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1.
(±)-Lamprolobine, the (+)-enatiomer of which was isolated from the leaves of Lamprolobium fruticosum, and (±)-epilamprolobine were synthesized from δ-valerolactam.  相似文献   

2.
A novel synthesis of ( ± )-methyl epijasomonate (2) and the first synthesis of ( ± )-methyl cucurbate (4) were achieved starting from 2-allylcyclohexane-1,3-dione (8). The synthetic epimer 2 had a stronger jasmin flavor than the trans-isomer 1 with 95% purity.  相似文献   

3.
The synthesis of (±)-licarin-B, a neolignan of Licaria aritu Ducke (Lauraceae), was achieved by pyrolysis of 3-hydroxy-3-piperonyl-1-propyl-2-methoxy-4-(E)-propenylphenyl ethers.  相似文献   

4.
(±)Hydroxytremetone (III) has been synthesized from 2-(α-hydoxyisopropyl)-6-hydroxycoumaran (V b) via its O-acetate V c by dehydration with phosphorus tribromide in pyridine solution, followed by acylation with a mixture of trifluoroacetic anhydride and acetic acid. Isohydroxytremetone (IX b) was also synthesized.  相似文献   

5.
The enzymatic properties of P2-2 enzyme were determined by using cells of M. radiodurans. The enzyme was: most active at 60°C incubation temperature, stable at 40°C in neutral buffer, and inactivated by heating at 80°C for 15min. Maximal lytic activity occurred at pH 8.5 in Tris-HCl buffer. The range of enzyme stability was between pH 5.5 and 8. Bivalent metal ions, p-chloromercuribenzoate and monoiodo acetate inhibited lytic activity. The molecular weight was estimated to be 16,000 daltons by gel filtration on Sephadex G-75. The enzymatic digestion of peptidoglycans from the cell walls of M. radiodurans and M. lysodeikticus liberated free amino groups, but neither reducing groups nor N-acetylhexosamine, indicating that the enzyme was an endopeptidase. From analysis of the N-terminal amino acids of the digests, it is suggested that the P2-2 enzyme cleaves the peptide bond at the carboxyl group of D-alanine in peptidoglycan.  相似文献   

6.
Synthesis of (±)-phyllostine, (±)-epoxydon, (±)-epiepoxydon, (±)-epoformin and (±)-epiepoformin by the retro-Diels—Alder reaction was described.  相似文献   

7.
An alternative synthesis of (±)-tubaic acid (I), a key intermediate compound of rotenone synthesis, has been accomplished by the Wittig reaction.  相似文献   

8.
Phosphodiesterase production with bis-p-nitrophenyl phosphate as a substrate by alkalophilic Bacillus No. A-40-2 increased with increasing Mn2+ concentration, showing maximum productivity at 10 mm. The enzyme production was negligible in the medium without Mn2+. The simultaneous addition of 10 mm Mn2+ and one of the several cations Mg2+, Co2+, Mo6+, and Pb2+ at suitable concentrations stimulated the enzyme production 1.8-fold at most over that with only 10 mm Mn2+. Inorganic phosphate hardly repressed the enzyme production. The enzyme was purified homogeneously. The purified enzyme had the optimum pH of 7.5 and was fairly stable from pH 7–11. The enzyme hydrolyzed 2′,3′-cyclic-nucleotides and 3′-nucleotides, but did not hydrolyze 3′,5′-cyclic-nucleotides or 5′-nucleotides, indicating it to be a 2′,3′-cyclic-nucleotide 2′-phosphodiesterase (EC 3.1.4.16). The enzyme had activity without metals, but Mg2+, Ca2+, Ba2+, and Mo6+ activated the enzyme reaction.  相似文献   

9.
We examined whether developing cotyledons of soybean seed had photosynthetic activities. The cotyledons evolved oxygen under illumination and the activity was inhibited by 3-(3′,4′-dichlorophenyl)-1,1-dimethylurea. The rate of oxygen evolution decreased during the development of seeds; about 30μ miol O2 · mg chlorophyll-1 · hr-1 at the early developing stage and about 10μ miol O2-mg chlorophyll-1 · hr-1 at the late developing stage. The rate of oxygen uptake remained at an almost constant level of 40^mol 02-mg chlorophyll-1 · hr-1 throughout the development. Photosynthetic 14CO2-fixation by the cotyledon was observed. Ribulose bisphosphate carboxylase was immunochemically detected in the developing cotyledons. These results show that functional photosynthetic apparatus is present in the developing cotyledons of soybean seeds.  相似文献   

10.
11.
(±)Sclerin (4,5,6,7-tetramethyl-8-hydroxyisochroman-1,3-dione), a mycerial extracts of Sclerotinia libertiana, and related compounds were synthesized. Alkylated-7-hydroxyindanones were obtained from alkylated phenols and α-bromobutyrylbromide, and these indanone derivatives were treated with benzaldehyde to give 2-benzylidene-7-hydroxyindanone derivatives. By ozonolysis of these benzylidene-indanones were obtained 8-hydroxyisochroman-1,3-diones.  相似文献   

12.
The antifungal activity of 22 derivatives of 1-(3,5-dichlorophenyl)-2,5-pyrrolidinedione and 6 derivatives of 3-(3,5-dichlorophenyl)-2,4-oxazolidinedione, having various substituents on the imido rings, against Botrytis cinerea was determined by the agar medium dilution method. The structure-activity relationships were analyzed using the physicochemical parameters of the molecules: such as the hydrophobic log P, the electronic σ*, and the steric Esc values with the multiple regression technique. Only the hydrophobic effect is significant in determining the activity variations of both series of compounds. Furthermore, the structure-activity relationships of these two series of compounds are represented by an identical equation, having only the hydrophobic term as a variable.  相似文献   

13.
Ibrahim-Ouali M  Romero E 《Steroids》2012,77(1-2):157-167
An efficient strategy for introducing a nitrogen atom in positions 3 and 11 of the steroidal skeleton, which are key positions for biological purposes, is described. This procedure involves an intramolecular Diels-Alder cycloaddition of o-quinodimethanes which are generated from a 3-azabicyclo[4.2.0]octa-1,3,5-trien-7-one. The characteristic (1)H and (13)C NMR spectroscopic features of the synthesized compounds are reported.  相似文献   

14.
Boron is an essential nutrient for plants, but it is toxic in excess. Transgenic rice plants expressing an Arabidopsis thaliana borate efflux transporter gene, AtBOR4, at a low level exhibited increased tolerance to excess boron. Those lines with high levels of expression exhibited reduced growth. These findings suggest a potential of the borate transporter BOR4 for the generation of high-boron tolerant rice.  相似文献   

15.
(±)-Sermundone (2), one of the hydroxyrotenoids, has been synthesized. Also a new cyclization method to dehydrorotenoids has been developed using alkali metal salts.  相似文献   

16.
An enzyme which catalyzes the oxidation of poly(vinyl alcohol) (PVA) has been purified from a fraction adsorbed to DEAE-Sephadex at pH 7.0 from PVA-degrading enzyme activities produced by a bacterial symbiotic mixed culture in a culture broth when the culture was grown in a minimal medium where PVA served as a sole source of carbon and energy. The enzyme was separated from a coexisting oxidized PVA hydrolase by dye-ligand chromatography on Matrex Gel Blue A. The purified enzyme was homogeneous as judged by polyacrylamide gel electrophoreses in the absence and presence of SDS.

The enzyme is a single polypeptide with a molecular weight of about 40,000 and has an isoelectric point of 4.5. The amino acid composition of the enzyme has been determined and found to have no histidine. The N- and C-terminal amino acid residues are both alanine. The enzyme solution is pink and shows absorption maxima at 276, 364, and 469 nm. One atom of non-heme iron has been detected per molecule in the enzyme.

The enzyme catalyzes the oxidation of PVA and also of various low molecular weight secondary alcohols to the corresponding ketones with the production of H202 and the consumption of 02. The molar ratio of these ketones, H202 and 02 is 1:1:1. The most effective electron acceptor is 02, while 2,6-dichlorophenolindophenol and nitro blue tetrazolium also serve as the acceptor with efficiencies to 02 of about 31 and 16%, respectively. The enzyme is, therefore, considered to be a secondary alcohol oxidase.

The enzyme is most active at pH 7.0 and at 45°C and is stable between pH 5.0 and 9.0 and at temperatures below 45°C. The activity is inhibited by Hg2+ and is restored by the addition of reduced glutathione, although p-chloromercuribenzoate has no effect.

The enzyme shows a common antigenicity in immunodiffusion and neutralization reactions with antisera to a secondary alcohol oxidase previously isolated from another fraction adsorbed on SP-Sephadex at pH 7.0 of the PVA-degrading enzyme activities [Agric. Biol. Chem., 43, 1225 (1979)]. The relations between these two secondary alcohol oxidases are discussed.  相似文献   

17.
(±)-Azetidine-2-carboxylic acid and 3-substituted-2-pyrrolidinones were synthesized from 2-pyrrolidinone via 3-bromo-2-methoxy-1-pyrroline (IIIa). The bromide (IIIa) was obtained by the bromination of 2-methoxy-l-pyrroline using NBS.  相似文献   

18.
The racemic total synthesis of elegansidiol, farnesiferol B, and farnesiferol D has been obtained following a Diels–Alder approach. Gillman addition, cross metathesis reaction are the other key steps involved in the target synthesis.  相似文献   

19.
Synthetic 2′-hydroxy-3,4′,6′-trimethoxy-4-benzyloxychalcone (I) affords (±)-7,3′-di-O-methyleriodictyol (II) and 7,3′-di-O-methylluteolin (or velutin, VII) identical with natural samples. Similarly synthetic 2′-hydroxy-4,4′,6′-trimethoxy-3-benzyloxychalcone (X) gives natural (±)-7,4′-di-O-methyleriodictyol (XI) and 7,4′-di-O-methylluteolin (or pilloin, IX). However, attempts to partially etherify II with one mole of prenyl bromide to obtain the natural prenyl ether failed; only the corresponding diprenyloxychalcone (IV) was obtained.  相似文献   

20.
A riboflavin α-glucoside-synthesizing enzyme from the acetone powder of pig liver was purified by a procedure including fractionation with ammonium sulfate, heat treatment, fractionation with acetone, gel filtration on a Sephadex G-150 column, calcium phosphate gel treatment, and isoelectric focusing. A final enzyme preparation was homogeneous on polyacrylamide disc gel electrophoresis and in the ultracentrifuge. The enzyme had a sedimentation coefficient of 9.90 S and an isoelectric point of pH 3.7. The enzyme had a pH optimum at 6.0 with maltose as substrate. The enzyme catalyzed the hydrolysis of diverse kinds of α-glucosidic substrates, and the transfer of α-glucosyl residue from these substrates to riboflavin. The Km value for maltose was 1.20×10?3m. The enzyme hydrolyzed phenyl α-maltoside to glucose and phenyl α-glucoside. Amylose was almost completely hydrolyzed to glucose by the enzyme. Maltotriose was obtained as the main transfer product after the treatment of maltose with the enzyme. The enzyme also catalyzed the transfer of α-glucosyl residue from maltose to pyridoxine, esculin, rutin, and adenosine. It was recognized that a single enzyme catalyzed not only the hydrolysis of maltose and α-glucosidic substrates but also the transfer of the α-glucosyl residue of these substrates to suitable acceptors.  相似文献   

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