Search results for "Natural product"
showing 10 items of 163 documents
Ancistrolikokine I and further 5,8'-coupled naphthylisoquinoline alkaloids from the Congolese liana Ancistrocladus likoko and their cytotoxic activit…
2018
Abstract The Congolese liana Ancistrocladus likoko (Ancistrocladaceae) produces naphthylisoquinoline alkaloids that are, chemotaxonomically remarkable, all based on the same coupling type, with the biaryl axis located between C-5 and C-8′. About 20 alkaloids, belonging to the subclass of 5,8′-linked naphthylisoquinolines, have so far been discovered in this plant species. Here, we report on the isolation and structure elucidation of six further such 5,8′-coupled monomeric alkaloids, named ancistrolikokines I (9), C3 (10), F2 (11), J (12), J2 (13), and J3 (14). They were identified in the twigs of A. likoko, along with the two new atropo-diastereomeric dimers michellamines A8 (15a) and B8 (1…
α,β-Dehydroamino acids in naturally occurring peptides
2014
α,β-Dehydroamino acids are naturally occurring non-coded amino acids, found primarily in peptides. The review focuses on the type of α,β-dehydroamino acids, the structure of dehydropeptides, the source of their origin and bioactivity. Dehydropeptides are isolated primarily from bacteria and less often from fungi, marine invertebrates or even higher plants. They reveal mainly antibiotic, antifungal, antitumour, and phytotoxic activity. More than 60 different structures were classified, which often cover broad families of peptides. 37 different structural units containing the α,β-dehydroamino acid residues were shown including various side chains, Z and E isomers, and main modifications: meth…
Acid-induced rearrangement of epoxygermacra-8,12-olides: synthesis and absolute configuration of guaiane and eudesmane derivatives from artemisiifolin
2010
A study on the acid-induced rearrangement of 4,5-epoxy- and 1,10-epoxygermacra-8,12-olides was carried out. From a 4,5-epoxy derivative, guaianes were obtained, whereas 1,10-epoxy derivatives furnished, depending on the stereochemistry of the C-1/C-10 epoxy ring, trans-5β,10α- or trans-5α,10β-eudesmanolides.
Marine Anticancer Agents: An Overview with a Particular Focus on Their Chemical Classes
2020
The marine environment is a rich source of biologically active molecules for the treatment of human diseases, especially cancer. The adaptation to unique environmental conditions led marine organisms to evolve di erent pathways than their terrestrial counterparts, thus producing unique chemicals with a broad diversity and complexity. So far, more than 36,000 compounds have been isolated from marine micro- and macro-organisms including but not limited to fungi, bacteria, microalgae, macroalgae, sponges, corals, mollusks and tunicates, with hundreds of new marine natural products (MNPs) being discovered every year.Marine-based pharmaceuticals have started to impactmodern pharmacology and diff…
Capillary Liquid Chromatography for the Determination of Terpenes in Botanical Dietary Supplements
2021
Dietary supplements of botanical origin are increasingly consumed due to their content of plant constituents with potential benefits on health and wellness. Among those constituents, terpenes are gaining attention because of their diverse biological activities (anti-inflammatory, antibacterial, geroprotective, and others). While most of the existing analytical methods have focused on establishing the terpenic fingerprint of some plants, typically by gas chromatography, methods capable of quantifying representative terpenes in herbal preparations and dietary supplements with combined high sensitivity and precision, simplicity, and high throughput are still necessary. In this study, we have e…
Synthesis of β- and γ-carbolines via ruthenium and rhodium catalysed [2+2+2] cycloadditions of yne-ynamides with methylcyanoformate
2011
A flexible approach towards substituted β- and γ-carbolines based on transition metal catalysed [2+2+2] cycloaddition reactions between functionalised yne-ynamides and methylcyanoformate is described. The versatility of this new reaction sequence is demonstrated by its application in the total synthesis of the marine natural product eudistomin U.
Horizontal Gene Transfer to a Defensive Symbiont with a Reduced Genome in a Multipartite Beetle Microbiome
2020
Associations between microorganisms and an animal, plant, or fungal host can result in increased dependence over time. This process is due partly to the bacterium not needing to produce nutrients that the host provides, leading to loss of genes that it would need to live independently and to a consequent reduction in genome size. It is often thought that genome reduction is aided by genetic isolation—bacteria that live in monocultures in special host organs, or inside host cells, have less access to other bacterial species from which they can obtain genes. Here, we describe exposure of a genome-reduced beetle symbiont to a community of related bacteria with nonreduced genomes. We show that …
Xylochemistry--Making Natural Products Entirely from Wood.
2015
The first total synthesis of the dimeric berberine alkaloid ilicifoline (ilicifoline B) is reported. Its carbon skeleton is constructed from ferulic acid, veratrole, and methanol. The synthesis reported herein employs starting materials solely derived from wood. The natural product is thus constructed entirely from renewable resources. The same strategy is applied to a formal total synthesis of morphinan alkaloids. The use of wood-derived building blocks (xylochemicals) instead of the conventional petrochemicals represents a sustainable alternative to classical synthetic approaches.
Arylpyridines, arylpyrimidines and related compounds as potential modulator agents of the VEGF, hTERT and c-Myc oncogenes.
2019
Twenty-four derivatives structurally related to honokiol have been synthesized and biologically evaluated. IC50 values were determined towards the HT-29, MCF-7 and HEK-293 cell lines. Some of these derivatives exhibited comparable or lower IC50 values than honokiol towards the HT-29 and MCF-7 cell lines or else higher selectivity indexes than the natural product. Twelve selected derivatives were evaluated for their ability to inhibit the expression of the VEGFA, hTERT and c-Myc genes and also to inhibit the production of total c-Myc protein and the secretion of the VEGF protein. One of the most promising compounds, 3-(2,4-dimethoxyphenyl)pyridine, may be a good candidate for further studies…
Natural Product Synthesis on Polymeric Supports—Synthesis and Biological Evaluation of an Indolactam Library
1999
Potent activators of protein kinase C in fibroblasts: This property was determined for several indolactam V analogues (1) with a new cell-based assay system. This tumor-promoting indole alkaloid and analogues thereof can be synthesized efficiently on the solid phase. The key steps of the combinatorial approach are a regioselective amination of the indole ring and an enantioselective enzymatic reaction.