Synthesis and immunological activity of an oligosaccharide-conjugate as a vaccine candidate against Group A Streptococcus

The synthesis and immunogenicity of a tetanus toxoid (TT)-conjugate of the hexasaccharide portion of the cell-wall polysaccharide (CWPS) of the Group A Streptococcus (GAS) is described. The synthesis relies on the reaction of an allyl glycoside of the hexasaccharide with cysteamine, followed by the reaction of the resultant amine with diethyl squarate to give the monoethyl squarate adduct. Subsequent reaction with the lysine ε-amino groups on TT gives the glycoconjugate containing 30 hexasaccharide haptens per TT molecule. The immunogenicity in mice is similar to that obtained with a native CWPS–TT conjugate, validating the glycoconjugate as a vaccine candidate against GAS infections.     

Coexpression of cancer-associated carbohydrate antigens,Tn and sialyl Tn

The expression of cancer-associated antigens, Tn and sialyl Tn, was examined using monoclonal antibodies, MLS 128 and MLS 102, recognizing these two antigens, respectively. A cell lysate from a human carcinoma cell line, LS 180 cells, was analysed by Western blotting using these two antibodies. Three glycoprotein bands were discernible with each antibody, of which two, corresponding to 250 and 210 kDa, were reactive with both the antibodies. LS 180 cells were metabolically labelled with³H-glucosamine and then the lysate from these cells was applied to two immunoaffinity columns. Sixty-five per cent of the Tn antigenic glycoproteins, based on radioactivity, bound to the MLS 102 affinity column. On the other hand, 45% of the sialyl Tn antigenic glycoproteins bound to the MLS 128 affinity column. These results indicate that some Tn and sialyl Tn antigens were expressed on the same polypeptide chains.The presence of non-sialylated GalNAc residues on the polypeptide chain with many Sia-GalNAc residues appears to be due to the incapability of three consecutive moieties of GalNAc-Ser/Thr to accept sialic acid.Abbreviations PSMF phenylmethylsulfonyl fluoride - SDS-PAGE sodium dodecyl sulfate polyacrylamide gel electrophoresis - GalNAc N-acetylgalactosamine - Sia sialic acid     

Synthesis and immunological evaluation of self-adjuvanting glycolipopeptide vaccine candidates

Synthesis of four glycolipids with different number of lauroyl groups on glucose or cellobiose as scaffolds is described. Their immunological evaluations either admixed with or covalently linked to J8, a peptide antigen derived from the C-terminus of the antiphagocytic M-protein of group A streptococcus, are also investigated. Administration of mixtures of J8 and glycolipids to B10BR (H-2(k)) mice induced low-levels of J8-specific IgG antibodies. While glycolipopeptides, in which J8 was covalently linked to the synthetic glycolipids, demonstrated high-levels of antibody titers comparable with the co-administration of these glycolipopeptides with complete Freund's adjuvant, suggesting clearly the strong potency of the synthesized glycolipids as self-adjuvanting moieties.     

Curcumin inspired 2-chloro/phenoxy quinoline analogues: Synthesis and biological evaluation as potential anticancer agents

Synthesis of twenty new curcumin inspired 2-chloro/phenoxy quinoline derivatives is outlined in this study. The obtained new chemical entities were screened in vitro for their cytotoxic activity towards various tumor cell lines. Of the compounds screened, 6c and 9d exhibited significant activity and the most active analogue 6c displayed promising cytotoxicity against PC-3 (IC₅₀ of 3.12?±?0.11?μM), DU-145, NCI-H460 and 4?T1 cell lines. Further, 6c and 9d have 2.1 and 1.4 times more aqueous solubility, respectively, than curcumin. Additionally, the promising candidate 6c could induce G2/M cell cycle arrest and apoptosis in PC-3 cells, as determined by AO-EB staining, DAPI staining, analysis of ROS levels as well as annexin binding assay.     

Synthesis and evaluation of novel sulfonamide analogues of 6/7-aminoflavones as anticancer agents via topoisomerase II inhibition

A series of new sulfonamide analogues of 6/7-aminoflavones were synthesized by using molecular hybridization approach. These new sulfonamide analogues were screened for antiproliferative activity against human hepatocellular carcinoma (HepG-2), human lung cancer cell line (A-549), human colorectal adenocarcinoma (Caco-2) cancer cell lines. Compounds 5p, 5q, 5t, 5v, 5w and 5x exhibited good anticancer activity against selected cancer cell lines. These compounds were further evaluated to predict their ability to inhibit topoisomerase-II enzyme. Compound 5x has shown potent antiproliferative activity (IC₅₀ value 0.98 µM) as compared to standard drug Adriamycin (IC₅₀ = 0.94 µM) indicating that these compounds exhibits anticancer activity via inhibition of topoisomerase-II enzyme. Docking results also have supported above observations by indicating that compounds are held in the active pocket by combination of various hydrogen and hydrophobic interactions with Top II-DNA-etoposide enzyme.     

Synthesis and anticancer activity studies of indolylisoxazoline analogues

A new library of thirteen indolylisoxazolines 6a–m has been synthesized by the treatment of indolylchalcones with hydroxylamine hydrochloride. Evaluation of anticancer activity of indolylisoxazolines 6a–m led to the identification of potent compounds 6c–d, 6i and 6l, with IC₅₀ ranging 2.5–5.0?µM against the tested cancer cell lines. Using a number of complementary techniques such as acridine orange/ethidium bromide staining, PARP1 cleavage and DNA strand breaks assay, we show that the compounds 6c and 6i induce apoptosis in highly aggressive C4-2 cells. Our data further revealed that 6c and 6i inhibited C4-2 cells proliferation without inducing reactive oxygen species (ROS). Finally, we show that compounds 6c and 6i also potently inhibit cell migration, indicating these compounds have the potential to serve as effective anti-cancer agents.     

Synthesis and immunological evaluation of an antitumor neoglycopeptide vaccine bearing a novel homoserine Tn antigen

As part of our program on Tn-specific anti-tumor immunotherapy, our aim was to vary the nature of the aglyconic part of the tumor-associated Tn antigen (alpha-d-GalNAc-Ser/Thr). This report describes the synthesis of Fmoc-hSer-(alpha-d-GalNAc)-OH (4) in 19% overall yield from protected aspartic acid. The building block 4 was incorporated as trimeric clusters into a glycopeptide vaccine [MAG:Tn(hSer)3-PV], using solid-phase peptide synthesis. When injected in mice, the resulting MAG induces a strong antibody response, which recognizes native tumor-associated antigens (TAA) at the surface of human tumor cells. This approach may be extended to the use of other nonnatural TAA in order to improve half-life of synthetic anti-cancer vaccines.     

Chemoselective assembly and immunological evaluation of multiepitopic glycoconjugates bearing clustered Tn antigen as synthetic anticancer vaccines

In this paper we investigated the use of regioselectively addressable functionalized templates (RAFTs) as new scaffolds for the design of anticancer vaccine candidates. We report the synthesis of well-defined multiepitopic RAFT scaffolds and their immunological evaluation. These conjugates exhibit clustered Tn analogue as tumor-associated carbohydrate antigen (TACA, B-cell epitope) and the CD4+ helper T-cell peptide from the type 1 poliovirus. The saccharidic and peptidic epitopes were both synthesized separately and combined regioselectively to the RAFT core using a sequential oxime bond formation strategy. B- and T-antigenicity and immunogenicity of the vaccine candidates were investigated in vitro and in vivo. These studies clearly demonstrate that the saccharidic part of the conjugates is recognized by Tn-specific monoclonal antibodies. Moreover, the antibodies elicited by immunization of mice with our vaccine candidates recognize the native form of Tn epitope expressed on human tumor cells. Together with oxime ligation technique, these results suggest that the RAFT scaffold provides a promising and suitable tool for engineering potent synthetic anticancer vaccine.     

Synthesis and biological evaluation of an anticancer vaccine containing the C-glycoside analogue of the Tn epitope

The C-saccharide analogue of the GalNAc (Tn epitope) has been covalently linked to the T cell epitope peptide (328)(-)(340)OVA using a chemoselective convergent synthetic approach. In this way, a non-hydrolyzable synthetic vaccine was obtained composed by a B epitope conjugated to a T cell epitope. This compound was tested in a proliferation assay with spleen cells from DO11.10 mice. The molecule was recognized by transgenic T cells although at a slightly lower efficiency if compared with the reference peptide OVA. An additional experiment with dendritic cells fixed with glutaraldehyde shows that the glycopeptide can bind to extracellular MHC molecules without need of internalization and processing and that the C-glycoside part does not interfere with TCR recognition. These observations constitute an important starting point for the use of this molecule as vaccine against the Tn-expressing TA3-Ha mouse mammary carcinoma.     

Synthesis and biological evaluation of benzyl styrylsulfonyl derivatives as potent anticancer mitotic inhibitors

We herein report the synthesis, biological activity and structure activity relationship of derivatives of benzylstyrylsulfone, benzylstyrylsulfine and benzylsulfonyl-N-phenylacetamide. A lead compound 7 represents a new class of mitotic inhibitors that demonstrates potent anti-proliferative activity and selectively induces cancer cell apoptosis while sparing non-transformed lung fibroblast.     

Synthesis and biological evaluation of novel 4,7-dihydroxycoumarin derivatives as anticancer agents

A series of novel 4,7-dihydroxycoumarin based acryloylcyanohydrazone derivatives were synthesized and evaluated for antiproliferative activity against four different cancer cell lines (A549, HeLa, SKNSH, and MCF7). Most of the compounds displayed potent cytotoxicity with IC₅₀ values ranging from 3.42 to 31.28 µM against all the tested cancer cell lines. The most active compound, 8h was evaluated for pharmacological mechanistic studies on cell cycle progression and tubulin polymerization inhibition assay. The results revealed that the compound 8h induced the cell cycle arrest at G2/M phase and inhibited tubulin polymerization with IC₅₀ = 6.19 µM. Experimental data of the tubulin polymerization inhibition assay was validated by molecular docking technique and the results exhibited strong hydrogen bonding interactions with amino acids (ASN-101, TYR-224, ASN-228, LYS-254) of tubulin.     

Synthesis and pharmacological evaluation of novel bisindolylalkanes analogues

In an effort to develop potent anti-cancer chemopreventive agents that act on topoisomerase II, a novel series of bisindolylalkanes analogues such as 3,3′-(thiochroman-4,4-diyl)bis(1H-indole) are synthesized. Structures of all compounds are elucidated by ¹H NMR, ¹³C NMR and HRMS. Anti-proliferative activities for all of these compounds are investigated by the method of MTT assay on 7 human cancer lines. Most of them showed antitumor activities in vitro, the half maximal inhibitory concentration (IC₅₀) value is 7.798 μg/mL of 3a against MCF7. Compound 3a showed comparable topoisomerase II inhibitory activity to etoposide (VP-16) at 100 μM concentration. The rest of the compounds also showed varying degree topoisomerase II inhibitory activity.     

Synthesis and in vitro anticancer evaluation of some fused indazoles,quinazolines and quinolines as potential EGFR inhibitors

derivatives of benzo[g]indazole 5a, b, benzo[h]quinazoline 7, 12a-c, 13a-c and 15a-c and benzo[h]quinoline 17a-c and 19a-c were synthesized from 6-methoxy-3,4-dihydronaphthalen-1(2H)-one (1). Anticancer activity of all the synthesized compounds was evaluated against four cancerous cell lines; HepG2, MCF-7, HCT116 and Caco-2. MCF-7 cells emerged as the most sensitive cell line against the target compounds. All the examined compounds, except 5a and 5b, displayed potent to moderate anticancer activity against MCF-7 cells with an IC₅₀ values ranging from 7.21 to 21.55 µM. In particular, compounds 15c and 19b emerged as the most potent derivatives against EGFR-expressing MCF-7 cells with IC₅₀ values = 7.70 ± 0.39 and 7.21 ± 0.43 μM, respectively. Additionally, both compounds did not display any significant cytotoxicity towards normal BHK-21 fibroblast cells (IC₅₀ value > 200 µM), thereby providing a good safety profile as anticancer agents. Furthermore, compounds 15c and 19b displayed potent inhibitory activity towards EGFR in the sub-micromolar range (IC₅₀ = 0.13 ± 0.01 and 0.14 ± 0.01 μM, respectively), compared to that of Erlotinib (IC₅₀ = 0.11 ± 0.01 μM). Docking studies for 15c and 19b into EGFR active site was carried out to explore their potential binding modes. Therefore, compounds 15c and 19b can be considered as interesting candidates for further development of more potent anticancer agents.     

Synthesis and evaluation of furoxan-based nitric oxide-releasing derivatives of tetrahydroisoquinoline as anticancer and multidrug resistance reversal agents

Multidrug resistance in tumor cells poses a major obstacle to efficient chemotherapy. Several types of agents have been recognized as multidrug resistance inhibitors, among which the tetrahydroisoquinolines is the most studied. In current study 16 furoxan-based nitric oxide-releasing derivatives of tetrahydroisoquinoline were synthesized. Their cytotoxic activities and effects in reversing multidrug resistance have been evaluated. The results revealed that these compounds had moderate cytotoxic effects. Compounds 7a-f, 7h, and 7l showed higher cytotoxicities than the rest, but lower than adriamycin on K562 cell line. Compounds 7d, 7f, and 7l exhibited potent MDR reversal activities on K562/A02 cell line. The accumulation assay indicated that compounds 7d, 7f, and 7l significantly increased the intracellular accumulation of rhodamine123 in K562/A02 cells. Furthermore, these three compounds produced high concentrations of NO in K562/A02 cells. Potentially, the high concentrations of NO produced by NO donor moieties will lead to an increased cytotoxicity to K562/A02 cells. Our results suggested that compounds 7d, 7f, and 7l had anticancer effects, as well as multidrug resistance reversal effects.     

Synthesis and biological evaluation of novel pyrazolopyrimidines derivatives as anticancer and anti-5-lipoxygenase agents

A novel series of 6-aryl-3-methyl-1-phenyl-1H-pyrazolo[3,4-d]pyrimidin-4(5H)-ones 3a-h were synthesized in a single step via condensation of carboxamide 2 with some aromatic aldehydes (presence of iodine). Treatment of aminopyrazole 1a with acetic anhydride afforded pyrazolopyrimidines 4 which on treatment with ethyl chloroacetate in refluxing dry DMF furnished a single product identified as ethyl 2-(3,6-dimethyl-4-oxo-1-phenyl-1H-pyrazolo[3,4-d]pyrimidin-5(4H)-yl) acetate 5. On the other hand, esterification of compound 6 with different alcohol, led to the formation of new esters linked pyrazolo[3,4-d]pyrimidinones hybrids 7a-f. The reaction of compound 2 with 3-propargyl bromide gave the compound 8 used as a dipolarophile to access to triazoles (4- and 5-regioisomers (9a-e) and (10a-e), respectively) via the 1,3-dipoar cycloaddition reaction. Finally, condensation reaction of aminopyrazole 1b with α-cyanocinnamonitiles gave the new pyrazolo[1,5-a]pyrimidine-3,6-dicarbonitriles 11a-e. Structures of compounds were established on the basis of ¹H/¹³C NMR and ESI-HRMS. Compounds were screened for their cytotoxic (HCT-116 and MCF-7) and 5-lipoxygenase inhibition activities. The structure-activity relationship (SAR) was discussed.     

Synthesis, characterization and biological evaluation of some 16E-arylidene androstane derivatives as potential anticancer agents

A series of new 16E-arylidene androstane derivatives were synthesized and characterized. The new compounds were screened for their anticancer activities against the human cancer cell lines SW480, A549, HepG2 and HeLa in vitro using the MTT assay. The results of the in vitro study showed that a number of compounds have shown IC₅₀ values lower than 20 μM against the four cancer cell lines.     

Synthesis,biological evaluation and virtual screening of some acridone derivatives as potential anticancer agents

Eleven novel acridone derivatives were synthesized and evaluated for their anticancer activity against 60 human cancer cell lines. Five compounds 8b, 8d, 8g, 8h, and 8k displayed very good in vitro antiproliferative activities well over 95% of the panels. The most active compound is 8k (5, 7-dibromo-3-phenyl-3,4-dihydroacridin-1 (2H)-one). In addition, 8k was the most sensitive agent in all 9 panels starting with prostate (0.075 µm), leukemia (0.116 µm), non-small cell lung cancer (0.164 µm), colon cancer (0.193 µm), CNS cancer (0.264 µm), melanoma (0.317 µm), renal cancer (0.403 µm), ovarian cancer (0.410 µm), and breast cancer (0.608 µm). Virtual screening studies also revealed that nine of the eleven compounds formed good binding interaction with the active site ATPase domain of human topoisomerase IIα (PDB: 1zxm). All nine derivatives exhibited binding affinities that ranged in values from −8.5 to −7.9 kcal/mol, indicating that they could be catalytic inhibitors of the nuclear enzyme, topoisomerase.     

Synthesis and characterization of mannosylated oligoribonucleotides

Oligoribonucleotide (RNA)–carbohydrate conjugates bearing mono- and divalent mannosides were readily obtained using 3,4-diethoxy-3-cyclobutene-1,2-dione as the linking agent in the presence of trace amount of triethylamine. The glycoconjugates were purified by HPLC and characterized by electrospray mass spectroscopy.     

Synthesis, molecular docking and evaluation of thiazolyl-pyrazoline derivatives as EGFR TK inhibitors and potential anticancer agents

Fourty-two thiazolyl-pyrazoline derivatives were synthesized to screen for their EGFR kinase inhibitory activity. Compound 4-(4-chlorophenyl)-2-(3-(3,4-dimethylphenyl)-5-p-tolyl-4,5-dihydro-1H-pyrazol-1-yl)thiazole (11) displayed the most potent EGFR TK inhibitory activity with IC(50) of 0.06 μM, which was comparable to the positive control. Molecular docking results indicated that compound 11 was nicely bound to the EGFR kinase. Compound 11 also showed significant antiproliferative activity against MCF-7 with IC(50) of 0.07 μM, which would be a potential anticancer agent.     

Synthesis and biological evaluation of RON-neoglycosides as tumor cytotoxins

Cardenolides such as digitoxin have been shown to inhibit cancer cell growth, to reduce cancer metastasis, and to induce apoptosis in tumor cells. Among the most potent digitoxin-based cytotoxins identified to date are MeON-neoglycosides generated via oxyamine neoglycosylation. Here, we report our studies of oxyamine neoglycosylation aimed at facilitating the elucidation of linkage-diversified digitoxin neoglycoside structure–activity relationships. We identified conditions suitable for the convenient synthesis of digitoxin neoglycosides and found that sugar structure, rather than RON-glycosidic linkage, exerts the strongest influence on neoglycoside yield and stereochemistry. We synthesized a library of digitoxin neoglycosides and assessed their cytotoxicity against eight human cancer cell lines. Consistent with previous findings, our data show that the structure of RON-neoglycosidic linkages influences both the potency and selectivity of digitoxin neoglycosides.