Synthesis of modified fragments of fibrinogen and their effect on the activity of proteolytic enzymes

New analogues of the Gly-Pro-Arg and Arg-Gly-Asp fragments of fibrinogen were synthesized: Gly-Pro-Arg-Pro (I), Gly-Pro-Arg-Pro-Met-OMe (II), Gly-Pro-Arg-Pro-Phe (III), Gly-Pro-Arg-Pro-Asp (IV), Gly-Pro-Arg-Pro-Glu (V), and Arg-Asn-Trp-Asp (VI). Their effect on the activity of proteases of various types was studied with the method of lysis of fibrin plates. All the peptides were found to inhibit plasmin activity (by 60–85%) and the γ-subunit of nerve growth factor (by 55–93%). Tetrapeptide (VI) proved to be an effective inhibitor of tissue activator of plasminogen and the γ-subunit of nerve growth factor (by 96 and 93%, respectively). The peptides exerted practically no effect on the activity of urokinase and moderately inhibited the activity of streptokinase [(III), IV), and (VI)], papain [(I), (II), IV), and (VI)], subtilisin [(V) and (VI)], α-chymotrypsin [(III), (V), and VI)], and Bacillus subtilis metalloprotease (VI). They inhibit trypsin [except for (I) and (III)] when applied on fibrin plates at a concentration of 1 × 10^?2 M, while, at the concentration of 1 × 10^?3 M, (I) and (II) induced an increase in proteolytic activity by 35 and 47%, respectively.     

Combination of 1,4-naphthoquinone with benzothiazoles had selective algicidal effects against harmful algae

A series of naphthoquinone-benzothiazole conjugates were synthesized as algicides, and their efficacies against harmful algal blooming species, such as Chattonella marina, Heterosigma akashiwo and Cochlodinium polykrikoides, were examined. The introduction of substituted benzothiazole at the C2 position of 1,4-naphthoquinone (compounds 1–9) resulted in higher algicidal activity against C. polykrikoides than the C6 conjugates (compounds 10–20). On the other hand, of the C6 conjugates, compounds 11 and 12 exhibited better algicidal activity against H. akashiwo, C. marina, and C. polykrikoides than the C2 conjugates. Further structure-activity analysis indicated that a replacement of the methoxy groups with hydroxyl groups (compounds 21–26) decreased the algicidal activity significantly. Among the various synthetic naphthoquinonebezothiazole conjugates tested, compound 12 was found to affect the most significant decrease in the level of C. polykrikoides growth, with an IC₅₀ of 0.19 μM. Compound 11 was found to be the most potent inhibitor against H. akashiwo and C. polykrikoides, with IC₅₀ values of 0.32 and 0.12 μM, respectively. Overall, these results highlight a possible method for controlling and inhibiting red tide forming algae using NQ derivatives.     

Photoreversible Modulators of Escherichia coli β-Galactosidase. 1-Benzoyl-1-cyano-2-(4,5-dimethoxy-2-nitrophenyl)-ethene and 1,1-Dicyano-2-(4,5-dimethoxy-2-nitrophenyl)-ethene

β-Galactosidase (EC 3.2.1.23) is known to be inhibited by some thiol reagents. 1-Benzoyl-1-cyano-2-(4,5-dimethoxy-2-nitrophenyl)-ethene (1) was shown to be an irreversible inhibitor, while 1, 1-dicyano-2-(4,5-dimethoxy-2-nitrophenyl)-ethene (2) was demonstrated as a positive irreversible modulator causing a rise of up to 186% in β-galactosidase activity. Compound 2 is, however, an irreversible inhibitor of the cysteine proteinase papain (preceding paper). Kinetic values of β-galactosidase at pH 8.3 with o-nitrophenyl β-D-galactopyranoside (ONPG) as the substrate and for compounds 1 and 2 were determined and in view of model experiments, it was assumed that both compounds possibly reacted with the thiol side chain of Cys in the active site inducing allosteric changes in the enzyme. Since the enzyme, modified by compound 1 or 2, was a 2-nitrobenzyl derivative, near-UV irradiation resulted in a recovery of up to 91% and a reduction of the enzyme's activity to 90%, respectively.     

Characterization of the sugar-O-methyltransferase LobS1 in lobophorin biosynthesis

Lobophorins A (1) and B (2) belong to a large group of spirotetronate natural products with potent antibacterial and antitumor activities. The cloning of the lobophorin biosynthesis gene cluster from the deep-sea-derived Streptomyces sp. SCSIO 01127 identified a sugar-O-methyltransferase-encoding gene lobS1. The lobS1 inactivation mutant accumulated two new lobophorin analogs 3 and 4, different from 1 and 2 by lacking the 4-methyl group at the terminal l-digitoxose, respectively. Biochemical experiments verified that LobS1 was a SAM-dependent sugar-O-methyltransferase that required divalent metal ions for better activity. Antibacterial assays revealed compounds 3 and 4 were generally less potent than compounds 1 and 2. These findings suggest that the methylation on the terminal digitoxose by LobS1 tailors lobophorin biosynthesis and highlights the importance of this methylation for antibacterial potence.     

Synthesis of eperezolid-like molecules and evaluation of their antimicrobial activities

3-Fluoro-4-(4-phenylpiperazin-l-yl)aniline (II) prepared from 3,4-difluoro nitrobenzene was converted to the corresponding Schiff bases (III) and (IV) by treatment with 4-methoxybenzaldehyde and indol-3-carbaldehyde, respectively. Treatment of amine (II) with 4-fluorophenyl isothiocyanate afforded the corresponding thiourea derivative (V). Compound (V) was converted to thiazolidinone and thiazoline derivatives (VI) and (VII) by cyclocondensation with ethylbromoacetate or 4-chlorophenacylbromide, respectively. The synthesis of carbothioamide derivative (X) was performed starting from compound (II) by three steps. Treatment of compound (X) with sodium hydroxide, sulfuric acid, or chlorophenacyl bromide generated the corresponding 1,2,4-triazole (XI), 1,3,4-thiadiazole (XII), and 1,3-thiazolidinone (XIII) derivatives, respectively. The structural assignments of new compounds were based on their elemental analysis and spectral (IR, ¹H-NMR, ¹³C-NMR, and LC-MS) data. In the antimicrobial activity study all the compounds revealed high anti-Mycobacterium smegmatis activity.     

2-Phenylpyridine ruthenacycles as effectors of glucose oxidase activity: inhibition by RuII and activation by RuIII

Cyclometalated Ru^II derivatives of 2-phenylpyridine (Hphpy) [Ru(phpy)(bpy)₂]Cl (1a) and [Ru(phpy)(phen)₂]Cl (1b) (bpy is 2,2′-bipyridine, phen is 1,10-phenanthroline) behave as noncompetitive inhibitors of glucose oxidase from Aspergillus niger in the enzyme-catalyzed oxidation of d-glucose by O₂ into the corresponding lactone at pH 5.0 and 25 °C. The enzymatic activity has been measured by monitoring the O₂ consumption. The inhibition constants K _i are 0.036 and 0.017 M for 1a and 1b, respectively, indicating that 1b inhibits the enzymatic activity more efficiently than 1a. The well-known coordination compound [Ru(bpy)₃]Cl₂ (2) behaves, in contrast, as a competitive inhibitor, with K _i = 0.018 M under the same conditions. The monophasic consumption of O₂ in the case of 1a, 1b, and 2 is replaced by a distinct two-phase kinetics in the presence of the cyclometalated Ru^III compound [Ru(phpy)(bpy)₂]Cl₂ (3), which was obtained from 1a in the presence of a large excess of H₂O₂ and the iron TAML activator. Interestingly, the rates of the first and the second phases are influenced by 3 in a different way. The rate of the first phase is noticeably higher in the presence of Ru^III, although the dependence is nonmonotonic and maximal acceleration is observed at the lowest loadings of 3. The rate of the second phase decreases monotonically on increasing the concentration of the ruthenium complex in solution. The nonmonotonic action of 3 was confirmed by using the doubly cyclometalated Ru^III derivative [Ru(phpy)₂(bpy)]Cl. The diverse rate variations induced by 3 accounted for acceleration by Ru^III of the O₂ reduction by the reduced form of glucose oxidase during the first phase, which ceases after the enzymatic reduction of Ru^III to the Ru^II species, the latter behaving similarly to 1a as the inhibitor of the enzyme.     

Enhanced β-turn conformational stability of tripeptides containing ΔPhe in cis over trans configuration

Conformations of three pairs of dehydropeptides with the opposite configuration of the ΔPhe residue, Boc-Gly-Δ^Z/EPhe-Phe-p-NA (Z- p -NA and E- p -NA), Boc-Gly-Δ^Z/EPhe-Phe-OMe (Z-OMe and E-OMe), and Boc-Gly-Δ^Z/EPhe-Phe-OH (Z-OH and E-OH) were compared on the basis of CD and NMR studies in MeOH, TFE, and DMSO. The CD results were used as the additional input data for the NMR-based calculations of the detailed solution conformations of the peptides. It was found that Z- p -NA, E- p -NA, Z-OMe, and Z-OH adopt the β-turn conformations and E-OMe and E-OH are unordered. There are two overlapping type III β-turns in Z- p -NA, type II’ β-turn in E- p -NA, and type II β-turn in Z-OMe and Z-OH. The results obtained indicate that in the case of methyl esters and peptides with a free carboxyl group, Δ^ZPhe is a much stronger inducer of ordered conformations than Δ^EPhe. It was also found that temperature coefficients of the amide protons are not reliable indicators of intramolecular hydrogen bonds donors in small peptides.     

Cytotoxic metabolites from the cultures of endophytic fungi from Panax ginseng

Two strains of endophytic fungi, Penicillium melinii Yuan-25 and Penicillium janthinellum Yuan-27, with strong anti-Pyricularia oryzae activity, were obtained from the roots of Panax ginseng. Based on bioactivity-oriented isolation, a new benzaldehyde derivative, ginsenocin (1), together with six known compounds, methyl 2,4-dihydroxy-3,5,6-trimethylbenzoate (2), 3,4,5-trimethyl-1,2-benzenediol (3), penicillic acid (4), mannitol (5), ergosterol (6), and ergosterol peroxide (7), were separated from the EtOAc extract of Yuan-25 culture, while brefeldin A (8) was isolated as the major constituent from the EtOAc extract of Yuan-27 culture. The chemical structures were determined based on spectroscopic methods. All the isolated compounds 1–8 were evaluated for their cytotoxicity against six human cancer cell lines. Brefeldin A (8) was the most cytotoxic constituent against all the tested cell lines with IC₅₀ values <0.12 μg/ml, while ginsenocin (1) and penicillic acid (4) also exhibited potent cytotoxicity with IC₅₀ values ranging from 0.49 to 7.46 μg/ml. Our results suggest that endophytic fungi isolated from P. ginseng are a promising natural source of potential anticancer agents.     

Influence of carbohydrate source on xanthone content in root cultures of Gentiana dinarica Beck

The effects of different types and concentrations of sugars on root growth and xanthone production in root culture of Gentiana dinarica were investigated. The results showed that sucrose, glucose and fructose all supported root growth, and sucrose was superior in terms of growth index, dry mass and fresh/dry mass ratio then fructose or glucose at the same concentrations. However, considering equimolar concentration of sugars, their contribution to the root growth was similar. The HPLC analysis of roots indicated the presence of xanthone compounds, and the contents of norswertianin-1-O-primeveroside (1), norswertianin-1-O-glucoside (2), gentioside (3) and norswertianin (4) were evaluated. In all samples, norswertianin-1-O-primeveroside (1) was present in highest concentration, followed by norswertianin-1-O-glucoside (2), whereas gentioside (3) and norswertianin (4) were present in lower amounts. The production of xanthones was affected by both type and concentration of sugar. In general, roots growing in media supplemented with sucrose contained higher levels of xanthones. The amounts of xanthone primeveroses (1) and (3) increased with the increase of concentrations of all types of sugars, whereas higher sugar concentrations resulted in reduction of the contents of norswertianin-1-O-glucoside (2) and aglycone norswertianin (4). The roots were also evaluated regarding the content of total phenolics and higher accumulation of total phenolic compounds was observed in roots grown in fructose-containing medium. Antioxidant activity was determined by 1,1-diphenyl-2-picrylhydrazyl (DPPH) radical scavenging assay, and high correlation between total phenolic content and antiradical activity was observed (r = ?0.83).     

Neurite Outgrowth of PC12 Cells by 4′-O-β-d-Glucopyranosyl-3′,4-Dimethoxychalcone from Brassica rapa L. ‘hidabeni’ was Enhanced by Pretreatment with p38MAPK Inhibitor

The cellular effects of eleven compounds including chalcone glycosides isolated from Brassica rapa L. ‘hidabeni’ and their synthetic derivatives were studied in rat pheochromocytoma PC12 cells. Of the compounds tested, 4′-O-β-d-glucopyranosyl-3′,4-dimethoxychalcone (A2) significantly increased the levels of the phosphorylated forms of extracellular signal-regulated kinases 1/2 (ERK 1/2), p38 mitogen-activated protein kinase (p38MAPK), and stress-activated protein kinases/Jun amino-terminal kinases (JNK/SAPK), but it did not affect Akt. Nerve growth factor (NGF), a well-known neurotrophic factor, increased the levels of phosphorylated ERK1/2, JNK/SAPK, and Akt but not p38MAPK, which may mediate marked neurite outgrowth. Signals evoked by A2 shared common characteristics with those induced by NGF; therefore, we evaluated the neuritogenic activity of A2 and found it induced only weak neurite outgrowth. However, this effect was enhanced by pre-treatment with a p38MAPK inhibitor, suggesting that the phosphorylation of p38MAPK down-regulated neurite outgrowth. From the results of this study, it was found that A2 in combination with a p38MAPK inhibitor can induce NGF-like effects. Hence, a combination of chalcone glycosides containing A2 and a p38MAPK inhibitor increases the likelihood that chalcone glycosides could be put to practical use in the form of drugs or alternative medicines to maintain neural health.     

Separation and purification of bioactive botrallin and TMC-264 by a combination of HSCCC and semi-preparative HPLC from endophytic fungus Hyalodendriella sp. Ponipodef12

Two dibenzo-α-pyrones, botrallin (1) and TMC-264 (2) were preparatively separated from crude ethyl acetate extract of the endophytic fungus Hyalodendriella sp. Ponipodef12, which was isolated from the hybrid ‘Neva’ of Populus deltoides Marsh × P. nigra L. using a combination of high-speed counter-current chromatography (HSCCC) and semi-preparative HPLC. Botrallin (1) with 74.73 % of purity and TMC-264 (2) with 82.29 % of purity were obtained through HSCCC by employing a solvent system containing n-hexane–ethyl acetate–methanol–water at a volume ratio of 1.2:1.0:0.9:1.0. It was the first time for TMC-264 (2) to be isolated from this fungus. TMC-264 (2) showed strong antimicrobial and antinematodal activity, and botrallin (1) exhibited moderate inhibitory activity on acetylcholinesterase.     

Mono- and digalactosyldiacylglycerols: potent nitric oxide inhibitors from the marine microalga Nannochloropsis granulata

Chemical investigation of a marine microalga, Nannochloropsis granulata, led to the isolation of four digalactosyldiacylglycerols namely, (2S)-1-O-eicosapentaenoyl-2-O-palmitoyl-3-O-(β-d-galactopyranosyl-6-1α-d-galactopyranosyl)-glycerol (1), (2S)-1-O-eicosapentaenoyl-2-O-palmitoleoyl-3-O-(β-d-galactopyranosyl-6-1α-d-galactopyranosyl)-glycerol (2), (2S)-1-O-eicosapentaenoyl-2-O-myristoyl-3-O-(β-d-galactopyranosyl-6-1α-d-galactopyranosyl)-glycerol (3), and (2S)-1,2-bis-O-eicosapentaenoyl-3-O-(β-d-galactopyranosyl-6-1α-d-galactopyranosyl)-glycerol (4), together with their monogalactosyl analogs (5–8). Among the isolated galactolipids 2 and 3 were new natural products. Complete stereochemistry of 1, 4, 5, 7, and 8 was determined for the first time by both spectroscopic techniques and classical degradation methods. Both mono- and digalactosyldiacylglycerols isolated from N. granulata possessed strong nitric oxide (NO) inhibitory activity against lipopolysaccharide-induced NO production in RAW264.7 macrophage cells through downregulation of inducible nitric oxide synthase expression indicating the possible use as anti-inflammatory agents.     

New taxa and nomenclatural changes in arceuthobium (viscaceae)

The following new taxa are recognized inArceuthobium: subgeneraArceuthobium andVaginata; sectionsVaginata, Campylopoda, andMinuta; seriesCampylopoda,Rubra, andStricta; speciesA. apachecum,A. californicum,A. guatemalense,A. hondurense, andA. pini; new formae spécialesA. abietinum f. sp.concoloris,A. abietinum f. sp.magnificae. New combinations:A. abietinum (Engelm.) Hawksworth & Wiens, andA. microcarpum (Engelm.) Hawksworth & Wiens.     

Generic delimitations of Central American Bignoniaceae

Generic delimitations in the Bignoniaceae are discussed, a number of Central American genera are reduced to synonymy, and a new genusPseudocatalpa is proposed. Generic mergers includeLevya withCydista, Saldanhaea withCuspidaria, Doxantha withMacfadyena, Pseudocalymma withPachyptera, andPhaedranthus withDistictis. New combinations necessitated by these mergers include the following:Arrabidaea costaricensis (Kränzl.) Gentry,A. pubescens (L.) Gentry,Cuspidaria floribunda (DC.) Gentry,C. weberbaueri (Spr.) Gentry,Cydista aequinoctialis var.hirtella (Benth.) Gentry,Distictis buccinatoria (DC.) Gentry,Macfadyena unguiscati (L.) Gentry,Melloa quadrivalvis (Jacq.) Gentry,Pachyptera alliacea (Lam.) Gentry,P. hymenaea (DC.) Gentry,P. kerere var.incarnata (Aubl.) Gentry,P. standleyi (Steyerm.) Gentry, andPseudocatalpa caudiculata (Standl.) Gentry. In addition, the fruits of several species are described for the first time, and their taxonomic significance is discussed.     

Five new galactolipids from the freshwater microalga Porphyridium aerugineum and their nitric oxide inhibitory activity

Chemical investigation of the freshwater rhodophyte microalga Porphyridium aerugineum led to the isolation of five new galactolipids, namely, (2S)-1-O-eicosapentaenoyl-2-O-arachidonoyl-3-O-β-d-galactopyranosylglycerol (1), (2S)-1-O-eicosapentaenoyl-2-O-linoleoyl-3-O-β-d-galactopyranosylglycerol (2), (2S)-1-O-arachidoyl-2-O-palmitoyl-3-O-(β-d-galactopyranosyl-6-1α-d-galactopyranosyl)-glycerol (6), (2S)-1-O-eicosapentaenoyl-2-O-arachidoyl-3-O-(β-d-galactopyranosyl-6-1α-d-galactopyranosyl)-glycerol (7), and (2S)-1-O-eicosapentaenoyl-2-O-linoleoyl-3-O-(β-d-galactopyranosyl-6-1α-d-galactopyranosyl)-glycerol (8) together with five known galactolipids. The stereo-structures of all new galactolipids were elucidated by spectroscopic analyses and both enzymatic and chemical degradation methods. This is the first report of galactolipids from P. aerugineum. The newly isolated galactolipids showed strong and dose-dependent nitric oxide (NO) inhibitory activity against lipopolysaccharide-induced NO production in RAW264.7 macrophage cells. Both galactolipids 1 and 2 possessed stronger NO inhibitory activity than N ^G-methyl-l-arginine acetate salt, a well-known NO inhibitor used as a positive control. Further study suggested that these galactolipids inhibit NO production through downregulation of inducible nitric oxide synthase expression.     

Density functional studies on photophysical properties and chemical reactivities of the triarylboranes: effect of the constraint of planarity

The geometric and electronic structures, absorption spectra, transporting properties, chemical reactivity indices and electrostatic potentials of the planar three-coordinate organoboron compounds 1-2 and twisted reference compound Mes ₃ B, have been investigated by employing density functional theory (DFT) and conceptual DFT methods to shed light on the planarity effects on the photophysical properties and the chemical reactivity. The results show that the planar compounds 1-2 exhibit significantly lower HOMO level than Mes ₃ B, owing to the stronger electronic induction effect of boron centers. This feature conspicuously induces a blue shifted absorption for 1, although 1 seemingly possesses more extended conjugation framework than Mes ₃ B. Importantly, the reactivity strength of the boron atoms in 1-2 is much lower than that in Mes ₃ B, despite the fact that the tri-coordinate boron centers of 1-2 are completely naked. The interesting and abnormal phenomenon is caused by the strong p-π electronic interactions, that is, the empty p-orbital of boron center is partly filled by π-electron of the neighbor carbon atoms in 1-2, which are confirmed by the analysis of Laplacian of the electron density and natural bond orbitals. Furthermore, the negative electrostatic potentials of the boron centers in 1-2 also interpret that they are not the most preferred sites for incoming nucleophiles. Moreover, it is also found that the planar compounds 1-2 can act as promising electron transporting materials since the internal reorganization energies for electron are really small.

New combinations for Panicum subgenus Panicum and subgenus Dichanthelium (Poaceae) of the Southeastern United States

Twenty-two new varietal combinations are made for the treatment of the genusPanicum of the Southeastern United States. The following 3 new combinations are made in the subgenusPanicum:Panicum rigidulum var.elongatum, P. rigidulum var.pubescens, P. rigidulum var.combsii. The following 19 new combinations are made in the subgenusDichanthelium:P. strigosum var.glabrescens P. strigosum var.leucoblepharis, P. dichotomum var.roanokense, P. dichotomum var.lucidum, P. dichotomum var.ramulosum, p. dichotomum var.mattamuskeetense, P. dichotomum var.yadkinense, P. ensifolium var.curtifolium, P. chamaelonche var.breve, P. portoricense var.nashianum, P. acuminatum var.fasciculatum, P. acuminatum var.unciphyllum, P. acuminatum var.columbianum, P. acuminatum var.lindheimeri, P. acuminatum var.densiflorum, P. acuminatum varlongiligulatum, P. acuminatum var.leucothrix, P. ovale var.pseudopubescens, andP. ovale var.villosum.     

Mycopteris,a new neotropical genus of grammitid ferns (Polypodiaceae)

Mycopteris, a new genus of grammitid ferns, is described and combinations are made for the species that belong to it. Mycopteris is diagnosed by castaneous rhizome scales with turgid cells, usually pectinate laminae, blackish petioles and rachises, blackish pinna costae and veins, reddish setae, cretaceous hydathodes, glabrous sporangia, and the presence of Acrospermum ascomes. It is entirely neotropical, ranging from Mexico east into the West Indies and south to Bolivia. Mycopteris is one of two genera of grammitid ferns that are consistently associated with Acrospermum, an epibiotic ascomycete that produces black clavate fruiting bodies. Seventeen species of Mycopteris are recognized here, including one new species (M. longipilosa) and one elevated from the rank of variety to species (M. costaricensis). The following additional combinations are made here: M. alsopteris, M. amphidasyon, M. attenuatissima, M. cretata, M. grata, M. leucolepis, M. leucostica, M. longicaulis, M. pirrensis, M. praeceps, M. semihirsuta, M. steyermarkii, M. subtilis, M. taxifolia, and M. zeledoniana. Lectotypes are chosen for Ctenopteris leucosticta, Polypodium amphidasyon, and Polypodium pectinatum var. hispidum. For each accepted species, full synonymy and geographical range are provided. Taxonomic discussion is provided for species not widely recognized in previous treatments.     

β-Peptoids: synthesis of a novel dimer having a fully extended conformation

Chiral imines 1a,b, already synthesized in our laboratory, were converted in good yield by reduction into the corresponding N-benzyl-γ-lactams 2a,b. Desilylation followed by oxidation of the hydroxymethyl functionality gave the N-benzyl-β-amino acids 5a,b in good yield and high purity. Starting from compound 6a, the corresponding β-peptoid dimer 8 was prepared, together with its derivatives 9 and 10, these latter displaying conformational restriction about the peptide bond, as evidenced by NMR data.