177 research outputs found

    The Potential of Higher Plants as a Source of New Drugs

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    The plant kingdom is still an untapped reservoir of new molecules with therapeutic potential. A selection of bioactive plant constituents recently discovered are presented with focus on new drugs or lead compounds in an advanced state of development. Obtaining pure new biologically active substances from plants remains a complex task. Biological and chemical screenings are complementary approaches for the rapid detection and isolation of new interesting plant constituents. Biological screening followed by activity-guided fractionation has been successfully used in our laboratories for the discovery of new antifungal metabolites and inhibitors of enzymes involved in the aetiology of prostate hyperplasia. High-performance liquid chromatography (HPLC) coupled to UV spectroscopy (LC/UV), mass spectrometry (LC/MS), and magnetic resonance (LC/NMR) proved to be highly efficient for the chemical screening of crude plant extracts. These hyphenated techniques were extensively used for the investigation of polyphenols with monoamine-oxidase inhibitory (IMAO) properties in Gentianaceae species

    On-line identification of minor flavones from sugarcane juice by LC/UV/MS and post-column derivatization

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    This work describes the on-line characterization of minor flavones from sugarcane (Saccharum officinarum) juice by high-performance liquid chromatography coupled to diode array UV detection and mass spectrometry (LC/UV/MS) using atmospheric pressure chemical ionization-collision-induced dissociation (APCI-CID-MS/MS) and post-column derivatization using UV shift reagents. HPLC-UV analysis with shift reagents provided information about the substitution pattern in the flavonoid skeleton and, combined with MS data, these techniques allowed for the on-line identification of five "garapa" flavones: luteolin-8-C-glucosyl-7-O-glucuronide; tricin-7-O-neohesperoside-4'-O-rhamnoside; tricin-7-O-methylglucuronate-4'-O-rhamnoside; tricin-7-O-methylglucuronide; swertisin, while four other compounds were partially identified as glycosylflavones. Only swertisin (7-O-methylapigenin-6-C-glucoside) was reported previously in sugarcane molasses.Este trabalho apresenta a identificação "on line" de flavonas minoritárias do suco da cana-de-açúcar (Saccharum officinarum), por cromatografia líquida de alta eficiência com detector UV acoplada à espectrometria de massas (CL/UV/EM) com ionização química à pressão atmosférica, dissociação induzida por colisão (IQPA-DIC-EM/EM) e derivatização pós-coluna utilizando reagentes de deslocamento de UV. As análises CLAE-UV com reagentes de deslocamento forneceram informações sobre a posição da substituição no esqueleto dos flavonóides e, em combinação com dados de EM, estas técnicas permitiram a identificação "on-line" de cinco flavonas da garapa: luteolina-8-C-glucosil-7-O-glucuronídeo; tricina-7-O-neoesperosideo-4'-O-ramnosídeo; tricina-7-O-metilglucuronato-4'-O-ramnosídeo; tricina-7-O-metilglucuronídeo; swertisina; e outras quatro substâncias foram parcialmente identificadas como flavonas glicosiladas. Somente a swertisina (7-O-metilapigenina-6-C-glicosídeo) foi anteriormente descrita no bagaço da cana-de-açúcar.FAPESPCNPqSwiss NSF National Science FoundationUniversity of Lausanne - Fondation Herbett

    Flavonoid profiling among wild type and related GM wheat varieties

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    Pleiotropic effects are one of the main concerns regarding genetically modified organisms (GMOs). This includes unintended side effects of the transgene or its genome insertion site on the regulation of other endogenous genes, which could potentially cause the accumulation of different secondary metabolites that may have not only an impact on diet as repeatedly worried by the public but also on the environment. Regarding amount and possible environmental effects, flavonoids represent the most prominent group of secondary metabolites in wheat. Many flavonoids function as signalling or defence molecules. We used a robust and reproducible analytical method to compare the flavonoid content of genetically modified (GM) wheat (Triticum aestivum L., Gramineae) expressing genes that confer increased fungal resistance with their non-GM siblings. The transgenes provide either a broad-spectrum fungal defence (chitinase/glucanase from barley) or bunt-specific resistance by a viral gene (KP4). Significant differences in flavonoid composition were found between different wheat varieties whereas different lines of GM wheat with increased antifungal resistance showed only minor differences in their flavonoid composition relative to their non-GM siblings. In a field test, no significant differences were detectable between infected and non-infected wheat of the same variety regardless of the presence of the transgene. Our results are in agreement with the hypothesis that the transgenes we used to increase wheat defence to fungal pathogens do not interfere with the flavonoid biosynthesis pathway. More significantly, the genetic background resulting from conventional breeding has a direct impact on the biological composition of flavonoids, and thus possibly on the environmen

    Ginkgo biloba

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    A by T. A. van Beek (2000) entitled, "Ginkgo biloba". The book covers all aspects of Ginkgo biloba and the phytopharmaceuticals derived from its leaves. Useful information on all anal. problems involving the four main classes of Ginkgo constituents is provided. The book features a selection of appropriate topics and contributions, providing a full coverage of a plant which is becoming a major phytopharmaceutical worldwide. It is well presented with some illustrations and with numerous and accurate literature refs. [on SciFinder (R)
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