Studies on the Glucanase of Sclerotinia Libertiana

Preparations of glucan obtained from baker’s yeast and sclerotia of Sclerotinia Libertiana were found to be completely hydrolysed by enzymes of the Sclerotinia fungus. Some differences in the molecular structure of the glucans were found upon examination of the modes of degradation by the successive action of Rhizopus- and Sclerotinia enzyme preparations of which the former had only a partial hydrolytic effect.

The dissolution of glucan in intact cells of yeast, that could be estimated from the rate of autolysis of the cells, was proved to be insignificant on the action of glucanase alone in the Sclerotinia enzyme solution. The combined action of glucanase with lipolytic enzyme in the fungus enzyme solution are shown to promote the solubilization of intact yeasts and sclerotium cells.     

Cytotoxic activity of butane type of 1,7-seco-2,7′-cyclolignanes and apoptosis induction by Caspase 9 and 3

All stereoisomers of methoxybutane and fluorobutane type of 1,7-seco-2,7′-cyclolignane were synthesized and cytotoxic activities of these compounds were compared with those of all stereoisomers of butane and butanol type compounds. Both enantiomers of butane type secocyclolignane showed higher cytotoxic activity (IC₅₀ = 16–20 μM) than methoxy type compounds, whereas none was observed for all the stereoisomers of butanol type secocyclolignane, however, (−)-Kadangustin J showed stereospecific cytotoxic activity (IC₅₀ = 47–67 μM). Since (R)-9′-fluoro derivative 23 was most potent (IC₅₀ = 19 μM) among the corresponding fluoro stereoisomers, (R)-9′-alkyl derivatives were synthesized, hydrophobic 9′-heptyl derivative 27 showing highest activity (IC₅₀ = 3.7 μM against HL-60, IC₅₀ = 3.1 μM against HeLa) in this experiment. Apoptosis induction caused by Caspase 3 and 9 for (R)-9′-heptyl derivative 27 was observed in the research on the mechanism. A degradation of DNA into small fragments was also shown by DNA ladder assay.     

Studies on the Glucanase of Sclerotinia libertiana

The digestion of yeast cells with the glucanase of Sclerotinia was found to be significantly increased by pretreating the cells with papaya lysozyme, as well as by pretreating with dilute sodium hydroxide solution. Defatted chlorella cells were digested to a certain extent with the glucanase alone. Pretreatment with lipolytic enzyme slightly stimulated the digestion of yeast cells by glucanase, but this effect was not found with the yeast cells treated by soaps or the defatted chlorella cells. Egg white lysozyme had no effect on digestion of yeast cells. The effect of papaya lysozyme seemed to have relation with the liberation of hexosamine compounds from the yeast-cell walls. It is suggested that, in normal cells, the glucan is present to form a further complex structure with certain other component, becoming insusceptible to the action of glucanase.     

Stereoselective Model Synthesis of the Optically Active Olivil Type of Lignan from D-Xylose

The olivil type of lignan, (2S,3R,4R)-4-benzyl-4- hydroxy-3-hydroxymethyl-2-(3,4-methylenedioxyphenyl)tetrahydrofuran, was stereoselectively synthesized from D-xylose.     

Stereoselective Synthesis of the Optically Active Samin Type of Lignan from L-Glutamic Acid

The optically active samin type of lignan, (1R,2S,5R, 6S)-6-(2-methoxy-4,5-methylenedioxyphenyl)-3,7-dioxabicyclo[3.3.0]octan-2-ol, was stereoselectively synthesized from L-glutamic acid via (2R,3R)-2-[(1S and R)- 1-[(tert-butyldimethylsilyl)oxy]-1-(2-methoxy-4,5-methylenedioxyphenyl)methyl]-3-[(tert-butyldiphenylsilyl)oxy]methyl-1,4-butanediol.     

New lignan glycosides from the root barks of Litsea glutinosa

An investigation on the chemical constituents in the root barks of Litsea glutinosa was performed for the first time. Three new lignan glycosides named Litseasins A–C (1–3), together with a known one (4), were obtained. The structures of the new compounds were established through extensive spectroscopic analyses including HR-ESI–MS, NMR, and circluar dichroism (CD). The new compounds were evaluated for their anti-inflammatory activities on lipopolysaccharide (LPS)-induce nitric oxide (NO) production in RAW264.7 murine macrophage cells. However, these compounds showed no inhibition on LPS-induced NO productions.     

Studies on the inhibition of glycogenolysis by D-galactosamine in rat liver hepatocytes.

Effect of galactosamine on glycogenolysis was studied in isolated hepatocytes. It was found that addition of galactosamine strongly inhibited glycogenolysis in normal hepatocytes. Galactosamine-inhibited glycogenolysis was not stimulated by epinephrine or glucagon. This inhibition was specific as no such inhibition was observed with galactose, 2-deoxy-glucose or glucosamine. The glucagon-stimulated cyclic AMP formation in galactosamine-treated hepatocytes was the same as in normal cells; Glc-1-P and Glc-6-P did not accumulate nor was lactate formation enhanced. The glucose production by hepatocytes from regenerating liver was only slightly inhibited by galactosamine and glucagon addition stimulated glycogenolysis in the presence of the amino sugar.     

Studies on the chemical nature of the lipidic J blood-group substance of cattle

Total lipids extracted from J-positive cattle serum, erythrocytes or spleen exhibit J blood-group activity. The J subsance is concentrated in a lipid fraction obtained by column chromatography. Following mild alkaline hydrolysis or reduction with complex hydrides (LiAlH₄, LiBH₄), the J activity remains detectable in this lipid fraction even though all acyl ester groups have been destroyed as revealed by ester group determination. This disagrees with the suggestion that fatty acyl esters are essential for J activity. This was confirmed by experiments with a water-soluble J-active product prepared by ozone treatment of glycosphingolipids from bovine spleen. The results of these experiments are in favour of a glycosphingolipid containing an unusually lang oligosaccharide chain. Furthermore, it appears that the terminal moiety of the J determinant is not necessarily an N-acetyl galactos-amine unit as suggested previously.     

Studies on the synthesis of CDP-diacylglycerol: Stimulation by GTP and inhibition by ATP and fluoride

The rat liver microsomal enzyme CTP: phosphatidate cytidylyltransferase (EC 2.7.7.41) which catalyzes the formation of CDP-diacylglycerol has been found to be markedly stimulated by GTP. The requirement for GTP is absolute, the novel GTP analogues such as guanosine 5′-[β,γ-methylene]-triphosphate, guanosine 5′-[α,β-methylene]-triphosphate, guanosine 5′-[β,γ-imido]-triphosphate and guanosine 3′-diphosphate 5′-diphosphate are without significant effect. Maximal stimulation occurs at 1 mM GTP. ATP at a concentration of 5 mM totally inhibits the formation of CDP-diacylglycerol even in the presence of optimal GTP concentration. Analogues of ATP such as adenosine 5′-[α,β-methylene]-triphosphate, adenosine 5′-[β,γ-methylene]-triphosphate and adenosine 5′-[β,γ-imido]-triphosphate are without effect on the reaction. The addition of fluoride (8 mM) likewise abolishes the stimulatory effect of GTP.     

Studies on the Structure of Gluco-oligosaccharides Obtained from the Partial Acid Hydrolyzate of Sclerotia of Sclerotinia libertiana

The defatted sclerotia powder was partially hydrolyzed with dilute acid, and the material obtained was fractionated by carbon column chromatography, separated into two disaccharides, three trisaccharides and three tetrasaccharides, respectively. In these hydrolyzates α, α-trehalose, Iaminaribiose, and gentiobiose were identified.     

草豆蔻中黄酮和双苯庚酮的抑菌活性

以两倍稀释法测定了草豆蔻(Alpinia katsumadaiHayata)种子中4种黄酮和双苯庚酮类化合物的抑菌效果。结果表明,反,反-1,7-二苯基-4,6-庚二烯-3-酮和山姜素对幽门螺杆菌(Helicobacter pylori)的最低抑菌浓度(M IC)达到1.25μg.mL-1,与阳性药相比对幽门螺杆菌具有较强的抑菌活性;豆蔻明和乔松素对幽门螺杆菌的M IC分别为2.56和0.32 mg.mL-1。反,反-1,7-二苯基-4,6-庚二烯-3-酮和豆蔻明对金黄色葡萄球菌(Staphylococcus aureusRosenbach)、表皮葡萄球菌〔S.epiderm idis(W inslow et W inshlow)Evans〕、大肠杆菌〔Escherichia coli(M igu la)Castellan i et Chalm ers〕等菌株的M IC分别为0.208~1.667和0.122~1.955 mg.mL-1,与阳性药相比具有较强的抑菌活性。乔松素和山姜素对金黄色葡萄球菌、表皮葡萄球菌、大肠杆菌等菌株的M IC分别为1.275~2.550和1.925~3.850 mg.mL-1,也有一定的抑菌作用。豆蔻明、乔松素、反,反-1,7-二苯基-4,6-庚二烯-3-酮和山姜素是草豆蔻的抑菌活性成分。     

油菜菌核病菌对速克灵的抗药性风险研究

在室内条件下通过菌丝生长速率法测定了分离自安徽省10个县市的油菜菌核病菌（Sclerotinia scleroti-orum）对速克灵的敏感性。结果表明,速克灵对各供试菌株的EC50值分布范围为0.0899-0.4966μg/mL,平均为0.2541μg/mL,且供试菌株在含速克灵质量浓度为10 000μg/mL的PDA平板上菌丝生长几乎完全被抑制。表明各供试菌株对速克灵十分敏感,但其敏感程度地区间存在较大差异。通过室内药剂直接诱变法,获得了抗速克灵突变株。抗性突变株抗性测定结果表明,某些地区的抗性菌株抗性消失,有些地区的抗性菌株抗性继续保持。结果显示安徽省油菜菌核病菌对速克灵具有潜在的抗药性风险。     

菌核病防治研究进展

菌核病是一种寄主种类广泛的重大植物病害,可侵染450多种重要作物和草类,在我国每年给油菜、大豆以及多种蔬菜带来10～30亿元的损失.介绍了菌核病的症状、危害以及致病机理等,概述了主要的防治措施,并报道了国内外在关于菌核病生物防治、转基因育种、分子机理等方面的研究进展.     

从滑桃树种壳中分离到具抗细菌活性的新木脂素(英文)

Five neolignans including four new ones were obtained from the seed endotheliums of Trewia nudiflora L. Their structures were determined to be 9‘-methyl americanol A(1), 9‘-methyl isoamericanol A(2), 9‘-ethyl americanol A(3), 9‘-butyl americanol A(4), and americanin (5). Two acetylated products 3,4-diacetyl americanin (5a) and 3,4,9-triacetyl americanin (5b) had been prepared from compound 5. All of these compounds were investigated on antibacterial assays when carbenicillin sodium, streptomycin sulfate and rifampicin were used as positive controls. Compounds 4 and 5 exhibited antibacterial activities against gram-positive bacterium Staphylococcus aureus and gram-negative bacterium Mycobacterium tuberculosis at the minimum inhibitory concentrations (MIC) of 50μg/mL and 100μg/mE respectively, but 5a and 5b did not exhibit antibacterial activity at 200μg/disk.     

Studies on the Chemical Constituents of Rhododendron capitatum Maxim

Ten compounds were isolated from the aqueous extract of Rhododendron capitatum Maxim and identified as scopoletin, fraxefin, grayanomxin Ⅰ, Ⅱ, Ⅳ, raffinose, hyperin, capitatin, quercetin and myricefin, respectively, on the basis of physico-chemical properies, UV, IR, NMR and MS data. The capitatin was a new compound.     

Initial Studies to Define the Physiologic Role of cN-II

IMP preferring cytosolic 5 ′-nucleotidase II (cN-II) is a widespread enzyme whose amino acid sequence is highly conserved among vertebrates. Fluctuations of its activity have been reported in some pathological conditions and its mRNA levels have been proposed as a prognostic factor for poor outcome in patients with adult acute myeloid leukemia. As a member of the oxypurine cycle, cN-II is involved in the regulation of intracellular concentration of 5′-inosine monophosphate (IMP), 5′-guanosine monophosphate (GMP), and also 5-phosphoribose 1-pyrophosphate (PRPP) and is therefore involved in the regulation of purine and pyrimidine de novo and salvage synthesis. In addition, several studies demonstrated the involvement of cN-II in pro-drug metabolism. Notwithstanding some publications indicating that cN-II is essential for the survival of several cell types, its role in cell metabolism remains uncertain. To address this issue, we built two eucaryotic cellular models characterized by different cN-II expression levels: a constitutive cN-II knockdown in the astrocytoma cell line (ADF) by short hairpin RNA (shRNA) strategy and a cN-II expression in the diploid strain RS112 of Saccharomyces cerevisiae. Preliminary results suggest that cN-II is essential for cell viability, probably because it is directly involved in the regulation of nucleotide pools. These two experimental approaches could be very useful for the design of a personalized chemotherapy.