Wen-Tai Li

Mutation in Enterovirus 71 Capsid Protein VP1 Confers Resistance to the Inhibitory Effects of Pyridyl Imidazolidinone

ABSTRACT Enterovirus 71 is one of the most important pathogens in the family of Picornaviridae that can cause severe complications in the postpoliovirus era, such as encephalitis, pulmonary edema, and even death. Pyridyl imidazolidinone is a novel class of potent and selective human enterovirus 71 inhibitor. Pyridyl imidazolidinone was identified by using computer-assisted drug design. This virologic investigation demonstrates that BPR0Z-194, one of the pyridyl imidazolidinones, targets enterovirus 71 capsid protein VP1. Time course experiments revealed that BPR0Z-194 effectively inhibited virus replication in the early stages, implying that the compound can inhibit viral adsorption and/or viral RNA uncoating. BPR0Z-194 was used to select and characterize the drug-resistant viruses. Sequence analysis of the VP1 region showed that the resistant variants differed consistently by seven amino acids in VP1 region from their parental drug-sensitive strains. Site-directed mutagenesis of enterovirus 71 infectious cDNA revealed that a single amino acid alteration at the position 192 of VP1 can confer resistance to the inhibitory effects of BPR0Z-194.

One-pot tandem copper-catalyzed library synthesis of 1-thiazolyl-1,2,3-triazoles as anticancer agents.

One-pot multicomponent synthesis to assemble compounds has been an efficient method for constructing a compound library. We have developed one-pot tandem copper-catalyzed azidation and CuAAC reactions that afford 1-thiazolyl-1,2,3-triazoles with anticancer activity. By utilizing this one-pot synthetic strategy, we constructed a library of 1-thiazolyl-1,2,3-triazoles in search of the potent lead compound. Furthermore, 1-thiazolyl-1,2,3-triazoles were evaluated for anticancer activity against the multidrug-resistant cancer cells MES-SA/Dx5. Most of the 1-thiazolyl-1,2,3-triazoles revealed cytotoxic effect against cancer cells at micromolar to low micromolar range. Testing some of the most potent compounds (5{4,2-4} and 5{5,1-3}) against the normal cell line Vero showed no significant toxicity (except 5{4,2}) to normal cells. This result indicates that compounds 5{4,3-4} and 5{5,1-3} possessed good potency and selectivity to cancer cells over normal cells.

Specificity of Pyrrolysyl-tRNA Synthetase for Pyrrolysine and Pyrrolysine Analogs

Pyrrolysine, the 22nd amino acid, is encoded by amber (TAG=UAG) codons in certain methanogenic archaea and bacteria. PylS, the pyrrolysyl-tRNA synthetase, ligates pyrrolysine to tRNA(Pyl) for amber decoding as pyrrolysine. PylS and tRNA(Pyl) have potential utility in making tailored recombinant proteins. Here, we probed interactions necessary for recognition of substrates by archaeal PylS via synthesis of close pyrrolysine analogs and testing their reactivity in amino acid activation assays. Replacement of the methylpyrroline ring of pyrrolysine with cyclopentane indicated that solely hydrophobic interactions with the ring-binding pocket of PylS are sufficient for substrate recognition. However, a 100-fold increase in the specificity constant of PylS was observed with an analog, 2-amino-6-((R)-tetrahydrofuran-2-carboxamido)hexanoic acid (2Thf-lys), in which tetrahydrofuran replaced the pyrrolysine methylpyrroline ring. Other analogs in which the electronegative atom was moved to different positions suggested PylS preference for a hydrogen-bond-accepting group at the imine nitrogen position in pyrrolysine. 2Thf-lys was a preferred substrate over a commonly employed pyrrolysine analog, but the specificity constant for 2Thf-lys was 10-fold lower than for pyrrolysine itself, largely due to the change in K(m). The in vivo activity of the analogs in supporting UAG suppression in Escherichia coli bearing genes for PylS and tRNA(Pyl) was similar to in vitro results, with L-pyrrolysine and 2Thf-lys supporting the highest amounts of UAG translation. Increasing concentrations of either PylS substrate resulted in a linear increase in UAG suppression, providing a facile method to assay bioactive pyrrolysine analogs. These results illustrate the relative importance of the H-bonding and hydrophobic interactions in the recognition of the methylpyrroline ring of pyrrolysine and provide a promising new series of easily synthesized pyrrolysine analogs that can serve as scaffolds for the introduction of novel functional groups into recombinant proteins.

Synthesis and biological activities of 2-amino-1-arylidenamino imidazoles as orally active anticancer agents.

2-Amino-1-arylidenaminoimidazoles, a novel class of orally (po) active microtubule-destabilizing anticancer agents, were synthesized. The compounds were designed from a hit compound identified in a drug discovery platform by using cancer cell-based high throughput screening assay. Selective synthesized compounds exerted cell cytotoxicity against human cancer cells. The underlying mechanisms for the anticancer activity were demonstrated as interacting with the tubulins and inhibiting microtubule assembly, leading to proliferation inhibition and apoptosis induction in the human tumor cells. Furthermore, two compounds showed in vivo anticancer activities in both po and intravenously (iv) administered routes and prolonged the life spans of murine leukemic P388 cells-inoculated mice. These new po active antimitotic anticancer agents are to be further examined in preclinical studies and developed for clinical uses.

The Immunologically Active Oligosaccharides Isolated from Wheatgrass Modulate Monocytes via Toll-like Receptor-2 Signaling

Background: Wheatgrass is a supplemental food that enhances immunity and improves various diseases; however, there remains a lack of scientific evidence for this. Results: Wheatgrass-derived α-(1,4)-linked heptaglucan maltoheptaose systematically increases immune activation. Conclusion: Maltoheptaose is an immune stimulator that activates monocytes via Toll-like receptor-2 signaling. Significance: This is the first work to address the immunostimulatory component of wheatgrass with well defined molecular structures and mechanisms. Wheatgrass is one of the most widely used health foods, but its functional components and mechanisms remain unexplored. Herein, wheatgrass-derived oligosaccharides (WG-PS3) were isolated and found to induce CD69 and Th1 cytokine expression in human peripheral blood mononuclear cells. In particular, WG-PS3 directly activated the purified monocytes by inducing the expression of CD69, CD80, CD86, IL-12, and TNF-α but affected NK and T cells only in the presence of monocytes. After further purification and structural analysis, maltoheptaose was identified from WG-PS3 as an immunomodulator. Maltoheptaose activated monocytes via Toll-like receptor 2 (TLR-2) signaling, as discovered by pretreatment of blocking antibodies against Toll-like receptors (TLRs) and also determined by click chemistry. This study is the first to reveal the immunostimulatory component of wheatgrass with well defined molecular structures and mechanisms.

Synthesis and biological evaluation of 2-amino-1-thiazolyl imidazoles as orally active anticancer agents.

SummaryDesigned from a high throughput screened hit compound, novel 2-amino-1-thiazolyl imidazoles were synthesized and demonstrated cytotoxicity against human cancer cells. 1-(4-Phenylthiazol-2-yl)-4-(thiophen-2-yl)-1H-imidazol-2-amine (compound 2), a 2-amino-1-thiazolyl imidazole, inhibited tubulin polymerization, interacted with the colchicine-binding sites of tubulins, and caused cell cycle arrest at the G2/M phase in human gastric cancer cells. Disruption of the microtubule structure in cancer cells by compound 2 was also observed. Compound 2 concentration-dependently inhibited the proliferation of cancer cells in histocultured human gastric and colorectal tumors. Given orally, compound 2 prolonged the lifespans of leukemia mice intraperitoneally inoculated with the murine P388 leukemic cells. We report 2-amino-1-thiazolyl imidazoles as a novel class of orally active microtubule-destabilizing anticancer agents.

Neuroprotective and Antineuroinflammatory Effects of Hydroxyl-Functionalized Stilbenes and 2-Arylbenzo[b]furans

The drugs currently used to treat Alzheimers disease (AD) are limited in the benefits they confer, and no medication has been clearly proven to cure or delay the progression of AD. Most candidate AD drugs are meant to reduce the production, aggregation, and toxicity of amyloid β (Aβ) or to promote Aβ clearance. Herein, we demonstrate the efficient synthesis of hydroxyl-functionalized stilbene and 2-arylbenzo[b]furan derivatives and report on the neuroprotective and anti-inflammatory effects of these phenolic compounds in vitro and in an animal model. Structure-activity relationships revealed that the presence of an acrylate group on 2-arylbenzo[b]furan confers neuroprotective and anti-inflammatory effects. Furthermore, compounds 11 and 37 in this study showed particular potential for development as disease-modifying anti-Alzheimers drugs, based on their neuroprotective effects on neuron cells, their antineuroinflammatory effects on glial cells, and the ability to ameliorate nesting behavior in APP/PS1 mice. These results indicate that 2-arylbenzo[b]furans could be candidate compounds for the treatment of AD.

BPR0C305, an orally active microtubule-disrupting anticancer agent.

BPR0C305 is a novel N-substituted indolyl glyoxylamide previously reported with in-vitro cytotoxic activity against a panel of human cancer cells including P-gp-expressing multiple drug-resistant cell sublines. The present study further examined the underlying molecular mechanism of anticancer action and evaluated the in-vivo antitumor activities of BPR0C305. BPR0C305 is a novel synthetic small indole derivative that demonstrates in-vitro activities against human cancer cell growth by inhibiting tubulin polymerization, disrupting cellular microtubule assembly, and causing cell cycle arrest at the G2/M phase. It is also orally active against leukemia and solid tumor growths in mouse models. Findings of these pharmacological and pharmacokinetic studies suggest that BPR0C305 is a promising lead compound for further preclinical developments.