Enzymatic synthesis and bioactivity of estradiol derivative conjugates with different amino acids

A series of N-protected amino acid-estradiol derivative conjugates have been synthesized by coupling of 17β-aminoestra-1,3,5 (10)-trien-3-ol (1) or 17β-hydrazonoestra-1,3,5 (10)-trien-3-ol (2) with different amino acids via the catalysis of subtilisin Carlsberg in organic solvent. Various factors, including the structure of amino acid residue, different N-protecting groups of amino acids, different esters of carboxyl group and water content of the reaction media that influence the efficiency of enzymatic reactions were systematically studied. In vitro biological activity studies revealed that the binding interactions between estradiol derivative conjugates and estrogen receptor can be affected by the properties of the conjugated amino acid, but the effects of the change in binding properties did not result in changes in biological activities in both MCF-7 and HeLa cell lines.     

Non-covalent glycosylated gold nanoparticles/peptides nanovaccine as potential cancer vaccines

Herein, we firstly developed a non-covalent glycosylated gold nanoparticles/peptides nanovaccine which is assembled by β-cyclodextrin (β-CD) based host-guest recognitions. This nanovaccine can generate significant titers of antibodies and improve the therapeutic effect against melanoma, suggesting the immunogenicity of peptide antigens can be improved by loading with this carrier. The novel vaccine carrier provides a platform for the transport of various antigens especially T cell-independent antigens.     

Design and synthesis of trivalent Tn glycoconjugate polymers by nitroxide-mediated polymerization

A new synthetic method for preparing Tn glycoconjugate polymers, containing tumor-associated carbohydrate antigens, by controlled living radical polymerization is reported. To mimic the authentic structures of Tn glycopeptide antigens and to explore the controlled living radical polymerization, three tumor-associated carbohydrate antigens (GalNAc, GalNAcα1-O-Ser, and GalNAcα1-O-Thr) were attached to a styrene-type monomer through a diethylene glycol spacer. Under nitroxide-mediated polymerization, controlled living radical polymerization proceeded to afford defined glycopeptide polymers with different Tn densities and compositions. The polydispersity index (PDI) and molecular weights were increased and conversions were decreased upon increasing the concentration of Tn glycoconjugate monomers. The resulting Tn glycoconjugate polymers were characterized by NMR and IR. The spectral data indicate that the Tn glycoconjugate moiety did attach to the polymer chain and Tn glycoconjugate density could be adjusted through the nitroxide-mediated polymerization conditions. The number of Tn units containing in the polymer chains could be estimated by NMR integration. This synthetic approach provides a new and efficient tool for constructing novel Tn glycoconjugate polymers.     

Chemical and chemoenzymatic synthesis of S-linked ganglioside analogues and their protein conjugates for use as immunogens

Analogues of the tumor-associated gangliosides GM(3) and GM(2) containing terminal S-linked neuraminic acid residues and an amino terminated, truncated ceramide homologue have been synthesized and conjugated to a protein. The synthesis involved coupling of a S-linked sialyl alpha(2-->3) galactose disaccharide with a glucosyl sphingosine analogue, followed by elaboration and deprotection to give amino-terminated glycosyl ceramide 1. Glycosyltransferase-catalyzed extension of the trisaccharide 1 provided access to the modified GM(2) tetrasaccharide 2 or sulphur-containing GD(3) analogue 30. Owing to their potentially enhanced resistance to endogenous exo-glycoside hydrolases and their inherent non-self character, carbohydrate antigens containing non-reducing terminal thioglycosidic linkages may be more immunogenic than O-linked antigens and may stimulate the production of antibodies capable of recognizing naturally occurring oligosaccharides. Our initial results suggest that in fact these antigens are viable immunogens and furthermore, that immune sera cross reacts with O-gangliosides in the context of a heterologous glycoprotein conjugate.     

Synthesis of two linear PADRE conjugates bearing a deca- or pentadecasaccharide B epitope as potential synthetic vaccines against Shigella flexneri serotype 2a infection

The blockwise synthesis of the 2-aminoethyl glycosides of a deca- and a pentadecasaccharide made of two and three repeating units, respectively, of the Shigella flexneri serotype 2a specific polysaccharide is reported. The strategy relies on trifluoromethanesulfonic acid mediated glycosylation of a pentasaccharide building block acting as a glycosyl donor and a potential glycoside acceptor. Both targets were made available in amounts large enough for their subsequent conversion into glycoconjugates. Indeed, efficient elongation of the spacer through an acetylthioacetyl moiety and subsequent conjugation onto a Pan HLA DR-binding epitope (PADRE) T-cell-universal peptide resulted in two fully synthetic neoglycopeptides, which will be evaluated as potential vaccines against S. flexneri serotype 2a infections.     

Total synthesis of plagiochin G and derivatives as potential cancer chemopreventive agents

A new and efficient total synthesis has been developed to obtain plagiochin G (22), a macrocyclic bisbibenzyl, and four derivatives. The key 16-membered ring containing biphenyl ether and biaryl units was closed via an intramolecular S_NAr reaction. All synthesized macrocyclic bisbibenzyls inhibited Epstein–Barr virus early antigen (EBV-EA) activation induced by the tumor promoter 12-O-tetradecanoylphorbol-13-acetate (TPA) in Raji cells and, thus, are potential cancer chemopreventive agents.     

Ferrocenyl-doped silica nanoparticles as an immobilized affinity support for electrochemical immunoassay of cancer antigen 15-3

The aim of this study is to elaborate a simple and sensitive electrochemical immunoassay using ferrocenecarboxylic (Fc-COOH)-doped silica nanoparticles (SNPs) as an immobilized affinity support for cancer antigen 15-3 (CA 15-3) detection. The Fc-COOH-doped SNPs with redox-active were prepared by using a water-in-oil microemulsion method. The use of colloidal silica could prevent the leakage of Fc-COOH and were easily modified with trialkoxysilane reagents for covalent conjugation of CA 15-3 antibodies (anti-CA 15-3). The Fc-COOH-doped SNPs were characterized by X-ray photoelectron spectroscopy (XPS) and transmission electron microscopy (TEM). The fabrication process of the electrochemical immunosensor was demonstrated by using cyclic voltammetry (CV) and electrochemical impedance spectroscopy (EIS) techniques. Under optimal conditions, the developed immunosensor showed good linearity at the studied concentration range of 2.0-240 U mL⁻¹ with a coefficient 0.9986 and a detection limit of 0.64 U mL⁻¹ at S/N = 3.     

Enhancing the immune response and tumor suppression effect of antitumor vaccines adjuvanted with non-nucleotide small molecule STING agonist

Vaccine adjuvants have been widely used to enhance the immunogenicity of the antigens and elicit long-lasting immune response. However, only few vaccine adjuvants have been approved by the FDA for human use so far. Therefore, there is still an urgent need to develop novel adjuvants for the potential applications in clinical trials. Herein, non-nucleotide small molecule STING agonist di ABZI was employed to construct glycopeptide antigen based vaccines for the first time. Immunological evaluation indicated di ABZI not only enhanced the production of antibodies and T cell immune responses, but also inhibited tumor growth in tumor-bearing mice in glycopeptide-based subunit vaccines. These results indicated that di-ABZI demonstrates a high potential as adjuvant for the development of cancer vaccines.     

A novel linker methodology for the synthesis of tailored conjugate vaccines composed of complex carbohydrate antigens and specific TH-cell peptide epitopes

Pathogenic organisms or oncogenically transformed cells often express complex carbohydrate structures at their cell surface, which are viable targets for active immunotherapy. We describe here a novel, immunologically neutral, linker methodology for the efficient preparation of highly defined vaccine conjugates that combine complex saccharide antigens with specific TH-cell peptide epitopes. This novel heterobifunctional approach was employed for the conjugation of a (1-->2)-beta-mannan trisaccharide from the pathogenic fungus Candida albicans as well as the carbohydrate portion of tumor-associated ganglioside GM2 to a TH-cell peptide epitope derived from the murine 60 kDa self heat-shock protein (hsp60). Moreover, the linkage chemistry has proven well suited for the synthesis of more complex target structures such as a biotinylated glycopeptide, a three component vaccine containing an immunostimulatory peptide epitope from interleukin-1 beta (IL-1 beta), and for the conjugation of complex carbohydrates to carrier proteins such as bovine serum albumin.     

Design and synthesis of a phenyl C-glycoside derivative of Spliceostatin A and its biological evaluation toward prostate cancer treatment

We designed and synthesized a novel phenyl C-glycoside analogue of Spliceostatin A, which is potent splicing inhibitor and has anti-cancer activities. We successfully synthesized its right phenyl C-glycoside sugar fragment in shorter steps compared to previous synthetic methods for Spliceostatin A and revealed an appropriate fragment combination with a Julia-coupling reaction. Regarding biological activity, the Ph-C-glycoside analogue of Spliceostatin A showed repressed cell proliferation in three prostate cancer cell lines and suppressed AR-V7 expression.     

Design, synthesis, and biological evaluation of a dansyled amino acid derivative as an imaging agent for apoptosis

To develop a small molecule-based biomarker for in vivo apoptosis imaging, a dansyled amino acid derivative (BNSBA) was designed and synthesized in good yield. The biological evaluation demonstrated that BNSBA selectively binds to apoptotic cancer cells and is localized within the cytoplasm of cells that bound annexin V on the plasma membrane.     

Design,synthesis and biological evaluation of quinazolin-4(3H)-one Schiff base conjugates as potential antiamoebic agents

In an effort to develop novel antiamoebic scaffolds having better efficacy than the standard drug metronidazole (IC₅₀ = 1.80 μM) used against Entamoeba histolytica, quinazolin-4(3H)-one Schiff base conjugates were synthesized and evaluated against HM1: IMSS strain of E. histolytica. Out of the thirteen compounds (S2-S14), six compounds (S2, S3, S4, S5, S6 and S11) were found to be better inhibitors than metronidazole and showed low cytotoxicity on HeLa cells, a cervical cancer cell line. The structure of intermediate compound S1 was confirmed by crystal structure studies.     

Design and synthesis of alepterolic acid and 5-fluorouracil conjugates as potential anticancer agents

Conjugates of alepterolic acid with 5-fluorouracil derivatives have been synthesized in 70–90% yields. The cytotoxic evaluation against two human cancer cell lines, viz. MCF-7 (breast) and A549 (lung), using MTT assay showed anticancer activities of the obtained compounds.     

Design, synthesis, and biological evaluation of estrone-derived hedgehog signaling inhibitors

The design, synthesis, and biological evaluation of new analogs of the naturally occurring compound cyclopamine, a hedgehog signaling inhibitor, are described. Structure-activity relationship studies lead to an evolving model for the pharmacophore of this medically promising compound class of anti-cancer chemotherapeutic agents.     

Synthesis,bioactivity and functional evaluation of linker-modified allatostatin analogs as potential insect growth regulators

Insect growth regulators play an important role in integrated pest management strategies.The FGLa–allatostatins(ASTs)are a family of neuropeptides that can inhibit juvenile hormone(JH)biosynthesis by the corpora allata(CA)of Diploptera punctata in vitro,are regarded as insect growth regulator candidates.In the search for new potential mimics and to explore the effect of linker length on inhibiting JH biosynthesis,a series of AST analogs were synthesized by modifying the linker of K24,which was found to have a significant effect on JH biosynthesis in vitro in our previous study.Functional evaluation demonstrated that all the target compounds can activate the Dippu-Ast R,albeit with different potencies.Analog L6 with the longest linker(n=5),exhibited not only a promising effect on inhibition of JH biosynthesis both in vitro and in vivo,but also good activity in inhibiting basal oocyte growth.Structure–activity relationships(SAR)studies showed that longer linkers provided greater contribution to activity.     

Syntheses and biological evaluation of new triazole-spirochromone conjugates as inhibitors of Mycobacterium tuberculosis

A series of novel 1,2,3-triazole fused spirochromone conjugates have been synthesized bearing both spirochromone moiety as well as a 1,2,3-triazole moiety. Some of the compounds have exhibited potential activity against Mycobacterium tuberculosis (virulent strain H37Rv). In particular 5e proved to be the most potent derivative exhibiting MIC = 0.78 μg/mL.     

Design,synthesis, and bioactivity evaluation of novel thiochromanone derivatives containing an oxime or oxime ether moiety

In this study, using botanical active component thiochromanone as the lead compound, a series of novel thiochromanone derivatives containing an oxime or oxime ether moiety were designed and synthesized. The half-maximal effective concentration (EC₅₀) values of compound 4a against Xanthomonas oryzae pv. oryzae (Xoo), Xanthomonas oryzae pv. oryzicolaby (Xoc), and Xanthomonas axonopodis pv. citri (Xac) were 6, 10, and 15 μg/ml, respectively, which were superior to those of Bismerthiazol and Thiodiazole-copper. Meanwhile, compound 4a also revealed better antifungal activity against Botrytis cinerea, with the EC₅₀ value of 18 μg/ml, than that of Carbendazim. To the best of our knowledge, this is the first report on the antibacterial and antifungal activities of this series of novel thiochromanone derivatives containing an oxime or oxime ether moiety.     

Design,synthesis, crystal structure and bioactivity evaluation of novel diethyl (arylfuranyl)(arylpyrazolylamino)methanephosphonates

A series of novel arylpyrazole derivatives containing aminomethanephosphonate and phenylfuran moieties were designed, synthesized and characterized by ¹H NMR, ³¹P NMR and IR spectroscopy and elemental analyses. The single crystal structure of diethyl [5-(4-chlorophenyl)furan-2-yl][3-cyano-1-(2,3,4-trifluorophenyl)-1H-pyrazol-5-ylamino]methanephosphonate (4l) was determined by X-ray diffraction. Preliminary bioassays showed that these phosphonates exhibit satisfactory insecticidal activities against Culexpipiens and Musca domestica at 0.1%. In particular, compound 4l exhibited a most promising KT50 value, which is superior to that of Dextraltetramethrin® and similar to Prallehtrin®. The structure-activity relationship was also preliminarily investigated.     

A cancer cell turn-on protein-CuSMn nanoparticle as the sensor of breast cancer cell and CH3O-PEG-phosphatide

A cancer activated protein-inorganic nanoparticle was used as breast cancer cell turn-on fluorescence sensor and NIR activated attenuator.