Synthesis and Evaluation of Paclitaxel-Loaded Gold Nanoparticles for Tumor-Targeted Drug Delivery.

The synthesis of a series of thiolated paclitaxel analogs is described as part of a novel nanomedicine program aimed at developing formulations of paclitaxel that will bind to gold nanoparticles for tumor targeted drug delivery. Preliminary evaluation of the new nanomedicine composed of 27 nm gold nanoparticles, tumor necrosis factor alpha (TNFα), thiolated polyethylene glycol (PEG-thiol), and one of several thiolated paclitaxel analogs is presented.

Synthesis and evaluation of orally active small molecule HIV-1 Nef antagonists.

The HIV-1 Nef accessory factor enhances viral replication and promotes immune system evasion of HIV-infected cells, making it an attractive target for drug discovery. Recently we described a novel class of diphenylpyrazolodiazene compounds that bind directly to Nef in vitro and inhibit Nef-dependent HIV-1 infectivity and replication in cell culture. However, these first-generation Nef antagonists have several structural liabilities, including an azo linkage that led to poor oral bioavailability. The azo group was therefore replaced with either a one- or two-carbon linker. The resulting set of non-azo analogs retained nanomolar binding affinity for Nef by surface plasmon resonance, while inhibiting HIV-1 replication with micromolar potency in cell-based assays without cytotoxicity. Computational docking studies show that these non-azo analogs occupy the same predicted binding site within the HIV-1 Nef dimer interface as the original azo compound. Computational methods also identified a hot spot for inhibitor binding within this site that is defined by conserved HIV-1 Nef residues Asp108, Leu112, and Pro122. Pharmacokinetic evaluation of the non-azo B9 analogs in mice showed that replacement of the azo linkage dramatically enhanced oral bioavailability without substantially affecting plasma half-life or clearance. The improved oral bioavailability of non-azo diphenylpyrazolo Nef antagonists provides a starting point for further drug lead optimization in support of future efficacy testing in animal models of HIV/AIDS.

Synthesis and structure-activity analysis of diphenylpyrazolodiazene inhibitors of the HIV-1 Nef virulence factor.

HIV-1 Nef is a critical AIDS progression factor yet underexplored target for antiretroviral drug discovery. A recent high-throughput screen for pharmacological inhibitors of Nef-dependent Src-family kinase activation identified a diphenylpyrazolodiazene hit compound with submicromolar potency in HIV-1 replication assays against a broad range of primary Nef variants. This compound, known as 'B9', binds directly to Nef and inhibits its dimerization in cells as a possible mechanism of action. Here were synthesized a diverse set of B9 analogs and identified structural features essential to antiretroviral activity. Chemical modifications to each of the three rings present in the parent compound were identified that did not compromise antiviral action. These analogs will guide the development of next-generation compounds with appropriate pharmacological profiles for assessment of antiretroviral activity in vivo.

Design and synthesis of simplified taxol analogs based on the T-Taxol bioactive conformation.

A series of compounds designed to adopt a conformation similar to the tubulin-binding T-Taxol conformation of the anticancer drug paclitaxel has been synthesized. Both the internally bridged analogs 37-39, 41 and the open-chain analogs 27-29 and 43 were prepared. The bridged analogs 37-39 and 41 were synthesized by Grubbs' metatheses of compounds 30-32 and 33, which, in turn, were prepared by coupling ß-lactams 24-26 with alcohols 22 and 23. Both the bridged and the open-chain analogs showed moderate to good cytotoxicity.

Novel Dual-Action Targeted Nanomedicine in Mice With Metastatic Thyroid Cancer and Pancreatic Neuroendocrine Tumors.

Background: The advantages of nanomedicines include preferential delivery of the payload directly to tumor tissues. CYT-21625 is the novel, first-in-class gold nanomedicine designed to target tumor vasculature and cancer cells by specifically delivering recombinant human tumor necrosis factor alpha (rhTNF) and a paclitaxel prodrug. Methods: We analyzed TNF receptor expression in publicly available gene expression profiling data and in thyroid tissue samples. Mice with metastatic FTC-133 and 8505C xenografts and the MEN1 conditional knock-out mice were treated weekly with CYT-21625 and gold nanoparticles with rhTNF only (CYT-6091); controls included mice treated with either paclitaxel or saline. In vivo luciferase activity was used to assess the effects on tumor growth. Computed tomography, magnetic resonance imaging, and 18F-Fludeoxyglucose positron emission tomography were used to study tumor selectivity in mice with insulin-secreting pancreatic neuroendocrine tumors (PNETs). All statistical tests were two-sided. Results: Anaplastic thyroid cancer (ATC) expressed statistically significantly higher levels of TNF receptor superfamily 1A and 1B messenger RNA (n = 11) and protein (n = 6) than control samples (n = 45 and 13, respectively). Mice (n = 5-7 per group) with metastatic ATC (P < .009) and FTC-133 xenografts (P = .03 at week 3, but not statistically significant in week 4 owing to reduced sample size from death in non-CYT-21625 groups) treated with CYT-21625 had a statistically significantly lower tumor burden. Treatment with CYT-21625 resulted in loss of CD34 expression in intratumoral vasculature, decreased proliferating cell nuclear antigen, and increased cleaved caspase-3. Intratumoral vascular leakage occurred only in mice with PNET and ATC treated with CYT-6091 and CYT-21625. CYT-6091 and CYT-21625 preferentially deposited in PNETs and statistically significantly decreased serum insulin levels (n = 3 per group, P < .001). There were no toxicities observed in mice treated with CYT-21625. Conclusions: CYT-21625 is effective in mice with PNETs and metastatic human thyroid cancer with no toxicities. Thus, CYT-21625 should be studied in patients with advanced PNETs and thyroid cancer.

Determination of warfarin alcohols by ultra-high performance liquid chromatography-tandem mass spectrometry: application to in vitro enzyme kinetic studies.

A sensitive, accurate, and reproducible ultra-high performance liquid chromatography-tandem mass spectrometry method was developed and validated for determination of warfarin and its alcohol metabolites (RS/SR- and RR/SS-warfarin alcohol) in 10mM Tris-HCl incubation buffer (pH 7.4). Sample preparation involved acidification with 4% formic acid, followed by liquid-liquid extraction using methyl tert-butyl ether. Chromatographic separation was achieved using a Hypersil Gold C18 (2.1mm×100mm, 1.9µm) analytical column with gradient elution of solvent A (water containing 0.01% formic acid) and solvent B (acetonitrile containing 0.1% formic acid). The flow rate was 0.4mL/min and the total run time was 5min. Detection of analytes was performed using heated electrospray ionization (negative mode) and selected reaction monitoring. Excellent linearity was observed for all analytes over the standard curve concentration ranges of 100-10,000ng/mL for warfarin, and 0.5-250ng/mL for warfarin alcohols. The intra- and inter-day accuracy and precision for analytes were within ±10.0%. Excellent recovery and negligible matrix effects were observed. The method is robust, sensitive, accurate and reproducible, and was successfully applied to in vitro enzyme kinetic studies of warfarin.

Bromophenols coupled with nucleoside bases and brominated tetrahydroisoquinolines from the red alga Rhodomela confervoides.

Three new bromophenols C-N coupled with nucleoside base derivatives (1-3) and three new brominated 1,2,3,4-tetrahydroisoquinolines (5-7), together with a new brominated tyrosine derivative (4), have been isolated from polar fractions of an ethanolic extract of the red alga Rhodomela confervoides. By spectroscopic and chemical methods including HRMS and 2D NMR data, their structures were determined as 7-[3-bromo-2-(2,3-dibromo-4,5-dihydroxybenzyl)-4,5-dihydroxybenzyl]-3,7-dihydro-1H-purine-2,6-dione (1), 7-(2,3-dibromo-4,5-dihydroxybenzyl)-3,7-dihydro-1H-purine-2,6-dione (2), 9-[3-bromo-2-(2,3-dibromo-4,5-dihydroxybenzyl)-4,5-dihydroxybenzyl]adenine (3), (-)-8S-(3-bromo-5-hydroxy-4-methoxy)phenylalanine (4), (-)-3S-8-bromo-6-hydroxy-7-methoxy-1,2,3,4-tetrahydroisoquinoline-3-carboxylic acid (5), methyl (-)-3S-8-bromo-6-hydroxy-7-methoxy-1,2,3,4-tetrahydroisoquinoline-3-carboxylate (6), and methyl (-)-3S-6-bromo-8-hydroxy-7-methoxy-1,2,3,4-tetrahydroisoquinoline-3-carboxylate (7). Compounds 5-7 were semisynthesized by using 4 as the starting material.

Bromophenols coupled with methyl gamma-ureidobutyrate and bromophenol sulfates from the red alga Rhodomela confervoides.

Four new bromophenols C-N coupled with methyl gamma-ureidobutyrate (1-4), a phenylethanol bromophenol (5), and three phenylethanol sulfate bromophenols (6-8) have been isolated from polar fractions of an ethanolic extract of the red alga Rhodomela confervoides. On the basis of spectroscopic evidence including HRMS and 2D NMR data, the structures of the new compounds were determined as methyl N'-(2,3-dibromo-4,5-dihydroxybenzyl)-gamma-ureidobutyrate (1), methyl N,N'-bis(2,3-dibromo-4,5-dihydroxybenzyl)-gamma-ureidobutyrate (2), methyl N'-[3-bromo-2-(2,3-dibromo-4,5-dihydroxybenzyl)-4,5-dihydroxybenzyl]-gamma-ureidobutyrate (3), methyl N'-(2,3-dibromo-4,5-dihydroxybenzyl)-N'-[3-bromo-2-(2,3-dibromo-4,5-dihydroxybenzyl)-4,5-dihydroxybenzyl]-gamma-ureidobutyrate (4), 2,3-dibromo-4,5-dihydroxyphenylethanol (5), 2,3-dibromo-4,5-dihydroxyphenylethanol sulfate (6), 3-bromo-4,5-dihydroxyphenylethanol sulfate (7), and 3-bromo-2-(2,3-dibromo-4,5-dihydroxybenzyl)-4,5-dihydroxyphenylethanol sulfate (8). The cytotoxicity of all compounds was evaluated against several human cancer cell lines including human colon cancer (HCT-8), hepatoma (Bel7402), stomach cancer (BGC-823), lung adenocarcinoma (A549), and human ovarian cancer (A2780). Among them, the phenylethanol and the phenylethanol sulfate bromophenols (5-8) showed moderate cytotoxicity against all tested cell lines.

Minor sesquiterpenes with new carbon skeletons from the brown alga Dictyopteris divaricata.

Five minor sesquiterpenes (1-5) with two novel carbon skeletons, together with a minor new oplopane sesquiterpene (6), have been isolated from the brown alga Dictyopteris divaricata. By means of spectroscopic data including IR, HRMS, 1D and 2D NMR, and CD, their structures including absolute configurations were assigned as (+)-(1R,5S,6S,9R)-3-acetyl-1-hydroxy-6-isopropyl-9-methylbicyclo[4.3.0]non-3-ene (1), (+)-(1R,3S,4S,5R,6S,9R)-3-acetyl-1,4-dihydroxy-6-isopropyl-9-methylbicyclo[4.3.0]nonane (2), (+)-(1R,3R,4R,5R,6S,9R)-3-acetyl-1,4-dihydroxy-6-isopropyl-9-methylbicyclo[4.3.0]nonane (3), (+)-(1S,2R,6S,9R)-1-hydroxy-2-(1-hydroxyethyl)-6-isopropyl-9-methylbicyclo[4.3.0]non-4-en-3-one (4), (-)-(5S,6R,9S)-2-acetyl-5-hydroxy-6-isopropyl-9-methylbicyclo[4.3.0]non-1-en-3-one (5), and (-)-(1S,6S,9R)-4-acetyl-1-hydroxy-6-isopropyl-9-methylbicyclo[4.3.0]non-4-en-3-one (6). Biogenetically, the carbon skeletons of 1-6 may be derived from the co-occurring cadinane skeleton by different ring contraction rearrangements. Compounds 1-6 were inactive (IC(50) > 10 mug/mL) against several human cancer cell lines.

Bromophenols coupled with derivatives of amino acids and nucleosides from the red alga Rhodomela confervoides.

Three new bromophenols coupled with pyroglutamic acid derivatives and one bromophenol coupled with deoxyguanosine were obtained from the red alga Rhodomela confervoides. By spectroscopic methods including 2D NMR and single-crystal X-ray structure analysis their structures were elucidated as N-(2,3-dibromo-4,5-dihydroxybenzyl)methyl pyroglutamate (1), N-(2,3-dibromo-4,5-dihydroxybenzyl)pyroglutamic acid (2), N-[3-bromo-2-(2,3-dibromo-4,5-dihydroxybenzyl)-4,5-dihydroxybenzyl]methyl pyroglutamate (3), and 2-N-(2,3-dibromo-4,5-dihydroxybenzylamino)deoxyguanosine (4), respectively. Compounds 1-4 were evaluated against several microorganisms and human cancer cell lines, but found inactive. To our knowledge this is the first report of bromophenols coupled with amino acid or nucleoside derivatives through the C-N bond.

Norsesquiterpenes from the brown alga Dictyopteris divaricata.

Three bisnorsesquiterpenes (1-3) with novel carbon skeletons and a norsesquiterpene (4) have been isolated from the brown alga Dictyopteris divaricata. By means of spectroscopic data including IR, HRMS, 1D and 2D NMR techniques, single-crystal X-ray diffraction, and CD, their structures including absolute configurations were proposed as (+)-(1R,6S,9R)-1-hydroxyl-6-isopropyl-9-methylbicyclo[4.3.0]non-4-en-3-one (1), (-)-(1S,6S,9R)-1-hydroxyl-6-isopropyl-9-methylbicyclo[4.3.0] non-4-en-3-one (2), (+)-(5S,6R,9S)-5-hydroxyl-6-isopropyl-9-methylbicyclo[4.3.0]non-1-en-3-one (3), and (-)-(1R,7S,10R)-1-hydroxy-11-norcadinan-5-en-4-one (4). Biogenetically, the carbon skeleton of 1-3 may be derived from the co-occurring cadinane skeleton by ring contraction and loss of two carbon units, and compound 4 from the oxidation of cadinane derivatives. Compounds 1-4 were inactive (IC50 > 10 microg/mL) against several human cancer cell lines including lung adenocarcinoma (A549), stomach cancer (BGC-823), breast cancer (MCF-7), hepatoma (Bel7402), and colon cancer (HCT-8) cell lines.

Cadinane sesquiterpenes from the brown alga Dictyopteris divaricata.

Seven new cadinane sesquiterpenes, (-)-(1R,6S,7S,10R)-1-hydroxycadinan-3-en-5-one (1), (+)-(1R,5S,6R,7S, 10R)-cadinan-3-ene-1,5-diol (2), (+)-(1R,5R,6R,7S,10R)-cadinan-3-ene-1,5-diol (3), (+)-(1R,5S,6R,7S,10R)-cadinan-4(11)-ene-1,5-diol (4), (+)-(1R,5R,6R,7R,10R)-cadinan-4(11)-ene-1,5,12-triol (5), (-)-(1R,4R,5S,6R,7S, 10R)-cadinan-1,4,5-triol (6), and (-)-(1R,6R,7S,10R)-11-oxocadinan-4-en-1-ol (7), together with nine known compounds were isolated from the brown alga Dictyopteris divaricata. The structures of the new natural products, as well as their absolute configuration, were established by means of spectroscopic data including IR, HRMS, 1D and 2D NMR, single-crystal X-ray diffraction, and CD. All compounds were inactive against several human cancer cell lines including lung adenocarcinoma (A549), stomach cancer (BGC-823), breast cancer (MCF-7), hepatoma (Bel7402), and colon cancer (HCT-8) cell lines.

Bromophenol derivatives from the red alga Rhodomela confervoides.

Eight new bromophenol derivatives, 2,3-dibromo-4,5-dihydroxybenzyl methyl sulfoxide (1), 4-(2,3-dibromo-4,5-dihydroxyphenyl)-3-butene-2-one (2), 2-(3-bromo-5-hydroxy-4-methoxyphenyl)-3-(2,3-dibromo-4,5-dihydroxyphenyl)propionic acid (3), 2-(3-bromo-5-hydroxy-4-methoxyphenyl)-3-(2,3-dibromo-4,5-dihydroxyphenyl)propionic acid methyl ester (4), 2-phenyl-3-(2,3-dibromo-4,5-dihydroxyphenyl)propionic acid (5), 4'-methoxy-2'',3',3''-tribromo-4'',5',5''-trihydroxydiphenylacetic acid (6), and 3-bromo-5-hydroxy-4-methoxyphenylacetic acid (7) and its methyl ester (8), together with a known bromophenol, 3-bromo-5-hydroxy-4-methoxybenzoic acid (9), were isolated from the red alga Rhodomela confervoides. Their structures were elucidated by spectroscopic methods including IR, EIMS, FABMS, ESIMS, HRFABMS, HRESIMS, 1D and 2D NMR, and single-crystal X-ray structure analysis. Compounds 1-4, 8, and 9 were found inactive against several human cancer cell lines and microorganisms.

Dibenzyl bromophenols with diverse dimerization patterns from the brown alga Leathesia nana.

Six novel dibenzyl bromophenols (1-6) with different dimerization patterns and two propyl bromophenol derivatives (7 and 8), together with 11 known bromophenol derivatives, were isolated from the ethanolic extract of the brown alga Leathesia nana. On the basis of spectroscopic methods the structures of the new compounds were determined as 5,6'-diethyloxymethyl-3,4,2'-tribromo-2,3',4'-trihydroxydiphenyl ether (1), 2-(2,3-dibromo-4,5-dihydroxybenzyl)-3,5-dihydroxy-4-methoxybenzyl alcohol (2), 6-(2,3-dibromo-4,5-dihydroxybenzyl)-2,3-dibromo-4,5-dihydroxy benzyl methyl ether (3), 9,10-dihydro-9,10-dimethoxy-3,4,7,8-tetrabromo-1,2,5,6-tetrahydroxyanthracene (4), (+)-3-(2,3-dibromo-4,5-dihydroxyphenyl)-4-bromo-5,6-dihydroxy-1,3-dihydroisobenzofuran (5), rel-(4aS,10aR)-(+/-)-6,7-dibromo-4a-hydroxy-3,8-dihydroxymethyl-10a-methoxy-1,4,4a,10a-tetrahydrodibenzo[b,e][1,4]dioxin-1-one (6), (E)-2-methyl-3-(2,3-dibromo-4,5-dihydroxyphenyl)propenal (7), and 2-methyl-3-(2,3-dibromo-4,5-dihydroxyphenyl)-1-propanol (8). Some compounds including 3 showed in vitro selective cytotoxicity against several human cancer cell lines. This is the first brown alga to be reported containing bromophenols.

Bromophenols from the brown alga Leathesia nana.

Two new bromophenols, (E)-3-(2,3-dibromo-4,5-dihydroxyphenyl)-2-methylpropenal (1) and 3-(2,3-dibromo-4,5-dihydroxyphenyl)-2-methyl-1-propanol (2), together with 11 known bromophenols (3-13), were isolated from the ethanolic extract of the brown alga Leathesia nana S. et G. Their structures have been elucidated by spectroscopic methods, including IR, MS, HRMS, 1D and 2D NMR techniques.