Search results for "alkaloids"
showing 10 items of 182 documents
Acetyltransfer in natural product biosynthesis--functional cloning and molecular analysis of vinorine synthase.
2004
Vinorine synthase (EC 2.3.1.160) catalyses the acetyl-CoA- or CoA-dependent reversible formation of the alkaloids vinorine (or 11-methoxy-vinorine) and 16-epi-vellosimine (or gardneral). The forward reaction leads to vinorine, which is a direct biosynthetic precursor along the complex pathway to the monoterpenoid indole alkaloid ajmaline, an antiarrhythmic drug from the Indian medicinal plant Rauvolfia serpentina. Based on partial peptide sequences a cDNA clone was isolated and functionally expressed in Escherichia coli. The Km values of the native enzyme for gardneral and acetyl-CoA were determined to be 7.5 and 57 microM. The amino acid sequence of vinorine synthase has highest level of i…
Deoxysarpagine Hydroxylase — A Novel Enzyme Closing a Short Side Pathway of Alkaloid Biosynthesis in Rauvolfia
2002
Microsomal preparations from cell suspension cultures of the Indian plant Rauvolfia serpentina catalyze the hydroxylation of deoxysarpagine under formation of sarpagine. The newly discovered enzyme is dependent on NADPH and oxygen. It can be inhibited by typical cytochrome P450 inhibitors such as cytochrome c, ketoconazole, metyrapone, tetcyclacis and carbon monoxide. The CO-effect is reversible with light (450 nm). The data indicate that deoxysarpagine hydroxylase is a novel cytochrome P450-dependent monooxygenase. A pH optimum of 8.0 and a temperature optimum of 35 degrees C were determined. K(m) values were 25 microM for NADPH and 7.4 microM for deoxysarpagine. Deoxysarpagine hydroxylase…
In vitro activities of antimicrobial agents against Candida species
1999
Objective. Antimicrobial mouthrinses may represent a valid alternative to topical antifungal agents. However, the action of antimicrobials could be affected by the different ingredients incorporated into mouthrinse products. The purpose of the present study was to investigate the in vitro antifungal and fungicidal activities of antimicrobials alone. Study Design. A broth macrodilution method was used to determine the minimum inhibitory concentration of 4 antimicrobial agents against Candida species. Minimum fungicidal concentration was also determined. Results. All antimicrobials showed antifungal activity against all tested organisms, but cetylpyridinium chloride received significantly low…
Role of Levo-tetrahydropalmatine and its metabolites for management of chronic pain and opioid use disorders.
2021
Abstract Background Opioids have been prescribed to reduce suffering from pain and to enhance quality of life. Due to the addictive potential and the lack of other effective alternatives to treat severe acute and chronic pains, opioids remain a serious public health issue. While, opioids directly influence the drug-seeking behavior, tolerance and withdrawal processes, through neuroadaptation, the brain's endogenous opioid system also adapts in the presence of chronic pain and could contribute to the difficulty of treatment. Despite the seemingly obvious interaction between the presence of pain and opioid-abuse, little is known about the underlying mechanisms in the brain. Purpose To review …
Partialsynthese neuer Ergolinderivate aus Clavinalkaloiden, 2. Mitt.1) O-Acyl-8-hydroxymethyl-6-methylergol-8-ene und -ergol-9-ene
1983
Die Titelverbindungen sind durch Acylierung von Elymoclavin (1) bzw. Lysergol (2) mit Saurechloriden, im Fall der Ester von 2 auch durch Isomerisierung von O-Acyl-1 mit aktiviertem Al2O3 darstellbar. Umgekehrt fuhrt die Acylierung von 2 in bestimmten Fallen spontan zur Bildung eines Gemisches der O-Acylderivate von 1 und 2.. Partial Synthesis of New Ergoline Derivatives from Clavine Alkaloids, II: O-Acyl-8-(hydroxymethyl)-6-methylergol-8-enes and -ergol9-enes The title compounds can be prepared by acylation of elymoclavine (1) and lysergole (2), respectively, with acid chlorides or, in the case of the esters of 2, by isomerization of O-acyl-1 with activated Al2,O3. On the other hand, in cer…
Anti-Eryptotic Activity of Food-Derived Phytochemicals and Natural Compounds
2022
Human red blood cells (RBCs), senescent or damaged due to particular stress, can be removed by programmed suicidal death, a process called eryptosis. There are various molecular mechanisms underlying eryptosis. The most frequent is the increase in the cytoplasmic concentration of Ca2+ ions, later exposure of erythrocytes to oxidative stress, hyperosmotic shock, ceramide formation, stimulation of caspases, and energy depletion. Phosphatidylserine (PS) exposed by eryptotic RBCs due to interaction with endothelial CXC-Motiv-Chemokin-16/Scavenger-receptor, causes the RBCs to adhere to vascular wall with consequent damage to the microcirculation. Eryptosis can be triggered by various xenobiotics…
Chemical Constituents and Biological Properties of Genus Doronicum (Asteraceae)
2021
The genus Doronicum, belonging to tribe Senecioneae (Fam. Asteraceae), is found mainly in the Asia, Europe and North Africa. This genus of plant has always been used in traditional medicinal treatments due to the many biological properties shown such as killing parasitic worms and for relieving constipation, as well as to improve heart health, to alleviate pain and inflammation, to treat insect bites, etc. According to the World Flora the genus Doronicum contains 39 subordinate taxa.[1-3] The purpose of this article, which covers data published from 1970 to 2021 with more than 110 articles, aims to carry out a complete and critical review of the Doronicum genus, examining traditional uses a…
Target analysis and retrospective screening of veterinary drugs, ergot alkaloids, plant toxins and other undesirable substances in feed using liquid …
2015
A comprehensive strategy combining a quantitative method for 77 banned veterinary drugs, mycotoxins, ergot alkaloids and plant toxins, and a post-target screening for 425 substances including pesticides and environmental contaminants in feed were developed using a QuEChERS-based extraction and an ultra-high performance liquid chromatography coupled to high-resolution mass spectrometry (UHPLC-HRMS). The quantitative method was validated after previous statistical optimisation of the main parameters governing ionisation, and presented recoveries ranging, in general, from 80 to 120%, with a precision in terms of Relative Standard Deviation (RSD) lower than 20%. The full-scan accurate mass data…
Synthesis and antiproliferative activity of thiazolyl-bis-pyrrolo[2,3-b]pyridines and indolyl-thiazolyl-pyrrolo[2,3-c]pyridines, nortopsentin analogu…
2015
Two new series of nortopsentin analogues, in which the imidazole ring of the natural product was replaced by thiazole and indole units were both substituted by 7-azaindole moieties or one indole unit was replaced by a 6-azaindole portion, were efficiently synthesized. Compounds belonging to both series inhibited the growth of HCT-116 colorectal cancer cells at low micromolar concentrations, whereas they did not affect the viability of normal-like intestinal cells. A compound of the former series induced apoptosis, evident as externalization of plasma membrane phosphatidylserine (PS), and changes of mitochondrial trans-membrane potential, while blocking the cell cycle in G2/M phase. In contr…
Two Decades of Progress in the Asymmetric Intramolecular aza-Michael Reaction.
2021
The asymmetric intramolecular aza-Michael reaction (IMAMR) is a very convenient strategy for the generation of heterocycles bearing nitrogen-substituted stereocenters. Due to the ubiquitous presence of these skeletons in natural products, the IMAMR has found widespread applications in the total synthesis of alkaloids and biologically relevant compounds. The development of asymmetric versions of the IMAMR are quite recent, most of them reported in this century. The fundamental advances in this field involve the use of organocatalysts. Chiral imidazolidinones, diaryl prolinol derivatives, Cinchone-derived primary amines and quaternary ammonium salts, and BINOL-derived phosphoric acids account…