ABSTRACT
Two consecutive prefractionated fractions of the Australian marine sponge extract, Pipestela candelabra, were identified to be selectively active on the human prostate cancer cells (PC3) compared to the human neonatal foreskin fibroblast non-cancer cells (NFF). Twelve secondary metabolites were isolated in which four compounds are new small peptides. Their structures were characterized by spectroscopic and chemical analysis. These compounds inhibited selectively the growth of prostate cancer cells with IC50 values in the picomolar to sub-micromolar range. Structure-activity relationship of these compounds is discussed.
Subject(s)
Antineoplastic Agents/pharmacology , Peptides/pharmacology , Porifera/metabolism , Prostatic Neoplasms/drug therapy , Animals , Antineoplastic Agents/chemistry , Antineoplastic Agents/isolation & purification , Australia , Cell Line, Tumor , Fibroblasts/drug effects , Fibroblasts/metabolism , Humans , Infant, Newborn , Inhibitory Concentration 50 , Male , Penis/cytology , Peptides/chemistry , Peptides/isolation & purification , Prostatic Neoplasms/pathology , Spectrum Analysis , Structure-Activity RelationshipABSTRACT
Inhibition of isoprenylcysteine Carboxylmethyltransferase (ICMT) is of particular interest as a potential target for the development of cancer chemotherapeutic agents. Screening for inhibitors of ICMT utilises a scintillation proximity assay (SPA) in which Biotin-S-Farnesyl-L-Cysteine (BFC) acts as a surrogate substrate. A solid-phase synthesis protocol for the preparation of BFC using 2-chlorotrityl chloride resin as a solid support has been developed to provide sufficient supply of BFC for high throughput screening (HTS) and subsequent chemistry campaigns to target inhibitors of ICMT. The BFC prepared by this method can be produced quickly on large scale and is stable when stored at -20 °C as a solid, in solution, or on the resin.
Subject(s)
Biotin/chemistry , Cysteine/chemistry , Protein Methyltransferases/metabolism , Cysteine/chemical synthesis , High-Throughput Screening Assays , Kinetics , Protein Methyltransferases/chemistry , Solid-Phase Synthesis Techniques , Substrate Specificity , Trityl Compounds/chemistryABSTRACT
Mass-directed isolation of the CH(2)Cl(2)/MeOH extract from the leaves of Cryptocarya obovata resulted in the purification of a new trypanocidal alpha-pyrone, 7',8'-dihydroobolactone (1). The chemical structure of 1 was determined by 1D/2D NMR, MS and CD data analysis. 7',8'-Dihydroobolactone was shown to inhibit Trypanosoma brucei brucei with an IC(50) of 2.8 microM.
Subject(s)
Lactones/pharmacology , Pyrones/pharmacology , Trypanocidal Agents/pharmacology , Cell Line, Tumor , Humans , Lactones/chemistry , Pyrones/chemistry , Trypanocidal Agents/isolation & purificationABSTRACT
CC chemokine receptor 5 (CCR5) is a pro-inflammatory chemokine receptor that is expressed on cells of the immune system, and specializes in cell migration in response to inflammation and tissue damage. Due to its key role in cell communication and migration, this receptor is involved in various inflammatory and autoimmune diseases, in addition to HIV infection. Met-RANTES is a modified CCR5 ligand that has previously been shown to antagonize CCR5 activation and function in response to its natural ligands in vitro. In vivo, Met-RANTES is able to reduce inflammation in models of induced inflammatory and autoimmune diseases. However, due to the fact that Met-RANTES is also capable of partial agonist activity regarding receptor signaling and internalization, it is clear that Met-RANTES does not function as a conventional receptor antagonist. To further elucidate the effect of Met-RANTES on CCR5, receptor trafficking was investigated in a CHO-CCR5-GFP cell line using the Opera confocal plate reader. The internalization response of CCR5 was quantified, and showed that Met-RANTES internalized CCR5 in a slower, less potent manner than the agonists CCL3 and CCL5. Fluorescent organelle labeling and live cell imaging showed CCL3 and CCL5 caused CCR5 to traffic through sorting endosomes, recycling endosomes and the Golgi apparatus. In contrast, Met-RANTES caused CCR5 to traffic through sorting endosomes and the Golgi apparatus in a manner that was independent of recycling endosomes. As receptor trafficking impacts on cell surface expression and the ability of the receptor to respond to more ligand, this information may indicate an alternative regulation of CCR5 by Met-RANTES that allows the modified ligand to reduce inflammation through stimulation of a pro-inflammatory receptor.
Subject(s)
CCR5 Receptor Antagonists , Chemokine CCL5/pharmacology , Receptors, CCR5/metabolism , Animals , CHO Cells , Ceramides/metabolism , Chemokine CCL3/pharmacology , Cricetinae , Cricetulus , Endosomes/drug effects , Endosomes/metabolism , Golgi Apparatus/metabolism , Humans , Ligands , Protein Transport , Receptors, CCR5/agonists , Receptors, CCR5/geneticsABSTRACT
Bioassay-guided fractionation of the organic extract from the marine sponge Acanthella costata resulted in the isolation of the known natural product, (-)-dibromophakellin (1). Using a fluorescence imaging plate reader (FLIPR) based assay, compound 1 was identified as displaying agonist activity against the alpha(2B) adrenoceptor, with an EC(50) of 4.2muM. Debromination and Suzuki-Miyaura coupling reactions were undertaken in order to provide structure activity data about the pyrrole ring of this marine metabolite. These synthetic studies generated the known natural product analogues, (-)-phakellin (2), and (-)-monobromophakellin (3), along with the new synthetic derivatives (-)-4-bromo-5-phenylphakellin (5) and (-)-4,5-diphenylphakellin (6). Substitution of the C-5 Br of 1 with H (2 and 3) or phenyl (5 and 6) resulted in loss of activity indicating that Br at C-5 is required for agonist activity.
Subject(s)
Adrenergic alpha-Agonists/isolation & purification , Heterocyclic Compounds, 4 or More Rings/pharmacology , Porifera/chemistry , Adrenergic alpha-Agonists/pharmacology , Animals , Australia , Cell Line , Humans , Spectrophotometry, Ultraviolet , Structure-Activity RelationshipABSTRACT
High-throughput screening of a plant and marine invertebrate extract library to find natural products that inhibit the malarial parasite enzyme target hemoglobinase II led to the isolation of two new active prenylated chalcones, bipinnatones A (1) and B (2), from aerial parts of the Queensland shrub Boronia bipinnata. Their structures were assigned from interpretation of 2D NMR and high-resolution ESIMS data. Compounds 1 and 2 inhibited hemoglobinase II with IC 50 values of 64 and 52 microM, respectively.
Subject(s)
Chalcones/isolation & purification , Enzyme Inhibitors/isolation & purification , Plasmodium falciparum/enzymology , Rutaceae/chemistry , Animals , Chalcones/chemistry , Chalcones/pharmacology , Enzyme Inhibitors/chemistry , Enzyme Inhibitors/pharmacology , Molecular Structure , Prenylation , Spectrum AnalysisABSTRACT
Isoprenylcysteine carboxyl methyltransferase (Icmt) is enzyme target in anticancer drug discovery. An Icmt natural product high-throughput screening campaign was conducted and a hit extract from the roots of Hovea parvicalyx was identified. 2'-Methoxy-3'-prenyl-licodione and 2'-methoxy-3',3''-diprenyl-licodione, two prenylated beta-hydroxychalcone compounds, together with the known flavanone (S)-glabrol, were isolated and identified as bioactive constituents. Their structures were determined largely by 1D and 2D NMR spectroscopy.
Subject(s)
Antineoplastic Agents/chemistry , Enzyme Inhibitors/chemistry , Fabaceae/chemistry , Protein Methyltransferases/antagonists & inhibitors , Magnetic Resonance Spectroscopy , Molecular Structure , Protein Methyltransferases/metabolismABSTRACT
The anticancer target isoprenylcysteine carboxyl methyltransferase (Icmt) was the focus of a natural product high-throughput screening campaign. The Australian marine sponge Pseudoceratina sp. yielded aplysamine 6, a new bromotyrosine derivative with an alpha,beta-unsaturated amide linkage, as the bioactive constituent. Its structure was determined by 1D and 2D NMR spectroscopy.
Subject(s)
Porifera/chemistry , Protein Methyltransferases/antagonists & inhibitors , Tyrosine/analogs & derivatives , Animals , Australia , Molecular Structure , Nuclear Magnetic Resonance, Biomolecular , Tyrosine/chemistry , Tyrosine/isolation & purification , Tyrosine/pharmacologyABSTRACT
A new natural product, lysianadioic acid, was isolated from the plant Lysiana subfalcata as a carboxypeptidase B (CPB) inhibitor. It is a potent inhibitor of CPB with an IC(50) of 0.36 microM. This is the first known example of a small molecule CPB inhibitor isolated from plant origin. Its structure was determined by NMR spectroscopy.
Subject(s)
Arginine/analogs & derivatives , Carboxypeptidase B/antagonists & inhibitors , Guanidines/chemistry , Guanidines/pharmacology , Loranthaceae/chemistry , Protease Inhibitors/chemistry , Protease Inhibitors/pharmacology , Succinates/chemistry , Succinates/pharmacology , Guanidines/isolation & purification , Nuclear Magnetic Resonance, Biomolecular , Plant Extracts/chemistry , Plant Extracts/isolation & purification , Plant Extracts/pharmacology , Protease Inhibitors/isolation & purification , Succinates/isolation & purificationABSTRACT
A novel vanillic acid derivative (1) and its sulfate adduct (2) were isolated from a green algae, Cladophora socialis. The structures of 1 and 2 were elucidated from NMR and HRESIMS experiments. Both compounds showed potent inhibitory activity against protein tyrosine phosphatase 1B (PTP1B), an enzyme involved in the regulation of insulin cell signaling. Compounds 1 and 2 had IC50 values of 3.7 and 1.7 microM, respectively.
Subject(s)
Chlorophyta/chemistry , Protein Tyrosine Phosphatase, Non-Receptor Type 1/antagonists & inhibitors , Vanillic Acid , Australia , Inhibitory Concentration 50 , Insulin/metabolism , Molecular Structure , Vanillic Acid/analogs & derivatives , Vanillic Acid/chemistry , Vanillic Acid/isolation & purification , Vanillic Acid/pharmacologyABSTRACT
Isoprenylcysteine methyltransferase (Icmt) catalyzes the carboxyl methylation of oncogenic proteins in the final step of a series of post-translational modifications. The inhibition of Icmt provides an attractive and novel anticancer target. A natural product high-throughput screening campaign was conducted to discover inhibitors of Icmt. The Australian marine sponge, Pseudoceratina sp., yielded spermatinamine, a novel alkaloid with a bromotyrosyl-spermine-bromotyrosyl sequence, as the bioactive constituent. Its structure was determined by 1D and 2D NMR spectroscopy. Spermatinamine is the first natural product inhibitor of Icmt.
Subject(s)
Antineoplastic Agents/toxicity , Biological Products/chemistry , Biological Products/toxicity , Neoplasms/enzymology , Protein Methyltransferases/antagonists & inhibitors , Spermine/analogs & derivatives , Tyrosine/analogs & derivatives , Antineoplastic Agents/chemistry , Enzyme Inhibitors/chemistry , Enzyme Inhibitors/toxicity , Magnetic Resonance Spectroscopy , Molecular Structure , Neoplasms/pathology , Protein Methyltransferases/metabolism , Spermine/chemistry , Spermine/toxicity , Tyrosine/chemistry , Tyrosine/toxicityABSTRACT
Four imidazo-azolo-imidazole alkaloids, axinellamines A-D, have been isolated from an Australian marine sponge, Axinella sp. (order: Halichondrida: family: Axinellidae). These compounds contain a unique perhydrocyclopenta-imidazo-azolo-imidazole carbon skeleton. Three of these compounds had bactericidal activity against Helicobacter pylori at 1000 &mgr;M.