Antitumor studies. Part 5: Synthesis, antitumor activity, and molecular docking study of 5-(monosubstituted amino)-2-deoxo-2-phenyl-5-deazaflavins

Various novel 5-(monosubstituted amino)-2-deoxo-2-phenyl-5-deazaflavins derivatives have been synthesized by direct coupling of 5-deazaflavins and N-alkyl or aryl amines. The antitumor activities against human tumor cell lines CCRF-HSB-2 and KB cells have been investigated in vitro and many compounds showed promising potential antitumor activities with less cytotoxicities. AutoDock molecular docking into PTK (PDB code: 1t46) has been done for lead optimization of these compounds as potential PTK inhibitors. Some of the synthesized 5-(monosubstituted amino)-2-deoxo-2-phenyl-5-deazaflavins at the 5-position exhibited reasonable binding affinities into PTK with the hydrogen bond through their C(5)-NH moiety.     

Antitumor studies. part 3: design, synthesis, antitumor activity, and molecular docking study of novel 2-methylthio-, 2-amino-, and 2-(N-substituted amino)-10-alkyl-2-deoxo-5-deazaflavins

Various novel 10-alkyl-2-deoxo-2-methylthio-5-deazaflavins have been synthesized by reaction of 6-(N-alkylanilino)-2-methylthiopyrimidin-4(3H)-ones with Vilsmeier reagent. The similar 2-(N-substituted amino) derivatives were prepared by nucleophilic replacement reaction of the 2-methylthio moiety by appropriate amines. The 2-oxo derivatives (i.e., 5-deazaflavins) were obtained by acidic hydrolysis of the 2-methylthio derivatives. The antitumor activities against CCRF-HSB-2 and KB cells and the antiviral activities against HSV-1 and HSV-2 have been investigated in vitro, and many compounds showed promising antitumor activities. Furthermore, AutoDock molecular docking into PTK has been done for lead optimization of these compounds as potential PTK inhibitors. Whereas, the designed 2-deoxo-5-deazaflavins connected with amino acids at the 2-position exhibited the good binding affinities into PTK with more hydrogen bonds.     

Antitumor studies. Part 4: Design, synthesis, antitumor activity, and molecular docking study of novel 2-substituted 2-deoxoflavin-5-oxides, 2-deoxoalloxazine-5-oxides, and their 5-deaza analogs

Various novel 10-alkyl-2-deoxo-2-methylthioflavin-5-oxides and their 2-alkylamino derivatives were prepared by facile nitrosative cyclization of 6-(N-alkylanilino)-2-methylthiopyrimidin-4(3H)-ones followed by nucleophilic replacement of the 2-methylthio moiety by different amines, and acidic hydrolysis of the 2-methylthio moiety afforded the corresponding flavin derivatives. 2-Deoxo-2-methylthio-5-deazaalloxazines and 2-deoxo-2-methylthioalloxazine-5-oxides were also prepared by Vilsmeier reaction and by nitrosation of 6-anilino-2-methylthiopyrimidin-4(3H)-ones, respectively. Then, they were subjected to nucleophilic replacement with appropriate amines to produce the corresponding 2-alkylamino derivatives. Regiospecific N(3)-alkylation of 2-deoxo-2-methylthioalloxazine-5-oxides was carried out with various alkylating agents in the usual way. The antitumor activities against CCRF-HSB-2 and KB tumor cells have been investigated in vitro, and many compounds showed promising antitumor activities. Furthermore, AutoDock molecular docking into PTK (PDB: 1t46) has been done for lead optimization of the aforementioned compounds as potential PTK inhibitors.     

Synthesis, characterization and reactions of 2-deoxo-5-deazaalloxazines

5-Deazaflavins and their homologues have been known as potential riboflavin antagonists, bioreductives, and compounds with potent antitumor activity. 2-Amino-4-methylquinoline-3-carbonitrile (2) was prepared as unreported starting material for several interesting 2-deoxo-5-deazalloxazine derivatives. Cyclization of 2 using formamide afforded the 2,4-deoxo-5-deazaalloxazine derivative 7, which was subjected to deamination with nitrous acid to give the 2-deoxo-5-deazaalloxazine (8). The compound 8 was also obtained via 13 by treating the latter with refluxing formic acid or formamide and used as a precursor for synthesis of several 2-deoxo-5-deazaalloxazines 18, 19, 20, 21 and 22. The pharmacological and biological properties of these compounds are still under investigation.     

Roots and shoots of tomato produce 6-deoxo-28-norcathasterone, 6-deoxo-28-nortyphasterol and 6-deoxo-28-norcastasterone, possible precursors of 28-norcastasterone

Roots and shoots of tomato (Lycopersicon esculentum) were investigated for the occurrence of biosynthetic precursors of 28-norcastasterone, a C27 brassinosteroid that we have shown to be present in shoots of tomato. A series of putative precursors, including 6-deoxo-28-norcathasterone, 6-deoxo-28-norteasterone, 3-dehydro-6-deoxo-28-norteasterone, 6-deoxo-28-nortyphasterol and 6-deoxo-28-norcastasterone, were synthesized and used as GC-MS standards, resulting in the identification of 6-deoxo-28-norcathasterone, 6-deoxo-28-nortyphasterol and 6-deoxo-28-norcastasterone in both roots and shoots. These findings indicate that the biosynthesis of 28-norcastasterone may parallel that of castasterone. The endogenous levels of brassinosteroids differed between roots and shoots, indicating that the biosynthesis of brassinosteroids is differently regulated between these tissues. Regulation of root growth by brassinosteroids is also discussed.     

Synthesis, biological active molecular design, and molecular docking study of novel deazaflavin-cholestane hybrid compounds

Novel deazaflavin-cholestane hybrid compounds, 3',8'-disubstituted-5'-deazacholest-2,4-dieno[2,3-g]pteridine-2',4'(3'H,8'H)-diones, have been synthesized by condensation reaction between 6-(monosubstituted amino)-pyrimidin-2,4(1H,3H)-diones and 2-hydroxymethylenecholest-4-en-3-one in presence of p-toluenesulfonic acid monohydrate and diphenyl ether. The antitumor activities against human tumor cell lines (CCRF-HSB-2 and KB cells) have been investigated in vitro, and many of these compounds showed promising antitumor activities. Furthermore, molecular docking study using LigandFit within the software package Discovery Studio 1.7 was done for lead optimization of these compounds as potential PTK inhibitors. In general, all of the synthesized steroid-hybrid compounds showed good binding affinities into PTK (PDB code: 1t46).     

Quantitative determination of 9-deoxo-16,16-dimethyl-9-methylene-PGE2 in human plasma by GC-MS,RIA and HPLC

Comparisons were made of 9-deoxo-16,16-dimethyl-9-methylene-PGE₂ levels in plasma determined by three assay methods. Plasma samples from Rhesus monkeys treated with 200 μg/kg 9-deoxo-16,16-dimethyl-9-methylene-PGE₂ intravenously were analyzed by radioimmunoassay (RIA) and by high pressure liquid chromatography (HPLC). In a second experiment known amounts of 11β-³H-9-deoxo-16,16-dimethyl-9-methylene-PGE₂ were added to human plasma at several concentration levels. The samples were analyzed by RIA, HPLC and gas chromatography-mass spectrometry (GC-MS). A limited number of comparisons have been made between RIA and GC-MS analysis of plasma samples from human subjects treated with 9-deoxo-16, 16-dimethyl-9-methylene-PGE₂. The results indicated that the three assay methods generally give comparable estimations of 9-deoxo-16,16-dimethyl-9-methylene-PGE₂ content in plasma.     

Synthesis and antitumor activity of duocarmycin derivatives: A-ring pyrrole compounds bearing beta-(5',6',7'-trimethoxy-2'-indolyl)acryloyl group

A series of A-ring pyrrole derivatives of duocarmycin bearing beta-(5',6',7'-trimethoxy-2'-indolyl)acryloyl group were synthesized, and evaluated for in vitro anticellular activity against HeLa S3 cells and in vivo antitumor activity against murine sarcoma 180 in mice. New Seg-B analogues bearing beta-(5',6',7'-trimethoxy-2'-indolyl)acryloyl group containing double bond as spacer had lower peripheral blood toxicity than the derivatives bearing 5',6',7'-trimethoxyindole-2'-carboxyl group in Seg-B of the natural type. Moreover, most of them exhibited potent antitumor activity against in vivo murine tumor models.     

Novel peptide derivatives of bleomycin A5: synthesis, antitumor activity and interaction with DNA

A series of novel amino acid and peptide derivatives of bleomycin (BLM) A(5) were synthesized. All the compounds possessed significant antitumor activities in vitro against HL-60, BGC-823, PC-3MIE8, and MDA-MB-435 cell lines. Their antitumor activities against MDA-MB-435 were 10-fold higher than BLM A5. The DNA cleavage studies indicated that the hydrophobic amino acid or peptide derivatives of BLM A5 could induce higher cleavage ratio of double to single strand DNA than BLM A5. From the DNA binding studies, we found that the derivatives containing either D-conformation amino acid or basic amino acid could facilitate DNA binding of BLM.     

Design, synthesis, and in vitro antitumor activity of new 1,4-diarylimidazole-2-ones and their 2-thione analogues

A series of new 1,4-diarylimidazol-2(3H)-one derivatives and their 2-thione analogues has been prepared and evaluated in vitro for antitumor activity against the NCI human cancer cell panel. Compounds bearing a 3,4,5-trimethoxyphenyl ring linked to either N-1 or C-4 position of the imidazole core demonstrated an interesting profile of cytotoxicity with preferential activity against leukemic cell lines. Compound 13 exhibited a potent antitumor activity against MOLT-4 (GI(50)=20 nM) and SR (GI(50)=32 nM) cell lines.     

Synthesis,biological evaluation and molecular docking studies of amide-coupled benzoic nitrogen mustard derivatives as potential antitumor agents

A series of amide-coupled benzoic nitrogen mustard derivatives as potential EGFR and HER-2 kinase inhibitors were synthesized and reported for the first time. Some of them exhibited significant EGFR and HER-2 inhibitory activity. Of all the studied compounds, compounds 5b and 5t exhibited the most potent inhibitory activity, which was comparable to the positive control erlotinib. Docking simulation was performed to position compounds 5b and 5t into the EGFR active site to determine the probable binding model. Antiproliferative assay results indicated that some of the benzoic nitrogen mustard derivatives possessed high antiproliferative activity against MCF-7. In particular, compounds 5b and 5t with potent inhibitory activity in tumor growth inhibition may function as potential antitumor agents.     

Structure-based drug design and AutoDock study of potential protein tyrosine kinase inhibitors

Different classes of compounds were investigated for their binding affinities into different protein tyrosine kinases (PTKs) employing a novel flexible ligand docking approach by using AutoDock 3.05 and 4. These compounds include many flavin analogs, which were developed in our group with varying degrees of cytotoxic activity (comparable or moderately superior to cisplatin and ara-c), and database selected analogs. They were docked onto twelve different families of PTKs retrieved from the Protein Data Bank. These proteins are representatives of plausible models of interactions with chemotherapeutic agents. A comparative study of the intact co-crystallized ligands of various types of PTKs was carried out. Results revealed that the new class of 5-deazapteridine and steroid hybrid compounds VIa,b, and d, and the vertical-type bispyridodipyrimidine with n-hexyl chain junction between its N-10 and N-10 atoms Xa, exhibited non-selective PTK binding capacities, with the lowest (Gb). On the other hand, 2-amino benzoic acid analog IIa, phenoxypyrido [3, 4-d]pyrimidine derivative IVc, tyrosine containing tripeptide Vd, and the one from Sumisho data base 831 are proposed to have selective PTK binding affinities to certain classes of tyrosine kinases, namely, HGFR (c-met), ZAP-70, insulin receptor kinase, EGFR, respectively. All These compounds of highest affinities were docked within the binding sites of PTKs with reasonable RMSD and 1-5 hydrogen bonds.     

Synthesis, X-ray crystallographic analysis, and antitumor activity of N-(benzothiazole-2-yl)-1-(fluorophenyl)-O,O-dialkyl-alpha-aminophosphonates

Alpha-aminophosphonates containing benzothiazole and fluorine moiety, 4a-4m, were synthesized by Mannich-type addition in ionic liquid media with high yield and short reaction time. Their structures were established by IR, (1)H NMR, (13)C NMR, and elemental analysis. The X-ray crystallographic data of compounds 4j and 4m were provided. The newly synthesized compounds were evaluated for their anticancer activities against PC3, A431, A375, and Bcap37 cells in vitro by the MTT method. Compound 4c is highly effective against PC3 cells and moderate to A431 cells. Hence, further study is necessary to find out the potential antitumor activities.     

Photochemical synthesis and anticancer activity of barbituric acid,thiobarbituric acid,thiosemicarbazide, and isoniazid linked to 2-phenyl indole derivatives

2-Phenyl-1H-indole-3-carbaldehyde-based barbituric acid, thiobarbituric acid, thiosemicarbazide, isoniazid, and malononitrile derivatives were synthesized under photochemical conditions. The antitumor activities of the synthesized compounds were evaluated on three different human cancer cell lines representing prostate cancer cell line DU145, Dwivedi (DWD) cancer cell lines, and breast cancer cell line MCF7. All the screened compounds possessed moderate anticancer activity, and out of all the screened compounds, 5-{1[2-(4-chloro-phenyl)2-oxo-ethyl]-2-phenyl-1H-indole-3-ylmethylene}-2-thioxo-dihydro-pyrimidine-4,6-dione (2b) and 5-{1[2-(4-methoxy-phenyl)2-oxo-ethyl]-2-phenyl-1H-indole-3-ylmethylene}-2-thioxo-dihydro-pyrimidine-4,6-dione (2d) exhibited marked antitumor activity against used cell lines. Additionally, barbituric acid derivatives were selective to inhibit cell line DWD and breast cancer cell lines.     

5-Fluorouracil-cisplatin adducts with potential antitumor activity

Using 5-fluorouracil (5-FU) and cis-diamminedichloroplatinum(II) (cisplatin, CDDP) as starting compounds, 5-FU-cisplatin adducts cis-[Pt(NH(3))(2)(HFU)Cl] (1) and cis-[Pt(NH(3))(2)(HFU)(2)] (2) were prepared. The obtained complexes were characterized by IR, ES-MS and 1H NMR spectroscopy. Complex 1 reacted with guanosine-5'-monophosphate (5'-GMP) and gave rise to a stable mixed-ligand complex cis-[Pt(NH(3))(2)(HFU)(GMP)] (3), whereas 2 did not undergo a similar reaction. In vitro cell growth inhibition tests of complexes 1 and 2 exhibited moderate antitumor activities against the melanoma B16-BL6 cell line. This work provides the basis for a potential alternative for the combinational use of 5-FU and CDDP in cancer therapy.     

Regioselective synthesis and antitumor screening of some novel N-phenylpyrazole derivatives

The versatile, hitherto unreported 4-acetyl-5-methyl-1-phenyl-3-phenylcarbamoyl-1H-pyrazole (3) was prepared via the reaction of 2-(2-phenylhydrazono)-2-chloro-N-phenylacetamide with pentan-2,4-dione in the presence of sodium ethoxide. Reaction of 3 with dimethylformamide-dimethylacetal (DMF-DMA) furnished the corresponding 4-[(E)-3-(dimethylamino)acryloyl]-5-methyl-1-phenyl-3-phenylcarbamoyl-1H-pyrazole (5). The latter product underwent regioselective 1,3-dipolar cycloaddition with some nitrilimines to afford the non-isolable dihydropyrazole intermediates which then lose dimethylamine yielding the corresponding pyrazole derivatives. The preliminary screening for the antitumor activity of all newly synthesized compounds was carried out against Ehrlich Ascites Carcinoma tumor cells.     

Design, synthesis and antitumor evaluation of phenyl N-mustard-quinazoline conjugates

A series of N-mustard-quinazoline conjugates was synthesized and subjected to antitumor studies. The N-mustard pharmacophore was attached at the C-6 of the 4-anilinoquinazolines via a urea linker. To study the structure-activity relationships of these conjugates, various substituents were introduced to the C-4 anilino moiety. The preliminary antitumor studies revealed that these agents exhibited significant antitumor activity in inhibiting various human tumor cell growths in vitro. Compounds 21b, 21g, and 21h were selected for further antitumor activity evaluation against human breast carcinoma MX-1 and prostate PC-3 xenograft in animal model. These agents showed 54-75% tumor suppression with low toxicity (5-7% body-weight changes). We also demonstrate that the newly synthesized compounds are able to induce DNA cross-linking through alkaline agarose gel shift assay and inhibited cell cycle arrest at G2/M phase.     

Novel thermosensitive 5-fluorouracil-cyclotriphosphazene conjugates: synthesis, thermosensitivity, degradability, and in vitro antitumor activity

A novel thermosensitive macromolecular prodrug of 5-fluorouracil (5-FU) was synthesized using cyclotriphosphazene, and its thermosensitivity, degradability, and in vitro antitumor activity were studied. A series of alpha-substituted glycine derivatives of 5-FU containing carboxylic groups were prepared, and cyclotriphosphazenes with amino groups were synthesized via the stepwise substitution of hexachlorocyclotriphosphazene (NPCl(2))(3) with methoxy-poly(ethylene glycol) (MPEG) or alkoxy ethylene oxide and lysine ethyl ester (LysOEt). The coupling reaction of the two derivatives, and their subsequent deprotection, yielded a thermosenstive 5-FU-cyclotriphosphazene conjugate, which exhibited a unique octopus-shaped molecular structure, in which the three hydrophilic PEG groups (or alkoxy ethylene oxides) were oriented in one direction, opposing the other three hydrophobic groups containing 5-FU, with respect to the trimer ring plane. This conjugate exhibited a reversible and thermosensitive phase transition in an aqueous medium, from soluble to insoluble states. The lower critical solution temperature (LCST) of the conjugate was controlled by substitution with different hydrophilic/hydrophobic side groups, and a few of the conjugates displayed LCSTs which were just below body temperature. This, of course, implies possible applications for local drug delivery by direct intratumoral injection. The conjugate exhibited gradual degradation at 37 degrees C in both neutral and acidic buffer solutions, and high temperature significantly facilitated its hydrolytic degradation. All of the conjugates displayed dose-dependent cytotoxicity against the leukemia L1210 cell line and exhibited more pronounced cytotoxic effects than did 5-FU.     

Novel angular furoquinolinones bearing flexible chain as antitumor agent: design, synthesis, cytotoxic evaluation, and DNA-binding studies

A series of novel N-substituted angular furoquinolinone derivatives were synthesized and evaluated for their antitumor activities against QGY, K562, HeLa, P388, and A549 cell lines in vitro. The derivatives bearing basic amino side chain showed an improved antitumor activity. Compound 5h N-(2-dimethylamino-ethyl)-2-(4,8,9-trimethyl-2-oxo-2H-furo[2,3-h]quinolin-1-yl)-acetamide exhibited the highest activities against P388 and A549 cell lines, which are evidenced by the IC(50) values that are four to five fold lower than that for unsubstituted parent compound. DNA-binding experiments suggested that these derivatives bind to DNA through intercalation.     

TX-1123: an antitumor 2-hydroxyarylidene-4-cyclopentene-1,3-dione as a protein tyrosine kinase inhibitor having low mitochondrial toxicity

A series of 2-hydroxyarylidene-4-cyclopentene-1,3-diones were designed, synthesized, and evaluated with respect to protein tyrosine kinase (PTK) inhibition, mitochondrial toxicity, and antitumor activity. Our results show that the cyclopentenedione-derived TX-1123 is a more potent antitumor tyrphostin and also shows lower mitochondrial toxicity than the malononitrile-derived AG17, a potent antitumor tyrphostin. The O-methylation product of TX-1123 (TX-1925) retained its tyrphostin-like properties, including mitochondrial toxicity and antitumor activities. However, the methylation product of AG17 (TX-1927) retained its tyrphostin-like antitumor activities, but lost its mitochondrial toxicity. Our comprehensive evaluation of these agents with respect to protein tyrosine kinase inhibition, mitochondrial inhibition, antitumor activity, and hepatotoxicity demonstrates that PTK inhibitors TX-1123 and TX-1925 are more promising candidates for antitumor agents than tyrphostin AG17.