

用合金触媒利用温度梯度法合成优质Ⅱ a型宝石级金刚石.研究发现,在约5.4GPa和约1300℃的条件下,除氮剂的加入使合成金刚石的温度区间变窄及金刚石晶体生长过程中更易俘获包裹体而出现熔坑,从而影响晶体的生长速度.实验解决了组装的稳定性问题;并通过调整组装,在除氮剂合适的掺入量下,使合成优质金刚石的最大生长速度达到2.16mg/h.结果实验获得了4.3mm的优质Ⅱa型金刚石大单晶.红外测试分析表明该金刚石含氮量小于10-7.     

Two-step process for synthesis of a single phase Na–A zeolite from coal fly ash by dialysis

Using the amorphous aluminosilicate in coal fly ash (FA), a single phase Na–A zeolite was synthesized from FA by dialysis. The FA and NaOH solution added into the tube made by semipermeable membrane were pretreated in the same NaOH solution at 85 °C for 24 h. After the pretreatment, the tube was removed and NaOH–NaAlO₂ solution was added into the residual solution to control SiO₂/Al₂O₃ molar ratio of the solutions from 0.9 to 4.3. The precipitates thus formed were aged for 24 h at 85 °C. The amorphous aluminosilicate in FA was dissolved during the pretreatment. When the NaOH–NaAlO₂ solution was added into the solution after the pretreatment and then aged, white precipitates were yielded over the whole SiO₂/Al₂O₃ range. At SiO₂/Al₂O₃=0.9, the material formed was identified as a single phase Na–A zeolite. The Na–X zeolite was slightly produced at SiO₂/Al₂O₃≥1.7.     

Regulation of mevalonate synthesis in low density lipoprotein receptor knockout mice fed n-3 or n-6 polyunsaturated fatty acids

3-Hydroxy-3-methylglutaryl (HMG)-CoA reductase, the rate-limiting enzyme in cholesterol biosynthesis, catalyzes the formation of mevalonate which is also required for cell proliferation. Changes in HMG-CoA reductase may mediate the differential effects of n-3 and n-6 polyunsaturated fatty acids (PUFA) on experimental mammary tumorigenesis, but the mechanisms by which these fatty acids regulate HMG-CoA reductase are unclear. To determine whether the low density lipoprotein receptor (LDL-R) is required for this regulation, groups of female LDL-R knockout (−/−) and wild-type (+/+) mice were fed 7% fat diets rich in either n-3 (menhaden oil) or n-6 (safflower oil) PUFA for 1 wk. Dietary PUFA and deletion of the LDL-R had independent effects on HMG-CoA reductase and serum lipids, and a significant diet-gene interaction was observed. The effects of PUFA on HMG-CoA reductase in the mammary gland, but not the liver, were mediated by the LDL-R. We also observed that differences in HMG-CoA reductase and serum LDL-cholesterol, high density lipoprotein cholesterol, and triglycerides between −/− and +/+ mice were dependent on whether the mice were fed n-3 or n-6 PUFA. Differences between −/− and +/+ mice were much greater when animals were fed n-6 PUFA rather than n-3 PUFA. These results show that the LDL-R mediates the effects of PUFA on HMG-CoA reductase in the mammary gland but not the liver. Furthermore, the composition of dietary PUFA profoundly influences the effects of deleting the LDL-R on HMG-CoA reductase and serum lipids and suggests that diet may influence the phenotype of other knockout or transgenic animals. This work was presented in part at the Third Congress of the International Society for the Study of Fatty Acids and Lipids, June 1–5, 1998, Lyon, France.     

Microscopic single particle characterization of zeolites synthesized in a soil polluted by copper or cadmium and treated with coal fly ash

In the perspective of the development of new soil remediation technologies, zeolites can be directly synthesized in soil from fused coal fly ash to reduce heavy metal mobility and availability. Such a process promotes the formation of metal hydroxide/oxide precipitates which can be also occluded inside the structure of the forming minerals. In this study, different types of zeolites (zeolite X, P, and A) were synthesized by treating soil samples, artificially contaminated by high concentrations of Cu or Cd ions, with fused coal fly ash at 30 and 60 °C. The formed zeolites were characterized for their amount, structure, chemical composition and size. To accomplish this survey, besides quantitative X-ray diffraction analyses (XRD), an automated single particle analysis (ASPA) method using electron probe X-ray microanalysis (EPXMA) was employed for the first time for direct zeolite characterization in soil samples. The obtained results provide new information for assessing the role of heavy metals in zeolite crystallization in coal fly ash-treated soils. Heavy metal contamination, while not significantly hindering the zeolite formation process, can influence crystal size and preferentially drive zeolite synthesis toward the formation of sodalite unit-based zeolite X and zeolite A, even at 60 °C. The presence and nature of metal precipitate occlusions inside the forming zeolite minerals might have also favored the preferential synthesis of certain zeolitic structures.     

预碳化辅助双氧水沉淀高碱铝酸钠溶液强化薄水铝石合成工艺(英文)

Hydrogen peroxide (H2O2) precipitation from sodium aluminate (SA) solution at close-ambient temperature is an efficient method to synthesize boehmite and its derived alumina with high surface area, but the precipitation yield of Al2O3 is usually below 50% in highly alkaline SA solutions. Here the synthesis of boehmite is enhanced through a precarbonization-assisted H2O2 route in highly alkaline SA solutions. It is found that the crystal structure of the precipitation product is evidently influenced by the precipitation conditions. As the precipitation temperature increases from 273 to 325 K, a small amount of gibbsite by-product is formed. As the aging temperature increases from 301 to 333 K, the crystallinity of boehmite decreases and part of the boehmite dissolves due to an increase in the pH value. Based on the above results, a precarbonization-assisted H2O2 route is proposed to obtain pure boehmite with more complete recovery of Al2O3 from highly alkaline SA solutions. The route includes a controllable precarbonization step of SA solutions with a molar ratio of Na2O to Al2O3 higher than 2︰1, followed by the H2O2-precipitated step with a molar ratio of H2O2 to Al2O3 less than 7︰1. Because of its facile operation conditions, no extraneous impurity, time saving and a possible recycle of the filtrate, the route has great potential to be an alternative method for preparation of boehmite and its derived alumina.     

Effects of a single ingestion of sodium taurocholate on esterified cholesterol concentration in liver and cholesterol turnover in the rat

The overall response of the rat’s cholesterol metabolism to a single ingestion of taurocholate (80 mg) was studied with the isotopic equilibrium method. The bile acid production, measured by the daily¹⁴CO₂ output of rats in isotopic equilibrium of [26-¹⁴C]-cholesterol, initially decreased and then increased. Conversely, the hepatic concentration of esterified cholesterol first increased and then decreased. Moreover, the ingestion of taurocholate increasing the intestinal absorption coefficient of dietary cholesterol increased the abosprtion and decreased the fecal excretion and the intestinal biosynthesis of cholesterol. The balance of these last effects is an excess cholesterol inflow. The classical hypothesis of negative feedback regulation of bile acid production fails to explain the observed biphasic effect of taurocholate. This compound, when its origin is exogenous, appears to stimulate the storage of esterified cholesterol in the liver, at the expense of bile acid synthesis. This accumulation rate takes into account not only the decrease in cholesterol transformation into bile acids but also the excess inflow of cholesterol. As the exogenous taurocholate was eliminated from the body, cholesteryl ester hydrolysis occurred and provided a supplementary source of free cholesterol for bile acid synthesis.     

醛-酮催化氨化合成吡啶及其烷基衍生物研究进展

醛-酮催化氨化合成吡啶及其烷基衍生物(俗称吡啶碱)是工业生产吡啶类化合物的主要方法。对醛-酮催化氨化合成吡啶碱的反应机理、催化剂的进展进行了介绍,阐述了无定形硅铝酸盐作为催化剂合成吡啶碱选择性和寿命低的原因,以金属对无定形硅铝酸盐或择形硅铝酸盐分子筛进行修饰可改进催化剂的催化性能。择形硅铝酸盐分子筛的酸性对吡啶类产物的分布有显著影响,改变分子筛的硅铝比,可以调节催化剂的酸性,从而提高生成吡啶碱的选择性。     

单槽脉冲电沉积法制备FePt薄膜

以FeSO4.7H2O和H2PtCl6.6H2O分别作为Fe2+源和Pt4+源,以铂片为阳极,纯铜片为阴极,采用单槽脉冲电沉积法制备FePt薄膜,通过X-射线衍射仪(XRD)、带有能谱的场发射扫描电镜(FESEM-EDAX)、振动样品磁强计(VSM)分析手段对薄膜进行了表征。结果表明,新制备的FePt薄膜组成为Fe22Pt58O20,具有面心立方(fcc)结构,FePt薄膜的矫顽力为2.0 kA/m,饱和磁化强度为420 kA/m,具有软磁性。     

Specific inhibition of hepatic fatty acid synthesis exerted by dietary linoleate and linolenate in essential fatty acid adequate rats

Dietary linoleate and linolenate were investigated for their ability to specifically inhibit liver and adipose tissue lipogenesis in meal-fed (access to food 900-1,200 hr), essential fatty acid (EFA) adequate rats. Supplementing a high carbohydrate diet containing 2.5% safflower oil with 3% palmitate 16∶0, oleate 18∶1, or linoleate 18∶2 did not affect in vivo liver or adipose tissue fatty acid synthesis. However, 18∶2 addition to the basal diet did result in a significant (P<0.05) decline of liver fatty acid synthetase (FAS) and glucose-6-phosphate dehydrogenase (G6PD) activities. When the safflower oil content of the basal diet was reduced to 1%, the addition of 3% 18∶2 or linolenate 18∶3 significantly (P<0.05) depressed hepatic FAS, G6PD, and in vivo fatty acid synthesis by 50%. Addition of 18∶1 caused no depression in hepatic FAS activity but did result in a significant (P<0.05) decline in liver G6PD activity and fatty acid synthesis which was intermediate between basal and basal +18∶2-or+18∶3-fed animals. Adipose tissue rates of lipogenesis were completely unaffected by dietary fatty acid supplementation. Similarly, the addition of 3 or 5% 18∶3 to a basal diet for only one meal resulted in no change in lipogenesis relative to that in animals fed the basal diet. The data indicate that, like rats fed EFA-deficient diets, dietary 18∶2 and 18∶3 exert a specific capacity to depress rat liver FAS and G6PD activities and rate of fatty acid synthesis. Michigan Agricultural Experiment station Journal Article No. 7581. D.R. Romsos is the recipient of Career Development Award K04 AM 00112     

以硝酸处理西藏硼砂矿制备硼酸及硝酸钠的研究

以硼酸母液浸溶西藏硼砂矿,对所得硼砂溶液进行酸化,生成硼酸和硝酸钠;控制反应浓度和其他相关工艺条件,使硼酸和硝酸钠同时结晶,再利用二者相对密度的不同,采用重力分离法实现了硼酸与硝酸钠的有效分离。实验证明：硼和钠收率分别达到92.0%和91.5%,产品质量符合国家标准。工艺过程不对硼酸母液进行蒸发。