Synthesis and Biological Properties of New Phosmidosine Analogs Having an N-Acylsulfamate Linkage

A new phosmidosine analog 10, in which the proline and 8-oxoadenosine moieties were linked by an N-acyl sulfamate linkage, was successfully synthesized by the sulfamoylation of an 8-oxoadenosine derivative 5 followed by coupling with an L-proline derivative 8. An L-alanine-substituted derivative 13 and its derivative 14 without the alanyl residue were also synthesized. The morphological reversion activity of these synthetic compounds in v-src ^ts NRK cells and their antitumor activity in L1210 and KB cells were studied. As the result, neither L-proline- nor L-alanine-substituted phosmidosine analogs 10 and 13 showed any antitumor activity. Contrary to these results, the derivative 14 lacking the amino acid residue showed potent antitumor activities against cancer cells.     

Synthesis of a biotin-conjugate of phosmidosine O-ethyl ester as a G1 arrest antitumor drug

This paper deals with the synthesis of a stable biotin–phosmidosine conjugate molecule 3 that is required for isolation of biomolecules that bind to phosmidosine (1). It was found that introduction of a biotin residue into the 6-N position of phosmidosine could be carried out by reaction of an N⁷-Boc-7,8-dihydro-8-oxoadenosine derivative 13 with phenyl chloroformate followed by displacement with a diamine derivative 6 along with the simultaneous removal of the Boc group and one of the two phenoxycarbonyl groups and the successive condensation with an N-tritylated biotin derivative 5. The condensation of an N-prolylphosphorodiamidite derivative 4 with an appropriately protected 7,8-dihydro-8-oxoadenosine derivative 17 having the biotin residue gave the coupling product 18, which was deprotected to give the biotin–phosmidosine (O-ethyl ester) conjugate 3.     

Structure-activity relationship of phosmidosine: importance of the 7,8-dihydro-8-oxoadenosine residue for antitumor activity

To study the structure-activity relationship of phosmidosine, a variety of phosmidosine derivatives 9a-g were synthesized by condensation of N-diisopropyl N'-(N-tritylprolyl)phosphorodiamidite 6 with appropriately protected nucleoside derivatives 7a-g. As the result, replacement of the 7,8-dihydro-8-oxoadenine base by adenine and 6-N-acetyladenine did not affect the antitumor activity. However, phosmidosine derivatives containing uracil, cytosine, and guanine in place of the 7,8-dihydro-8-oxoadenine base did not show significant activity. A plausible explanation for the selective expression of phosmidosine compared with that of phosmidosine analogs having other amino acids in place of proline is also discussed. These results suggest that phosmidosine serves as an inhibitor of prolyl adenosine 5'-phosphate (prolyl-AMP) to inhibit the peptide synthesis in cancer-related cells.     

Synthesis of nucleotide antibiotics having N-acyl phosphoramidate linkages.

This paper reports the synthesis of nucleotide antibiotics having N-acyl phosphoramidate linkages. The key reaction, the construction of the N-acyl phosphoramidate linkage was achieved by the reaction of nucleoside 5'-phosphoramidite derivatives with carboxamide derivatives in the presence of 5-(3,5-dinitrophenyl)-1H-tetrazole as a very effective activator. By use of this activator, Phosmidosine was synthesized by condensation of an appropriately protected 8-oxoadenosine 5'-O-phosphoramidite derivative with an N-protected prolinamide derivative. In the case of Agrocin 84, the two P-N bonds were constructed progressively. The N-acyl phosphoramidate linkage at the 5'-position of the ribose moiety was similarly synthesized. After phosphorylation of the amino group of the adenine moiety, a fully protected Agrocin 84 derivative, which would be converted to Agrocin 84, was successfully synthesized.     

Synthesis and biological evaluation of some 17-picolyl and 17-picolinylidene androst-5-ene derivatives

Starting from dehydroepiandrosterone (1) 17-picolyl (2), 17-picolinylidene (7), 17-picolinylidene-16-one (10 and 11), and 17-picolyl-16-one (15) derivatives of androst-5-ene were synthesized in one, two, four and five steps respectively. By the Oppenauer oxidation or dehydration of 2, 7, 10, and 11 with 2,3-dichloro-5,6-dicyano-1,4-benzoquinone (DDQ), the corresponding A and B ring modified derivatives 3, 5, 6, 8, 9, and 12-14 were obtained. The structure of 2 was unambiguously proved by the appropriate X-ray structural analysis. Compounds 3, 5, 9, 12-14 showed inhibitory activity against the enzyme aromatase. Antibacterial activity, toxicity to brine shrimp Artemia salina, antitumor activity against three tumor cell lines (human cervix carcinoma HeLa cells, human melanoma FemX cells, and human myelogenous leukemia K562 cells) and toxicity against peripheral blood mononuclear cells were evaluated. Three tested compounds, namely 11, 13, and 15, showed strong activity against all three cell lines, the IC(50) values being in the range of 4-10 microM.     

Synthesis and properties of new substituted 1,2,4-triazoles: potential antitumor agents

Cycloaddition of the reactive intermediates 4 with 1-(cyanomethyl)benzotriazole (5) and its N-2 isomer 9 furnished, after spontaneous rearrangements, the 1,2,4-triazole derivatives 8 and 10. Analogously, reaction of 4 with ethyl cyanoacetate lead to the 1,3,5-trisubstituted 1,2,4-triazoles 12, which gave on treatment with hydrazine the corresponding hydrazides 13. Treatment of 13d with galactose or phenyl isothiocayanate gave the 1-D-galactose-acylhydrazone 14 and the 1,2,4-triazole derivative 15, respectively. Compounds 8c; 10b,c; 13a,c and 14 were selected for the antitumor screening, whereby 8c, 13a, and 13c showed remarkable activity against leukemia, ovarian, renal and lung cancers (8c with Gl(50) of 0.70 microM, 0.07 microM against leukemia (CCRF-CEM and RPMI-8226), 0.02 microM against ovarian (OVCAR-3) and 0.60 microM against renal (CARKI-1) and lung cancers, respectively).     

Synthesis of derivatives of NK109, 7-OH benzo[c]phenanthridine alkaloid, and evaluation of their cytotoxicities and reduction-resistant properties

The N5-C6 double bond of NK109 (an antitumor benzo[c]phenanthridine alkaloid) is easily reduced under biological environment. To suppress the inactivation caused by reduction, we synthesized 5-, 6-, and 8-substituted NK109. 5-Substituted derivatives (4a-c) were reduced more easily than NK109. 6-Substituted ones (10a-f) inhibited biological reduction, but showed weak cytotoxic activity. 8-O-Substituted ones (13a-h), especially 8-O-hydroxyethyl NK109 (13d), suppressed biological reduction and exhibited strong cytotoxic activity.     

Synthesis and Antitumor Activity of Panaxadiol Pyrazole and Isooxazole Derivatives

In this study, we designed and synthesized 19 nitrogen-containing heterocyclic derivatives of panaxadiol (PD). We first reported the antiproliferative activity of these compounds against four different tumor cells. The results of the MTT assay showed that the PD pyrazole derivative (compound 12b ) had the best antitumor activity and could significantly inhibit the proliferation of four tested tumor cells. For A549 cells, the IC₅₀ value was as low as 13.44±1.23 μM. Western blot analysis showed that the PD pyrazole derivative was a bifunctional regulator. On the one hand, it can down-regulate the expression of HIF-1α by acting on PI3 K/AKT signaling pathway in A549 cells. On the other hand, it can induce the decrease of CDKs protein family and E2F1 protein expression levels, thus playing a crucial role in cell cycle arrest. According to the results of molecular docking, we found that multiple hydrogen bonds were formed between the PD pyrazole derivative and two related proteins, and the docking score of the derivative was also significantly higher than that of the crude drug. In summary, the study of the PD pyrazole derivative laid a foundation for the development of ginsenoside as an antitumor agent.     

6-Acyl-4-aryl/alkyl-5,7-dihydroxycoumarins as anti-inflammatory agents

A series of coumarin derivatives were synthesized in two steps from phloroglucinol. The anti-inflammatory activities of these derivatives were evaluated by means of inhibiting NO production in LPS-induced RAW 264.7 cells. Derivatives 3, 8, 10, 11, and 13 exhibited low micromolar levels of anti-inflammatory activities, and these derivatives also protected DNA against hydroxyl radical attack. Coumarin derivative 8 was the most potent derivative among those tested herein against NO production in LPS-induced RAW 264.7 cells with an IC(50) value of 7.6 microM, and it effectively reduced the hydroxyl radical production by 50% at 100 microM in the electron spin resonance study.     

Design, synthesis and antitumor evaluation of novel thalidomide dithiocarbamate and dithioate analogs against Ehrlich ascites carcinoma-induced solid tumor in Swiss albino mice

A series of 16 novel thalidomide sulfur analogs containing one and two sulfur atoms 2 and 4-18, respectively, were designed and synthesized. These compounds were screened for in vitro antitumor activity against Ehrlich ascites carcinoma (EAC) cell line and exhibited potent cytotoxic activity. On the bases of the obtained results for in vitro cytotoxic activity, thalidomide sulfur analogs containing two sulfur atoms 8, 9, 13 and 14 were selected and tested in vivo against EAC-induced solid tumor in female mice compared to thalidomide 1 as well as its analog 2 and exhibited a highly significant reduction in tumor volume (TV). Results illustrated the antioxidative activity of these compounds as the level of hepatic lipid peroxidation decreased and levels of antioxidant enzymes like superoxide dismutase (SOD) and catalase were elevated. The histopathological investigations revealed that thalidomide sulfur analogs 2, 8, 9, 13 and 14 have antimitotic, apoptotic and necrotic activities against solid tumor. These compounds lead to increase of Fas-L expression. The immunohistochemical studies showed a decrease in Ki67 and vascular endothelial growth factor (VEGF) staining in tumor cells from treated-animals when compared with non-treated groups, which suggests an inhibition of tumor proliferation rate and angiogenic process associated with tumor growth. Compounds 9 and 13 were the most potent compounds in tumor necrosis without liver necrosis. At the same time, treatment with compound 9 resulted in liver degeneration.     

Preparation of chitosan-copper complexes and their antitumor activity

Copper complexes of chitosan have been synthesized. Complexes with different copper to chitosan ratios were tested in vitro as potential antitumor agents with 293 cells and HeLa cells. At the ratio of 0.11 mol copper per one chitosan residue, the complex exhibited a higher antitumor activity and less toxicity than other copper-chitosan complexes tested. In addition, this study showed that copper-chitosan complex inhibited tumor cell proliferation by arresting the cell cycle progression at the S phase in 293 cells.     

Synthesis and antitumor activity of β-carboline 3-(substituted-carbohydrazide) derivatives

A series of β-carboline derivatives bearing a substituted-carbohydrazide moiety at C-3 were synthesized and evaluated for their antitumor activity against eight human cancer cell lines. The β-carboline N-(substituted-benzylidene)carbohydrazides showed, in general, a greater antitumor activity than their N-(alkylidene)carbohydrazide analogues. The N(9)-methylation of β-carboline N-(substituted-benzylidene) carbohydrazides resulted in a decrease of antitumor activity. Among compounds tested, the benzylidene-carbohydrazides 3, 4, 11, 13, 16, 21 and 22 were the most active, possessing IC(50) less than 10 μM for six of the eight tumor cell lines assayed. The derivative 4 displayed the most significant activity toward all tested cell lines, with a remarkable cytotoxicity against renal (786-0) cell lines (IC(50)=0.04 μM). Compound 4 was assayed for its in vivo antineoplastic activity in the Ehrlich solid carcinoma assay.     

Synthesis and biological activities of 2'-deoxy-2'-fluoro-4'-thioarabinofuranosylpyrimidine and -purine nucleosides

As part of our ongoing investigation of the synthesis of biologically interesting 2'-modified-4'-thionucleosides, we synthesized 2'-deoxy-2'-fluoro-4'-thioarabinofuranosylpyrimidine and -purine nucleosides, and evaluated their antiviral and antitumor activities. In the pyrimidine series, beta-anomers of 5-ethyluracil, 5-iodouracil, 5-chloroethyluracil, and 5-iodocytosine derivatives showed potent and selective anti-HSV-1 and HSV-2 activities in vitro. In the purine series, guanine and 2,6-diaminopurine derivatives showed prominent antiviral activities with slight cytotoxicity. On the other hand, the 5-fluorocytosine derivative (5F-4'-thioFAC) showed potent antitumor activity against both leukemia and solid tumor. Its antitumor spectrum against 14 human solid tumor and one leukemic cell lines was compared with that of 4'-thioFAC. The results showed that 5F-4'-thioFAC had an antitumor spectrum similar to that of 4'-thioFAC. However, 5F-4'-thioFAC was about 10 times less active than 4'-thioFAC.     

Synthesis and properties of new rubomycin derivatives

Condensation of rubomycin (daunorubicin) with respective hydrazides yielded novel substituted hydrazones: 13-cyanoacetyl hydrazone rubomycin, 13-L-phenylalanyl hydrazone rubomycin, 13-BOC-3-(uracilyl-1)-DL-alanyl hydrazone rubomycin and 13-BOC-3-(adenylyl-9)-DL-alanyl hydrazone rubomycin. With successive treatment of rubomycin with hydrazine hydrate and respective ketones novel asymmetric azines were prepared: 13-cyclopentylidene hydrazone rubomycin, 13-alpha,alpha'-dimethyl-cyclopentylidene hydrazone rubomycin and 13-(1-phenylethylidene-1) hydrazone rubomycin. 14-Adenylyl-N9-rubomycin was synthesized by interaction of 14-bromorubomycin with adenine and hydrogenation of its analog, 14-N-imidazolyl rubomycin by sodium borhydrite yielded 13-dihydro-14-N-imidazolyl rubomycin. There was observed correlation between the antimicrobial activity of the derivatives against B. mycoides and their cytostatic effect on the cells of murine leukemia NK/LI. The high in vitro activity of 13-cyclopentylidene hydrazone rubomycin showed satisfactory correlation with the results of the study on the antitumor effect in animals.     

Synthesis of OSW saponin analogs with modified sugar residues and their antiproliferative activities

Eight monosaccharide analogs of the potent antitumor OSW saponins (2-9) were synthesized. One analog, 2-O-acetyl-alpha-l-arabinopyranoside 3, showed antiproliferative activity against the Jurkat cells (IC(50)=0.078microM) comparable to that of the disaccharide derivative (1).     

Antitumor activity of amides of dihydrobetulonic acid in vitro and in vivo

Amides containing homopiperidine and piperazine cycles were synthesized from dihydrobetulonic acid obtained by the oxidation of dihydrobetulin. All substances were shown to have a high antitumor activity (CCID₅₀ = 3.5–36.2 μM) in vitro in lymphoid (CEM-13, U-937) and monocytic (MT-4) human cell lines. Amides containing the methyl- and ethylpiperazine residues do not influence the viability of Lung Lewis Carcinoma cells in culture and do not have a significant effect on its transplants in C57BL/6 mice. However, these amides efficiently inhibit the development of metastases in lungs of these mice. The antimetastatic activity of the studied amides increases with changing the methyl by ethyl aliphatic residue in the piperazine cycle.     

Increased antibacterial activity of 15-residue murine lactoferricin derivatives.

LFM W8 is a synthetic 15-residue lactoferricin derivative (H2N-EKCLRWQWEMRKVGG-COOH), corresponding to residues 16-30 of the mature murine lactoferrin protein except that the asparagine residue in position 8 of the native peptide is replaced with tryptophan. We have previously reported that the two tryptophan residues in positions 6 and 8 are of crucial importance for the antibacterial activity of many lactoferricin derivatives but, despite fulfilling this requirement, LFM W8 is inactive against Escherichia coli and Staphylococcus aureus. In order to solve this puzzle, a quantitative structure-antibacterial activity relationship study of synthetic LFM W8 derivatives was performed by replacing the glutamate residues in positions 1 and 9 with arginine or alanine, and the valine residue in position 13 with tyrosine. The results from the study were analyzed using multivariate data analysis. The derived mathematical model clustered the peptides into distinct groups which reflected their antibacterial activities, pointed out correlations between different structural parameters, highlighted the structural parameters that were important for antibacterial activity, and enabled us to predict the activity of a 15-residue bovine lactoferricin derivative. The results showed that net charge and micelle affinity, as determined from the ratio of alpha-helicity in sodium dodecyl sulfate micelles and in 1,1,1,3,3,3-hexafluoro-2-propanol, were the most important structural parameters affecting antibacterial activity. The most active derivative, LFM R1,9 W8 Y13, displayed a minimal inhibitory concentration of 10 and 12 microM against E. coli and S. aureus, respectively. This represented more than 50-fold and 40-fold increases in antibacterial activity, respectively, compared with LFM W8.     

Synthesis and biological evaluation of cryptophycin analogs with substitution at C-6 (fragment C region)

Analogs of the antitumor agents cryptophycins 1 and 8 with dialkyl substitution at C-6 (fragment C) were synthesized and evaluated for in vitro cytotoxicity against human leukemia cells (CCRF-CEM). The activity of these analogs decreased as the size of the substituents at C-6 increased. The C-6 spirocylopropyl compound (2g) was highly potent in vitro and showed excellent antitumor activity in animal models.     

The C8 side chain is one of the key functional group of Garcinol for its anti-cancer effects

Garcinol from the fruit rind of Garcinia indica shows anti-carcinogenic and anti-inflammatory properties, but its mechanism and key functional groups were still need to be identified. Our previous computer modeling suggested that the C8 side chain of Garcinol is so large that it may influence the bioactivity of the compound. 8-Me Garcinol, a derivative of Garcinol in which the bulky side chain at the C8 position of Garcinol is replaced with a much smaller methyl group, was synthesized through a 12-step procedure starting from 1,3-cyclohexanedione. The antitumor activity of Garcinol and 8-Me Garcinol was evaluated in vitro by MTT, cell cycle and cell apoptosis assays. The results showed that 8-Me Garcinol had weaker inhibitory activity on cells proliferation, and little effects on cell cycle and apoptosis in oral cancer cell line SCC15 cells when compared with Garcinol. All of the results indicated 8-Me Garcinol exerts weaker antitumor activity than Garcinol, and the C8 side chain might be an important active site in Garcinol. Changing the C8 side chain will affect the inhibitory effect of Garcinol.