ABSTRACT
BACKGROUND: The putative pharmacophore of a naturally cytotoxic limonoid haperforin B1, E-5-iodomethylene-6,6-dimethyl-5,6-dihydropyran-2-one (IDDP) was synthesized and its biological activity was investigated. MATERIALS AND METHODS: The cytotoxicity of IDDP was assessed using human breast, lung, colorectal and epidermal carcinomas, chronic myeloid leukemia and glioblastoma cell lines. Cell cycle analysis was performed by flow cytometry. The induction of apoptosis was studied by a caspase assay and by annexin V-propidium iodide double staining. The organization of actin and tubulin microfilaments was analysed by immunocytochemical labeling. RESULTS: IDDP was shown to inhibit the growth of a panel of human cancer cell lines independently of their p53 status with IC(50) ranging from 0.07 to 0.50 microM. All the treated cells were arrested in the G(2)/M phase in a time-dependent manner before cell death occurred through an apoptotic pathway. Immunocytochemical studies revealed that the normal organization of microfilaments and microtubules was disrupted in IDDP exposed cells. CONCLUSION: IDDP can be considered as a promising anticancer agent.
Subject(s)
Antineoplastic Agents/pharmacology , Apoptosis/drug effects , Cell Division/drug effects , G2 Phase/drug effects , Neoplasms/drug therapy , Pyrones/pharmacology , Antineoplastic Agents/chemical synthesis , Antineoplastic Agents/chemistry , Humans , Molecular Structure , Neoplasms/metabolism , Neoplasms/pathology , Pyrones/chemical synthesis , Pyrones/chemistry , Tumor Cells, CulturedABSTRACT
A new highly selective inhibitor of acetylcholinesterase (AChE) was discovered by high-throughput screening. Compound 1 was synthesized from a natural product, the N-3-isobutyrylcycloxobuxidine-F 2. A new extraction protocol of this compound is described. The hemisynthesis and optimization of 1 are reported. The analogs of 1 were tested in vitro for the inhibition of both cholinesterases (AChE and BuChE). These compounds selectively inhibited AChE. Extensive molecular docking studies were performed with 2 and AChE employing Discover Biosym software to rationalize the binding interaction. The results suggested that ligand 2 binds simultaneously to both catalytic and peripheral sites of AChE.
Subject(s)
Acetylcholinesterase/chemistry , Benzoxazines/chemical synthesis , Cholinesterase Inhibitors/chemical synthesis , Heterocyclic Compounds, 4 or More Rings/chemical synthesis , Models, Molecular , Triterpenes/chemical synthesis , Animals , Benzoxazines/chemistry , Binding Sites , Butyrylcholinesterase/chemistry , Catalytic Domain , Cattle , Cholinesterase Inhibitors/chemistry , Crystallography, X-Ray , Electrophorus , Heterocyclic Compounds, 4 or More Rings/chemistry , Humans , Molecular Structure , Species Specificity , Structure-Activity Relationship , Torpedo , Triterpenes/chemistry , Triterpenes/isolation & purificationABSTRACT
Allosteric potentiation of acetylcholine nicotinic receptors is considered to be one of the most promising approaches for the treatment of Alzheimer's disease. However, the exact localization of the allosteric binding site and the potentiation mechanism at the molecular level are presently unknown. We have performed the "blind docking" of three known allosteric modulators (galanthamine, codeine and eserine) with the Acetylcholine Binding Protein and models of human alpha7, alpha3beta4 and alpha4beta2 nicotinic receptors, created by homology modeling. Three putative binding sites were identified in the channel pore, each one showing different affinities for the ligands. One of these sites is localized opposite to the agonist binding site and is probably implicated in the potentiation process. On the basis of these results, a possible mechanism for nicotinic acetylcholine receptor (nAChRs) activation is proposed. The present findings may represent an important advance for understanding the allosteric modulation mechanism of nAChRs. [Figure: see text].
Subject(s)
Receptors, Nicotinic/chemistry , Receptors, Nicotinic/metabolism , Allosteric Site , Amino Acid Sequence , Conserved Sequence , Humans , Models, Molecular , Molecular Sequence Data , Protein Structure, Quaternary , Protein Subunits/chemistry , Protein Subunits/metabolism , Sequence AlignmentABSTRACT
Open D-ring galanthamine analogues were prepared using ring-opening reactions of the quaternarized urethane or oxazolidine functions and were evaluated for their acetylcholinesterase (AChE) and butyrylcholinesterase (BChE) inhibition potency.