Synthesis of new mesogenic compounds having the isoflavone core group

Two new series of calamitic liquid crystals containing the isoflavone moiety within the central core have been prepared and their liquid crystalline properties studied. The compounds exhibit typical nematic, smectic A and C mesophases. The influence of the linking group between a terminal alkyl chain and the central core has been proven to determine the variety of mesomorphism displayed by the compounds.     

黄芪异黄酮类化合物抗氧化活性的密度泛函理论研究

本文采用密度泛函理论中的B3LYP方法在6-311G(d,p)水平上对黄芪中的四种异黄酮类化合物毛蕊异黄酮、毛蕊异黄酮苷、芒柄花素、芒柄花苷进行了优化计算,从四个分子的几何结构、酚羟基氢原子上的NBO电荷、酚羟基解离能、HOMO和LUMO能级以及其能级差△E(LUMO-HOMO)等方面分析了四种黄芪异黄酮类化合物清除自由基的活性.C3.位的酚羟基为毛蕊异黄酮苷元及其苷分子的最大可能活性位点,C7位酚羟基也具有一定的活性,可以增加分子本身的抗氧化活性,C7位酚羟基为芒柄花素分子的活性位点.C3,位或C7位上酚羟基氢原子带正电荷越大、酚羟基的解离能越小、△E(LUMO-HOMO)越小、HOMO能级相对越高分子的抗氧化活性越高.糖苷取代C7位酚羟基上的H原子,可以提高HOMO、LUMO的轨道能级,但是分子失去了7位酚羟基,从而降低了毛蕊异黄酮苷分子的抗氧化活性.结果表明,四种黄芪异黄酮类化合物的抗氧化能力大小为:毛蕊异黄酮＞毛蕊异黄酮苷＞芒柄花素＞＞芒柄花苷.对芒柄花素和羟基自由基反应的过渡态进行了计算研究.     

Purification of phospholipase C by hydrophobic interaction affinity chromatography.

A simple procedure is described for the purification of phosphatidylcholine-hydrolyzing phospholipase C(PLC). Lecithin, the substrate for PLC, was ligated hydrophobically to octyl-Sepharose in 2 M (NH4)2SO4. The washed lecithin-conjugated resin was then used to purify PLC from crude preparations by affinity chromatography. PLC binds to the lecithin moiety in the presence of Zn2+ and is eluted with an acidic buffer containing EDTA. PLC activity was recovered in the eluate. Both sodium dodecyl sulphate polyacrylamide gel electrophoresis and pI electrofocusing showed that the eluate contained a single monomeric protein with an apparent molecular mass of 66 kDa and a pI of 5.5.     

Chemistry of isoflavone heteroanalogs.

Benzodioxane analogs of chalcones were isomerized to the corresponding flavanones and isoflavones. The PMR and IR spectra of these compounds were discussed.For Communication 11, see [1].Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 3, pp. 319–323, March, 1989.     

Effects of different carriers on the production of isoflavone powder from soybean cake

The objectives of this study were to use soybean cake as the raw material for the production of isoflavone powder and compare the effects of different carriers as well as drying methods on the powder quality. Results showed that with spray drying, a level of 40% maltodextrin as carrier produced the highest yield (mass) of isoflavone powder, followed by 10% gelatin and 1% sodium alginate. However, a reversed trend was observed for the isoflavone content. With 1% sodium alginate, freeze drying generated the greatest yield of isoflavone powder, followed by vacuum drying and spray drying. The isoflavone content also exhibited the same tendency. With poly-gamma-glutamic acid (gamma-PGA) as carrier, all six levels studied (0.57, 0.28, 0.14, 0.028, 0.014 and 0.003%) were capable of forming powder containing high amounts of total isoflavone, which was comparable to that using 1% sodium alginate by freeze drying. Both high- and low-molecular-weight gamma-PGA showed similar effects in terms of powder yield and isoflavone content.     

Purification and some properties of phospholipase C from Achromobacter xylosoxidans.

A non-haemolytic phospholipase C (EC 3.1.4.3) was purified from the culture medium of Achromobacter xylosoxidans with a 5% yield and a purification factor of 330. A combination of ultrafiltration, acetone precipitation and two subsequent affinity chromatographic steps was used. The affinity chromatography is a new application of 2-(4-aminophenylsulphonyl)ethyl-cellulose, a sorbent that has previously been used for the purification of phospholipase C from Bacillus cereus. The purified enzyme gave four distinct bands on polyacrylamide gel electrophoresis, and each band was catalytically active. Under our experimental conditions, the phospholipids examined were hydrolysed in the following order: phosphatidylcholine, phosphatidylethanolamine, sphingomyelin. Neither the synthetic substrate p-nitrophenylphosphorylcholine nor phosphatidylinositol was hydrolysed under different experimental conditions. For maximal hydrolytic activity toward phosphatidylcholine, the enzyme required Triton X-100 and Ca2+ ions. EDTA was inhibitory, but the enzyme activity was almost completely restored by Zn2+. The molecular mass of the phospholipase C, estimated by gel permeation, was 34,000 daltons.     

Organoboron compounds: XXXI. The determination of activation parameters for the restricted rotation about the boron-nitrogen bond using 13C NMR

Variable temperature ¹³C NMR has been used to provide reliable activation parameters ΔG^*, ΔH^* and ΔS^* for restricted rotation about the boron-nitrogen bond in a series of di-s-butylaminophenylboranes.     

Chemistry of isoflavone heteroanalogs. 11. Benzodioxane analogs of chalcone,flavone, and isoflavone

Benzodioxane analogs of chalcones and their epoxides have been prepared. Different types of analogs of natural flavonolignan — silibin — have been synthesized from these compounds. The PMR spectra of the new compounds and the results of the preliminary biological testings are reported and discussed.For article 10, see [1].Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 2, pp. 192–198, February, 1986.     

Synthesis and evaluation of fluorogenic substrates for phospholipase D and phospholipase C

Fluorogenic analogues of phosphatidylcholine and lysophosphatidylcholine, DDPB and lysoDDPB, were synthesized by an enzyme-assisted strategy. The analogues were evaluated as substrates for phospholipases C and D and lysophospholipase D. DDPB was cleaved by bacterial and plant phospholipase D (PLD) enzymes and represents the first direct fluorogenic substrate for real-time measurement of PLD activity. Both fluorogenic substrates have potential in screening for PLD and PC-PLC inhibitors and for monitoring spatiotemporal changes in PLD activity in cells. [structure: see text]     

13C, 13C coupling constants and 13C chemical shifts of aromatic carbonyl compounds. Effects of ortho- and peri-interactions involving the carbonyl substituent

Carbon-13 n.m.r. data have been determined for a series of 26 aromatic carbonyl compounds including benzoyl, naphthoyl and pyrenoyl derivatives ¹³C labelled in the carbonyl group. Doubly labelled anthraquinone has also been included. The compounds investigated comprise non-hindered molecules and molecules in which the carbonyl substituent is subject to ortho- or peri-interactions affecting conjugation of the carbonyl group with the aromatic ring. The dependence of long range ¹³C,¹³C coupling constants involving the carbonyl carbon, in particular ²J and ³J, on steric conditions is discussed, as is the possibility of deciding on the orientation of the carbonyl bond. The following results have emerged. ²J(s-t)>²J(s-c) for ketones and aldehydes, and the reverse is valid for acids and acid derivatives. (s-t and s-c refer to the orientation of the C?O group relative to the aromatic bond in question with respect to the connecting single bond). For ketones ³J(t,s-c)<³J(t,s-t), and both of these ³J(t) values decrease with increasing angle of twist, θ, about the single bond, whereas ³J(c,s-c) increases with θ. For acids and acid derivatives no similar regularity was found. (The initial t and c refer to the geometry of the three-bond coupling path). Generally it is found that ³J(t)>³J(c) and ³J(t)>²J, confirming earlier results. Theoretical calculations on a few model compounds are qualitatively in accordance with the experimental results. Some sign determinations for coupling constants are presented. A short discussion is given of substituent effects on chemical shifts. Observed trends are consistent with earlier results.     

The effects of coexisting lipids on the action of Bacillus thuringiensis phosphatidylinositol-specific phospholipase C toward liposomal substrate.

The hydrolytic activity of phosphatidylinositol (PI)-specific phospholipase C (PI-PLC) from Bacillus thuringiensis was studied in detail toward mixed liposomes consisting of PI and one of other phospholipids and cholesterol. Among PI-liposomes, small unilamellar vesicles (SUV) were the most sensitive to PI-PLC; the enzymatic hydrolysis of PI in SUV was not less than 10-fold that in large unilamellar vesicles (LUV) or in multilamellar vesicles (MLV). Thus, in a survey of the effects of coexisting lipids on PI-PLC activity, PI-SUV was used. Phosphatidylcholine (PC) was stimulative for the enzyme activity toward PI-SUV at any molar ratio of PC to PI. Also, the effects of the addition of sphingomyelin (SM), phosphatidylethanolamine (PE) and cholesterol on the enzymatic hydrolysis of PI were studied in detail on the basis of concentration of total lipids or PI.     

Quantitative determination of phosphocholine and the activity of phospholipase C

Summary 1. A quantitative method for determining phosphocholine by means of thin-layer chromatography has been proposed.2. In the enzymatic cleavage of lecithins with phospholipase C, this method permits the amount of diglycerides formed to be determined as well as the phosphocholine.3. The agreement of the results of the analysis of phosphocholine and the diglycerides is a reliable criterion of the activity of the phospholipase C.Khimiya Prirodnykh Soedinenii, Vol. 2, No. 4, pp. 233–235, 1966     

Quantitative determination of phosphocholine and the activity of phospholipase C

Summary 1. The ester of dextran and pelentanic acid with a maximum value of 140 has been synthesized.2. The influence of some reaction conditions on the composition of the esters obtained has been investigated.Khimiya Prirodnykh Soedinenii, Vol. 1, No. 4, pp. 245–246, 1965     

13C NMR spectra of biologically active compounds.

The¹³C spectra of 25 new substituted cyclopropanes of the pyrethoid series have been investigated and a stereochemical assignment has been made of the stereoisomers formed. As the criterion for stereochemical assignment it is proposed to use the values of the chemical shifts for the -carbon atoms of the substituents in the cyclopropane ring.Institute of Chemistry, Bashkir Branch, USSR Academy of Sciences, Ufa. Translated from Khimiya Prirodnykh Soedinenii, No. 2, pp. 266–272, March–April, 1989.     

Neutron activation analysis of refractory compounds

Instrumental neutron activation techniques for the determination of 26–36 impurities in MoSi₂, WSi₂, TiB₂, NbB₂, TiC, NbC and SiC with detection limit of 0.1–0.000001 ppm in the range of contents of 100–0.001 ppm have been developed. The determination of this large number of elements was achieved with using complex conditions of irradiation, including varying neutron energy and choosing optimal time parameters. The contents of short-lived radionuclides also have been determined. Self-shielding and disturbance of neutron flux, absorption of -rays were taken into account both with the help of literature data and preliminarily obtained experimental results.     

Electrophilic activation of acetyl-substituted heteroaromatic compounds

The chemistry of acetyl-substituted pyridines, thiazoles, quinoline, isoquinolines, and pyrazine (1-9 and 28) has been studied. These heteroarenes (1-8) condense with benzene in good yields (74-96%) in the Bronsted superacid, CF(3)SO(3)H (triflic acid). In these acid-catalyzed hydroxyalkylation reactions, compounds 1-8 are significantly more reactive than acetophenone. It is proposed that compounds 1-8 readily form dicationic electrophiles in triflic acid.     

Effects of tris(pyrazolyl)borato ligand substituents on dioxygen activation and stabilization by copper compounds

Dinuclear [Cu2(mu-O)2(Tp(R,R')2] complexes, analogues of the active site of oxyhemocyanin, are theoretically studied, and the effect of the substituents of the tris(pyrazolyl)borate ligands, Tp(R,R'), is analyzed. Density functional theory calculations reveal that the type of bridging oxygen, peroxo, or bisoxo is strongly influenced by the nature and position of the R substituents because of variable substituent...bridging oxygen interactions, as well as electronic effects. The electronic effects of ligands at the 5 position are not significant, but peroxo complexes are favored by electron-withdrawing groups at the 3 position while bisoxo ones are strongly sterically disfavored.