Search results for "Pyrones"
showing 10 items of 11 documents
Comparative HPLC/ESI-MS and HPLC/DAD study of different populations of cultivated, wild and commercial Gentiana lutea L.
2015
The root of Gentiana lutea L., famous for its bitter properties, is often used in alcoholic bitter beverages, food products and traditional medicine to stimulate the appetite and improve digestion. This study presents a new, fast, and accurate HPLC method using HPLC/ESI-MS and HPLC/DAD for simultaneous analysis of iridoids (loganic acid), secoiridoids (gentiopicroside, sweroside, swertiamarin, amarogentin) and xanthones (isogentisin) in different populations of G.lutea L., cultivated in the Monti Sibillini National Park, obtained wild there, or purchased commercially. Comparison of HPLC/ESI-MS and HPLC/DAD indicated that HPLC/ESI-MS is more sensitive, reliable and selective. Analysis of twe…
A rapid and reliable size-exclusion chromatographic method for determination of kojic dipalmitate in skin-whitening cosmetic products
2007
A size-exclusion chromatographic method has been developed to determine the relatively novel skin-whitening agent called kojic dipalmitate (KDP) in skin-whitening cosmetic products. Preliminary experiments were carried out in order to select the solvent for standard and sample solution, and also for mobile phase composition. A PLGel Mixed-D (polystyrene/divinylbenzene co-polymer) column and isocratic mobile phase of pure tetrahydrofuran (at 1.5 mL min(-1) flow rate) were used. Detection was carried out by means of an UV/vis spectrometry detector set at 248 nm. A study of interferences reveals that KDP can be determined without interferences coming from cosmetic matrices. Most other cosmetic…
Potassium regulates IL-1 beta processing via calcium-independent phospholipase A2.
2000
Abstract We report that potassium leakage from cells leads to activation of the Ca2+-independent phospholipase A2 (iPLA2), and the latter plays a pivotal role in regulating the cleavage of pro-IL-1β by the IL-converting enzyme caspase-1 in human monocytes. K+ efflux led to increases of cellular levels of glycerophosphocholine, an unambiguous indicator of phospholipase A2 activation. Both maturation of IL-1β and formation of glycerophosphocholine were blocked by bromoenol lactone, the specific iPLA2 inhibitor. Bromoenol lactone-dependent inhibition of IL-1β processing was not due to perturbation of the export machinery for pro-IL-1β and IL-1β or to caspase-1 suppression. Conspicuously, activ…
Styryl-pyrones from Goniothalamus arvensis
1998
Two novel styrl-pyrones, (+)-garvensintriol and (+)-etharvendiol, together with a known cytotoxic furano-furone, (+)-goniofufurone, have been isolated from the stem bark of Goniothalamus arvensis. A different relative configuration, cis-erythro-erythro for garvensintriol and cis-threo-erythro for etharvendiol, is established, and their absolute stereochemistry is discussed.
3-acetylaltholactone and related styryl-lactones, mitochondrial respiratory chain inhibitors.
2000
A novel furano-pyrone, 3-acetylaltholactone, and two other known styryl-lactones, altholactone and 5-acetoxyisogoniothalamin oxide, have been isolated from Goniothalamus arvensis (Annonaceae) stem bark. We report here the isolation and structural elucidation of these compounds with furane-pyrone and styryl-pyrone skeletons, postulating also for the first time their mechanism of cytotoxicity based on inhibition on mammalian mitochondrial respiratory chain.
Neonatal representation of odour objects: distinct memories of the whole and its parts
2014
Extraction of relevant information from highly complex environments is a prerequisite to survival. Within odour mixtures, such information is contained in the odours of specific elements or in the mixture configuration perceived as a whole unique odour. For instance, an AB mixture of the element A (ethyl isobutyrate) and the element B (ethyl maltol) generates a configural AB percept in humans and apparently in another species, the rabbit. Here, we examined whether the memory of such a configuration is distinct from the memory of the individual odorants. Taking advantage of the newborn rabbit's ability to learn odour mixtures, we combined behavioural and pharmacological tools to specifically…
Perceptual blending in odor mixtures depends on the nature of odorants and human olfactory expertise.
2012
International audience; Our olfactory system is confronted with complex mixtures of odorants, often recognized as single entities due to odor blending (e.g., coffee). In contrast, we are also able to discriminate odors from complex mixtures (e.g., off-odors). Therefore, the olfactory system is able to engage either configural or elemental processes when confronted with mixtures. However, the rules that govern the involvement of these processes during odor perception remain poorly understood. In our first experiment, we examined whether simple odorant mixtures (binary/ternary) could elicit configural perception. Twenty untrained subjects were asked to evaluate the odor typicality of mixtures…
Kavapyrone enriched extract fromPiper methysticum as modulator of the GABA binding site in different regions of rat brain
1994
Regional differences in the modulation of [3H] muscimol binding to GABAA receptor complexes by kavapyrones, compounds of the rhizome of the plant Piper methysticum which possess sedative activity, were demonstrated using membrane fractions obtained from target brain centers of kavapyrone action: hippocampus (HIP), amygdala (AMY) and medulla oblongata (MED), and from brain centers outside the main kavapyrone effects as frontal cortex (FC) and cerebellum (CER). The kava extract enhanced the binding of [3H] muscimol in a concentration-dependent manner with maximal potentiation of 358% over control in HIP followed by AMY and MED (main target brain centers). Minimal stimulation was observed in C…
Design and synthesis of pironetin analogue/colchicine hybrids and study of their cytotoxic activity and mechanisms of interaction with tubulin
2014
We here report the synthesis of a series of 12 hybrid molecules composed of a colchicine moiety and a pironetin analogue fragment. The two fragments are connected through an ester-amide spacer of variable length. The cytotoxic activities of these compounds and their interactions with tubulin have been investigated. Relations between the structure and activity are discussed. Since the spacer is not long enough to permit a simultaneous binding of the hybrid molecules to the colchicine and pironetin sites on tubulin, a further feature investigated was whether these molecules would interact with the latter through the pironetin end (irreversible covalent binding) or through the colchicine end (…
On the structure of passifloricin A: asymmetric synthesis of the delta-lactones of (2Z,5S,7R,9S,11S)- and (2Z,5R,7R,9S,11S)tetrahydroxyhexacos-2-enoi…
2003
Stereoselective syntheses of the delta-lactone of (2Z,5S,7R,9S,11S)-tetrahydroxyhexacos-2-enoic acid, the structure reported for passifloricin A, and of its (5R)-epimer are described. The creation of all stereogenic centers relied upon Brown's asymmetric allylation methodology. The lactone ring was created via ring-closing metathesis. The NMR data of both synthetic products, however, were different from those of the natural product. The published structure of passifloricin A is thus erroneous and will require further synthetic work to be unambiguously assigned. [structure: see text]