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At least 631 records · Page 35Linked to original sources
PubMed2001

Liquid chromatography/atmospheric pressure chemical ionization mass spectrometry of terpene lactones in plasma of volunteers dosed with Ginkgo biloba L. extracts.

Liquid chromatography/atmospheric pressure chemical ionization mass spectrometry (LC/APCI-ITMS) was applied to evaluate the levels of ginkgolides A and B and bilobalide in plasma of volunteers after administration of Ginkgo biloba extracts in free (Ginkgoselect) or phospholipid complex (Ginkgoselect Phytosome) forms, providing 9.6 mg of total terpene lactones. The maximum plasma concentrations, C(max), of total ginkgolides A, B and bilobalide were 85.0 and 181.8 microg/mL for Ginkgoselect and Ginkgoselect Phytosome, respectively. The C(max) values were reached at 120 min for the free form and at 180--240 min for the phospholipid complex form. In both cases, the mean elimination half-life of each terpene lactone was in the range 120--180 min. Due to its sensitivity (about 1 ng/mL) and specificity, LC/APCI-ITMS proved to be a very powerful tool for pharmacokinetic studies of these phytochemicals.

Adult↗
PubMed1976

On the effect of glucono-delta-lactone on the yeast Pichia polymorpha.

Investigation has been made into the action of glucono-delta-lactone on living cells of Pichia polymorpha in relation to the uptake of D-(U-14C)glucose, and the incorporation of (2-14C) uracil and L-(U-14C) threonine into RNA and protein respectively. Other factors such as the action of glucono-delta-lactone on cell morphology and on enzymic synthesis have also been studied. The action of this compound on beta-glucanase has been found to take place in the hydrolytic power and not in the synthesis.

Ascomycota↗
PubMed1975

Effect of zexbrevins A and B. Two new sesquiterpene lactones, on the immune response of mice.

Two newly described sesquiterpene lactones, Zexbrevin A and Zexbrevin B, were administered to mice at microgram doses before a single immunizing dose of sheep red blood cells (SRBC), bovine serum albumine (BSA), or Egg albumin (Ea). It was found out that drug treated and immunized animals displayed high numbers of specific spleen rosette forming cells (RFC), as well as elevated titers of circulating antibodies, as compared with mice stimulated solely with antigens. 500 mug of Zexbrevin A and Zexbrevin B was about the best dose for rosette increase; 700 mug or lesser amounts of both drugs induced a decline in the rosette numbers. It was evident that Zexbrevins had to be administered 48 hours before antigen stimulation; no potentiation was obtained if the drugs were given 3 to 11 days before the antigen. No effect was obtained, as well, when mice were treated with drug and antigen on the same day. In the presence of Zexbrevins the radioactive thymidine uptake of cultured normal mouse spleen cells will not increase above controls, indicating that mitogenic effects appear not to be involved in the potentiation. It is concluded that the sesquiterpene lactones exert in mice a potent stimulation of the in vivo response.

Animals↗
PubMed2001

A new triterpene lactone from the roots of Patrinia scabiosaefolia.

A new triterpene lactone named patrinolide A (1) has been isolated from the roots of Patrinia scabiosaefolia (Valerianaceae). Its structure was determined to be 11beta,21beta-dihydroxy-3-oxooleanan-28,13beta-olide on the basis of spectral analysis, including 2D-NMR techniques. Key words: Patrinia scabiosaefolia, Valerianaceae, Lactone, Patrinolide, 11beta,21beta-dihydroxy-3-oxooleanan-28,13beta-olide.

Korea↗
PubMed2003

A simple and robust set-up for on-column sample preconcentration--nano-liquid chromatography--electrospray ionization mass spectrometry for the analysis of N-acylhomoserine lactones.

A simple method for the simultaneous, rapid and sensitive determination of N-acylhomoserine lactone signaling molecules in bacterial isolates, without prior sample preconcentration and with minimal sample cleanup, is presented. The analysis relies on the combination of analyte preconcentration and separation on a single device: a relatively large sample volume (1-5 microL) is directly loaded onto a laboratory-made, miniaturized (75 microm i. d.) reverse phase nano-liquid chromatography column, connected on-line to a microelectrospray-ionization ion trap mass spectrometer. In a first step the analyte is adsorbed (and so concentrated) at the beginning of the column, and is eluted and selectively separated in a second step by the organic mobile phase. Sample preconcentration follows the mechanisms of solid phase extraction on a nano-scale, while separation takes place according to classical liquid chromatography separation principles. The columns can be manufactured easily, are simply connected, and used with minimal solvent amounts; this makes this method extremely robust and cost-effective. The analytical setup was found to be routinely quantitative down to a concentration of 10 ng/mL (corresponding to a total analyte amount of 10 pg or ca. 50 fmol). The limit of detection was reached at 1 ng/mL (1 pg, ca. 5 fmol). Compared to the classical AHL analysis of bacterial cultures with biosensors, where selectivity and sensitivity is often limited, this rapid analytical technique is a substantial qualitative and quantitative improvement. Two unsubstituted N-acylhomoserine lactones could be identified and quantified from a Burkholderia cepacia culture supernatant in a chloroform extract.

4-Butyrolactone↗
PubMed2005

VolSurf analysis of pharmacokinetic properties for several antifungal sesquiterpene lactones isolated from Greek Centaurea sp.

Sesquiterpene lactones are terpenoid compounds characteristic of the Asteraceae (Compositae) possessing a variety of biological activities, such as cytotoxic, antitumor, antibacterial, and antifungal. The prediction of the pharmacokinetic profile of several antifungal sesquiterpene lactones, isolated from Greek taxa of Centaurea sp., was undertaken in this study using the VolSurf procedure. The molecules were projected on the following pre-calculated ADME models: Caco-2 cell permeability, plasma protein affinity, blood-brain barrier permeation and thermodynamic solubility. The in silico projection revealed a non optimal pharmacokinetic profile for the studied compounds. ADME in silico screening of a semi-synthetic derivatives virtual library has been performed in order to optimize the pharmacokinetic properties. A number of derivatives were proposed as it was predicted to have higher Caco-2 cell permeability, while the pharmacokinetic behaviour regarding BBB penetration, protein binding and solubility was mainly preserved.

Antifungal Agents↗
PubMed1995

Macrocyclic lactone synthesis by lipases in water-in-oil microemulsions.

Five microbial lipases from Chromobacterium viscosum, Candida cylindracea, Pseudomonas (source Fluka), Pseudomonas (source Genzyme) and lipoprotein lipase ex Microbial (Genzyme) have been screened for lactonisation activity towards 16-hydroxyhexadecanoic acid (HHA) in a variety of different w/o microemulsion systems. With the exception of Candida cylindracea (CC), all the lipases exhibited lactonisation activity although they were inherently more active in microemulsion systems based on the anionic surfactant sodium bis(2-ethylhexyl)sulphosuccinate (AOT) than in those based on the cationic surfactant cetyltrimethylammonium bromide (CTAB). Lactone yields are typically 50-60% and are markedly better than those reported previously using microemulsions in combination with chemical catalysts. Lipase stability is superior in the CTAB microemulsion systems, while lipase stability in the low water content AOT microemulsion systems was still good with the exception of CC lipase, which is rapidly inactivated. Buffering the water pools of AOT microemulsions using diglycine buffer at pH 8.0 improved biocatalyst stability. The lactonisation activity of lipases in CTAB w/o microemulsion systems compares favourably with that obtained using the same preparations as a solid suspension in the corresponding water-saturated organic solvent. In addition, the unusual solubility properties of microemulsions allowed the use of considerably higher concentrations of substrate in the microemulsion systems as compared to water-saturated organic solvents such as n-heptane. Lactone yields obtained at equivalent concentrations in the corresponding organic solvents containing conventional condensation catalysts were consistently measured at approx. 10%.

4-Aminopyridine↗
PubMed1987

The influence of the sesquiterpene lactones from Geigeria on mast cell degranulation.

The sesquiterpene lactones isolated from Geigeria were found to be incapable of inducing rat peritoneal mast cell degranulation at levels of 0.3-1.6 mM. The sulphydryl reagent, N-ethylmaleimide, too was unable to trigger mast cell secretion. Instead, it was observed that these compounds inhibited the release of histamine induced by Compound 48/80. Pretreatment of the lactones and N-ethylmaleimide with the amino acid, L-cysteine, reduced their inhibition ability of histamine release to a considerable extent, but not completely. Geigerin(V), which lacks an alpha-methylene group and the chemically prepared cysteine-adduct of dihydrogriesenin(I), were also capable of inhibiting mast cell secretion by Compound 48/80, but to a lesser extent.

Alkylation↗
PubMed1994

A synthetic route to 3-C-alkyl (or 3-C-phenyl-) 2,3-dideoxy-D-erythro-pentono-1,4-lactones: intermediates in the synthesis of 2(3H)-furanones.

A series of 3-C-alkyl- (and 3-C-phenyl-) 2,3-dideoxy-D-erythro-pentono-1,4-lactones, compounds which are important in the synthesis of modified nucleosides and antibiotic sugars, were synthesized from D-ribonolactone. By a route that proceeded via 5-O-protected D-ribonolactone, 5-O-protected 2,3-dideoxy-D-glycero-pent-2-enono-1,4-lactones were synthesized and reacted with R2CuLi or a complex PhSCu(RMgBr)n to give respectively the 3-C-alkyl or 3-C-phenyl compounds. Details of the preparation of the O-protected intermediates, as well as the selection of the organometallic reagents, are provided.

4-Butyrolactone↗
PubMed1995

Biochemically active sesquiterpene lactones from Ratibida mexicana.

Bioactivity-directed fractionation of the methanol extract of the roots of Ratibida mexicana resulted in the isolation of two bioactive sesquiterpene lactones, isoalloalantolactone and elema-1,3,11-trien-8,12-olide. Both compounds caused a significant inhibition of the radicle growth of Amaranthus hypochondriacus and Echinochloa crus-galli, exerted moderate cytotoxic activity against three different solid tumour cell lines and inhibited significantly the radial growth of three phytopathogenic fungi. Isoalloalantolactone also caused the inhibition of ATP synthesis, proton uptake and electron transport (basal, phosphorylating and uncoupled) from water to methylviologen, therefore acting as a Hill's reaction inhibitor. The lactone did not affect photosystem I but inhibited photosystem II. The site of inhibition of isoalloalantolactone is located in the span of P680 to QA redox enzymes because the uncoupled electron transport from water to silicomolybdate and, from DPC to DCIP are inhibited approximately to the same extent.

Antifungal Agents↗
PubMed1981

Lactones derived from kainic acid: novel selective antagonists of amino acid-induced Na+ fluxes in rat striatum slices.

The effects of amino acid lactones chemically derived from the neuroexcitant kainic acid on the response of rat striatal slices to excitatory amino acids, were studied. These compounds antagonize to varying extents the effects of kainic acid and N-methyl-D-aspartic acid but have no effect on the responses to glutamic or quisqualic acid. Some of the lactones antagonize preferentially the effects of kainic acid. This study further confirms the existence of heterogenous populations of excitatory amino acid receptors in the rat striatum.

Amino Acids↗
PubMed1991

Method for separation and determination of lactone and hydroxy acid forms of a new HMG CoA reductase inhibitor (RG 12561) in plasma.

The new drug RG 12561 (I) is a lactone that is undergoing clinical evaluation for its cholesterol lowering effect based on potent HMG CoA reductase inhibitory activity displayed by its open hydroxy acid form. To determine the dispositional characteristics of the drug, a method was developed for determination of the two forms in plasma. A 0.25-ml aliquot of plasma was deproteinized with 0.5 ml of methanol, and the lactone was extracted with hexane-ethyl acetate (75:25, v/v). The methanolic plasma was then acidified followed by extraction of the hydroxy acid with hexane-ethyl acetate. The extracts were dried, reconstituted and analyzed by isocratic, reversed-phase high-performance liquid chromatography using ultraviolet absorbance at 254 nm. The separations were performed utilizing a C18 column with mobile phase consisting of acetonitrile, 2-propanol and 0.1 M acetate buffer (pH 5), the proportions of which differed depending on the form of drug analyzed. The method was found to be selective and a quantitation limit of 50 ng/ml was established. Validation studies demonstrated that the method was sufficiently accurate and precise for determining disposition of the drug in the dog.

Animals↗
PubMed2005

Isolation, characterization and biological evaluation of datura lactones as potential immunomodulators.

Phytochemical investigation of Datura quercifolia (Solanaceae) plant yielded a new datura lactone, 1beta,5alpha,12alpha-trihydroxy-6alpha,7alpha,24alpha,25alpha-diepoxy-20S,22R with-2-enolide (1), along with two known compounds, 2 and 3. The structure of 1 was established on the basis of spectral analysis, as well as by its chemical transformation into known datura lactones. These compounds have been evaluated for immunomodulatory activity by observing their effect on antibody production, T-cell and B-cell activation, and cytokine production from splenocytes. Compound 2 was found to be the most promising immunostimulator in the present study.

Animals↗
PubMed2005

Synthesis and anti-viral activity of a series of sesquiterpene lactones and analogues in the subgenomic HCV replicon system.

Hepatitis C virus (HCV) infection is a severe liver disease that often leads to liver cirrhosis and hepatocellular carcinoma (HCC). Current therapy is inadequate to conquer this viral disease. In this study, we identified parthenolide (1), an active component in feverfew, a popular remedy for fever and migraine, as a lead compound with an EC50 value of 2.21 microM against HCV replication in a subgenomic RNA replicon assay system. Parthenolide is able to potentiate the interferon alpha-exerted anti-HCV effect. Several commercially available sesquiterpene lactones (2-5) structurally analogous to parthenolide and a series of synthesized Michael-type adducts of parthenolide (12-18) also exhibit micromolar concentrations for anti-HCV activities. Structure-activity relationship was elucidated to reveal that the spatial arrangement of the terpenoid skeleton fused with an alpha-methylene-gamma-lactone moiety produces maximal anti-HCV activity. In addition, a strong anti-HCV potency indicates a possibility of secondary amino adducts (12-18) converting back to parthenolide or being replaced by the nucleophilic residues of proteins inside cells. This work shows that screening of natural products is a viable and fast way for identifying novel molecular diversity as potential drug leads.

Blotting, Northern↗
PubMed2004

N-Sulfonyl homoserine lactones as antagonists of bacterial quorum sensing.

A series of 11 new analogues of N-acylhomoserine lactones in which the carboxamide bond was replaced by a sulfonamide one, has been synthesised. These compounds were evaluated for their ability to competitively inhibit the action of 3-oxohexanoyl-L-homoserine lactone, the natural ligand of the quorum sensing transcriptional regulator LuxR, which in turn activates expression of bioluminescence in the model bacterium Vibrio fischeri. Several compounds were found to display antagonist activity. Molecular modeling suggests that the latter prevent a cascade of structural rearrangements necessary for the formation of the active LuxR dimer.

4-Butyrolactone↗
PubMed2005

Novel indole alpha-methylene-gamma-lactones as potent inhibitors for AKT-mTOR signaling pathway kinases.

In an effort to generate novel anticancer agents, a series of hybrids of alpha-methylene-gamma-lactones and 2-phenyl indoles has been synthesized and evaluated for inhibition activities on the phosphorylation of AKT, mTOR, p70S6 kinase, and 4E-BP1. The results indicate that substitutes on the gamma-position of lactones have a rather significant influence on inhibition activities.

Adaptor Proteins, Signal Transducing↗
PubMed2006

Himbacine derived thrombin receptor (PAR-1) antagonists: structure-activity relationship of the lactone ring.

The structure-activity relationship (SAR) of the lactone ring of himbacine derived thrombin receptor (PAR-1) antagonists (e.g., 2-5) is described. The effect of the lactone carbonyl group on binding to PAR-1 is dependent on the substitution pattern of the pyridine ring. A stereoselective intramolecular Michael addition reaction to the vinyl pyridine group was observed for these pyridine analogs of himbacine in basic conditions at elevated temperature.

Alkaloids↗