GC-MS analysis of essential oils of heartwood and resin of Shorea robusta.

The essential oils of Shorea robusta heartwood and resin were isolated by hydrodistillation of their respective petroleum ether extracts. Nine and seventeen compounds representing 80.35 % and 78.43 % of the oil, respectively were identified by GC-MS. Germacrene-D was found to be the chief constituent of both the oils. This is the first report on heartwood and resin oils of Shorea robusta.

Two crystal polymorphs of a flavonoid from Melicope ellyrana.

The crystal structure determinations of two crystalline components of the hexane extract of the fruit of the indigenous Australian tree Melicope ellyrana have shown them to be polymorphs of the same compound, namely the flavonoid 4',5-dihydroxy-3,3',8-trimethoxy-7-(3-methylbut-2-enyloxy)flavone [systematic name: 5-hydroxy-2-(4-hydroxy-3-methoxyphenyl)-3,8-dimethoxy-7-(3-methylbut-2-enyloxy)-4H-1-benzopyran-4-one], C(23)H(24)O(8). The two polymorphs, one monoclinic (polymorph A) and the other triclinic (polymorph B), show significant conformational differences, particularly in the enyloxy side chain, while only one (polymorph A) shows intermolecular hydrogen bonding.

Comprehensive chemical profiling of gramineous plant root exudates using high-resolution NMR and MS.

Root exudates released into soil have important functions in mobilizing metal micronutrients and for causing selective enrichment of plant beneficial soil micro-organisms that colonize the rhizosphere. Analysis of plant root exudates typically has involved chromatographic methods that rely on a priori knowledge of which compounds might be present. In the research reported here, the combination of multinuclear and 2-D NMR with GC-MS and high-resolution MS provided de novo identification of a number of components directly in crude root exudates of different plant types. This approach was applied to examine the role of exudate metal ion ligands (MIL) in the acquisition of Cd and transition metals by barley and wheat. The exudation of mugineic acids and malate was enhanced by Fe deficiency. which in turn led to an increase in the tissue content of Cu, Mn, and Zn. The presence of elevated Cd maintained at a free activity pCd of 8.8 (10(-8.8) M), resulted in reduced phytosiderophore production by Fe deficient plants. The buffer morpholinoethane sulfonate (MES), which is commonly used in chelator-buffering nutrient solutions, was detected in the root exudate mixture, suggesting uptake and re-secretion of this compound by the roots. The ability to detect this compound in complex mixtures containing organic acids, amino acids, and other substances suggests that the analytical methods used here provide an unbiased method for simultaneous detection of all major components contained in root exudates.

Electrospray ionization mass spectrometry of stable nitroxide free radicals and two isoindoline nitroxide dimers.

Electrospray ionization (ESI) mass spectra were recorded for a range of substituted isoindoline nitroxides, two isoindoline nitroxide dimers and two piperidinyl nitroxides. In all cases the dominant molecular species arise from oxidation rather than protonation, an unusual process in ESI. Fragment ion spectroscopy was used to establish fragmentation mechanisms for the nitroxides under ESI conditions.

Volatile constituents of Vitex negundo leaves.

Volatile constituents of Vitex negundo leaves growing in Dehra Dun (India) were analysed by gas chromatography-mass spectrometry (GC-MS) and showed the presence of sixty-six compounds. Such a study has not been done earlier on the Indian oil. Thirty-five compounds, constituting 74.96% of the oil, were identified. The main compounds are viridiflorol (19.55%), beta-caryophyllene (16.59%), sabinene (12.07%), 4-terpineol (9.65%), gamma-terpinene (2.21%), caryophyllene oxide (1.75%), 1-oceten-3-ol (1.59%), and globulol (1.05%). Viridiflorol is being reported for the first time in the oil of Vitex species.

Solution conformation of an intramolecular DNA triplex containing a nonnucleotide linker: comparison with the DNA duplex.

The solution properties of the parallel intramolecular DNA triplex d(GAGAGA-oct-TCTCTC-oct-CTCTCT) (oct = -O-(CH2)8-O-PO2-O-(CH2)8-O-PO2-) and the duplex d(GAGAGA-oct-TCTCTC) have been examined by UV melting and high-resolution nuclear magnetic resonance spectroscopy (NMR). All nucleotides were primarily in the S conformation (i.e. near C2'-endo) in both the duplex and the triplex. However, the sugars of the Hoogsteen pyrimidine strand had a lower fraction of the S state than the Watson-Crick strands. Glycosidic torsion angles derived from nuclear Overhauser effect (NOE) build-up curves were found in the range -103 degrees to -133 degrees, with a clear alternation in magnitude along the GAGAGA strand in the triplex, whereas the glycosidic torsion angles were more similar in the duplex. Internucleotide NOEs were also consistent with an overall B-like geometry, rather than the A family. However, particularly in the Hoogsteen strand, some sequential NOE intensities were intermediate between those of the B and A forms. Distance and torsion constraints derived from NMR experiments were used to generate structures and were refined by restrained molecular dynamics. Extensive chemical shift differences between residues in the triplex and duplex were found for the purine strand, and there were remarkable differences in the pattern of shift differences for the A and G residues that correlated with differences in glycosidic torsion angles. Although there are differences in structure between the free duplex and that in the triplex, they are in important respects similar, indicating that only small conformational adjustments are needed to make parallel triple helices.

Structure of the ascarosides from Ascaris suum.

Six glycosides have been identified from the nematode Ascaris suum. The glycon part of all six glycosides is alpha L-3,6-dideoxymannose, previously known as ascarylose. The major components (4 and 5) and the minor components (8 and 9) have been shown by NMR and electrospray MS to involve a mixture of two homologous aglycons: the 2, omega-1 diols of hentriacontane and tritriacontane. Compounds 4 and 5 are glycosylated on only one of the hydroxy groups, while 8 and 9 are glycosylated on both. These compounds resemble ascarosides B and C previously isolated from Parascaris equorum. However, these aglycons are reported to be based on the 2,6-diol of hentriacontane. Compounds 6 and 7 are based on 2-hydroxy-nonacosane and 2-hydroxy-28-methylnonacosane glycosylated at C-2 with the same sugar. Although 6 and 7 are related to ascaroside A, previously isolated from P. equorum, these earlier reports suggest the chain in ascaroside A to be unbranched.

Physicochemical properties of proteinases from selected psychrotrophic bacteria.

The physicochemical properties of eight extracellular proteinases secreted by psychrotrophic bacteria of dairy origin have been studied. Seven of these proteinases were able to withstand ultra heat treatment (UHT) with D values at 140 degrees C ranging from 2 to 300 s. The six Pseudomonas fluorescens proteinases were glycoproteins of mol. wt 47000-49500. The two Serratia marcescens proteinases, of mol. wt of 51000, did not contain carbohydrate but in other respects were similar to the Pseudomonas proteinases. The proteinases were inhibited by various metal chelators and all contained Ca and Zn in similar proportions. Their amino acid compositions were similar, with alanine as the N-terminal group, cysteine completely absent and very low levels of methionine. Isoelectric points ranged from 5.10 to 8.25. Their physical and chemical properties enabled them to be classified as alkaline metalloendopeptidases. A similarity index (S delta n) was used to predict sequence homology between ten proteinases of known amino acid composition. Comparisons of S delta n of these proteinases showed only minor sequence differences except for those of Ps. fluorescens MC60. Heat resistance could not be related wholly to similarities in protein sequence, but could be related both to the strength of stabilizing Ca2+-protein interactions and to the randomness inherent within the folding of the peptide chain.