A new chromone from the stems of Cneorum tricoccum

From the stems of Cneorum tricoccum L. 3,3-dimethylallylspatheliachromene, spatheliabischromene and alloptaeroxylin methyl ether have been isolated as well as the new natural product ptaerochromenol methyl ether, which was chemically interconverted to isoheteropeucenin methyl ether.     

Pyranocoumarins as chemotaxonomic markers in Eriostemon coccineus and Philotheca citrina

Examination of the aerial parts of Eriostemon coccineus and Philotheca citrina has shown both to contain the unusual pyranocoumarins avicennol, avicennin and cis-avicennol. Three minor coumarins isolated from P. citrina have been identified as avicennol methyl ether, cis-avicennol methyl ether and avicennol ethyl ether. Philotheca citrina also yielded another pyranocoumarin, dipetalolactone, and the common lignan sesamin. Eriostemon coccineus, in addition to coumarins, gave the furoquinoline alkaloids maculosidine and γ-fagarine and two dihydrocinnanic acid derivatives, eriostoic acid and a new compound with a substitution pattern comparable to cis-avicennin and which has been assigned the trivial name cis-avicennic acid. The co-occurrence of these rare pyranocoumarins supports the contention that Philotheca is closely allied to certain taxa currently placed in Eriostemon sect. Nigrostipulae.     

New Withanolides from Nicandra physaloides (Solanaceae)

Two new withanolides, named nicandrenone methyl ether (1), 26S nicandrenone methyl ether (2), together with ten known compounds were isolated from the whole plants of Nicandra physaloides (Solanaceae). Their chemical structures were deduced on the basis of spectroscopic analysis. Ten known compounds were identified as nicandrenone (3), Nic-7 (4), nicaphysalin E (5), pinosylvin monomethyl ether (6), 2S-pinocembrin (7), (1S, 2R)-1, 2-bis (4-hydroxy-3-methoxyphenyl)-1, 3-propanediol (8), vanillin (9), indole-3-carboxylic acid (10), vanillic acid (11) and drummondol (12).     

Enzymatic cyclization of all-trans pentaprenyl and hexaprenyl methyl ethers by a cell-free system from the protozoon Tetrahymena pyriformis. The biosynthesis of scalarane and polycyclohexaprenyl derivatives

A cell-free system from the protozoon Tetrahymena pyriformis capable of cyclizing squalene into tetrahymanol cyclizes all-trans pentaprenyl methyl ether to a scalarane-type sesterterpene and all-trans hexaprenyl methyl ether to bicyclo-, tricyclo-, tetracyclo- and pentacyclohexaprenyl methyl ethers, each corresponding to a possible cationic intermediate. The structures of the cyclization products have been determined by spectroscopic methods and are compatible with a biogenetic scheme involving polyprenyl ether cyclization. This is the first direct proof of an enzymatic cyclization of higher isoprenic alcohol derivatives, and we assume it was performed by the squalene-to-hopane cyclase of the protozoon. The formation of a scalarane-type sesterterpene from C25 polyprenyl methyl ether suggests that these terpenoids, whose presence is restricted to a few sponges, might be in fact microbial metabolites. Tricyclopolyprenyl derivatives have been identified in the organic matter from numerous sediments and they were interpreted as being chemical fossils of still unidentified microorganisms. The cyclization of hexaprenyl methyl ether is the first attempt of identification of these tricyclopolyprenol derivatives in living organisms.     

A new β-d-quinovoside from commercial Ipomoea purga

Treatment of convolvulin (the ether insoluble portion of purified jalap resin) with sodium methoxide in methanol has yielded a new β-d-quinovoside. Periodate oxidation and methylation studies together with chemical and spectroscopic analyses have shown this fragment to consist of one molecule of d-quinovose glycosidically linked to a molecule of methyl 11-hydroxytetradecanoate.     

Enantioselective lipase-catalyzed kinetic resolution of N-(2-ethyl-6-methylphenyl)alanine

The enzyme (BSL2), a highly active lipase expressed from newly constructed strain of Bacillus subtilis BSL2, is used in the kinetic resolution of N-(2-ethyl-6-methylphenyl)alanine from the corresponding racemic methyl ester. Reaction conditions are optimized to enhance the enantioselectivity. The effects of various racemic alkyl esters, substrate concentration, operating temperature, pH of the aqueous medium and organic solvents on activity and enantioselectivity of BSL2 for kinetic resolution are also studied. A high enantiomeric ratio (E = 60.7) is reached in diisopropyl ether/water (10%, v/v) and the enantioselectivity is about 22-fold higher than that in pure buffered aqueous solution. The results show that the reaction medium greatly influences BSL2 reaction and its enantioselectivity in the hydrolysis of racemic methyl ester.     

Cyclic hydroxamic acids in dicotyledonous plants

DIBOA (2a) was identified in Scoparia dulcis (Scrophulariaceae) and in six Acanthaceae species: Acanthus mollis, A. spinosus, Aphelandra aurantiaca, A. squarrosa, Crossandra infundibuliformis and C. pungens. Both Crossandra species contained 7-hydroxyDIBOA (2c), and both Aphelandra species contained its methyl ether, DIMBOA (2b). No hydroxamates were found in 28 species from 19 other genera of Acanthaceae.     

Lipase-catalyzed enantioselective hydrolysis of methyl 2-fluoro-2-arylpropionates in water-saturated isooctane

Lipases from Candida rugosa, Candida antartica B and Carica papaya are employed as the biocatalyst for the hydrolytic resolution of methyl 2-fluoro-2-arylpropionates in water-saturated isooctane, in which excellent to good enantioselectivity without the formation of byproducts is obtained for the papaya lipase when using (R,S)-2-fluoronaproxen methyl ester (1) and methyl (R,S)-2-fluoro-2-(4-methoxyphenyl)propionate (2), but not methyl (R,S)-2-fluoro-2-(naphth-1-yl)propionate (3) as the substrates. The thermodynamic analysis indicates that the enantiomer discrimination for the papaya lipase is driven by the difference in activation enthalpy for compound 1, 2 or (R,S)-naproxen methyl ester (4). The kinetic analysis also demonstrates that in comparison with (S)-4, the insertion of the 2-fluorine moiety in (R)-1 has increased k₂, but not K_m, and consequently the lipase activity.     

The Phytophthora effector Avh94 manipulates host jasmonic acid signaling to promote infection

The oomycete pathogen Phytophthora sojae is a causal agent of soybean root rot.Upon colonization of soybeans,P.sojae secretes various RXLR effectors to suppress host immune responses,supporting successful infection.Previous research has demonstrated that the RXLR effector Avh94 functions as a virulence effector,but the molecular mechanism underlying its role in virulence remains unknown.Here,we demonstrate that Avh94 overexpression in plants and pathogens promotes Phytophthora infection.Avh94 in...     

Phytoalexin induction in the sapwood of plants of the Maloideae (Rosaceae): Biphenyls or dibenzofurans

Following fungal inoculation or natural infection, five biphenyl phytoalexins (aucuparin and its 2′ and 4′ oxygenated derivatives) were induced variously in the sapwood of Aronia, Chaenomeles, Eriobotrya, Malus(three spp.) and of Sorbus aucuparia. By contrast, 14 dibenzofuran phytoalexins were induced variously in sapwood of Cotoneaster (7 spp.), Crateagus, Cydonia, Mespilus, Photinia, Pseudocydonia, Pyracantha, Pyrus and two Sorbus spp. (S. chamaemespilum and S. domestica). These were five cotonefurans, three eriobofurans, five pyrufurans and a 2,3,4,7,8-pentaoxygenated dibenzofuran trimethyl ether. No plant has yet been found to produce both types of phytoalexin, although o-hydroxybiphenyls are theoretically precursors of the dibenzofurans. The ability to synthesize either biphenyls or dibenzofurans appears to be genus-specific, except in the case of Sorbus. In 18 of the 38 species tested, these phytoalexins were accompanied by constitutive antifungal phenolics, most of which appeared to be released from bound (glycosidic) forms during the infection process. These were identified variously as hydroquinone, p-hydroxyacetophenone, acetovanillone, 5,7-dihydroxychromone, chrysin, sakuranetin and naringenin. Woody members of the subfamilies Prunoideae and Spiraeoideae failed to yield any phytoalexins on induction, but did contain constitutive antifungal compounds. The limited frequency of the phytoalexin response within the family as a whole is considered in relation to the accumulation of constitutive antifungal agents in these plants.     

Lignans from Saururus chinensis inhibiting the transcription factor NF-kappaB

The sesquineolignans, saucerneol D and saucerneol E were isolated from the roots of Saururus chinensis together with four known lignans, manassantin A, manassantin B, (-)-saucerneol methyl ether, and (+)-saucernetin. Structure elucidation was based on the analysis of spectroscopic data and anti-inflammatory activity was studied using HeLa cells transfected with NF-kappaB reporter construct. All compounds except for (+)-saucernetin inhibited NF-kappaB dependent reporter gene expression with IC50 values of 2.5-16.9 microM.     

Internal flavonoid patterns of diploids and tetraploids of two exudate chemotypes of Pityrogramma triangularis (Kaulf.) Maxon

The internal flavonoid patterns of Pityrogramma triangularis fronds were found to distinguish diploids and tetraploids of two exudate chemotypes (the ceroptin and the kaempferol methyl ether types). The flavonoid data suggest that the tetraploid-kaempferol methyl ether chemotype is of alloploid origin involving the two diploid chemotypes because the flavonoid pattern for the former represents a pattern additive of the two diploids, while the tetraploid-ceroptin chemotype may be of autoploid origin, as deduced from the similarity of the diploids and tetraploids.     

Novel microbial epoxide hydrolases for biohydrolysis of glycidyl derivatives

Microbial isolates from biofilters and petroleum-polluted bioremediation sites were screened for the presence of enantioselective epoxide hydrolases active towards tert-butyl glycidyl ether, benzyl glycidyl ether, and allyl glycidyl ether. Out of 270 isolated strains, which comprised bacteria, yeasts, and filamentous fungi, four were selected based on the enantioselectivities of their epoxide hydrolases determined in biotransformation reactions. The enzyme of Aspergillus niger M200 preferentially hydrolyses (S)-tert-butyl glycidyl ether to (S)-3-tert-butoxy-1,2-propanediol with a relatively high enantioselectivity (the enantiomeric ratio E is about 30 at a reaction temperature of 28 °C). Epoxide hydrolases of Rhodotorula mucilaginosa M002 and Rhodococcus fascians M022 hydrolyse benzyl glycidyl ether with relatively low enantioselectivities, the former reacting predominantly with the (S)-enantiomer, the latter preferring the (R)-enantiomer. Enzymatic hydrolysis of allyl glycidyl ether by Cryptococcus laurentii M001 proceeds with low enantioselectivity (E = 3). (R)-tert-Butyl glycidyl ether with an enantiomeric excess (ee) of over 99%, and (S)-3-tert-butoxy-1,2-propanediol with an ee-value of 86% have been prepared on a gram-scale using whole cells of A. niger M200. An enantiomeric ratio of approximately 100 has been determined under optimised biotransformation conditions with the partially purified epoxide hydrolase from A. niger M200. The regioselectivity of this enzyme was determined to be total for both (S)-tert-butyl glycidyl ether and (R)-tert-butyl glycidyl ether.     

Secretion of the dufour glands of two african desert ants, Camponotus aegyptiacus and Cataglyphis savignyi (Hymenoptera: Formicidae)

Dufour glands of minor workers of Camponotus aegyptiacus contain a mixture of linear and methyl branched hydrocarbons and a trace of dodecyl acetate. Major workers contain a similar mixture of hydrocarbons but also large quantities of dodecyl acetate, some other long chain acetates and traces of propionates and farnesyl acetate. Cataglyphis savignyi has pentadecane as the most abundant compound with traces of ketones, alcohols and an aldehyde. Camponotus vagus, a Mediterranean species, has a more typical formicine mixture with undecane being the major compound. A summary of Camponotus Dufour substances demonstrates the species-specificity of this secretion.     

Capillary gas-liquid chromatography of glycine-conjugated bile acids without prior hydrolysis

A method is described for the gas-liquid chromatographic (GLC) analysis of intact glycine conjugates of the major bile acids present in human plasma. It is, therefore, now possible to analyze glycine-conjugated and unconjugated bile acids together on a single GLC column without the necessity for a hydrolytic step. A large number of derivatives of bile acid glycine conjugates were examined, but only acetate- and silyl ether-derivatives of carboxylic acid methyl esters were found initially to be suitable. It was not possible to make acetates consistently, and trimethylsilyl ethers did not allow resolution of the glycine conjugates of cholic and chenodeoxycholic acids. Dimethylethylsilyl ether methyl ester derivatives were subsequently found to give the best results. Chromatographic conditions for successful analysis of these derivatives were examined and it was found to be necessary to use wall-coated capillary columns of thin film thickness (0.12 micron) and very high carrier gas flow rates (ca. 20 ml/min hydrogen). Using acetonitrile and Bond Elut extraction, fractionation on Sep-Pak SIL cartridges, and derivatization as dimethylethylsilyl ether methyl esters, the capillary gas-liquid chromatography of intact glycine-conjugated bile acids from human plasma was demonstrated for the first time.     

假酸浆中新的醉茄内酯类化合物

从假酸浆（Nicandra physaloides）全草中分离得到12个化合物,其中两个为新的醉茄内酯类化合物,经波谱学方法将其结构鉴定为nicandrenone methyl ether （1） 和26S-nicandrenone methyl ether （2）;已知化合物为三个醉茄内酯,nicandrenone （3）,Nic-7 （4）,nicaphysalin E （5）,以及pinosylvin monomethyl ether （6）,2S-pinocembrin （7）,（1S, 2R）-1, 2-bis （4-hydroxy-3-methoxyphenyl）-1, 3-propanediol （8）,vanillin （9）,indole-3-carboxylic acid （10）,vanillic acid （11） 和drummondol （12）。     

Analysis of lycopene geometrical isomers in biological microsamples by liquid chromatography with coulometric array detection

Methods of analysis for determining low quantities of lycopene cis–trans isomers in biological tissues are needed. Development of two liquid chromatography (LC) methods based on the polymeric C₃₀ stationary phase equipped with coulometric electrochemical array detection (ED) is described. Separation of 13 lycopene isomers including prolycopene, (a novel tetra-cis-lycopene found in Tangerine tomatoes) was accomplished with both isocratic and gradient methods using different proportions of methanol, methyl tert.-butyl ether, water and 1 M ammonium acetate buffer. Carotenoids were detected at potential settings between 200 and 620 mV. Differences in generated current–voltage curves aided in tentative identification of trans carotenoid species and select cis isomers of lycopene. These methods were successfully applied in the analysis of small quantities of plasma, buccal mucosal cells, prostate and cervical tissues. Limits of detection for trans-lycopene by ED were found to be 50 fmol representing a 10- to 100-fold increase over conventional UV–Vis absorbance methods.     

Identification of a gene, pilF, required for type 4 fimbrial biogenesis and twitching motility in Pseudomonas aeruginosa

Many bacterial pathogens produce a class of surface structures called type 4 fimbriae. In Pseudomonas aeruginosa these fimbriae are responsible for adhesion and translocation across host epithelial surfaces. We have identified a novel gene involved in the complex process of type 4 fimbrial biogenesis. This gene, termed pilF, is located on SpeI fragment S at 30 min on the P. aeruginosa genomic map, which is the sixth region on the chromosome shown to contain a fimbrial-associated gene. The PilF protein has a predicted M_r of 22 402, and together with a highly homologous upstream ORF shares a chromosomal arrangement similar to that found in Haemophilus influenzae. A pilF mutant is blocked in the export/assembly of the fimbrial subunit PilA, and accumulates this protein in the membrane fraction. Complementation studies indicate that the cloned pilF gene is able to restore the expression of surface fimbriae, twitching motility and susceptibility to fimbrial-specific bacteriophage     

Binding of ferulic acid to cytochrome c enhances stability of the protein at physiological pH and inhibits cytochrome c-induced apoptosis

Ferulic acid (FA) is one of the most effective components of a traditional Chinese medicine, angelica, and cytochrome c plays a vital role in apoptosis. Here we report the application of fluorescence spectroscopy, isothermal titration calorimetry (ITC), differential scanning calorimetry (DSC), and circular dichroism (CD) to investigate the mechanism for the interaction of bovine heart cytochrome c with FA and the effect of the binding on native state stability of the protein at physiological pH. Fluorescence spectroscopic studies together with ITC measurements indicate that FA binds to cytochrome c with moderate affinity and quenches the intrinsic fluorescence of the protein in a static way. ITC experiments show that the interaction of cytochrome c with FA is driven by a moderately favorable entropy increase in combination with a less favorable enthalpy decrease for the first binding site of the protein. The melting temperature of cytochrome c in the presence of FA measured by DSC and CD increases 4.0 and 5.0 °C, respectively, compared with that in the absence of FA. Taken together, these results indicate that FA binds to and stabilizes cytochrome c at physiological pH. Furthermore, binding of FA to cytochrome c inhibits cytochrome c-induce apoptosis of human hepatoma cell line SMMC-7721. Our data provide insight into the mechanism of drug–protein interactions, and will be helpful to the understanding of the mechanism for FA-inhibited and cytochrome c-induced apoptosis.