Isolation of herbicidal compounds,quercetin and β-caryophyllene,from Digera muricata

Synthetic herbicides are available to control weeds but these herbicides have many concerns. Eco-friendly herbicides obtained from plants is a better alternative to synthetic ones. Despite that the herbicidal activity of Digera muricata extracts have been reported but there are no studies regarding the isolation and identification of herbicidal compounds from D. muricata. Herein, we are reporting the identification of two herbicidal compounds from chloroform extract obtained from D. muricata. The chloroform extract was initially tested on the germination and early growth of two weeds; Avena fatua and Melilotus indicus as well as wheat where a significant decline in % age germination and growth of both weeds was observed. Among the 8 different fractions obtained using different chromatographic techniques, fractions 2 and 7 were found to be phytotoxic to both test weeds. The herbicidal efficacy was tested at 200, 150, 100, 50, 25 μg/ml. These two fractions were further purified on Reversed Phase High Pressure Liquid Chromatography (RP-HPLC). Fraction 2 yielded 3 sub-fractions (2A, 2B & 2C), while fraction 7 yielded 2 sub-fractions (7A, 7B). Fraction 2B caused 43%, 53%, and 57% decline in seed germination, shoot dry weight, and root dry weight of A. fatua, while these values against M. indicus were 50%, 81% and 84%, respectively. Fraction 7A caused 25%, 36%, and 42% decline in seed germination, shoot dry weight, and root dry weight of A. fatua, while these values against M. indicus were 35%, 62% and 69%, respectively, at 200 μg/ml conc. Cyanazine caused 61% and 50% reduction in seed germination of A. fatua and M. indicus, respectively. The herbicidal effects of these two fractions were found nonsignificant against wheat. Fourier Transform Infrared Spectroscopy (FT-IR), elemental analysis (C,H) and Nuclear Magnetic Resonanace (NMR) analyses of these two fractions depicted the presence of quercetin (Fraction 2B) and β-caryophyllene (Fraction 7A). In post emergence bioassays, the isolated compounds caused significant decrease in the biomass of both weeds. Plasma membrane integrity assays revealed electrolyte leakage in treated leaf discs of both weeds. It was concluded that quercetin and β-caryophyllene isolated from D. muricata exhibited toxicity towards both test weeds without harming wheat.     

Three-component synthesis of polysubstituted pyrroles from α-diazoketones, nitroalkenes, and amines

Polysubstituted pyrroles are regiospecifically synthesized via the copper-catalyzed three-component reaction of α-diazoketones, nitroalkenes, and amines under aerobic conditions. The cascade process involves an N-H insertion of carbene, a copper-catalyzed oxidative dehydrogenation of amine, and a [3 + 2] cycloaddition of azomethine ylide.     

Potential Biodegradable Implants from ϵ-Caprolactone and D,L-Lactide Copolymers: Synthesis,Properties, and In Vivo Degradation

Random copolymers of ?-caprolactone (CL) and D, L-lactide (DLLA) were synthesized by ring-opening polymerization using stannous octoate as catalyst. The effect of polymerization conditions, such as feeding dose, reaction temperature, polymerization time, and catalyst content on the properties of the copolymers was evaluated to prepare suitable copolymers with controlled properties for biodegradable implant applications. The results showed that the polymerization conditions influenced the thermal and mechanical properties of the copolymers strongly and controllable and tunable properties of random copolymers could be obtained by adjusting the copolymer compositions. The optimum reaction conditions to prepare the CL-DLLA copolymers for implant applications are 30–87 mol.% DLLA content in feeding dose, 110°C reaction temperature, and 24 h polymerization time. The results of in vivo implantation revealed the excellent degradability of CL-DLLA copolymers. Copolymers of CL and DLLA with different compositions and properties would be suitable for the application of biodegradable implants.     

Protofilaments, filaments, ribbons, and fibrils from peptidomimetic self-assembly: implications for amyloid fibril formation and materials science

Deciphering the mechanism(s) of β-sheet mediated self-assembly is essential for understanding amyloid fibril formation and for the fabrication of polypeptide materials. Herein, we report a simple peptidomimetic that self-assembles into polymorphic β-sheet quaternary structures including protofilaments, filaments, fibrils, and ribbons that are reminiscent of the highly ordered structures displayed by the amyloidogenic peptides Aβ, calcitonin, and amylin. The distribution of quaternary structures can be controlled by and in some cases specified by manipulating the pH, buffer composition, and the ionic strength. The ability to control β-sheet-mediated assembly takes advantage of quaternary structure dependent pK(a) perturbations. Biophysical methods including analytical ultracentrifugation studies as well as far-UV circular dichroism and FT-IR spectroscopy demonstrate that linked secondary and quaternary structural changes mediate peptidomimetic self-assembly. Electron and atomic force microscopy reveal that peptidomimetic assembly involves numerous quaternary structural intermediates that appear to self-assemble in a convergent fashion affording quaternary structures of increasing complexity. The ability to control the assembly pathway(s) and the final quaternary structure(s) afforded should prove to be particularly useful in deciphering the quaternary structural requirements for amyloid fibril formation and for the construction of noncovalent macromolecular structures.     

Stellarins F and G, two new cyclopeptides from Stellaria yunnanensis

In the previous papers,we reported the structural elucidation of stellarins A-E,fivenew cyclopeptides from the fresh roots of Stellaria yunnanensis Franch.Further chemical study on this plant led to the isolation of two other new cyclopeptides named stellarins F(l) and G(2).By a combination of 2D-NMR,enzymatic degradation and FABMS,their structures were established to be cyclo(Gly-Ala-Gly-Ser-Pro-Trp-Phe-Pro) and cyclo(Gly-Ala-Tyr-Leu-Ala),respectively.     

Lignans,flavonoids and coumarins from Viola philippica and their α-glucosidase and HCV protease inhibitory activities

Two lignans including a new one, five flavonoids and five coumarins were isolated from the whole plant of Viola philippica (synonymised as Viola yedoensis Makino). The new compound was structurally determined as (7R,8S,8′S) -3,3′-dimethoxy- 4,4′,9-trihydroxy- 7,9′-epoxy-8,8′-lignan 9-O-rutinoside by analysis of its NMR, MS and CD spectroscopic data. The known compounds were characterised by comparing their NMR and MS data with those reported. Among the known compounds, 5-hydroxy-4′-methoxyflavone-7-O- rutinoside, 6,7-di-O-β-D- glucopyranosylesculetin, and 7R,8S-dihydrodehydrodiconiferyl alcohol 4-O-β-D- glucopyranoside were isolated and identified from this genus for the first time. Of these compounds, 5-hydroxy-4′-methoxyflavone-7-O-rutinoside and (7R,8S,8′S) -3,3′-dimethoxy- 4,4′,9-trihydroxy- 7,9′-epoxy-8,8′-lignan 9-O-rutinoside were potently active against α-glucosidase, while the two dimeric coumarins, 5, 5′-bi (6, 7-dihydroxycoumarin) and 6,6′,7,7′-tetrahydroxy-5,8′-bicoumarin potently inhibited HCV protease.     

Gnetifolin L and O, Two Dimeric Stilbenes from Gnetum Montanum

GnetuI)1monlanlImgr0wsinthes0uthernpart0fChinaandhasbeenusedf0rthetreatment0fbronchitisandarthritisinf0lkmedicinel.Previously,aninvestigationofthisspeciesledt0theis0lationofs0meaIkal0idsanddibenzyletherderivatives2.lnourstudies,tenc0mp0nentsincludingresveratr0l,is0rhapontigenin,daucoster0l,O-sitosterol,stearicacid,gnetif0linE,gnet0l,is0rhapontigenin-3-O-6-gluc0pyra(-)8-viniferinandgnetifolinCwere0btainedfromthisplant'.Inthefurtherstudy,f0urnewdimericstilbenesnamedgnetif0IinMandN',gnetifoli…     

Isolation, Purification, and Properties of α-Amylase from Bacillus subtilis-7A

Cultivation ofBacillus subtilis-7A on waste from alcohol production yielded an active extracellular enzyme -amylase with MW 75 kDa. The enzyme was isolated from the culture medium by 60% saturated ammonium sulfate and purified until homogeneous by gel filtration on Sephadex G-100 and ion-exchange chromatography on DEAE-cellulose. The optimum temperatures for the complex and purified enzyme are 30 and 50°C, respectively. The optimum activity for both preparations occurred at pH 6.5. The substrate specificity of the isolated preparations was studied.     

Synthesis of Chiral Cyclohexenones from α-Campholenic,Fencholenic, and β-Campholenic Derivatives

Summary. Optically active dimethylcyclohexenones, potential building blocks for enantioselective syntheses of various naturally active substances, were prepared. These compounds were obtained by oxidation with KMnO₄/Pb(OAc)₄ or ozonolysis of the corresponding cyclopentenic precursors, followed by aldol condensation. During the course of the preparation intermediate diols and chiral polyfunctional carbonyl derivatives were separated and identified analytically.     

Production, Purification, Immobilization, and Characterization of a Thermostable β-Galactosidase from Aspergillus alliaceus

A fungal strain isolated from rotten banana and identified as Aspergillus alliaceus was found capable of producing thermostable extracellular ??-galactosidase enzyme. Optimum cultural conditions for ??-galactosidase production by A. alliaceus were as follows: pH?4.5; temperature, 30?°C; inoculum age, 25?h; and fermentation time, 144?h. Optimum temperature, time, and pH for enzyme substrate reaction were found to be 45?°C, 20?min, and 7.2, respectively, for crude and partially purified enzyme. For immobilized enzyme?Csubstrate reaction, these three variable, temperature, time, and pH were optimized at 50?°C, 40?min, and 7.2, respectively. Glucose was found to inhibit the enzyme activity. The K _m values of partially purified and immobilized enzymes were 170 and 210?mM, respectively. Immobilized enzyme retained 43?% of the ??-galactosidase activity of partially purified enzyme. There was no significant loss of activity on storage of immobilized beads at 4?°C for 28?days. Immobilized enzyme retained 90?% of the initial activity after being used four times.     

Base-free two-step synthesis of 1,3-diketones and β-ketoesters from α-diazocarbonyl compounds, trialkylboranes, and aromatic aldehydes

We describe a convergent, base-free two-step synthesis of 1,3-diketones and β-ketoesters from α-diazocarbonyl compounds, trialkylboranes, and aromatic aldehydes in a three-component process. The synthetic potential of this protocol was underscored by the synthesis of several symmetrical 1,3,5-triaryl-4-alkyl and 1,3,4,5-tetraryl substituted pyrazoles in a three-step sequence.     

Facile access to α,β-dehydroalanine and α,β-dehydroamino butyric acid derivatives from DL-serines and threonines

Not only α,β-dehydroamino acids are important constituents for a number of bioactive peptides in nature, but also they are important building blocks for a variety of synthetic amino acids in organic synthesis. Methods to prepare dehydroamino acids have been reported extensively in the literature; however, efficient and convenient protocols are still required. Here we have developed a convenient method to prepare dehydroalanine (ΔAla) and dehydroamino butyric acid (ΔAbu) derivatives derived from DL-serines and DL-threonines, respectively. 4-Toluenesulfonyl chloride (TsCl) and 1,8-diazabicyclo[5.4.0]undec-7-ene (DBU) were employed in this procedure, which carried out activation of hydroxyl group and β-elimination in one pot. Because it is convenient and easy to handle, this method will attract the attention of synthetic chemists.     

Synthesis of symmetrical acetylenic hydrocarbons and their α,ω-di-derivatives from α,α,α-trichloro- and α,α,α,ω-tetrachloro-alkanes

Summary By the action of sodium in xylene on polychloro hydrocarbons containing -CCl₂-CCl₂- or- CC1=CC1-, groupings the corresponding symmetrical acetylenic hydrocarbons containing 10,14, and 18 carbon atoms in the molecule were obtained. From ,-disubstituted tetrachloroalkanes by the same method 1,10-diethoxy-5-decyne, 1,14-diethoxy-7-tetradecyne, and 1,14-bisdiethylamino-7-tetradecyne were obtained.The spectra were determined in the Optical Laboratory of the Institute of Heteroorganic Compounds of the USSR by N. A. Chumaevskii, who we thank.     

Synthetic, structural, and biosynthetic studies of an unusual phospho-glycopeptide derived from α-dystroglycan

Aberrant glycosylation of α-dystroglycan (α-DG) results in loss of interactions with the extracellular matrix and is central to the pathogenesis of several disorders. To examine protein glycosylation of α-DG, a facile synthetic approach has been developed for the preparation of unusual phosphorylated O-mannosyl glycopeptides derived from α-DG by a strategy in which properly protected phospho-mannosides are coupled with a Fmoc protected threonine derivative, followed by the use of the resulting derivatives in automated solid-phase glycopeptide synthesis using hyper-acid-sensitive Sieber amide resin. Synthetic efforts also provided a reduced phospho-trisaccharide, and the NMR data of this derivative confirmed the proper structural assignment of the unusual phospho-glycan structure. The glycopeptides made it possible to explore factors that regulate the elaboration of critical glycans. It was established that a glycopeptide having a 6-phospho-O-mannosyl residue is not an acceptor for action by the enzyme POMGnT1, which attaches β(1,2)-GlcNAc to O-mannosyl moietes, whereas the unphosphorylated derivate was readily extended by the enzyme. This finding implies a specific sequence of events in determining the structural fate of the O-glycan. It has also been found that the activity of POMGnT1 is dependent on the location of the acceptor site in the context of the underlying polypeptide/glycopeptide sequence. Conformational analysis by NMR has shown that the O-mannosyl modification does not exert major conformational effect on the peptide backbone. It is, however, proposed that these residues, introduced at the early stages of glycoprotein glycosylation, have an ability to regulate the loci of subsequent O-GalNAc additions, which do exert conformational effects. The studies show that through access to discrete glycopeptide structures, it is possible to reveal complex regulation of O-glycan processing on α-DG that has significant implications both for its normal post-translational maturation, and the mechanisms of the pathologies associated with hypoglycosylated α-DG.     

Synthesis, characterization, and biological evaluation of new N-glycosides derived from O-pivaloylated β-d-glucopyranosylamine

The novel synthesis of N-(2,3,4,6-tetra-O-pivaloyl-??-d-glucopyranosyl) benzo[d] oxazol-2-amine 4 was described in this study. The new compounds N-arylthioureas 3a-c and 4, along with a series of glucose-modified imines 5a-g, were evaluated for their antitumor activity against human myeloid leukemia cell lines (HL-60 cells), gastric carcinoma (BGC-823 cells), liver carcinoma (Bel-7402 cells), and oral carcinomas (KB cells). The antibacterial potency of these compounds was also determined using an inhibition zone diameter test. Although none of the compounds were active against human cancer cells, compound 4 was found to be the most active compound against Escherichia coli.     

Kinetics of α hydrogen abstractions from thiols, sulfides and thiocarbonyl compounds

Hydrogen abstraction reactions involving organosulfur compounds play an important role in many industrial, biological and atmospheric processes. Despite their chemical relevance, little is known about their kinetics. In this work a group additivity model is developed that allows predicting the Arrhenius parameters for abstraction reactions of α hydrogen atoms from thiols, alkyl sulfides, alkyl disulfides and thiocarbonyl compounds by carbon-centered radicals at temperatures ranging from 300 to 1500 K. Rate coefficients for 102 hydrogen abstractions were obtained using conventional transition state theory within the high-pressure limit. Electronic barriers were calculated using the CBS-QB3 method and the rate coefficients were corrected for tunneling and hindered rotation about the transitional bond. Group additivity values for 46 groups are determined. To account for resonance and hyperconjugative stabilization in the transition state, 8 resonance corrections were fitted to a set of 32 reactions. The developed group additivity scheme was validated using a test set containing an additional 30 reactions. The group additivity scheme succeeds in reproducing the rate coefficients on average within a factor of 2.4 at 300 K and 1.4 at 1000 K. Mean absolute deviations of the Arrhenius parameters amount to, respectively, 2.5 kJ mol(-1) for E(a) and 0.13 for log A, both at 300 and 1000 K. This work hence illustrates that the recently developed group additivity methods for Arrhenius parameters extrapolate successfully to hetero-element containing compounds.     

Syntheses of quinolines and their derivatives from α,β-unsaturated aldehydes

Chemistry of Heterocyclic Compounds - The methods for the synthesis of quinoline and its hydrogenated derivatives from α,β-unsaturated aldehydes have been summarized for the first time....     

Eucaglobulin, A New Complex of Gallotannin and Monoterpene from Eucalyptus globulus

EucalyPtusgl0bulusLabill.(Myrtaceae)isakindofmedicinalplantwidelydistributedintheYunnanpr0vinceofChina.ItSleaves,rootSandffoitShavebeenusedastraditionalremediesforthetreatmentofinfluenza,dysentery,enteritis,rheumatalgiaandbleeding.BesidesvolatileterpenoidconstituentSintheessential0iloftheleavesandfruits,theoccurrenceofanumber0fphloroglucinol-sesquiterpene-or-m0n0terpene-c0upledcomPoundsnamedmacrocarpals'andeugl0bals'intheleavesandbudshasbeenrepofted.Inordertostudythechendcalandbioactivecon…     

Two New O-terpenoidal Coumarins, Excavacoumarin A and B from Clausena excavata

Cla!tsenaexcavataBurm.f(Rutaceae)isabushwidelydistributedinYunnan,China.Leavesandbarksofthisplanthavebeenusedasfolkrnedicineforthetreatmentofdysentery,enteritis,andurethrainfection1.ClalISenaspeciesareknowntobetherichsourcesofcarbazolealkaloidsandcoumarins=-j.TheconstituentsofCexcavalacollectedinXishuangbannahavebeenstudied'andthispaperdescribestheisolationandstructureelucidationoftwonewO-terpenoidalcoumarins,excavacoumarinA(2)andexcavacoumarinB(3),andthel3CNMRspectraldataassignmentsfora…     

Ferrocenyltriazoles from 3β,28-Diacylbetulin: Synthesis and Cytotoxic Activity

Russian Journal of Organic Chemistry - The reaction of 30-bromo-3β,28-diacylbetulin with sodium azide afforded 30-azido-3β,28-diacyloxylup-20(29)-enes. The products were subjected to a...