nsc-600032 and combretastatin

Herein is reported a convergent synthesis of isocombretastatins A, a novel class of potent antitubulin agents. These compounds having a 1,1-diarylethylene scaffold constitute the simplest isomers of natural Z-combretastatins A that are easy to synthesize without need to control the Z-olefin geometry. The discovery of isoCA-4 with biological activities comparable to that of CA-4 represents a major progress in this field.

Topics: Antineoplastic Agents; Bibenzyls; Cell Line, Tumor; Cell Proliferation; Chlorophenols; Humans; Models, Molecular; Molecular Conformation; Peptides, Cyclic; Stereoisomerism; Tubulin Modulators

Several stilbenoid compounds having structural similarity to the combretastatin group of natural products and characterized by the incorporation of two nitrogen-bearing groups (amine, nitro, serinamide) have been prepared by chemical synthesis and evaluated in terms of biochemical and biological activity. The 2',3'-diamino B-ring analogue 17 demonstrated remarkable cytotoxicity against selected human cancer cell lines in vitro (average GI 50 = 13.9 nM) and also showed good activity in regard to inhibition of tubulin assembly (IC 50 = 2.8 microM). In addition, a single dose (10 mg/kg) of compound 17 caused a 40% tumor-selective blood flow shutdown in tumor-bearing SCID mice at 24 h, thus suggesting the potential value of this compound and its corresponding salt formulations as new vascular-disrupting agents.

Topics: Animals; Antineoplastic Agents; Bibenzyls; Disease Models, Animal; Drug Design; Drug Screening Assays, Antitumor; Humans; Inhibitory Concentration 50; Leukemia P388; Mice; Molecular Structure; Neoplasms; Regional Blood Flow; Stilbenes; Tubulin

A novel series of dihydronaphthalene and benzosuberene analogs bearing structural similarity to the combretastatins in terms of 1,2-diarylethene, trimethoxyphenyl, and biaryl functionality has been synthesized. The compounds have been evaluated in regard to their ability to inhibit tubulin assembly and for their cytotoxicity against selected human cancer cell lines. From this series of compounds, benzosuberene analogs 2 and 4 inhibited tubulin assembly at concentrations comparable to that of combretastatin A-4 (CA4) and combretastatin A-1 (CA1). Furthermore, analog 4 demonstrated remarkable cytotoxicity against the three human cancer cell lines evaluated (for example GI(50)=0.0000032 microM against DU-145 prostate carcinoma).

Topics: Antineoplastic Agents; Benzocycloheptenes; Bibenzyls; Cell Line, Tumor; Cell Proliferation; Crystallography, X-Ray; Dose-Response Relationship, Drug; Drug Design; Drug Screening Assays, Antitumor; Humans; Models, Molecular; Molecular Structure; Naphthalenes; Neoplasms; Stereoisomerism; Structure-Activity Relationship; Tubulin

Combretastatin A4 phosphate (CA4P) and its structural analog, combretastatin A1 phosphate (CA1P), are soluble prodrugs capable of interacting with tubulin and causing rapid vascular shutdown within tumors. CA4P has completed Phase I clinical trials, but recent preclinical studies have shown that CA1P displays a greater antitumor effect than the combretastatin A4 (CA4) analog at equal doses. The aim of this study, therefore, is to compare pharmacokinetics and metabolism of the two compounds to determine whether pharmacokinetics plays a role in their differential activity.. NMRI mice bearing MAC29 tumors received injection with either CA4P or CA1P at a therapeutic dose of 150 mg x kg(-1), and profiles of both compounds and their metabolites analyzed by a sensitive and specific liquid chromatography/mass spectroscopy method.. The metabolic profile of both compounds is complex, with up to 14 metabolites being detected for combretastatin A1 (CA1) in the plasma. Many of these metabolites have been identified by liquid chromatography/mass spectroscopy. Initial studies, however, focused on the active components CA4 and CA1, where plasma and tumor areas under the curve were 18.4 and 60.1 microg x h x ml(-1) for CA4, and 10.4 and 13.1 microg x h x ml(-1) for CA1, respectively. In vitro metabolic comparisons of the two compounds strongly suggest that CA1 is metabolized to a more reactive species than the CA4.. Although in vitro studies suggest that variable rates of tumor-specific prodrug dephosphorylation may explain these differences in pharmacokinetics profiles, the improved antitumor activity and altered pharmacokinetic profile of CA1 may be due to the formation of a more reactive metabolite.

Topics: Animals; Antineoplastic Agents; Antineoplastic Agents, Phytogenic; Area Under Curve; Bibenzyls; Calibration; Cell Line, Tumor; Chromatography; Chromatography, High Pressure Liquid; Coloring Agents; Female; Humans; Inhibitory Concentration 50; Mass Spectrometry; Mice; Models, Chemical; Phosphorylation; Prodrugs; Stilbenes; Tetrazolium Salts; Thiazoles; Time Factors

Peptide hormones are often rapidly internalized after binding to and activation of their receptors which are sometimes over-expressed on tumor cells. Thus, peptide ligands are increasingly being utilized for specific tumor cell targeting and internalization of radioactive isotopes for tumor imaging and for specifically delivering and internalizing cytotoxic moieties. Here, we describe a new carbamate linker system containing a series of built-in nucleophile assisted releasing (BINAR) groups which enable the 'fine-tuning' of intracellular cleavage rates of free cytotoxic agents containing reactive OH groups. Release rates were found to fit well with the chemical model and several conjugates of camptothecin and one of combretastatin were shown to have potent cytotoxic effects on cultures of human neuroblastoma IMR-32 cells which over-express somatostatin receptors.

Topics: Amino Acid Sequence; Animals; Antineoplastic Agents; Bibenzyls; Camptothecin; Carbamates; Cross-Linking Reagents; Dose-Response Relationship, Drug; Drug Screening Assays, Antitumor; Humans; Inhibitory Concentration 50; Neuroblastoma; Peptides; Rats; Somatostatin; Stilbenes; Structure-Activity Relationship; Tumor Cells, Cultured

A methanol extract of Combretum erythrophyllum showed inhibitory bioactivities in a yeast-based microtiter assay for DNA-damaging agents. Bioassay-guided fractionation of this extract yielded two known bioactive compounds, combretastatin A-1 and (-)-combretastatin, and two new bioactive glucosides, combretastatin A-1 2'-beta-D-glucoside (1) and combretastatin B-1 2'-beta-D-glucoside (2). The structures of the new compounds were assigned by (1)H and (13)C NMR, DEPT, HMQC, and HMBC spectra.

Topics: Antineoplastic Agents, Phytogenic; Bibenzyls; Carbohydrate Sequence; DNA Damage; DNA Repair; Drug Screening Assays, Antitumor; Glycosides; Humans; Magnetic Resonance Spectroscopy; Mass Spectrometry; Molecular Sequence Data; Plant Extracts; Plants, Medicinal; South Africa; Spectrophotometry, Ultraviolet; Stilbenes; Tumor Cells, Cultured; Wood