ABSTRACT
Cyclin dependent kinases (CDKs) along with the complementary cyclins form key regulatory checkpoint controls on the cell cycle. Flavopiridol is a synthetic flavone that shows potent and selective cyclin-dependent kinase inhibitory activity. In this paper, we report modifications of the 3-hydroxy-1-methylpiperidinyl (D ring) of flavopiridol and their effect on CDK inhibitory activity.
Subject(s)
Chromones/chemistry , Chromones/pharmacology , Enzyme Inhibitors/chemistry , Enzyme Inhibitors/pharmacology , Flavonoids/chemistry , Flavonoids/pharmacology , Piperidines/chemistry , Piperidines/pharmacology , Pyridines/chemistry , Pyridines/pharmacology , Structure-Activity Relationship , Antineoplastic Agents/chemistry , Antineoplastic Agents/pharmacology , Chromones/chemical synthesis , Cyclin-Dependent Kinases/antagonists & inhibitors , Drug Screening Assays, Antitumor , Enzyme Inhibitors/metabolism , Flavonoids/metabolism , Piperidines/metabolism , Pyridines/chemical synthesis , Tumor Cells, CulturedABSTRACT
A series of guanylhydrazone, amidine, and hydrazone derivatives of 2-phenylimidazo[1,2-a]pyridine have been prepared and evaluated for macrofilarial activity against Acanthocheilonema viteae and Brugia pahangi in jirds. Compounds with 4',6-bis-substitution by cyclic guanylhydrazone groups show activity. 4',6-Bis-amidines show some activity but are more toxic; 4'- or 6-monosubstituted compounds are inactive. 2,6-Bis-substituted compounds lacking the phenyl ring are inactive. 4',6-Bis-substituted compounds having additional double bonds inserted between the heterocyclic ring and the phenyl ring or between the substituent and the ring system show reduced activity.
Subject(s)
Amidines/chemical synthesis , Filaricides/chemical synthesis , Hydrazones/chemical synthesis , Pyridines/chemical synthesis , Amidines/chemistry , Amidines/pharmacology , Animals , Brugia pahangi , Dipetalonema , Filariasis/drug therapy , Filaricides/chemistry , Filaricides/pharmacology , Gerbillinae , Hydrazones/chemistry , Hydrazones/pharmacology , Male , Pyridines/chemistry , Pyridines/pharmacology , Structure-Activity RelationshipABSTRACT
Levuglandin (LG) E2 is rapidly sequestered by covalent binding with proteins. The reaction of LGE2 with a protein in neutral aqueous solution exhibits two phases. A metastable adduct rapidly accumulates initially. In the second phase, a protein-bound pyrrole is generated. Pyrrole formation and stability were monitored with an immunoassay using antibodies that were raised against a stable isostere. That LG-derived pyrroles are the major products (> 76%) of the LGE2-protein reaction is suggested by the level of antibody binding found for LG-protein adducts compared with that found for a pyrrole derived from LGE2 and 6-amino-1-hexanol. Because the initial metastable LG-protein adduct is a reactive electrophile, it can be trapped with amines, such as glycine, to give stable ternary adducts that do not cross-react with the antibodies. Although highly alkylated pyrroles are chemically sensitive compounds, the protein-bound LG-derived pyrrole appears to be stable in aqueous solution at pH 7.4. Thus, it shows no decrease in immunoreactivity over several weeks. This discovery leads to the expectation that such pyrroles will accumulate in vivo, especially in proteins that do not turn over rapidly. Thus, the LG-derived protein-bound pyrrole may be a useful marker of oxidative lipid damage, and an immunoassay for this post-translational protein modification can be exploited as a mild, sensitive method for detecting and quantifying the generation of LGs in chronic inflammatory states.
Subject(s)
Prostaglandins E/metabolism , Pyrroles/metabolism , Animals , Drug Stability , Enzyme-Linked Immunosorbent Assay , Hemocyanins/immunology , Hemocyanins/metabolism , Prostaglandins E/immunology , Protein Binding , Pyrroles/chemistry , RabbitsABSTRACT
Levuglandin E2 (LGE2), a rearrangement product derived from the prostaglandin endoperoxide, PGH2, causes repair-resistant DNA-protein cross-links and cell death (LD50 = 230 nM) in V79 Chinese hamster lung fibroblasts. The half-life for sequestration of LGE2 by covalent binding to cellular nucleophiles is at least an hour for 10 microM LG. This suggests that the in vivo production and distribution of free LGs should be measurable on this time scale. Following removal of the LGE2 and the return of the cultures to normal growth medium, additional DNA-protein cross-links continued to form over the ensuing 6-24 h. The results suggest that LG adducts to DNA or protein are not repaired, but react further at sites on protein or DNA in close proximity to the initial adducts, forming cross-links in a slow phase of the process.
Subject(s)
Cell Nucleus/metabolism , Cross-Linking Reagents/pharmacology , DNA/metabolism , Nuclear Proteins/metabolism , Prostaglandins E/pharmacology , Animals , Cell Line , Cell Nucleus/drug effects , Cell Survival/drug effects , Clone Cells , Dose-Response Relationship, Drug , Hydrogen-Ion Concentration , Kinetics , LungABSTRACT
Prevention by glycine of protein crosslinking which accompanies binding of levuglandin E2 (LGE2) is shown to involve binding of glycine with the protein-LGE2 adduct. With ovalbumin, the LGE2 adduct initially binds nearly 2 equivalents of glycine, but the capacity to bind glycine decreases with time reflecting a competition, inter alia, with crosslinking.
Subject(s)
Cross-Linking Reagents , Glycine/metabolism , Ovalbumin/metabolism , Electrophoresis, Polyacrylamide Gel , Kinetics , Prostaglandins E/metabolismABSTRACT
Levuglandin E2 (LGE2) is a gamma-keto aldehyde produced by rearrangement of the prostaglandin endoperoxide PGH2 under the aqueous conditions of its biosynthesis. We show that exogenous LGE2 enters cells and efficiently inhibits the first synchronous cell division of fertilized sea urchin eggs. We attribute this inhibition to covalent modification of tubulin and thereby to inhibition of microtubule assembly.
