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1.
Bioorg Med Chem ; 23(13): 3712-21, 2015 Jul 01.
Article in English | MEDLINE | ID: mdl-25937235

ABSTRACT

A screening program aimed at discovering novel anticancer agents based on natural products led to the selection of koningic acid (KA), known as a potent inhibitor of glycolysis. A method was set up to produce this fungal sesquiterpene lactone in large quantities by fermentation, thus allowing (i) an extensive analysis of its anticancer potential in vitro and in vivo and (ii) the semi-synthesis of analogues to delineate structure-activity relationships. KA was characterized as a potent, but non-selective cytotoxic agent, active under both normoxic and hypoxic conditions and inactive in the A549 lung cancer xenograft model. According to our SAR, the acidic group could be replaced to keep bioactivity but an intact epoxide is essential.


Subject(s)
Antineoplastic Agents/chemical synthesis , Lung Neoplasms/drug therapy , Animals , Antineoplastic Agents/isolation & purification , Antineoplastic Agents/pharmacokinetics , Antineoplastic Agents/pharmacology , Cell Hypoxia , Cell Line, Tumor , Fermentation , Glycolysis/drug effects , Humans , Inhibitory Concentration 50 , Lung Neoplasms/metabolism , Lung Neoplasms/pathology , Mice , Mice, Nude , Sesquiterpenes/chemical synthesis , Sesquiterpenes/isolation & purification , Sesquiterpenes/pharmacokinetics , Sesquiterpenes/pharmacology , Structure-Activity Relationship , Trichoderma/chemistry , Trichoderma/metabolism , Tumor Burden/drug effects , Xenograft Model Antitumor Assays
3.
Biochemistry ; 45(27): 8402-10, 2006 Jul 11.
Article in English | MEDLINE | ID: mdl-16819839

ABSTRACT

The human topoisomerase I-mediated DNA relaxation reaction was studied following modification of the enzyme at the active site tyrosine (position 723). A series of unnatural tyrosine analogues was incorporated into the active site of human topoisomerase I by utilizing misacylated suppressor tRNAs in an in vitro protein synthesizing system. The relaxation activities of the modified human topoisomerase I analogues having varied steric, electronic, and stereochemical features were all greatly diminished relative to that of the wild type. It was found that modifications involving replacement of the nucleophilic tyrosine OH group with NH2, SH, or I groups eliminated DNA relaxation activity, as did changing the orientation of the nucleophilic tyrosine OH group. Only tyrosine analogues having the phenolic OH group in the normal position with respect to the protein backbone were active; the relative activities could be rationalized in chemical terms on the basis of the H-bonding and the electronic effects of the substituents attached to the meta position of the aromatic ring. In addition, the poisoning of one of the modified human topoisomerase I analogues, as part of covalent binary complexes with DNA, by CPT and 20-thio CPT was evaluated.


Subject(s)
DNA Topoisomerases, Type I/chemistry , Topoisomerase I Inhibitors , Tyrosine/analogs & derivatives , Tyrosine/chemistry , Binding Sites , Camptothecin/pharmacology , Enzyme Inhibitors/pharmacology , Humans
4.
Org Lett ; 7(5): 835-7, 2005 Mar 03.
Article in English | MEDLINE | ID: mdl-15727453

ABSTRACT

14-Azacamptothecin, a potent, water-soluble analogue of the antitumor agent camptothecin, has been prepared by a convergent synthesis. The key condensation of the AB and DE rings with concomitant formation of ring C of 14-aza CPT was carried out in two stages, the latter of which involved a radical cyclization strategy. [structure: see text]


Subject(s)
Antineoplastic Agents/chemical synthesis , Camptothecin/analogs & derivatives , Topoisomerase I Inhibitors , Antineoplastic Agents/pharmacology , Camptothecin/chemical synthesis , Camptothecin/pharmacology , Cyclization , Humans , Molecular Structure , Water/chemistry
5.
Bioorg Med Chem ; 13(4): 1381-6, 2005 Feb 15.
Article in English | MEDLINE | ID: mdl-15670945

ABSTRACT

A recent X-ray crystallographic analysis of the binding of a water soluble camptothecin analogue to the human topoisomerase I-DNA covalent binary complex has suggested the existence of some novel features in the way that camptothecin is bound to the binary complex. Four additional models based on chemical and biochemical data have also been proposed. Presently we describe S-containing analogues of camptothecin prepared on the basis of these models, and report their ability to form stable ternary complexes with human topoisomerase I, and to mediate cytotoxicity at the locus of topoisomerase I. The results indicate that replacement of the 20-OH group of CPT with a SH functionality results in diminution of the potency of CPT as a topoisomerase I poison, while replacement of the O atoms at positions 20 and 21 with S atoms results in essentially complete loss of topoisomerase I inhibitory activity.


Subject(s)
Camptothecin/metabolism , DNA Topoisomerases, Type I/metabolism , Enzyme Inhibitors/metabolism , Oxygen/chemistry , Autoradiography , Crystallography, X-Ray , Humans , Magnetic Resonance Spectroscopy , Spectrometry, Mass, Electrospray Ionization
6.
J Am Chem Soc ; 127(3): 838-9, 2005 Jan 26.
Article in English | MEDLINE | ID: mdl-15656613

ABSTRACT

On the basis of an analysis of luotonin A and its D-ring deaza analogue as topoisomerase I poisons and topoisomerase I-dependent cytotoxic agents, a novel analogue of the structurally related antitumor antibiotic camptothecin (CPT) was prepared. 14-Azacamptothecin was found to have much greater aqueous solubility than CPT, to inhibit topoisomerase I-mediated DNA relaxation more efficiently than CPT, and to stabilize the covalent binary complex to almost the same extent. 14-Aza CPT was found to be slightly less active than CPT in mediating cytotoxicity toward yeast expressing human topoisomerase I, possibly as a consequence of its greater off-rate from the CPT-topoisomerase I-DNA ternary complex.


Subject(s)
Camptothecin/analogs & derivatives , Camptothecin/chemistry , Camptothecin/pharmacology , Enzyme Inhibitors/chemistry , Enzyme Inhibitors/pharmacology , Topoisomerase I Inhibitors , Humans , Kinetics , Pyrroles/chemistry , Pyrroles/pharmacology , Quinones/chemistry , Quinones/pharmacology , Solubility , Water/chemistry
7.
Bioorg Med Chem ; 12(7): 1585-604, 2004 Apr 01.
Article in English | MEDLINE | ID: mdl-15028252

ABSTRACT

This review provides a detailed discussion of recent advances in the medicinal chemistry of camptothecin, a potent antitumor antibiotic. Two camptothecin analogues are presently approved for use in the clinic as antitumor agents and several others are in clinical trials. Camptothecin possesses a novel mechanism of action involving the inhibition of DNA relaxation by DNA topoisomerase I, and more specifically the stabilization of a covalent binary complex formed between topoisomerase I and DNA. This review summarizes the current status of studies of the mechanism of action of camptothecin, including topoisomerase I inhibition and additional cellular responses. Modern synthetic approaches to camptothecin and several of the semi-synthetic methods are also discussed. Finally, a systematic evaluation of novel and important analogues of camptothecin and their contribution to the current structure-activity profile are considered.


Subject(s)
Antineoplastic Agents , Camptothecin , Animals , Antineoplastic Agents/chemical synthesis , Antineoplastic Agents/pharmacology , Camptothecin/analogs & derivatives , Camptothecin/chemical synthesis , Camptothecin/pharmacology , Cell Division/drug effects , Cell Line, Tumor , DNA/chemistry , DNA/drug effects , DNA/metabolism , DNA Topoisomerases, Type I/metabolism , Humans , Molecular Structure , Structure-Activity Relationship , Topoisomerase I Inhibitors
8.
Org Lett ; 6(3): 321-4, 2004 Feb 05.
Article in English | MEDLINE | ID: mdl-14748583

ABSTRACT

[structure: see text] In an effort to improve the water solubility of camptothecin, four 20-O-phosphate and phosphonate analogues have been prepared. These analogues are freely water soluble, stable at physiological pH, and stabilize the human topoisomerase I-DNA covalent binary complex with the same sequence selectivity as camptothecin itself. All four compounds inhibited the growth of yeast expressing human topoisomerase I in an enzyme-dependent fashion.


Subject(s)
Camptothecin/analogs & derivatives , Camptothecin/pharmacology , Topoisomerase I Inhibitors , Camptothecin/chemistry , DNA/chemistry , DNA/metabolism , DNA Topoisomerases, Type I/metabolism , Humans , Hydrogen-Ion Concentration , Molecular Structure , Saccharomyces cerevisiae , Solubility
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