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PubMed2002

Structure and biosynthesis of cetoniacytone A, a cytotoxic aminocarba sugar produced by an endosymbiontic Actinomyces.

Cetoniacytone A (1) and some related minor components (2, 6, 7) were produced by Actinomyces sp. (strain Lu 9419), which was isolated from the intestines of a rose chafer (Cetonia aureata). The structures of the novel metabolites were established by detailed spectroscopic analysis. The absolute configuration of 1 was determined by X-ray analysis and derivatisation with chiral acids. 1 exhibits a significant cytotoxicity against selected tumor cell lines. The biosynthesis of 1 was studied by feeding 13C labelled precursors. The results suggest that the characteristic p-C7N skeleton of the aminocarba sugar is formed via the pentose phosphate pathway by cyclisation of a heptulose phosphate intermediate.

Actinomyces↗
PubMed2003

EI-1941-1 and -2, novel interleukin-1beta converting enzyme inhibitors produced by Farrowia sp. E-1941. I. Biochemical characterization of EI-1941-1 and -2.

EI-1941-1 and -2 isolated from the culture broths of Farrowia sp. selectively inhibited the human recombinant ICE activity with IC50 values of 0.086 and 0.006 microM, respectively, without inhibiting elastase and cathepsin B. EI-1941-1 and -2 also inhibited mature interleukin-1beta secretion from THP-1 cells induced by LPS with IC50 values of 5.0 and 10.3 microM, respectively. Biochemical characterizations of EI-1941-1 and -2 are described in this article.

Cyclohexanones↗
PubMed2003

EI-1941-1 and -2, novel interleukin-1 beta converting enzyme inhibitors Produced by Farrowia sp. E-1941. II. Taxonomy of producing strain, fermentation, isolation, physico-chemical properties, and biological properties.

EI-1941-1 and -2, novel interleukin-1 beta converting enzyme (ICE) inhibitors, were isolated from the culture broths of Farrowia sp. E-1941. EI-1941-1 and -2 selectively inhibited the human recombinant ICE activity with IC50 values of 0.086 and 0.006 microM, respectively. Taxonomy and fermentation of the producing strain and isolation, physico-chemical properties, structure elucidation, and biological properties of EI-1941-1 and -2 are described.

Caspase Inhibitors↗
PubMed1999

Regulation of lung surfactant secretion by phospholipase A2.

Arachidonic acid has been shown to stimulate lung surfactant secretion from alveolar epithelial type II cells. To identify the (phospho)lipases responsible for generating arachidonic acid during lung surfactant secretion, the effects of various (phospho)lipase inhibitors on phosphatidylcholine (PC) secretion from rat alveolar type II cells were investigated. N-(p-amylcinnamoyl)anthranilic acid (ACA), a general inhibitor of phsopholipase A2 (PLA2), inhibited ATP-stimulated PC secretion in a dose-dependent manner. ACA also blocked PC secretion from type II cells stimulated by other secretagogues including phorbol 12-myristate 13-acetate, Ca2+ ionophore A23187 and terbutaline, indicating that PLA2 acts at a late step distal to the generation of second messengers. To determine which PLA2 isoform(s) is involved in lung surfactant secretion, selective inhibitors to different types of PLA2 were used to inhibit PLA2 activity in type II cells. The cytosolic PLA2 (cPLA2) inhibitor, arachidonyl trifluoromethyl ketone, was found to inhibit ATP-stimulated PC secretion, whereas the secretory PLA2 inhibitors, oleoyloxyethylphosphocholine, aristolochic acid, or p-bromophenacyl bromide, and the Ca2+-independent PLA2 inhibitors, palmitoyl trifluoromethyl ketone, or haloenol lactone suicide substrate, had no effect. In addition to PLA2, arachidonic acid is released from diacylglycerol (DAG) by DAG and monoacylglycerol lipases. The DAG lipase inhibitor, RHC-80267 also blocked ATP-stimulated PC secretion. The results suggest that both pathways for generating arachidonic acid via cPLA2 and DAG lipase may participate in lung surfactant secretion.

Adenosine Triphosphate↗
PubMed1998

Relationship between dimedone concentration and formaldehyde captured in plant tissues.

In different parts of water-melon plants (Citrullus vulgaris L.) formaldehyde (HCHO), in dimedone adduct form (formaldemethone), and fully N-methylated substances were identified and determined by OPLC as well as HPLC, capillary GC and GC-MS methods using authentic substances. The HCHO captured originates from dynamic methylation and demethylation processes in which this simplest aliphatic aldehyde is bound in the form of highly reactive hydroxymethyl groups. Dimedone will react with the small quantity of HCHO in equilibrium with the hydroxymethyl groups and it follows from this that the rate of HCHO captured as the dimedone adduct will increase parallel to the increasing concentration of dimedone applied, as a methanolic solution, until a plateau is reached. The level of HCHO was very high in the roots of water-melon seedlings.

Chromatography, Gas↗
PubMed2000

Cyclolinteinone, a sesterterpene from sponge Cacospongia linteiformis, prevents inducible nitric oxide synthase and inducible cyclo-oxygenase protein expression by blocking nuclear factor-kappaB activation in J774 macrophages.

We investigated the effect of cyclolinteinone, a sesterterpene from Caribbean sponge Cacospongia linteiformis, on inducible NO synthase (iNOS) and cyclo-oxygenase-2 (COX-2) protein expression in lipopolysaccharide (LPS)-stimulated J774 macrophages. Incubation of J774 cells with LPS (1 microgram/ml) caused an increase of both iNOS and COX-2 protein expression, which was prevented in a concentration-dependent fashion by cyclolinteinone (12.5, 25 and 50 microM). Electrophoretic mobility-shift assay indicated that cyclolinteinone blocked the activation of nuclear factor-kappaB (NF-kappaB), a transcription factor necessary for either iNOS or COX-2 induction. Cyclolinteinone also blocked disappearance of I(kappa)B-alpha from cytosolic fraction and nuclear translocation of NF-kappaB subunits p50 and p65. These results show that cyclolinteinone down-regulates iNOS and COX-2 protein expression by inhibiting NF-kappaB activation and suggest that it may represent a novel anti-inflammatory compound capable of controlling the excessive production of prostaglandins and nitric oxide occurring in several inflammatory diseases.

4-Butyrolactone↗
PubMed2000

Diacylglycerol mediates the T-cell receptor-driven Ca(2+) influx in T cells by a novel mechanism independent of protein kinase C activation.

The mechanism of Ca(2+) influx in nonexcitable cells is not known yet. According to the capacitative hypothesis, Ca(2+) influx is triggered by IP(3)-mediated Ca(2+) release from the intracellular Ca(2+) stores. Conversely, many workers have reported a lack of association between release and influx. In this work, the role of diacylglycerol (DAG) as the mediator of T-cell receptor (TCR)-driven Ca(2+) influx in T cells was investigated. Stimulation of mouse splenic T cells with naturally occurring DAG caused Ca(2+) entry in a dose- and time-dependent manner. Such stimulation was blocked by Ni(2+), a divalent cation known to block Ca(2+) channels. Inhibition of protein kinase C (PKC) by calphostin C did not inhibit, but slightly enhanced, the DAG-stimulated Ca(2+) entry. However, inhibition of DAG metabolism by DAG kinase and lipase inhibitors enhanced the DAG-stimulated Ca(2+) entry. DAG lipase and kinase inhibitors also enhanced the Ca(2+) entry in T cells stimulated through TCR/CD3 complex with anti-CD3 antibody. Calphostin C did not affect the anti-CD3-stimulated Ca(2+) entry. These results showed that TCR-driven Ca(2+) influx in T cells is mediated by DAG through a novel mechanism(s) independent of PKC activation.

Animals↗
PubMedDate not supplied

Polyclonal-based ELISA for the identification of cyclohexanedione analogs that inhibit maize acetyl coenzyme-A carboxylase.

Cyclohexanedione herbicides inhibit monocotyledonous acetyl coenzyme-A carboxylase (ACCase; E.C. 6.4.1.2.), which catalyzes the first committed step in fatty acid biosynthesis. Although the target site has been identified, little is known about the mechanisms involved in herbicide binding. An immunological study was undertaken to create a model to better characterize the herbicide-enzyme interaction. Cyclohexanedione-specific antiserum was raised in New Zealand white rabbits by immunizing them with a cyclohexanedione analog-bovine serum albumin conjugate. Two indirect enzyme-linked immunosorbent assays (ELISA) were developed using 2 different cyclohexanedione analogs conjugated to ovalbumin as coating conjugates. Nineteen cyclohexanedione analogs, 13 active ACCase inhibitors, and 6 inactive analogs were tested for their ability to compete with both coating conjugates for antiserum binding. All active ACCase inhibitors were observed to compete with both coating conjugates, whereas all inactive analogs failed to compete with at least one coating conjugate. On the basis of these results, the immunological model could be used to distinguish all active ACCase inhibitors from inactive analogs using the 2 ELISAs sequentially.

Acetyl-CoA Carboxylase↗
PubMed2001

[Evolution of a case of tyrosinemia type I treated with NTBC].

Tyrosinemia type I is an autosomal recessive inherited disorder caused by deficient fumarylacetoacetase activity. Treatment with 2-(2-nitro-4-trifluoro-methylbenzoyl)-1,3-cyclohexanedione (NTBC), an inhibitor of 4-hydroxyphenylpyruvate dioxygenase, has successfully been applied for the last few years. Our aim was to evaluate the clinical and biochemical response to treatment with NTBC of a 18-year-old patient with a chronic form of tyrosinemia type I, whose main clinical feature was vitamin D-resistant rickets leading to severe osteoporosis with multiple bone fractures and skeletal deformities. After treatment, toxic metabolites became undetectable and porphobilinogen synthase activity returned to normal. Renal function improved, blood hemoglobin returned to normal and alfa-fetoprotein decreased. The patient's general condition greatly improved. However, the alfa-fetoprotein concentration slowly increased during the second year of NTBC treatment and hepatocellular carcinoma developed. NTBC treatment should be considered even in advanced cases of tyrosinemia type I, although only as a palliative therapy.

4-Hydroxyphenylpyruvate Dioxygenase↗
PubMedDate not supplied

Determination of clethodim and its oxidation metabolites in crops by liquid chromatography with confirmation by LC/MS.

A method was developed for determination of the herbicide clethodim (C0) and its oxidation metabolites clethodim sulfoxide (C1) and clethodim sulfone (C2) in agricultural products. Upon extraction, both C0 and C1 were oxidized to C2 by m-chloroperoxybenzoic acid, and C2 was determined by liquid chromatography (LC). The C2 peak was confirmed by liquid chromatography/mass spectrometry (LC/MS) with electrospray ionization (ESI). Recoveries of C0 from radish, tomato, onion, sweet potato, kidney bean, carrot, cabbage, and lettuce ranged from 91 to 118% following fortification at 0.05-1.0 ppm. The detection limit of C2 in crops was 0.01 ppm (S/N > 3). The fortified samples of onion, sweet potato, kidney bean, and carrot were confirmed by LC/MS (ESI), and the peak of C2 was detected.

Chromatography, Liquid↗
PubMedDate not supplied

Adsorption and degradation of the weak acid mesotrione in soil and environmental fate implications.

The ability of soils to adsorb and degrade pesticides strongly influences their environmental fate. This paper examines the adsorption and degradation of a weak acid, a new herbicide mesotrione 12-[4-(methylsulfonyl)-2-nitrobenzoyl]-1,3-cyclohexanedione], in 15 different soils from Europe and the USA. Experiments were conducted to understand the influence of soil properties, covering a wide range of soil textures, soil pH values (4.4 to 7.5), and organic carbon contents (0.6 to 3.35%). Mesotrione adsorption (Kd values ranged from 0.13 to 5.0 L/kg) was primarily related to soil pH, and to a lesser extent by percent organic carbon (%OC). As soil pH rose. mesotrione Kd values got smaller as mesotrione dissociated from the molecular to anionic form. Mesotrione degradation (half-lives ranged from 4.5 to 32 d) was also related to soil pH, getting shorter as soil pH rose. Simple regression of mesotrione adsorption against soil pH and %OC and against degradation provided a close fit to the data. The correlation between mesotrione adsorption and degradation means that Kd and half-life values are only relevant for use in environmental fate assessment if these values are "paired" for the same soil pH and %OC. The implications were as illustrated for leaching, raising important issues about combining pesticide adsorption and degradation behavior in environmental fate assessments.

Adsorption↗
PubMed2001

Primus (florasulam 50 G/L), a new triazolopyrimidine sulfonanilide herbicide to control broad-leaved weeds in maize when applied in early postemergence (1 to 6 leaf stage of maize). Preliminary results.

OBJECTIVE: PRIMUS was developed in maize in Belgium in 1999 and 2000 in the course of research into limiting or replacing the use of triazines in maize. One of the imperatives of this research was to find the lowest possible residue content (MRL). SELECTIVITY TEST: An application of florasulam, at the dose of 5 g of active substance (a.s.) at the 2 to 3 leaf stage of the maize was found to be selective on 132 (in 1999) and 126 (in 2000) varieties of maize. EFFICACY TEST: Florasulam was tested at doses of between 1 and 5 g a.s./hectare. The treatments were applied in early postemergence at the 3-5 leaf stage of the maize or in 2 separate applications: at the 1 leaf stage with a dose of 2 g a.s. florasulam at the 4 leaf stage with a dose of 2 g a.s. florasulam The herbicide was fully effective on the sensitive flora. A summary of the results is presented. A detailed weed spectrum is defined. PROGRAMMES: Herbicide programmes were developed on the basis of these findings. The results showed that the best partners for florasulam were triketones (sulcotrione and mesotrione) in very low doses. Sulcotrione was applied at doses of 75 to 150 g a.s./ha and mesotrione at 25 to 50 g a.s./ha. Triple mixes of florasulam + triketone + nicosulfuron in very low doses and 1 or 2 applications were also tested. The results were highly encouraging and this work should lead to practical recommendations. PHYTOTOXICITY: Phytotoxicity was observed on some occasions. The phytotoxicity results for the different figures seem, however, to depend more on the climate (difference between daytime and night-time temperatures just before and after the treatment) than on the products tested in the mixes. However, the florasulam + nicosulfuron (sulfonyl-urea antigrasses) may sometimes cause serious problems with selectivity. The phytotoxicity noted in the tests was usually short-lived (30 days). CONCLUSION: The results of the tests show that it is possible to consider replacing atrazine-based programmes with very low doses of modern herbicides applied at early stages of the maize. A mixture of active substances is vital. Repeated very low doses at the 1/2 and 4/5 leaf stages of the maize were found to be the most effective.

Cyclohexanones↗