Biosynthetic relationship of citral-trans and citral-cis in cymbopogon flexuosus (lemongrass)

Use of [¹⁴C,³H]-labelled precursors revealed that leaf blades of Cymbopogon flexuosus converted geraniol (3,7-dimethylocta-trans-2,6-diene-1-ol) into citral-trans with loss of pro-(1S) hydrogen whereas nerol lost the pro-(1R) hydrogen while being converted into citral-cis. Secondly, the citral-trans is converted into citral-cis and vice versa and there is no separate route for the biosynthesis of either of the two aldehyde isomers.     

Interconversion of trans, trans and cis, trans farnesol by enzymes from Andrographis

When trans, trans-farnesol [4,8,12-¹⁴C₃,1-³H₂] is isomerized to cis, trans-farnesol by soluble enzymes from Andrographis paniculata tissue cultures, 50% of the tritium label is lost. The same loss is observed when isomerization occurs in the opposite direction. This is in accordance with the proposed mechanism for isomerization via aldehydes.     

Identification of some volatile compounds from Citrullus vulgaris

Volatile compounds from watermelon (Citrullus vulgaris obtained by vacuum steam distillation—extraction of the fruit at 60–70° in a water-recycling apparatus, were separated by gas chromatography and subjected to spectral analyses. Evidence was obtained for the following new constituents, hexanal, trans-2-heptenal, trans-2-octenal, nonanal, trans-2-nonenal, trans,cis-2,6-nonadienal, nonan-1-ol, trans-2-nonen-1-ol, cis-3-nonen-1-ol, trans,cis-2,6-nonadien-1-ol, trans-2-decenal, trans-2-undecenal, geranial and β-ionone.     

In Vivo and in Vitro binding of platinum to metallothionein

The in vivo binding of platinum to metallothionein (MT) has been observed in rat tissues following injections of the cis and trans isomers of DDP (dichlorodiammine-platinum(II)). Platinum in either cis-DDP or trans-DDP does not directly induce MT; platinum-MT is produced by the replacement of previously bound zinc in the protein. The binding of Pt(II) to MT depends on the availability of SH groups in MT. Preinjection with CdCl₂ significantly enhances the association of Pt(II) with MT fractions compared to the degree of association resulting from injections with either cis-DDP or trans-DDP without CdCl₂ pretreatment. In vitro experiments in which tissue extracts including a known (Cd,Zn)-MT were incubated with either cis-DDP or trans-DDP show that these isomers differ with respect to the transfer of Pt to MT; the equilibrium in both cases was reached when approximately 40% of the available Pt is bound to MT but with this equilibrium value attained in 2 h in the case of trans-DDP and only after 72 h in the case of cis-DDP. Pt-MTs were also formed by a series of incubation steps in which a native MT was used to prepare the apoprotein which was subsequently incubated with either cis-DDP or trans-DDP. Spectrophotometry established that a shoulder occurs at 285 nm for the Pt-MTs resulting from the incubation with either isomer. A competitive double-antibody radioimmunoassay for MT demonstrated that these Pt-MTs had complete cross-reactivity with a native (Cd,Zn)-MT. Gel filtration of tissue extracts after either in vivo or in vitro treatment with DDP showed that Pt was bound to a molecular species with properties characteristic of MT. These results were verified by atomic absorption spectrophotometry and polyacrylamide gel electrophoresis assays.     

Metabolism and biological activity of all-trans 4,4-difluororetinyl acetate

All-trans [11-³H]4,4-difluororetinyl acetate was synthesized by treating methyl all-trans [11-³H]4-oxoretinoate with diethylaminosulfurtrifluoride, followed by reduction and acetylation of the product. After oral administration of the radioactive difluoro analog in oil to rats, difluororetinol, difluororetinyl palmitate and related esters, 4-oxoretinol, 4-oxoretinoic acid and polar conjugated derivatives were identified in the intestine, liver, kidney and / or blood. The major metabolic products were difluororetinyl palmitate and related esters, which were stored in the liver. The presence of the difluoro analog in liver oil from treated rats was confirmed by ¹⁹F-NMR spectroscopy. Neither retinol nor retinyl esters were detected as products of the metabolism of the difluoro analog. Nonetheless, all-trans difluororetinyl acetate showed 26 ± 12% of the biological activity of all-trans retinyl acetate in the rat growth assay. Presumably, the difluoro analog is active per se in growth rather than by conversion to retinol or to one of its known growth-promoting metabolites. In general, however, the difluoro analog was metabolized in a manner very similar to vitamin A. The vitamin A moiety of administered difluororetinyl acetate and retinyl acetate was poorly stored (1.8–3.3%) in the liver of vitamin A-depleted rats, confirming and extending past reports that the liver storage mechanism is severely impaired when initial liver stores are very low.     

Cytokinins in immature seeds of Dolichos lablab

Five cytokinins, trans-zeatin, 9-β-d-ribofuranosyl-trans-zeatin, 9-β-d-ribofuranosyl-cis-zeatin, 6-(trans-4-O-β-d-glucopyranosyl-3-methyl-2-butenylamino)purine and 6-(trans-4-O-β-d-glucopyranosyl-3-methyl-2-butenylamino)-9-β-d-ribofuranosylpurine were identified from immature seeds of Dolichos lablab.     

Neolignans from Magnolia kachirachirai

Two new neolignans named kachirachirol-A and B were isolated from the leaves of Magnolia kachirachirai and their chemical structures determined to be 2-(p-hydroxyphenyl)-7-methoxy-3-methyl-5-trans-propenylbenzofuran and rel-(2S,3S)-2-catechyl-2,3-dihydro-7-methoxy-3-methyl-5-trans-propenylbenzofuran.     

Fatty acid changes during maturation of Momordica charantia and Trichosanthes Anguina Seeds

Changes in fatty acids were studied during maturation of Momordica charantia and Trichosanthes anguina seeds, which contain cis-9, trans-11, trans-13-octadecatrienoic acid (α-eleostearic) and cis-9, trans-11, cis-13-octadecatrienoic acid (punicic), respectively. The two seeds matured 30 and 35 days after flowering, respectively. Total lipids as well as α-eleostearic acid accumulated rapidly from 10 to 20 days in M. charantia. In T. anguina the active period of lipid synthesis was from 15 to 30 days but punicic acid continued to be synthesized until maturity. In both species, the disappearance of linolenic acid and the reduction in concentration of linoleic acid were concomitant with the formation of conjugated fatty acids. The conjugated fatty acids were absent from monoacylglycerols and phospholipids of both species, and also from the diacylglycerols of M. charantia, throughout maturation     

Flavonoids and tannins of Acacia species

The heartwoods of Acacia giraffae and A. galpinii were selected from South African Acacias as representative of those with abnormally high and minimal tannin contents respectively. A. galpinii contains amongst other analogues, the first natural (+)-2,3-trans-3,4-trans-teracacidin (7,8,4′-trihydroxy-flavan-3,4-diol and novel 3-O-methyl-, 7,8-di-O-methyl- and 7,8,4′-tri-O-methylflavonol analogues. (−)-2,3-cis-3,4-cis-Melacacidin (7,8,3′,4′-tetrahydroxyflavan-3,4-diol) is also present, but tannins are absent. By contrast, from the large excess of leueofisetinidin tannins which characterizes the wood of A. giraffae, only (+)-catechin, (+)-2,3-trans-3,4-trans-leucofisetinidin (7,3′,4′,trihydroxyflavan-3,4-diol and all-trans-(+)-leueofisetinidin-(+)-catechin could be isolated.     

Identification of two chromone phytoalexins in the sweet pea, Lathyrus odoratus

A major phytoalexin isolated from the Helminthosporium Carbonum-inoculated leaflets and pods of Lathyrus odoratus has been identified by spectroscopic procedures as 5,7-dihydroxy-3-ethylchromone (lathodoratin). Small amounts of the corresponding 7-O-methyl ether (methyl-lathodoratin) are also formed by this plant. Both compounds similarly occur as phytoalexins in the closely related legume L. hirsutus but are absent from the other Lathyrus species examined. The unusual 3-substitution of the chromone nucleus appears to be essential for fungitoxicity since the synthetic isomer 5,7-dihydroxy-2-ethylchromone is apparently inactive.     

New norlignans of Sequoiadendron gigantea; phytochemical comparison with Sequoia sempervirens

The permethyl ethers of three new norlignans (sequirins-E, -F, and -G) from Sequoiadendron gigantea heartwood have been characterized by NMR and MS as 2-(3,4-dimethoxyphenyl)-4-(4-methoxyphenyl-, 2,4-(3,4-dimethoxyphenyl)-, and 2-(3,4-dimethoxyphenyl)-4-(3,4,5-trimethoxyphenyl)-5-hydroxytetrahydropyran respectively, with the 2,5-trans,4,5-trans stereochemistry. Sequirins A-D, characteristic norlignans of Sequoia sempervirens Endl., could not be detected in S. gigantea heartwood, nor could sequirins E-G be found in S. sempervirens heartwood. Agatharesinol was a common constituent.     

Heterogeneity of C55-polyprenol from leaves of Magnolia campbellii

Polyprenols from leaves of Magnolia campbellii occur as a mixture of alcohols composed from 9 to 13 isoprene units. Pure C₅₅-polyprenol (M.W. 766) was isolated from this material using column chromatography on Lipidex-5000, and was shown to be a mixture of molecules differing with respect of the proportion of trans- and cis-isoprene units. It was suggested that all-trans-geranylgeranyl pyrophosphate is not the only primer for the elaboration of long chain cis/trans-polyprenols in plant photosynthesizing tissues.     

Sulphate ester of trans-4-hydroxypipecolic acid in seeds of Peltophorum

An acidic compound isolated from seed of the legume Peltophorum africanum has been characterised on the basis of FAB-MS, EIMS, ¹³C and ¹H NMR as trans-4-hydroxypipecolic acid-4-sulphate. This is the first naturally occurring sulphate ester of a non-protein amino acid to be described. The possible systematic significance of the distribution of the ester within Peltophorum and related genera is considered.     

Transformations of the Vaska-type complex trans-[RhCl(CO)(PTA)2] (PTA = 1,3,5-triaza-7-phosphaadamantane) during stepwise addition of HCl: Synthesis, characterization and crystal structure of trans-[RhCl2(PTA)(PTAH)]

The new aqua-soluble rhodium(I) complex trans-[RhCl₂(PTA)(PTAH)] (1) {PTAH = N-protonated form of 1,3,5-triaza-7-phosphaadamantane (PTA)} has been synthesized via the reaction of trans-[RhCl(CO)(PTA)₂] with aqueous HCl or N-chlorosuccinimide, or by the treatment of RhCl₃ with PTA. Compound 1 has been characterized by IR, ¹H and ³¹P{H} NMR spectroscopies, ESI-MS(+), elemental and single crystal X-ray diffraction analyses, the latter showing a square planar {RhCl₂P₂} geometry. Besides, the stepwise addition of diluted HCl to an aqueous solution of trans-[RhCl(CO)(PTA)₂] has been monitored by ³¹P{¹H} NMR and ESI-MS(+) techniques, allowing to detect a number of intermediate Rh(I) species.     

Effects of cis and trans regulatory variations on the expression divergence of heat shock response genes between yeast strains

Phenotypic variation among individuals in a population can be due to DNA sequence variation in protein coding regions or in regulatory elements. Recently, many studies have indicated that mutations in regulatory elements may be the major cause of phenotypic evolution. However, the mechanisms for evolutionary changes in gene expression are still not well understood. Here, we studied the relative roles of cis and trans regulatory changes in Saccharomyces cerevisiae cells to cope with heat stress. It has been found that the expression level of ~ 300 genes was induced at least two fold and that of ~ 500 genes was repressed at least two fold in response to heat shock. From the former set of genes, we randomly selected 65 genes that showed polymorphism(s) between the BY and RM strains for pyrosequencing analysis to explore the relative contributions of cis and trans regulatory variations to the expression divergence between BY and RM. Our data indicated that the expression divergence between BY and RM was mainly due to trans regulatory variations under either the normal condition or the heat stress condition. However, the relative contribution of trans regulatory variation was decreased from 76.9% to 61.5% after the heat shock stress. These results indicated that the cis regulatory variation may play an important role in the adaption to heat stress. In our data, 43.1% (28 genes) of the 65 genes showed the same trend of cis or trans variation effect after the heat shock stress, 35.4% (23 genes) showed an increased cis variation effect and 21.5% (14 genes) showed an increased trans variation effect after the heat shock stress. Thus, our data give insights into the relative roles of cis and trans variations in response to heat shock in yeast.     

Identification of cis/trans isomers of bis(acetylacetonato)nickel(II) complexes in solution based on electronic spectra

Electronic spectra of Ni(acac)₂ were studied in acetone, DMF, and some other solvents for the purpose of identifying the cis/trans isomers from the spectra (acac⁻ = acetylacetonate anion). The spectral components were investigated in the spin-allowed transition bands, and a relationship was found between the spectral pattern and the cis/trans isomers. According to this relationship, it was concluded that the cis isomer was formed in DMF and in N-methylformadide, whereas the trans isomer was formed in acetone and in pyridine. Based on the DFT computation, the cis-[Ni(acac)₂(DMF)₂] was found to be stabilized by intramolecular hydrogen bonds between acetylacetonate and DMF.     

Synthesis, in vitro and in silico evaluation of novel trans-stilbene analogues as potential COX-2 inhibitors

25 new trans-stilbene and trans-stilbazole derivatives were investigated using in vitro and in silico techniques. The selectivity and potency of the compounds were assessed using commercial ELISA test. The obtained results were incorporated into 2D QSAR assay. The most promising compound 4-nitro-3′,4′,5′-trihydroxy-trans-stilbene (N1) was synthetized and its potency and selectivity were confirmed. N1 was classified as preferential COX-2 inhibitor. Its ability to inhibit COX-2 in MCF-7 cell line was established and its cytotoxicity by MTT test was assessed. The compound was more cytotoxic than celecoxib within studied concentration range. Finally, the investigated trans-stilbene was docked into COX-1 and COX-2 active sites using “CDOCKER” protocol.     

Biosynthesis of trans-2-hexenal in chloroplasts from Thea sinensis

The biosynthetic pathway of trans-2-hexenal, leaf aldehyde, in isolated chloroplasts of Thea sinensis leaves. was examined using a tracer experiment. A high and specific incorporation of radioactivity into cis-3-hexenal and trans-2-hexenal, was observed when linolenic acid-[U-¹⁴C] was incubated with the isolated chloroplasts. Thus, trans-2-hexenal was biosynthesized via cis-3-hexenal from linolenic acid in the chloroplasts.     

The steam volatile leaf oils of some species of Eucalyptus subseries Strictinae

The volatile leaf oils of Eucalyptus stenostoma, E. fraxinoides, E. triflora, E. dendromorpha, E. burgessiana, E. rupicola, E. approximans subsp. approximans, E. approximans subsp. codonocarpa and E. paliformis were qualitatively very similar to each other but significantly different from the leaf oils of the remaining species of the subseries. Their leaf oils were characterized by high concentrations of p-cymene and by the presence of α- and β-phellandrene, variable amounts of piperitone, trans- and cis-piperitol and trans- and cis-p-menth- 2-en-1-ol. The three last named alcohols have not been previously reported from the Myrtaceae.     

Evidence for trans-trans and cis-cis farnesyl pyrophosphate synthesis in Gossipium hirsutum

A protein fraction capable of catalysing the formation of all four geometrical isomers of farnesyl pyrophosphate has been isolated from cotton roots. Using neryl pyrophosphate and isopentenyl pyrophosphate as substrates the product was found to be cis-cis farnesyl pyrophosphate and possibly trans-cis farnesyl pyrophosphate. Geranyl pyrophosphate and isopentenyl pyrophosphate as substrates yielded trans-trans and possible cis-trans farnesyl pyrophosphate. During purification of the active protein fraction, the ratio of utilization of geranyl pyrophosphate and neryl pyrophosphate did not remain constant, indicating that two enzymes may be involved, one specific for cis C₁₀-substrate and the other for trans C₁₀-substrate.