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At least 901 records · Page 50Linked to original sources
PubMed2001

Verbalactone, a new macrocyclic dimer lactone from the roots of Verbascum undulatum with antibacterial activity.

A novel macrocyclic dimer lactone, named verbalactone, was isolated from the roots of Verbascum undulatum and exhibited interesting antibacterial activity. It is the first time that 1,7-dioxacyclododecane is reported as the ring system of a natural product. The structure and the absolute stereochemistry of the new compound were determined by spectral methods and chemical correlation.

Anti-Bacterial Agents↗
PubMed2004

Isolation and structure elucidation of a novel antimalarial macrocyclic polylactone, menisporopsin A, from the fungus Menisporopsis theobromae.

An antimalarial macrocyclic polylactone, menisporopsin A (1), was isolated from a cell extract of the seed fungus Menisporopsis theobromae. The structure of 1 was elucidated on the basis of spectroscopic analysis and chemical transformations, with the absolute configuration established by application of the modified Mosher method and by using chiral HPLC. Menisporopsin A (1) possesses an unprecedented residue, 2,4-dihydroxy-6-(2,4-dihydroxy-n-pentyl)benzoic acid. This compound exhibited antimalarial activity, with an IC(50) value of 4.0 microg mL(-1), and antimycobacterial activity (MIC value of 50 microg mL(-1)).

Animals↗
PubMed2004

Activity of macrocyclic jatrophane diterpenes from Euphorbia kansui in a TrkA fibroblast survival assay.

Three new macrocyclic diterpenes, kansuinins F (1), G (2), and H (3), together with four known jatrophane diterpenes, kansuinins D (4), E (5), and A (6) and 3beta,5alpha,7beta,15beta-tetraacetoxy-9alpha-nicotinoyloxyjatropha-6(17)-11E-dien-14-one, were isolated from the roots of Euphorbia kansui. Compounds 1 and 2 were assigned as 6(17)-en-11,12-epoxy-14-one-type jatrophane diterpenes, and compound 3 as a 6(17)-en-11,14-epoxy-12-one jatrophane diterpene. The structures of compounds 1-3 and the relative configurations of compounds 4 and 5 were determined by spectral data analysis. Kansuinin E (5) exhibited a specific survival effect on fibroblasts that expressed TrkA, a high-affinity receptor for nerve growth factor.

Diterpenes↗
PubMedDate not supplied

Macrocyclic pyrrolizidine alkaloids from Senecio anonymus. Separation of a complex alkaloid extract using droplet counter-current chromatography.

Ten 12-membered macrocyclic pyrrolizidine alkaloids, all of them esters of the necines, retronecine or otonecine, have been isolated from Senecio anonymus. The separation, carried out by droplet counter-current chromatography, afforded senecionine [1], integerrimine [2], retrorsine [3], senkirkine [5], neosenkirkine [6], otosenine [10], hydroxysenkirkine [7], and a new alkaloid given the trivial name anonamine [9]. Traces of usaramine [4] and another new alkaloid, hydroxyneosenkirkine [8], were detected by 1H nmr. In addition, the previously unreported 3a beta-hydroxy-4-ethoxy-2,6-perhydroindoledione [11] was isolated. X-ray structures were obtained for neosenkirkine [6], hydroxysenkirkine [7], anonamine [9], and [11]. 1H-13C heteronuclear shift correlated nmr (HETCOR) provided unambiguous chemical shift assignments for 13C-nmr data. Antitumor activity was assayed using the A204-rhabdomyosarcoma cell line in soft agarose.

Antineoplastic Agents, Phytogenic↗
PubMedDate not supplied

Biological activity of novel macrocyclic alkaloids (budmunchiamines) from Albizia amara detected on the basis of interaction with DNA.

Extracts derived from Albizia amara were found to demonstrate activity in a recently developed hplc system designed to detect compounds capable of interacting with DNA. Further investigation led to the procurement of four sets of alkaloid isolates X1-X4 that were found to be macrocyclic pithecolobine alkaloids. All four isolates interacted with calf thymus DNA and were generally cytotoxic with a battery of cultured mammalian cells. As determined with Salmonella typhimurium strain TM677, isolates X1 and X3 were bactericidal, but not mutagenic. Isolate X1 was found to inhibit the catalytic activity of DNA polymerase, RNA polymerase, and HIV-1 reverse transcriptase. With DNA polymerase, the reaction was shown to be inhibited in a manner that was competitive with respect to DNA. In addition, isolate X1 inhibited each of the following: platelet aggregation, human lymphocyte transformation, phorbol-ester-induced chemiluminescence with human granulocytes, and cyclooxygenase activity. Detection of these alkaloids on the basis of their interaction with DNA exemplifies the validity of this approach.

Alkaloids↗
PubMed1996

New macrocyclic spermine (budmunchiamine) alkaloids from Albizia gummifera: with some observations on the structure--activity relationships of the budmunchiamines.

The CH2Cl2 extract of the stem bark of Albizia gummifera yielded four macrocyclic spermine alkaloids (budmunchiamines), three of them being new analogues. On the basis of spectral analysis and comparison with related compounds they were identified as budmunchiamine G (1) and the new analogues budmunchiamine K (2), 6'xi-hydroxybudmunchiamine K (3), and 9-normethylbudmunchiamine K (4). The four isolated alkaloids and other related budmunchiamines isolated from Albizia schimperana were all active against two Gram-positive and two Gram-negative bacteria at MIC levels below 80 micrograms mL(-1), and showed toxicity to brine shrimp larvae (with LC50 values below 100 micrograms mL(-1)). The negative impact of side chain hydroxylation and N-demethylation on both measures of biological activity was shown to be considerable.

Alkaloids↗
PubMed1998

Macrocyclic diterpenoids from Euphorbia semiperfoliata.

In addition to known compounds, the aerial parts of E. semiperfoliata afforded an abietanolide (3), 13 jatrophane polyesters (4-9, 12, 14-19), two 4-deoxyphorbol diesters (23, 24), and a pair of epimeric diterpenes (21, 22) with a novel carbon skeleton, which was named euphoperfoliane. Structures were determined by spectroscopic analysis, and the main conformational features of jatropha-6(17),11-dienes are discussed in detail. The obtained isolation yield of several jatrophanes was unprecedented within the spurges (Euphorbia spp.), making E. semiperfoliata a unique source of macrocyclic diterpenoids.

Carbohydrate Sequence↗
PubMed1999

Longithorols C-E. Three new macrocyclic sesquiterpene hydroquinone metabolites from the australian ascidian, aplidium longithorax

Chemical investigation of a Great Barrier Reef ascidian, Aplidium longithorax has resulted in the isolation of two new para-substituted cyclofarnesylated hydroquinone compounds, longithorols C (1) and D (2), and a novel macrocyclic chromenol, longithorol E (3). Longithorol C (1) had its absolute stereochemistry determined by the advanced Mosher method and all compounds had their structures determined by interpretation of spectroscopic data.

Journal Article↗
PubMed2000

New circulin macrocyclic polypeptides from Chassalia parvifolia.

Four new macrocyclic polypeptides were isolated and identified from an extract of the tropical tree Chassalia parvifolia. Circulins C-F are 29-30 amino acid cyclic peptides in which the entire primary amino acid chain is covalently cyclized via peptide bonds. Their structures were deduced from a combination of FABMS analyses, N-terminal Edman degradation, endoproteinase digestion, and amino acid analyses. All the peptides share a high degree of sequence homology and contain six cysteine residues forming three intramolecular disulfide bridges. Circulins C-F inhibited the cytopathic effects of in vitro HIV-1 infection with EC(50) values of 50-275 nM.

Alkylation↗
PubMed2000

A new approach to macrocyclization via alkene formation in catalytic diazo decomposition. Synthesis of patulolides A and B.

[reaction: see text] Effective synthetic uses of bisdiazocarbonyl compounds for the selective construction of diverse macrocycles, including the synthesis of patulolides A and B, by catalytic "carbene dimer" formation are reported. Control of stereochemistry and efficient methods for product isomerization or kinetic isomer differentiation have been achieved.

Alkenes↗
PubMed2000

Stereoselectivity of macrocyclic ring-closing olefin metathesis.

[reaction: see text] Macrocyclic ring-closing olefin metathesis using ruthenium catalyst 3 was performed to produce a 14-membered lactone. The E/Z ratio of lactone was high regardless of the R group (auxiliary) or the initial alkene stereochemistry. A kinetic study demonstrates that the high E/Z ratio is due to secondary metathesis reactions that isomerize the product to the thermodynamic E/Z ratio.

Alkenes↗
PubMed2000

Synthesis of the ring system of phomactin D using a Suzuki macrocyclization.

[reaction: see text]The ring system of phomactin D was synthesized in racemic form in an efficient manner from 2,3-dimethylcyclohexanone. Notable transformations include (1) an alkylation of the enolate of a vinylogous thiolester to install a quaternary stereocenter, (2) a conjugate addition of cyanide to an alpha,beta-unsaturated aldehyde, (3) the formation of a Weinreb amide directly from a cyanohydrin, and (4) an intramolecular Pd-mediated Suzuki coupling of a B-alkyl-9-BBN derivative and a vinyl iodide to form the macrocyclic ring.

Cyclization↗
PubMed2000

Novel synthesis of hybrid calixphyrin macrocycles

The reaction of benzaldehyde with excess pyrrole at room temperature in the absence of solvent affords a mixture of meso-substituted polypyrranes species. After separation by column chromatography, these may be used to prepare a range of calix[4]phyrin macrocycles by condensation with acetone under conditions of acid catalysis.

Journal Article↗
PubMed2000

A novel synthesis of biaryl-containing macrocycles by a domino Miyaura arylboronate formation: intramolecular Suzuki reaction.

[reaction: see text] A novel macrocyclization procedure is developed on the basis of a domino process. Thus, treatment of linear diiodide 11 under defined conditions gave the 15-membered m,m-cyclophane 12 via aryl-aryl bond formation. Two distinct cross-coupling manifolds, Miyaura's arylboronic ester synthesis and intramolecular Suzuki reaction, proceed in an ordered fashion. Concentration is an important factor for the success of this process.

Boron Compounds↗
PubMed2001

Tandem hetero diels-alder reaction: synthesis of oxygenated macrocycles.

[structure: see text]. C2-symmetric, oxygenated macrocycles have been synthesized from simple acyclic precursors in a single step by a tandem hetero Diels-Alder reaction. Thermolysis and Lewis acid catalysis can effect this novel transformation. The tandem reaction product is formed in preference to the intramolecular cycloaddition product, and an explanation for this result is proposed.

Catalysis↗