The oxidation of spermidine or homospermidine with bovine serum amine oxidase (BSAO) was monitored in situ, using proton nuclear magnetic resonance spectroscopy in water with 10% D2O. NMR assignments were performed by spin decoupling and COSY spectra or by comparison with data from synthetic aminoaldehydes. The results represent the first in situ characterisation of the highly reactive aminoaldehydes and showed oxidation at the N1 amino group of spermidine and homospermidine. Comparison of homospermidine with a variety of substrates revealed that among straight chain di- and polyamines both an aminopropyl group and two primary amino groups separated by seven (norspermidine) or eight (spermidine) carbon atoms were required for optimal substrate ability. However, highest activity was seen with the substrate N-(4-aminobutyl)hexahydropyrimidine, showing that the substrate channel of BSAO has a dual substrate preference, with moderately bulky substituents at the distal end of a diamine contributing equally well as an alkyl amino group. Cytotoxic investigations of a variety of substrates for BSAO, confirmed previous results, that cytotoxicity is primarily linked to polyamines encompassing the aminopropyl moiety. No acrolein was observed at any time during the oxidation showing that it reacts very fast with available amino groups forming a variety of derivatives.

The main phenolic by-products in the O-benzylation of 1,2,4-trihydroxy- or 1,2,4-triacetoxybenzene to 1,2,4-tribenzyloxybenzene have been identified as due to incomplete O-benzylation and C-benzylation. In addition, dibenzyldimethyl-ammonium chloride is formed from DMF and benzyl chloride. The main factors controlling these reactions paths are discussed. An efficient procedure for preparing 1,2,4-tribenzyloxybenzene using NaH in DMF is reported.

AIM:To study the antagonistic activity by Pseudomonas fluorescens strain 96.578 on the plant pathogenic fungus Rhizoctonia solani.METHODS AND RESULTS:Strain 96.578 produced a new cyclic lipopeptide, tensin. High tensin production per cell was detected in liquid media with glucose, mannitol or glutamate as growth substrate while fructose, sucrose and asparagine supported low production. Tensin production was nearly constant in media with different initial C levels, while low initial N contents reduced production. When applied to sugar beet seeds, strain 96.578 produced tensin during seed germination. When challenged with strain 96.578 or purified tensin, Rhizoctonia solani reduced radial mycelium extension but increased branching and rosette formation.CONCLUSION:The antagonistic activity of strain 96.578 towards Rhizoctonia solani was caused by tensin.SIGNIFICANCE AND IMPACT OF THE STUDY:When coated onto sugar beet seeds, tensin production by strain 96.578 could be of significant importance for inhibition of mycelial growth and seed infection by Rhizoctonia solani.

Halogenated furanones produced by the benthic marine macroalga Delisea pulchra inhibit swarming motility of Serratia liquefaciens MG1. This study demonstrates that exogenously added furanones control transcription of the quorum sensing regulated gene swrA in competition with the cognate signal molecule N-butanoyl-L-homoserine lactone. This in turn results in reduced production of the surface-active compound serrawettin W2, which is crucial for surface translocation of the differentiated swarm cells, It is demonstrated that furanones interfere with interspecies communication during swarming of mixed cultures and that the mode of interference in quorum-sensing control and interspecies communication is not through inhibition of autoinducer synthesis.

The crystal structure of the non-ribosomal lipoundecapeptide tensin from Pseudomonas fluorescens has been solved as an ethyl acetate/bis-water solvate (tensin ethyl acetate dihydrate, C67H115N12O20. C4H8O2. 2H(2)O) to a resolution of 0.8 Angstrom. The primary structure of tens in is beta-hydroxydecanoyl-D-Leu-D-Asp-D-allo-Thr-D-Leu-D-Leu-D-Ser-L-Leu-D-Gln-L-Leu-Ile-L-Glu, The peptide is a lactone linking the Thr3 O-gamma atom to the C-terminal C atom. The stereochemistry of the beta-hydroxy acid has been shown to be S. The peptide shows structural resemblance to the non-ribosomal cyclic lipopeptide fengycin from Bacillus subtilis. The structure of tensin is essentially helical (3(10)-helix), with the cyclic peptide wrapping around a hydrogen-bonded water molecule, The lipopeptide is amphipathic in good agreement with its function as a biosurfactant.

Solistatin, (+)-(3R,5R)-7-(2′-methyl-1′-naphthyl)-3-hydroxyheptan-5-olide (1), has been isolated from Penicillium solitum. The structure and relative stereochemistry were established by NMR spectroscopy and mass spectrometry. The absolute stereochemistry was determined by chemical degradation and comparison of CD data.

Pseudomonas fluorescens DR54 showed antagonistic properties against plant pathogenic Pythium ultimum and Rhizoctonia solani both in vitro and in planta. Antifungal activity was extractable from spent growth media, and fractionation by semi‐preparative HPLC resulted in isolation of an active compound, which was identified as a new bacterial cyclic lipodepsipeptide, viscosinamide, using 1D and 2D 1H‐, 13C‐NMR and mass spectrometry. The new antibiotic has biosurfactant properties but differs from the known biosurfactant, viscosin, by containing glutamine rather than glutamate at the amino acid position 2 (AA2). No viscosin production was observed, however, when Ps. fluorescens DR54 was cultured in media enriched with glutamate. In vitro tests showed that purified viscosinamide also reduced fungal growth and aerial mycelium development of both P. ultimum and R. solani. Viscosinamide production by Ps. fluorescens DR54 was tightly coupled to cell proliferation in the batch cultures, as the viscosinamide produced per cell mass unit approached a constant value. In batch cultures with variable initial C, N or P nutrient levels, there were no indications of elevated viscosinamide production during starvation or maintenance of the cultures in stationary phase. Analysis of cellular fractions and spent growth media showed that a major fraction of the viscosinamide produced remained bound to the cell membrane of Ps. fluorescens DR54. The isolation, determination of structure and production characteristics of the new compound with both biosurfactant and antibiotic properties have promising perspectives for the application of Ps. fluorescens DR54 in biological control.

Dipodazine, (Z)-1′,3-didehydro-3-(3″-indolylmethylene)-piperazine-2,5-dione (1), has been isolated from Penicillium dipodomyis and is also present in P. nalgiovense. The structure was established by spectroscopical methods.

AbstractChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 100 leading journals. To access a ChemInform Abstract of an article which was published elsewhere, please select a “Full Text” option. The original article is trackable via the “References” option.

Spectroscopic and crystallographic data for the title compound (4S,5R)-4-amino-5-methyl-3-isoxazolidinone are reported. The title compound crystallizes with one half equivalent of water in a zwitterionic structure, C4H8N2O2.0.5H(2)O, stabilized by intermolecular hydrogen bonds.

AbstractChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 100 leading journals. To access a ChemInform Abstract of an article which was published elsewhere, please select a “Full Text” option. The original article is trackable via the “References” option.

A nonswarming Serratia liquefaciens mutant deficient in serrawettin W2 production was constructed by transposon mutagenesis. Sequence homology indicated that insertion had occurred in gene swrA, which encodes a putative peptide synthetase. Expression of swrA is controlled by quorum sensing.

The mechanism, stereochemistry and products of the dimerisation of indole-3-acetic acid 1a and its propyl ester 1b in TFA and H3PO4 have been investigated. The major products in both acids were 2-(indolin-2-yl)indole dimers, 3a/b, which were readily converted into the corresponding pentacyclic lactams 5a/b with the pyrido[1,2-a:3,4-b']biindole skeleton. Ccompound 5a was studied by X-ray crystallography and shown to be the 2,3-trans-isomer. The reaction proceeds via electrophilic attack of the protonated species 2 on free 1 with steric approach central to form the trans-stereoisomeric 3 and/or 5.

Three derivatives of tryptophanamide, N-b-methoxycarbonyl-L-tryptophanamide (2a), N-b-acetyl-L-tryptohanamide (2b), and N-b-trifluoroacetyl-L-tryptophanamide (2c), have been prepared and their reaction with trifluoroacetic acid investigated. The structure of the diastereomeric pyrroloindoles 6a and 7a formed from 2a on cyclisation was established through crystal structure determination of 7a and NMR experiments. In the case of 2b two diastereomeric dimers 8a and 9b were isolated with smaller amounts of two related lactams 11 and 12. From 2c diastereomeric dimers 8c and 9c were found in addition to a small amount of an aromatic biindole 10c. The change from cyclisation to dimerisation is correlated with the decrease in side chain nucleophilicity from 2a to 2c. The stereochemistry of the products was determined by NOE results in combination with CD spectra and Cotton effects.

Huazhongilexone, isolated from Ilex centrochinensis, was originally assigned the structure 3 ',5,5 ',7-tetrahydroxyflavanone. The racemic flavanone has been synthezised. Huazhongilexone is different from the synthetic compound and thus must have a different structure. In addition the new (+/-)-3 ',5 '-dimethoxy-5,7-dihydroxyflavanone has been prepared and characterized.

AbstractChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 100 leading journals. To access a ChemInform Abstract of an article which was published elsewhere, please select a “Full Text” option. The original article is trackable via the “References” option.

Four halogenated indole-imidazole alkaloids, securamine A-D, have been isolated from the marine bryozoan Securiflustra securifrons and their structures determined by NMR and mass spectrometry. Securamine A and B are in equilibrium with two macrocyclic alkaloids, securine A and B, respectively.