Synthesis and in vitro antitumoral activity of new hydrazinopyrimidine-5-carbonitrile derivatives

A new series of 2-amino-6-(2-alkyl or arylidenehydrazinyl)-4-(dialkylamino)pyrimidine-5-carbonitriles, 5-24, were synthesized in satisfactory overall yield, using 2-amino-4-(dialkylamino)-6-hydrazino-5-pyrimidinecarbonitriles 3, 4, as key intermediates, by applying classical synthetic methods to construct the hydrazone moiety at C-6 of the pyrimidine ring. Hydrazinopyrimidine derivatives 5-24 were evaluated for their in vitro anticancer activity toward cell lines of nine different types of human cancers. Some of the newly prepared compounds demonstrated inhibitory effects on the growth of a wide range of cancer cell lines generally at 10(-5)M level and in some cases at 10(-7)M concentrations.     

Synthesis and in vitro antitumoral activity of new N-phenyl-3-pyrrolecarbothioamides

A new series of N-phenylpyrrolecarbothioamides were obtained from base catalyzed intramolecular cyclization of 3-amino-3-(alkyl or arylamino)propenethioamides. Pyrrole derivatives were evaluated for their in vitro anticancer activity toward cell lines of nine different types of human cancer. Some of newly prepared compounds demonstrated inhibitory effects on the growth of a wide range of cancer cell lines generally at 10(-6) M level and in some case at 10(-8) M concentrations.     

Structure-activity relationship in the antitumor activity of 6-, 8- or 6,8-substituted 3-benzylamino-β-carboline derivatives

We synthesized 47 kinds of 3-amino- or 3-benzylamino-β-carboline derivatives with a substituent on the 6-, 8-, or 6,8-carbon atoms and evaluated their antitumor activities for Hela S-3 and Sarcoma 180 cell lines using a 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide assay. Consequently, we succeeded to develop 3-benzylamino-8-methylamino-β-carboline (17a) and 8-methylamino-3-(3-phenoxybenzyl)amino-β-carboline (17c) with antitumor activity with IC(50) values of 0.046, 0.032 μM, respectively, against HeLa S-3 cell line, which are higher than that of previously reported 3-(3-phenoxybenzyl)amino-β-carboline (10e) of 0.074 μM. Furthermore, effects of Cl group at 6-carbon atom on the type of cell death was evaluated using 3-benzylamino-6-chloro-β-carboline (10b), 3-benzylamino-β-carboline (10d), N-(3-benzylamino)-6-chloro-9H-β-carbolin-8-yl)benzamide (14g), and N-(3-benzylamino-9H-β-carbolin-8-yl)benzamide (17b) to show no effect. Hoechst 33342 staining and DNA fragmentation assay suggested that these compounds induced cell death by apoptosis. In addition, using flow cytometry analysis, we established that the cell death pathway was through the arrest of the cell cycle in the G(2)/M phase.     

The PIKfyve–ArPIKfyve–Sac3 triad in human breast cancer: Functional link between elevated Sac3 phosphatase and enhanced proliferation of triple negative cell lines

The phosphoinositide 5-kinase PIKfyve and 5-phosphatase Sac3 are scaffolded by ArPIKfyve in the PIKfyve–ArPIKfyve–Sac3 (PAS) regulatory complex to trigger a unique loop of PtdIns3P–PtdIns(3,5)P₂ synthesis and turnover. Whereas the metabolizing enzymes of the other 3-phosphoinositides have already been implicated in breast cancer, the role of the PAS proteins and the PtdIns3P–PtdIns(3,5)P₂ conversion is unknown. To begin elucidating their roles, in this study we monitored the endogenous levels of the PAS complex proteins in cell lines derived from hormone-receptor positive (MCF7 and T47D) or triple-negative breast cancers (TNBC) (BT20, BT549 and MDA-MB-231) as well as in MCF10A cells derived from non-tumorigenic mastectomy. We report profound upregulation of Sac3 and ArPIKfyve in the triple negative vs. hormone-sensitive breast cancer or non-tumorigenic cells, with BT cell lines showing the highest levels. siRNA-mediated knockdown of Sac3, but not that of PIKfyve, significantly inhibited proliferation of BT20 and BT549 cells. In these cells, knockdown of ArPIKfyve had only a minor effect, consistent with a primary role for Sac3 in TNBC cell proliferation. Intriguingly, steady-state levels of PtdIns(3,5)P₂ in BT20 and T47D cells were similar despite the 6-fold difference in Sac3 levels between these cell lines. However, steady-state levels of PtdIns3P and PtdIns5P, both regulated by the PAS complex, were significantly reduced in BT20 vs. T47D or MCF10A cell lines, consistent with elevated Sac3 affecting directly or indirectly the homeostasis of these lipids in TNBC. Together, our results uncover an unexpected role for Sac3 phosphatase in TNBC cell proliferation. Database analyses, discussed herein, reinforce the involvement of Sac3 in breast cancer pathogenesis.     

Discovery of 5-substituted 2-amino-4-chloro-8-((4-methoxy-3,5-dimethylpyridin-2-yl)methyl)-7,8-dihydropteridin-6(5H)-ones as potent and selective Hsp90 inhibitors

A new series of compounds, 5-substituted 2-amino-4-chloro-8-((4-methoxy-3,5-dimethylpyridin-2-yl)methyl)-7,8-dihydropteridin-6(5H)-ones, have been designed and identified as potent and selective inhibitors of Hsp90. These compounds demonstrated nanomolar potency toward both Hsp90-regulated Her2 degradation and the growth of a panel of human tumor cell lines in cell-based assays. High selectivity of these compounds toward Hsp90 was evident given that they did not inhibit a panel of 34 kinases at 10 μM. The structure–activity relationship (SAR) of this series is reported here.     

Estrogenic and anti-estrogenic compounds from the Thai medicinal plant, Smilax corbularia (Smilacaceae)

From the rhizomes of Smilax corbularia Kunth. (Smilacaceae), 11 compounds, (2R,3R)-2″-acetyl astilbin, (2R,3R)-3″-acetyl astilbin, (2R,3R)-4″-acetyl astilbin, (2R,3R)-3″-acetyl engeletin, (2R,3S)-4″-acetyl isoastilbin, 2-(4-hydroxyphenyl)-3,4,9,10-tetrahydro-3,5-dihydroxy-10-(3,4-dihydroxyphenyl)-(2R,3R,10R)-2H,8H-benzo [1,2-b:3,4-b′] dipyran-8-one, 2-(4-hydroxyphenyl)-3,4,9,10-tetrahydro-3,5-dihydroxy-10-(3,4-dihydroxyphenyl)-(2R,3R,10S)-2H, 8H-benzo [1,2-b:3,4-b′] dipyran-8-one, 3,4-dihydro-7-hydroxy-4-(3,4-dihydroxyphenyl)-5-[(1E)-2-(4-hydroxyphenyl) ethenyl]-2H-1-benzopyran-2-one, 3,4-dihydro-7-hydroxy-4-(3,4-dihydroxy-phenyl)-5-[(1E)-2-(3,4-dihydroxyphenyl) ethenyl]-2H-1-benzopyran-2-one, 3,4-dihydro-7-hydroxy-4-(4-hydroxy-3-methoxyphenyl)-5-[(1E)-2-(4-hydroxyphenyl) ethenyl]-2H-1-benzopyran-2-one, and 5,7,3′,4′-tetrahydroxy-3-phenylcoumarin along with 34 known compounds were isolated and characterized as 19 flavonoids, 14 catechin derivatives, 6 stilbene derivatives, and 6 miscellaneous substances. All isolates had their estrogenic and anti-estrogenic activities determined using the estrogen-responsive human breast cancer cell lines MCF-7 and T47D. The major constituents were recognized as flavanonol rhamnosides by the suppressive effect on estradiol induced cell proliferation at a concentration of 1 μM. Meanwhile, flavanonol rhamnoside acetates demonstrated estrogenic activity in both MCF-7 and T47D cells at a concentration of 100 μM, and they enhanced the effects of co-treated E2 on T47D cell proliferation at concentrations of more than 0.1 μM.     

Synthesis of novel 3,5-diaryl pyrazole derivatives using combinatorial chemistry as inhibitors of tyrosinase as well as potent anticancer,anti-inflammatory agents

In the present article, we have synthesized a combinatorial library of 3,5-diaryl pyrazole derivatives using 8-(2-(hydroxymethyl)-1-methylpyrrolidin-3-yl)-5,7-dimethoxy-2-phenyl-4H-chromen-4-one (1) and hydrazine hydrate in absolute ethyl alcohol under the refluxed conditions. The structures of the compounds were established by IR, ¹H NMR and mass spectral analysis. All the synthesized compounds were evaluated for their anticancer activity against five cell lines (breast cancer cell line, prostate cancer cell line, promyelocytic leukemia cell line, lung cancer cell line, colon cancer cell line) and anti-inflammatory activity against TNF-α and IL-6. Out of 15 compounds screened, 2a and 2d exhibited promising anticancer activity (61–73% at 10 μM concentration) against all selected cell lines and IL-6 inhibition (47% and 42% at 10 μM concentration) as in comparison to standard flavopiridol (72–87% inhibition at 0.5 μM) and dexamethasone (85% inhibition at 1 μM concentration), respectively. Cytotoxicity of the compounds checked using CCK-8 cell lines and found to be nontoxic to slightly toxic. Out of 15, four 3,5-diaryl pyrazole derivatives exhibiting potent inhibitory activities against both the monophenolase and diphenolase actions of tyrosinase. The IC₅₀ values of compounds (2a, 2d, 2h and 2l) for monophenolase inhibition were determined to range between 1.5 and 30 μM. Compounds 2a, 2d, 2h and 2l also inhibited diphenolase significantly with IC₅₀ values of 29.4, 21.5, 2.84 and 19.6 μM, respectively. All four 3,5-diaryl pyrazole derivatives were active as tyrosinase inhibitors (2a, 2d, 2h and 2l), and belonging to competitive inhibitors. Interestingly, they all manifested simple reversible slow-binding inhibition against diphenolase.     

Synthesis of two novel thioacridinic derivatives and comparison of their in vitro biological activities.

Two novel compounds, 3-amino-9-(diethylaminoethylthio) acridine and 9-diethylaminoethylthioacridine, were synthesized and characterized. They were shown to be cytotoxic against K562 and Raji cell lines. A concentration of 10(-5) M killed around 40% of the cells after 3 h time of incubation. Intercalation into DNA was more efficient when a protonated nitrogen was present in a side chain of the ring system. At the cytotoxic concentrations (10(-5) M, 10(-6) M), inhibition of nucleic acid synthesis in K562, Raji cell lines and human leukocytes has been shown. The results presented suggest that the cytotoxicity and the inhibition of nucleic acid synthesis of the two compounds studied are inversely related to their intercalating capability into the DNA helix.     

Cytotoxicities, cell cycle and caspase evaluations of 1,6-diaryl-3(Z)-hexen-1,5-diynes, 2-(6-aryl-3(Z)-hexen-1,5-diynyl)anilines and their derivatives

Compounds 3, 6-7, 9-10, 15-17, and 20-21 showed growth inhibition effects on a full panel of 60 human cancer cell lines, and most of the average IC50 values of the indicated analogues were from < 0.01 to 96.6 microM, in which analogues 16 and 17 revealed the highest cytotoxic activity with the cancer cell lines at 10(-7) M concentration range. During the cell cycle analysis, a moderate to high apoptotic progress induction was shown by 3, 9, 16-17, and 20 compared with the control, which 2-(6-(2-thienyl)-3(Z)-hexen-1,5-diynyl)aniline 16 showed the highest apoptotic effect. Structures 16-17 displayed a significant G2/M phase arrest in the cell growth cycle compared with other derivatives, which the proportions of the G2/M phase cells were accumulated to 71.5% and 82.6%, respectively. Moreover, the colorimetric assay of 16-17 also provided advanced evidence to the relationship between the compounds and the caspase-3 enzyme, which was one of the major promoters of apoptotic effect.     

Synthesis and cytotoxicity of 3,4-diaryl-2(5H)-furanones

A series of 3,4-diaryl-2(5H)-furanone derivatives were synthesized and evaluated for their cytotoxicity in a small panel of cancer cell lines. Four out of 10 compounds in this series, for example 3-(3,4,5-trimethoxyphenyl)-4-(4-methoxyphenyl)-, 3-(3,4,5-trimethoxyphenyl)-4-(3-hydroxy-4-methoxyphenyl)-, 3-(3,4,5-trimethoxyphenyl)-4-(3-amino-4-methoxyphenyl)-, and 3-(3,4,5-trimethoxyphenyl)-4-(2-naphthyl)-2(5H)-furanones, were found to have potent cytotoxic activities with ED50 values of less than 20 nM in most of the cell lines tested.     

Effects of 1,25-dihydroxyvitamin D3 on cell-cycle kinetics of T 47D human breast cancer cells

The replication of several human and animal cancer cell lines is regulated in vitro and in vivo by 1,25-dihydroxyvitamin D3 [1,25-(OH)2D3], the hormonally active form of vitamin D3. We have examined the effects of concentrations of 1,25-(OH)2D3, which inhibit cellular replication, on the cell-cycle kinetics of a 1,25-(OH)2D3-responsive human breast cancer cell line, T 47D. After 6 or 7 days of treatment, a time period representing approximately five cell population doublings of control cultures, concentrations of 1,25-(OH)2D3 in the range 10(-9) M to 10(-6) M caused a time- and concentration-dependent decrease in cell numbers. Treatment of cells growing in charcoal-treated fetal calf serum with 10(-8) M 1,25-(OH)2D3 for 6 days reduced cell numbers to 49% +/- 9% (n = 9) of control, and this was associated with a marked increase in the proportion of cells in the G2 + M phase of the cell cycle from 9.7% +/- 0.5% (n = 11) to 19.6% +/- 2.3% (n = 9), significant by paired analysis (P less than 0.002). At higher concentrations of 1,25-(OH)2D3 (10(-7)-10(-6) M), there was a concentration-dependent decline in S phase and increases in both G0/G1 and G2 + M phase cells. Detailed analysis of the temporal changes in cell-cycle phase distribution following treatment with 2.5 X 10(-8) and 10(-7) M 1,25-(OH)2D3 showed an initial accumulation of cells in G0/G1 and depletion of S phase cells during the first 24 hr of treatment. This decline in S phase cells was not accompanied by a decline in % G2 + M indicating a transition delay in G2 or mitosis. At the lower dose these changes returned to control values at 48 hr and at later times were associated with a slight but consistent decline in G0/G1 phase and an increase in G2 + M. In contrast cells treated with 10(-7) M 1,25-(OH)2D3 had significantly elevated % G0/G1 cells at days 2 and 3, consistent with a transition delay through G1 phase. This was confirmed in stathmokinetic experiments which demonstrated an approximate sevenfold decrease in the rate of exit of cells from G0/G1 following 4 days of exposure to 10(-7) M 1,25-(OH)2D3. This accumulation of cells in G0/G1 was accompanied by a fall in % S phase cells.(ABSTRACT TRUNCATED AT 400 WORDS)     

1,25-Dihydroxyvitamin D3 and the regulation of human cancer cell replication

Several human and animal cancer cell lines have been shown to possess specific high affinity receptors for 1,25-dihydroxyvitamin D3 (1,25-(OH)2D3). The replication of several of these cell types has also been shown to be regulated by this hormone, both in vitro and in vivo. To further understand the mechanisms of these actions, we have examined cancer cells in vitro and in vivo. The in vitro studies extend our previous reports on the treatment of human breast cancer cells (T 47D) with 10(-9) to 10(-6) M 1,25-(OH)2D3, which resulted in a dose- and time-dependent decrease in cell numbers over 6 days. Treatment with 10(-8) M 1,25-(OH)2D3, which reduced cell numbers to approximately one half of those found in control cultures at 6 days, was associated with a doubling of the proportion of cells in the G2 + M phase of the cell cycle and was accompanied by a significant decline in the proportion of G0/G1 cells. At higher concentrations there was a significant decline in S phase cells with accumulation of cells in both G0/G1 and G2 + M phases. The antiestrogen, tamoxifen, at a concentration which caused similar effects on cell number, resulted in proportional decreases in both S and G2 + M phase cells and accumulation of G0/G1 cells. The effects of 1,25-(OH)2D3 on T 47D cell proliferation were associated with time- and concentration-dependent reductions in epidermal growth factor receptor levels to a minimum level of about half that seen in control cultures. The in vivo experiments extend our previous studies, which demonstrated marked inhibition of the growth of human cancer xenografts in immunosuppressed mice by 1,25-(OH)2D3. Xenograft growth was inhibited with 1,25-(OH)2D3 (0.1 microgram ip three times per week) but growth was rapidly restored when the 1,25-(OH)2D3 was withdrawn. Thus, there are clear-cut time- and dose-dependent, yet reversible, effects of 1,25-(OH)2D3 on the replication of human cancer cells in vitro and in vivo, which are possibly mediated through changes in growth factor receptor levels. Further study of these effects may advance understanding of the hormonal control of cellular replication in human cancers.     

Estrogenic constituents of the heartwood of Dalbergia parviflora

From the heartwood of Dalbergia parviflora, five compounds, dalparvin A (1), B (2), C (3), dalparvinol C (4), and neokhriol A (5), along with 11 known compounds, kenusanone G (6), cajanin (7), sophorol (8), alpinetin (9), hesperetin (10), 3'-O-methylorobol, odoratin, (2R)(3R)-2,3-trans 7-hydroxy-5-methoxydihydroflavonol, (6aR, 11aR)-3,8-dihydroxy-9-methoxypterocarpan, (6aR, 11aR)- vesticarpan, and methyl-3,4-dihydroxy-2-methoxybenzoate were isolated and characterized. Isolates were evaluated for their cell proliferation stimulatory activity against MCF-7, T-47D, and BT20 human breast cancer cell lines. Along with 7-10, two compounds 2 and 3 stimulated not only MCF-7, but also T-47D human breast cancer cell proliferation. Compound 6 had activity only against MCF-7 cells, and the activity of 7 was more than equivalent to that of daidzein. On the other hand, none of the isolates had any significant effects on BT20 cell proliferation, and these results indicated that the stimulative activity of these compounds was not general to any cell proliferations. Furthermore, these compounds were tested in the estrogen-responsive transient luciferase reporter assay.     

Characterization and detection of lysine-arginine cross-links derived from dehydroascorbic acid

Covalently cross-linked proteins are among the major modifications caused by the advanced Maillard reaction. So far, the chemical nature of these aggregates is largely unknown. L-dehydroascorbic acid (DHA, 5), the oxidation product of L-ascorbic acid (vitamin C), is known as a potent glycation agent. Identification is reported for the lysine-arginine cross-links N6-[2-[(4-amino-4-carboxybutyl)amino]-5-(2-hydroxyethyl)-3,5-dihydro-4H-imidazol-4-ylidene]-L-lysine (9), N6-[2-[(4-amino-4-carboxybutyl)amino]-5-(1,2-dihydroxyethyl)-3,5-dihydro-4H-imidazol-4-ylidene]-L-lysine (11), and N6-[2-[(4-amino-4-carboxybutyl)amino]-5-[(1S,2S)-1,2,3-trihydroxypropyl]-3,5-dihydro-4H-imidazol-4-ylidene]-L-lysine (13). The formation pathways could be established starting from dehydroascorbic acid (5), the degradation products 1,3,4-trihydroxybutan-2-one (7, L-erythrulose), 3,4-dihydroxy-2-oxobutanal (10, L-threosone), and L-threo-pentos-2-ulose (12, L-xylosone) were proven as precursors of the lysine-arginine cross-links 9, 11, and 13. Products 9 and 11 were synthesized starting from DHA 5, compound N6-[2-[(4-amino-4-carboxybutyl)amino]-5-[(1S,2R)-1,2,3-trihydroxypropyl]-3,5-dihydro-4H-imidazol-4-ylidene]-L-lysine (16) via the precursor D-erythro-pentos-2-ulose (15). The present study revealed that the modification of lysine and arginine side chains by DHA 5 is a complex process and could involve a number of reactive carbonyl species.     

2''-Deoxy-3,7-dideazaguanosine and related compounds. Synthesis of 6-amino-1-(2-deoxy-beta-D-erythro-pentofuranosyl) and 1-beta-D-arabinofuranosyl-1H-pyrrolo[3,2-c]pyridin-4(5H)-one via direct glycosylation of a pyrrole precursor.

The synthesis of two new analogs of 2'-deoxyguanosine, 6-amino-1-(2-deoxy-beta-D-erythro-pentofuranosyl)-1H-pyrrolo[3,2-c] pyridin-4(5H)-one (8) and 6-amino-1-beta-D-arabinofuranosyl-1H-pyrrolo[3,2-c]-pyridin-4(5H)-one (13) has been accomplished by glycosylation of the sodium salt of ethyl 2-cyanomethyl-1H-pyrrole-3-carboxylate (4c) using 1-chloro-2-deoxy-3,5-di-O-p-toluoyl-alpha-D-erythro-pentofuranose( 5) and 1-chloro-2,3,5-tri-O-benzyl-alpha-D-arabinofuranose (9), respectively. The resulting blocked nucleosides, ethyl 2-cyanomethyl-1-(2-deoxy-3,5-di-O-p-toluoyl-beta-D-erythro- pentofuranosyl)-1H-pyrrole-3-carboxylate (6) and ethyl 2-cyanomethyl-1-(2,3,5-tri-O-benzyl-beta-D-arabinofuranosyl)- 1H-pyrrole-3-carboxylate, were ring closed with hydrazine to form 5-amino-6-hydrazino-1-(2-deoxy-beta-D-erythro-pentofuranosyl)-1H- pyrrolo[3,2-c]-pyridin-4(5H)-one (7) and 5,6-diamino-1-(2,3,5-tri-O-benzyl-beta-D-arabinofuranosyl)-1H- pyrrolo[3,2-c]pyridin-4(5H)-one (11), respectively. Treatment of 7 with Raney nickel provided the 2'-deoxyguanosine analog 8 while reaction of 11 with Raney nickel followed by palladium hydroxide/cyclohexene treatment gave the 2'-deoxyguanosine analog 13. The anomeric configuration of 8 was assigned as beta by proton NMR, while that of 13 was confirmed as beta by single-crystal X-ray analysis of the deblocked precursor ethyl 2-cyanomethyl-1-beta-D-arabinofuranosyl-1H-pyrrole-3-carboxylate (10a).     

Facile one-pot synthesis,antiproliferative evaluation and structure-activity relationships of 3-amino-1H-indoles and 3-amino-1H-7-azaindoles

A highly efficient method has been developed for the one-pot synthesis of substituted 3-amino-1H-indole and 3-amino-1H-7-azaindole derivatives starting from ethyl 2-cyanophenylcarbamate/ethyl 3-cyanopyridin-2-ylcarbamate, and α-bromoketones in good to excellent yields. All newly synthesized analogues were screened for their antiproliferative activities against four cancer cell lines. The most promising compound 8v demonstrated 13-, 5-, and 1.4-fold improvement compared to fluorouracil in inhibiting HeLa, HepG2, and MCF-7 cell proliferation with IC₅₀ values of 3.7, 8.0, and 19.9 μM, respectively. Furthermore, 8v induced significant cell cycle arrest at the G₂/M phase in HeLa cell lines via a concentration-dependent manner. These encouraging findings indicate that the common 3-amino-1H-7-azaindole is a very favorable scaffold for the design of novel anticancer small-molecule drugs.     

Synthesis, X-ray crystal structural study, antiviral and cytostatic evaluations of the novel unsaturated acyclic and epoxide nucleoside analogues

A series of the novel purine and pyrimidine nucleoside analogues were synthesised in which the sugar moiety was replaced by the 4-amino-2-butenyl (2-6 and 10-18) and oxiranyl (8 and 20) spacer. The Z- (2-6) and E-isomers (10-18) of unsaturated acyclic nucleoside analogues were synthesized by condensation of 2- and 6-substituted purine and 5-substituted uracil bases with Z- (1) or E-phthalimide (9) precursors. The oxiranyl nucleoside analogues (8 and 20) were obtained by epoxidation of 1 and 9 with m-chloroperoxybenzoic acid and subsequent coupling with adenine. The new compounds were evaluated for their antiviral and antitumor cell activities. Among the olefinic nucleoside analogues, Z-isomer of adenine containing 4-amino-2-butenyl side chain (6) exhibited the best cytostatic activities, particularly against colon carcinoma (SW 620, IC50 = 26 microM). Its E-isomer 15 did not show any antiproliferative activity against malignant tumor cell lines, except for a slight inhibition of colon carcinoma (SW 620, IC50 = 56.5 microM) cells. In general, Z-isomers showed better cytostatic activities than the corresponding E-isomers. (Z)-4-Amino-2-butenyl-adenine nucleoside analogue 6 showed albeit modest but selective activity against HIV-1 (EC50 = 4.83 microg mL(-1)).     

Synthesis of 1-(2-deoxy-beta-D-ribofuranosyl)-2,4-difluoro-5-substituted-benzene thymidine mimics, some related alpha-anomers, and their evaluation as antiviral and anticancer agents

A group of unnatural 1-(2-deoxy-beta-D-ribofuranosyl)-2,4-difluorobenzenes having a variety of C-5 substituents (H, Me, F, Cl, Br, I, CF3, CN, NO2, NH2), designed as thymidine mimics, were synthesized for evaluation as anticancer and antiviral agents. The coupling reaction of 3,5-bis-O-(p-chlorobenzoyl)-2-deoxy-alpha-D-ribofuranosyl chloride with an organocadmium reagent [(2,4-difluorophenyl)2Cd] afforded a mixture of the alpha- and beta-anomeric products (alpha:beta = 3:1 to 10:1 ratio). Treatment of the alpha-anomer with BF3.Et2O in nitroethane at 110-120 degrees C for 30 min was developed as an efficient method for epimerization of the major alpha-anomer to the desired beta-anomer. The 5-substituted (H, Me, Cl, I, NH2) beta-anomers exhibited negligible cytotoxicity in a MTT assay (CC50 = 10(-3)-10(-4) M range), relative to thymidine (CC50 = 10(-3)-10(-5) M range), against a variety of cancer cell lines. In contrast, the 5-NO2 derivative was more cytotoxic (CC50 = 10(-5)-10(-6) M range). A number of 5-substituted beta-anomers, and some related alpha-anomers, that were evaluated using a wide variety of antiviral assay systems [HSV-1, HSV-2, varicella-zoster virus (VZV), vaccinia virus, vesicular stomatitis, cytomegalovirus (CMV) and human immunodeficiency (HIV-1, HIV-2) viruses], showed that this class of unnatural C-aryl nucleoside mimics are inactive antiviral agents.     

A novel approach for the selective determination of tryptophan in blood serum in the presence of tyrosine based on the electrochemical reduction of oxidation product of tryptophan formed in situ on graphite electrode

In this study, a novel method was proposed for the selective determination of tryptophan (TRP) in blood serum in the presence of tyrosine. This method is based on the electrochemical reduction of 2-amino-3-(5-oxo-3,5-dihydro-2H-indol-3-yl)-propionic acid (5-O-3,5DH-TRP) formed by the oxidation of TRP on the electrochemically treated pencil graphite (ETPG) electrode surface at a suitable potential value. The parameters affecting the TRP determination were deeply investigated. The optimal pH value was determined as 3. The highest reduction current intensity was obtained at the accumulation potential and time values of +0.95 V and 120 s, respectively. The reduction peak current values of 5-O-3,5DH-TRP versus TRP concentration at the ETPG electrode showed linearity in the range from 0.5 μM to 50.0 μM (R(2)=0.9962) with a detection limit of 0.05 μM (S/N=3). The reduction peak intensity of 5-O-3,5DH-TRP on the ETPG electrode showed no significant change in the presence of different interfering substances. The analytical application of the proposed novel method was successfully tested by using human blood serum samples.