1,721,128 research outputs found
Hypericins as potential leads for new therapeutics
No full text70 Years have passed since the first isolation of the naphthodianthrones hypericin and pseudohypericin from Hypericum perforatum L. Today, they continue to be one of the most promising group of polyphenols, as they fascinate with their physical, chemical and important biological properties which derive from their unique chemical structure. Hypericins and their derivatives have been extensively studied mainly for their antitumor, antiviral and antidepressant properties. Notably, hypericin is one of the most potent naturally occurring photodynamic agents. It is able to generate the superoxide anion and a high quantum yield of singlet oxygen that are considered to be primarily responsible for its biological effects. The prooxidant photodynamic properties of hypericin have been exploited for the photodynamic therapy of cancer (PDT), as hypericin, in combination with light, very effectively induces apoptosis and/or necrosis of cancer cells. The mechanism by which these activities are expressed continues to be a main topic of discussion, but according to scientific data, different modes of action (generation of ROS & singlet oxygen species, antiangiogenesis, immune responces) and multiple molecular pathways (intrinsic/extrinsic apoptotic pathway, ERK inhibition) possibly interrelating are implicated. The aim of this review is to analyse the most recent advances (from 2005 and thereof) in the chemistry and biological activities (in vitro and in vivo) of the pure naphthodianthrones, hypericin and pseudohypericin from H. perforatum. Extracts from H. perforatum were not considered, nor pharmakokinetic or clinical data. Computerised literature searches were performed using the Medline (PubMed), ChemSciFinder and Scirus Library databases. No language restrictions were imposed. © 2010 by the authors; licensee Molecular Diversity Preservation International
Constituents of the distilled essential oils of citrus reticulata and C. Paradisi from nigeria
No full textHydrodistilled essential oils from the fruit of Citrus paradisi Macfad. (Rutaceae), and fruit peel and leaf of Citrus reticulata L. occurring in Nigeria, were studied by GC and GC/MS on two separate columns. All oils yielded predominantly comparable amounts of monoterpene hydrocarbons (81.0–98.0%). Limonene was the main constituent in mandarin (67.0%) and grapefruit (94.2%) peel oils, while γ-terpinene (53.0%) and linalool (16.1%) were the chief constituents of mandarin leaf oil. Marked differences existed in the composition of the major and minor constituents of tangerine oils. Aliphatic aldehydes and alcohols were also detected in all oils. © 2007, Taylor & Francis Group, LLC. All rights reserved
Labdane diterpenes from Marrubium velutinum and Marrubium cylleneum
No full textFrom the aerial parts of Marrubium velutinum and Marrubium cylleneum, seven labdane diterpenes, velutine A, 15-epi-velutine A, velutine B, 15-epi-velutine B, velutine C, cyllenine A and 15-epi-cyllenine A, have been isolated together with five known diterpenes and four known flavones. The structures of the isolated compounds were established by means of NMR [1H- 1H-COSY, 1H-13C-HMQC, HMBC, HMQC-TOCSY, NOESY] and MS spectral analyses. Complete NMR assignments are reported for known compounds. © 2005 Elsevier Ltd. All rights reserved
Quercus ilex L.: A rich source of polyacylated flavonoid glucosides
No full textFrom the methanolic extract of Quercus ilex leaves a series of acylated flavonol glucosides were identified, among them five new naturally occurring compounds. The constituents, which were all p-coumaroyl glucosides of kaempferol, were characterised either as pure compounds or as inseparable, complicated mixtures of cis and trans isomers. Their complete structure elucidation was done by 2D NMR (COSY, HSQC, HMBC, ROESY) and HPLC-DAD-MS analyses. 2D NMR spectral data allowed the discrimination between different isomers. Quantitative analysis of the methanolic extract of the plant revealed that it is a rich source of acylated flavonoid glucosides (1.22%). Under the experimental conditions chosen HPLC-DAD-MS analyses showed that cis isomers are less polar than trans isomers and their detailed identification, the first in the literature so far, could serve as a tool for the detailed characterisation of analogous isomers by HPLC-DAD-MS in other complicated plant extracts. © 2010 Elsevier Ltd. All rights reserved
Secondary metabolites from Marrubium velutinum, growing wild in Greece
No full textFrom the aerial parts of Marrubium velutinum, two new phenylethanoid glycosides, velutinosides III-IV have been isolated together with four known phenylethanoid glycosides, as well as one new acylated flavone and five known flavonoids. The structures of the isolated compounds were established by means of NMR, MS, and UV spectral analyses. © 2005 Verlag der Zeitschrift für Naturforschung
Labdane diterpenes from Marrubium thessalum
No full textFrom the aerial parts of Marrubium thessalum, four labdane diterpenes, 13S-preperegrinine, 3α-hydroxymarrubiin, 9α,13R-15,16-bisepoxy-15β-methoxy-3-oxo-labdan-6β,19-oli de and 15-methoxyvelutine C, have been isolated together with four known diterpenes and one methoxylated flavone, ladanein. The structures of the isolated compounds were established by means of NMR (COSY, HSQC, HMBC, NOESY, and ROESY) and MS spectral analyses. Complete NMR assignments are reported for 13R-preperegrinine. Characteristic compounds of the plant were peregrinine and ladanein. © 2009 Elsevier Ltd. All rights reserved
Analysis of the leaf oil of syzygium malaccense merr. et perry from nigeria
No full textThe hydrodistilled essential oil from fresh leaves of Syzygium malaccense Merr. et Perry. grown in Nigeria has been studied by GC and GC/MS for the first time. Identification of the substances was made by comparison of mass spectra and retention indices with literature records. The oil was largely composed of monoterpenes (61.1%) characterized mainly by (+)-α-pinene (7.3%), (−)-β-pinene (8.0%), p-cymene (13.5%), and α-terpineol (7.5%). The sesquiterpenes constituted 30.8% of the oil with (−)-β-caryophyllene (9.0%) as the major component. © 2007, Taylor & Francis Group, LLC. All rights reserved
Phenols and polyphenols as Carbonic anhydrase inhibitors
No full textPhenols are among the largest and most widely distributed groups of secondary metabolites within the plant kingdom. They are implicated in multiple and essential physiological functions. In humans they play an important role as microconstituents of the daily diet, their consumption being considered healthy. The physical and chemical properties of phenolic compounds make these molecules versatile ligands, capable of interacting with a wide range of targets, such as the Carbonic Anhydrases (CAs, EC 4.2.1.1). CAs reversibly catalyze the fundamental reaction of CO2 hydration to bicarbonate and protons in all living organisms, being actively involved in the regulation of a plethora of patho/physiological processes. This review will discuss the most recent advances in the search of naturally occurring phenols and their synthetic derivatives that inhibit the CAs and their mechanisms of action at molecular level. Plant extracts or mixtures are not considered in the present review
An update on natural products with carbonic anhydrase inhibitory activity
No full textCarbonic anhydrases (CAs, EC 4.2.1.1) catalyze the fundamental reaction of CO2 hydration in all living organisms, being actively involved in the regulation of a plethora of patho/physiological processes. They represent a typical example of enzyme convergent evolution, as six genetically unrelated families of such enzymes were described so far. It is more than 70 years that synthetic compounds, mainly sulfonamides, have been used in clinical practice as diuretics and systemic acting antiglaucoma drugs. Recent studies using natural product libraries and isolated constituents from natural sources (such as fungi and plants) have disclosed novel chemotypes possessing carbonic anhydrase inhibition activities. These natural sources offer new opportunities in the search for new and more effective carbonic anhydrase inhibitors, and may serve as new leads for the design and development of future drugs. This review will discuss the most recent advances in the search of naturally occurring products and their synthetic derivatives that inhibit the CAs and their mechanisms of action at molecular level. Plant extracts are not considered in the present review
Analysis of the constituents and quality control of Viola odorata aqueous preparations by HPLC-DAD and HPLC-ESI-MS
No full textIn the present study, a method based on liquid chromatography with diode array detection (HPLC-DAD) coupled to an electrospray ionisation (ESI) interface was developed for the determination of the constituents in the aqueous preparations of Viola odorata L. flowering tops. The developed assay was fast, simple and effective and permitted the quality control of the preparations. The aim of this work was to assess the qualitative and quantitative profile of the investigated preparations, which find until today wide applications in food and cosmetic industry, and to propose a validated method for their quality control. Characteristic constituents of V. odorata flowers are considered to be the anthocyanins; however, a detailed literature research showed that data concerning their chemical content are scarce. HPLC-DAD-ESI-MS analyses supported by extensive preparative chromatographic investigations and 2D NMR analyses revealed the predominance of complex flavonol glycosides and permitted the complete characterisation of the content of V. odorata preparations. This is the first report of detailed analysis of the chemical composition of V. odorata flowers. © 2010 Springer-Verlag
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