Synthesis and biological evaluation of dihydrofuran-fused perhydrophenanthrenes as a new anti-influenza agent having novel structural characteristic

Dihydrofuran-fused perhydrophenanthrenes were synthesized by means of o-quinodimethane chemistry with high generality and stereoselectivity, and found to exhibit potent anti-influenza activity. These compounds exerted an inhibitory effect on various strains of influenza virus growth, including influenza A and B, with a concentration dependent manner, and direct cytotoxicity was low. Several biological experiments suggested that these new drugs affected a virus replication process before mRNA synthesis stage. Novel rigid cage-type of structural characteristic of the compounds has not been found in hitherto anti-influenza drugs, and will provide new basis and motif for exploring promising and unprecedented anti-influenza agents.     

Synthesis and anti-influenza virus activity of dihydrofuran-fused perhydrophenanthrenes with a benzyloxy-type side-chain

As one of our ongoing research project concerning development of a novel anti-influenza virus agent, dihydrofuran-fused perhydrophenanthrenes were derivatized by means of Williamson ether synthesis and Suzuki–Miyaura cross coupling reactions. Newly synthesized compounds were subjected to evaluation of anti-influenza virus activity using influenza A/Aichi/2/68 (H3N2 subtype) virus strain by a plaque titration method. These investigations revealed that incorporation of benzyl-type ether substituents was effective for exerting the inhibition activity of influenza virus proliferation.     

Design and synthesis of novel Cdc25A-inhibitors having phosphate group as a hydrophilic residue

Compounds (6a-e) were synthesized by phosphorylation of hydrophobic perhydroindan derivatives derived from vitamin D(3), and were found to show strong inhibitory activity towards dual-specificity phosphatase Cdc25A (IC(50)=0.7-24.5 microM).     

Synthesis and activity of a cyclo-heptapeptide containing Lys-Gly-Asp-sequence as a novel anti-platelet agent

Linear hepta-peptide Cys-Lys-Gly-Asp-Trp-Asp-Cys was synthesized first and then disulfide bond was formed between the Cys1 and Cys7 to develop cyclo-heptapeptide containing Lys-Gly-Asp-sequence. Structural simulation showed that Lys-Gly-Asp-motif (KDG) displayed functional conformation. The cyclo-heptapeptide exhibited potent anti-platelet aggregation activity based on specific recognition and interaction with the GPIIb-IIIa receptor on platelet cell membrane. The specific and potent anti-platelet activity makes the KGD-containing cyclo-heptapeptide a possible therapeutic agent.     

Forskolin as a novel lipolytic agent

Forskolin is a novel lipolytic agent which elevates cAMP and FFA release in rat adipocytes in a manner different from existing lipolytic factors. This effect of Forskolin is potentiated by all lipolytic hormones tested, i.e. epinephrine, ACTH, and glucagon and is also reversible. The same batch of adipocytes can be repeatedly stimulated after washing. The effective concentration of Forskolin is in the micromolar range. Its action is due to an activation of cAMP synthesis by adenylate cyclase. There is no effect on cAMP hydrolysis. In contrast to stimulation by lipolytic hormones, Forskolin-activated membrane adenylate cyclase was not further stimulated by GPP(NH)P. These results suggest that Forskolin may be a useful analytical agent in the study of adenylate cyclase mediated function in intact adipocytes.     

Propolis as a novel antibacterial agent

Propolis (bee glue) is a bee glue, sticky resinous material released from various plant sources such as bud exudates, flowers, and leaves modified by bee secretions and wax propolis is composed of resins, waxes, polyphenols, polysaccharides, volatile materials, and secondary metabolites that are responsible for various bioactivity such as antibacterial, anti-angiogenic, antiulcer, anti-inflammatory, antioxidant, and anti-viral activities. The physico-chemical characteristics and the natural properties of various kinds of propolis have been studied for the past decade. Novel active anti-microbial compounds have been identified in propolis. Those compounds positively modulated the antimicrobial resistance of multidrug resistant bacteria. Published research has indicated that propolis and its derivatives has many natural antimicrobial compounds with a broad spectrum against different types of bacteria and that it enhanced the efficacy of conventional antibiotics. Besides, the combination of propolis with other compounds such as honey has been studied whereby, such combinations have a synergistic effect against bacterial strains such as Escherichia coli and Staphylococcus aureus. The activity of propolis is very much dependent on seasonal and regional factors, and Middle Eastern propolis have shown best antibacterial efficacy. Propolis and its main flavonoids ingredients should not be overlooked and should be evaluated in clinical trials to better elucidate their potential application in various fields of medicine. Clinical antibacterial potential and its use in new drugs of biotechnological products should be conducted. This review aims at highlighting some of the recent scientific findings associated with the antibacterial properties of propolis and its components.     

Synthesis of well-defined amphiphilic block copolymers having phospholipid polymer sequences as a novel biocompatible polymer micelle reagent

To realize safer and effective drug administration, novel well-defined and biocompatible amphiphilic block copolymers containing phospholipid polymer sequences were synthesized. At first, the homopolymer of 2-methacryloyloxyethylphosphorylcholine (MPC) was synthesized in water by reversible addition-fragmentation chain transfer (RAFT) controlled radical polymerization. The "living" polymerization was confirmed by the fact that the number-average molecular weight increased linearly with monomer conversion while the molecular weight distribution remained narrow independent of the conversion. The poly(MPC) thus prepared is end-capped with a dithioester moiety. Using the dithioester-capped poly(MPC) as a macro chain transfer agent, AB diblock copolymers of MPC and n-butyl methacrylate (BMA) were synthesized. Associative properties of the amphiphilic block copolymer (pMPC(m)-BMA(n)) with varying poly(BMA) block lengths were investigated using NMR, fluorescence probe, static light scattering (SLS), and quasi-elastic light scattering (QELS) techniques. Proton NMR data in D2O indicated highly restricted motions of the n-butyl moieties, arising from hydrophobic associations of poly(BMA) blocks. Fluorescence spectra of N-phenyl-1-naphthylamine indicated that the probes were solubilized in the polymer micelles in water. The formation of polymer micelles comprising a core with poly(BMA) blocks and shell with hydrophilic poly(MPC) blocks was suggested by SLS and QELS data. The size and mass of the micelle increased with increasing poly(BMA) block length. With an expectation of a pharmaceutical application of pMPC(m)-BMA(n), solubilization of a poorly water-soluble anticancer agent, paclitaxel (PTX), was investigated. PTX dissolved well in aqueous solutions of pMPC(m)-BMA(n) as compared with pure water, implying that PTX is incorporated into the hydrophobic core of the polymer micelle. Since excellent biocompatible poly(MPC) sequences form an outer shell of the micelle, pMPC(m)-BMA(n) may find application as a promising reagent to make a good formulation with a hydrophobic drug.     

A synthetic peptide as a novel anticryptococcal agent

An engineered, killer decapeptide (KP) has been synthesized based on the sequence of a recombinant, single-chain anti-idiotypic antibody (KT-scFv) acting as a functional internal image of a yeast killer toxin. Killer decapeptide exerted a strong fungicidal activity against Candida albicans, which was attributed to peptide interaction with beta-glucan. As this polysaccharide is also a critical component of the cryptococcal cell wall, we wondered whether KP was also active against Cryptococcus neoformans, a human pathogen of increasing medical importance. We found that KP was able to kill both capsular and acapsular C. neoformans cells in vitro. Furthermore, KP impaired the production of specific C. neoformans virulence factors including protease and urease activity and capsule formation, rendering the fungus more susceptible to natural effector cells. In vivo treatment with KP significantly reduced fungal burden in mice with cryptococcosis and, importantly, protected the majority of immunosuppressed animals from an otherwise lethal infection. Given the relevance of cryptococcosis in immunocompromised individuals and the inability of conventional drugs to completely resolve the infection, the results of the present study indicate KP as an ideal candidate for further studies on novel anticryptococcal agents.     

The phenolic hydroxyl group of carvacrol is essential for action against the food-borne pathogen Bacillus cereus

The natural antimicrobial compound carvacrol shows a high preference for hydrophobic phases. The partition coefficients of carvacrol in both octanol-water and liposome-buffer phases were determined (3.64 and 3.26, respectively). Addition of carvacrol to a liposomal suspension resulted in an expansion of the liposomal membrane. Maximum expansion was observed after the addition of 0.50 micromol of carvacrol/mg of L-alpha-phosphatidylethanolamine. Cymene, a biological precursor of carvacrol which lacks a hydroxyl group, was found to have a higher preference for liposomal membranes, thereby causing more expansion. The effect of cymene on the membrane potential was less pronounced than the effect of carvacrol. The pH gradient and ATP pools were not affected by cymene. Measurement of the antimicrobial activities of compounds similar to carvacrol (e.g., thymol, cymene, menthol, and carvacrol methyl ester) showed that the hydroxyl group of this compound and the presence of a system of delocalized electrons are important for the antimicrobial activity of carvacrol. Based on this study, we hypothesize that carvacrol destabilizes the cytoplasmic membrane and, in addition, acts as a proton exchanger, thereby reducing the pH gradient across the cytoplasmic membrane. The resulting collapse of the proton motive force and depletion of the ATP pool eventually lead to cell death.     

Synthesis, characterization, and thermodynamic study of a polyvalent lytic peptide-polymer conjugate as novel anticancer agent

We designed and synthesized a new polyvalent lytic peptide-polymer conjugate as a novel chemotherapeutic agent capable of overcoming multidrug resistance. A hexapeptide (KWKWKW or (KW)?) was designed and conjugated to dextran in multiple copies to afford a polyvalent conjugate. A robust synthesis procedure involving click chemistry and the detailed characterization of the conjugate were reported here. The conjugate Dex-(KW)? exhibited significantly enhanced anticancer potency in vitro by up to 500-fold compared to monomeric (KW)?. The LC?? value was comparable to that of conventional lytic peptides which have more than 20 residues. No hemolytic activity was shown by the conjugates up to 300 μM. Thermodynamic study indicated that the binding of conjugates was predominantly entropy-driven while the binding of free peptides was mainly enthalpy-driven, implying a deeper penetration of conjugate into the core of lipid bilayer. The binding affinity of conjugate to neutral membrane is much higher than that to free peptide (K(conj) ≈ 8822.9 M?1, K(pep) ≈ 1884.7 M?1). In binding to negatively charged membrane, the conjugate surpassed free peptides at high concentrations when the binding of free peptides became saturated. The higher binding capability, attributed to the high local concentration of peptides mounted on a polymer backbone, explains the superior anticancer activity of polyvalent Dex-(KW)?.     

Role of the phenolic hydroxyl group in the biological activities of simplified analogue of aplysiatoxin with antiproliferative activity

The 18-deoxy derivative (3) of a simplified analogue (1) of aplysiatoxin with antiproliferative activity was synthesized to examine the role of the phenolic hydroxyl group at position 18 in the biological activities of 1. Compound 3 as well as 1 showed significant affinity for protein kinase Cδ (PKCδ), and the antiproliferative activity of 3 was slightly higher than that of 1. However, the anti-tumor-promoting activity of 3 was less than that of 1 in vitro, suggesting that the phenolic hydroxyl group of 1 is necessary for the anti-tumor-promoting activity but not for the binding of PKCδ and antiproliferative activity. Moreover, PKC isozyme selectivity of 3 was similar to that of 1, suggesting non-PKC receptors for these compounds to play some roles in the anti-tumor-promoting activity of 1.     

Unsaturated genistein disaccharide glycoside as a novel agent affecting microtubules

Genistein, due to its recognized chemopreventive and antitumor potential, is a molecule of interest as a lead compound in drug design. While multiple molecular targets for genistein have been identified, so far neither for this isoflavonoid nor for its natural or synthetic derivatives disruption of microtubules and mitotic spindles has been reported. Here we describe such properties of the synthetic glycosidic derivative of genistein significantly more cytotoxic than genistein, 7-O-(2,3,4,6-tetra-O-acetyl-β-d-galactopyranosyl)-(1→4)-(6-O-acetyl-hex-2-ene-α-d-erythro-pyranosyl)genistein, shortly named G21. We found that G21 causes significant mitotic delay, frequent appearance of multipolar spindles, and alteration of the interphase microtubule array.     

Algal biomass as a source for novel oral nano-antimicrobial agent

In the present study, sulphated polysaccharide Ulvan from Ulva lactuca was used for the synthesis of biogenic Selenium Nanoparticles (SeNPs) conjugate and Mouth rinse was prepared using this conjugate. The synthesis of nanoparticles was confirmed by UV–Visible spectrophotometry and characterized using Fourier transform infrared spectroscopy (FTIR), transmission electron microscope (TEM) and X-ray diffraction (XRD). TEM showed that the average size of the nanoparticle was 85 nm and spherical in shape. Furthermore, nanoparticle conjugates were evaluated for cell viability using MTT assay 3T3-L1 cell line and at 30 µl/ml showed 34% cell viability. The antimicrobial activity of SeNPs mouth rinse was tested against oral pathogens such as Streptococcus mutans, Staphylococcus aureus, Lactobacillus, and Candida albicans and it was effective against all tested microorganism at the concentration of 100 µl/ml. The present study has shown that Ulvan from algal biomass can be a safe and effective source for the development of oral nano-antimicrobial agents.     

Synthesis of pseudopeptides based L-tryptophan as a potential antimicrobial agent

Four compounds named L-BTrpPA, L-Trp-o-PA, L-Trp-m-PA and L-Trp-p-PA, pseudopeptides constructed from pyridine and tryptophan units, were synthesized and tested against the Gram-positive, Gram-negative strains of bacteria and human pathogenic fungi. L-Trp-o-PA proved to be a broad-spectrum antimicrobial agent, showing a significant inhibition of the growth of Gram-positive bacteria (Staphylococcus aureus, methicillin-resistant S. aureus, Bacillus subtilis, Micrococcus luteus), and pathogenic fungi (Candida spp., Cryptococcus neoformans, Rhodotorula glutinis, Saccharomyces cerevisiae, Aspergillus spp., Rhizopus nigricans) tested and activity against Gram-negative bacteria (Escherichia coli, Pseudomonas aeruginosa and Proteus vulgaris, Enterobacter aerogenes) tested. The in vitro cell cytotoxicity of L-Trp-o-PA was evaluated using haemolytic assay, in which the compound was found to have low lytic property, even up to the concentration of 4000 microg/mL, it only lysed 6-7% of erythrocytes, which was 100-fold greater than the MICs (minimum inhibitory concentration).     

Synthesis and biological activity of novel alpha-substituted beta-phenylpropionic acids having pyridin-2-ylphenyl moiety as antihyperglycemic agents

We previously reported the identification of novel oximes having 5-benzyl-2,4-thiazolidinedione with antihyperglycemic activity. We now report the synthesis and biological activity of a novel series of oximes and amides having alpha-substituted-beta-phenylpropionic acids. In this series, we obtained potent PPAR alpha/gamma dual agonist (S)-9d, with which activation of PPAR alpha and PPAR gamma was considerably more potent than that of the reference compounds GW9578 22 and rosiglitazone 3, respectively. This means (S)-9d is of the strongest class of PPAR alpha/gamma dual agonists. In the course of this study, we also obtained 8h, which indicated potent plasma glucose lowering effect in spite of weak PPAR alpha/gamma agonistic activity.     

Triclosan-lysozyme complex as novel antimicrobial macromolecule: a new potential of lysozyme as phenolic drug-targeting molecule

A novel anti-infection strategy to alleviate antibiotic-resistance problem and non-specific toxicity associated with chemotherapy is explored in this study. It is based on utilizing a bacteriolytic enzyme (lysozyme) as a carrier to allow specific targeting of a potential phenolic antimicrobial drug (triclosan) to microbial cells. Lysozyme (LZ) was complexed, via electrostatic and hydrophobic condensation at alkaline pH, to various degrees with triclosan (TCS), a negatively charged phenolic antimicrobial that inhibits bacterial fatty acid synthesis. Fluorescence and absorbance spectra analysis revealed non-covalent association of TCS with the aromatic residues at the interior of LZ molecule. The conjugation greatly promoted the lytic activity of LZ as the degree of TCS derivatization increased. The complexation with LZ turned TCS into completely soluble in aqueous solution. TCS-LZ complexes showed significantly enhanced bactericidal activity against several strains of Gram-positive and Gram-negative bacteria compared to the activity of TCS or LZ alone when tested at the same molar basis. Strikingly, TCS-LZ complex, but not LZ or TCS alone, exhibited unique specificity to scavenge superoxide radicals, generated by the natural xanthine/xanthine oxidase coupling system, without affecting the catalytic function of oxidase. This finding is the first to describe that the membrane disrupting function of lysozyme can be utilized to specifically target antimicrobial drug(s) to pathogen cells and heralding a fascinating opportunity for the potential candidacy of TCS-LZ as novel antimicrobial strategy for human therapy.