2-Amino-1-methyl-6-phenylimidazo[4,5-b]pyridine (PhIP) is a prominent heterocyclic aromatic amine (HAA) found in meat and fish cooked at moderate to high temperature. It is considered as a potent dietary factor promoting colon carcinogenesis. However, the role of intestinal cells in PhIP bioacti...
The absolute configuration of lyngbyatoxin A (teleocidin A-1) and teleocidin A-2, potent tumor promoters on mouse skin, has been determined by chemical degradation including ozonolysis.
The synthesis of a homochiral nitrile oxide from a baker's yeast reduction product and its use in the preparation of a lyngbyatoxin A intermediate are detailed.
Teleocidin isolated from Streptomyces mediocidicus, its catalytically hydrogenated compound dihydroteleocidin B, and lyngbyatoxin A isolated from marine blue-green alga Lyngbya majuscula as well as its hydrogenated product, tetrahydrolyngbyatoxin A were tested for their ability to induce differe...
Effects of Lyngbyatoxin A from the blue-green alga Lyngbya majuscula on rabbit aorta contractions. Toxicon29, 1009–1017, 1991.—The contractile effects of the tumor promoter and protein kinase C activator, lyngbyatoxin A, were studied in rabbit aorta rings. Contractions to 1 μM lyngbyatoxin A ...
An eleven-step synthesis of tumor promoters, lyngbyatoxin A (=teleocidin A-1) (1) and teleocidin A-2 (2) was achieved from 1-tosylpyrrole (4) using a novel reaction forming 7-alkyl-4-aminoindoles (11).
Lyngbyatoxin A is produced by marine algae, and causes local cutaneous toxicity in swimmers. The purpose of this research was (1) to determine the partition coefficient of lyngbyatoxin A in octanol/water and (2) to use methods in vitro to measure the penetration and distribution of lyngbyatoxin ...
This paper deals with an approach to the enantioselective total synthesis of Lyngbyatoxin A, with focus on the stereocontrolled introduction of the quaternary stereogenic centre. The key step in the synthesis involves an enantiospecific Lewis-acid mediated rearrangement of chiral vinyl epoxides ...
Lyngbyatoxin A, isolated from a marine blue-green alga, and dihydroteleocidin B, a hydrogenated derivative of teleocidin, induce ornithine decarboxylase in mouse skin. In addition, dihydroteleocidin B was recently shown to be a potent tumor promoter in mouse skin. The present studies demonstrate...
Histopathological changes induced in mice by lyngbyatoxin A were studied in connection with the occurrence of the toxin in marine turtles implicated in human intoxication.Lyngbyatoxin A showed an i.p. lethal dose 250 μg/kg in immature mice (3-week old) and most severely damaged capillaries of v...
Fast Detection Strategy for Cyanobacterial blooms and associated Cyanotoxins (FDSCC) is a multidisciplinary strategy that allows early detection, in 24 man-hours, of cyanobacteria and related cyanotoxins in water and bivalve samples. This approach combines the advantages of remote/proximal sensi...
A mild, efficient, ligand free and environmentally benign approach towards the construction of sp2 C-sp3 N bond has been developed via copper catalysed Ullmann type of coupling between 4-chlorocoumarin with N-terminus unprotected amino acids in microwave-aqua conditions, yielding a series of N-c...
The consequences of improper regulation of collagen turnover include diseases such as tumor cell metastasis and arthritis. Several fluorogenic triple-helical peptide (fTHP) substrates have been constructed presently to examine collagenolytic behavior. These substrates incorporate l- or d-2-amino...
A high enantiomeric excess (>99.5%) synthesis of l-2-amino-3-(7-methoxy-4-coumaryl) propionic acid (l-Amp) is described. The two step synthesis route of this non-proteinogenic amino acid includes an oxazinone derivative as glycine enolate, which is alkylated with the fluorogenic group.
A unique dipeptide was isolated from bovine brain using five steps of ion-exchange chromatography. Its acid hydrolysate contained equimolar amounts of β-alanine and hypusine. The structure of the peptide was elucidated as α-(β-alanyl)hypusine using dansylation technique. About 1 μmol of the ...
The in vitro stability and animal pharmacokinetics of 99mTc bound to Sandoz and C110 IgG antibodies via a modified MAG3 has been compared with the hydrazino nicotinamide (SHNH) moiety as standard. For both antibodies, the stabilities of the label to challenge at up to 50:1 cysteine: IgG molar ra...
Non-small cell lung cancer accounts for 80–85% of all lung cancer cases and is the leading cause of cancer death indicating inefficient current treatment. Acridine derivatives interact with DNA and inhibit topoisomerase leading to cell growth arrest or cell death. The aim of this study was to e...
Bovine seminal ribonuclease (BS-RNase) is a 27 kDa homodimeric enzyme and a member of the pancreatic RNase A superfamily. It is the only RNase with a quaternary structure and it is a mixture of two dimeric forms. In the most abundant form the active site is formed by the swapping of the N-termin...
3D domain swapping is the process by which two or more protein molecules exchange part of their structure to form intertwined dimers or higher oligomers. Bovine pancreatic ribonuclease (RNase A) is able to swap the N-terminal α-helix (residues 1–13) and/or the C-terminal β-strand (residues 11...
Structural roles of loop regions are frequently overlooked in proteins. Nevertheless, they may be key players in the definition of protein topology and in the self-assembly processes occurring through domain swapping. We here investigate the effects on structure and stability of replacing the lo...
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