Gigi Ngar Chee Chiu

Synthesis and Heterocyclizations of 3,4-Dihydroquinazolin-2-yl Guanidine in the Search of New Anticancer Agents

The cyclocondensations of 3,4-dihydroquinazolin-2-yl guanidine with a variety of electrophilic reagents viz. aldehydes, ketones, triethyl orthoformate, diethyl ethoxymethylenemalonate, carbon disulfide and trichloroacetonitrile were found to afford 1,3,5-triazino[2,1-b]quinazolines. However, some unexpected reactions were also observed. The structural properties such as tautomerism and hinderance to conformational rotation were also investigated. The results of biological testing suggested that the 1,3,5-triazino[2,1-b]quinazoline nucleus could be a new promising scaffold for the development of potential anticancer agents.

Discovery of mixed type thymidine phosphorylase inhibitors endowed with antiangiogenic properties: Synthesis, pharmacological evaluation and molecular docking study of 2-thioxo-pyrazolo[1,5-a][1,3,5]triazin-4-ones. Part II

In our drug discovery program, a series of 2-thioxo-pyrazolo[1,5-a][1,3,5]triazin-4-ones were designed, synthesized and evaluated for their TP inhibitory potential. All the synthesized analogues conferred a varying degree of TP inhibitory activity, comparable or better than positive control, 7-deazaxanthine (7-DX, 2) (IC50 valuexa0=xa042.63xa0μM). A systematic approach to the lead optimization identified compounds 3c and 4a as the most promising TP inhibitors, exhibiting mixed mode of enzyme inhibition. Moreover, selected compounds demonstrated the ability to attenuate the expression of the angiogenic markers (viz. MMP-9 and VEGF) in MDA-MB-231 cells at sublethal concentrations. In addition, molecular docking studies revealed the plausible binding orientation of these inhibitors towards TP, which was in accordance with the experimental results. Taken as a whole, these compounds would constitute a new direction for the design of novel TP inhibitors with promising antiangiogenic properties.

Protective role of functionalized single walled carbon nanotubes enhance ex vivo expansion of hematopoietic stem and progenitor cells in human umbilical cord blood.

UNLABELLEDnIn this study, carboxylic acid functionalized single walled carbon nanotubes (f-SWCNT-COOH) was shown to support the viability and ex vivo expansion of freeze-thawed, non-enriched hematopoietic stem and progenitor cells (HSPC) in human umbilical cord blood-mononucleated cells (UCB-MNC). Our in vitro experiments showed that f-SWCNT-COOH increased the viability of the CD45(+) cells even without cytokine stimulation. It also reduced mitochondrial superoxides and caspase activity in CD45(+) cells. f-SWCNT-COOH drastically reduced the proportions of CD45(-) cells in the non-enriched UCB-MNC. Phenotypic expression analysis and functional colony forming units (CFU) showed significant ex vivo expansion of HSPC, particularly of CD45(+)CD34(+)CD38(-) population and granulocyte-macrophage (GM) colonies, in f-SWCNT-COOH augmented cultures supplemented with basal cytokines. In vivo data suggested that f-SWCNT-COOH expanded UCB-MNC could repopulate immunodeficient mice models with minimal acute or sub-acute symptoms of graft-versus-host disease (GVHD) and f-SWCNT-COOH dependent toxicity.nnnFROM THE CLINICAL EDITORnIn this paper a novel method is presented by using single wall functionalized carbon nanotubes to enhance viability and ex vivo expansion of freeze-thawed, non-enriched hematopoietic stem and progenitor cells in human umbilical cord blood -mononucleated cells. Detailed data is presented about enhanced viability, including improved repopulation of immunodeficient mice models with minimal acute or sub-acute symptoms of graft-versus-host disease.

Application of Static Modeling ­­in the Prediction of In Vivo Drug–Drug Interactions between Rivaroxaban and Antiarrhythmic Agents Based on In Vitro Inhibition Studies

Rivaroxaban, a direct Factor Xa inhibitor, is indicated for stroke prevention in nonvalvular atrial fibrillation (AF). Studies have revealed that the clearance of rivaroxaban is largely attributed to CYP3A4, CYP2J2 metabolism, and P-glycoprotein (P-gp) efflux pathways. Amiodarone and dronedarone are antiarrhythmic agents employed in AF management. Amiodarone, dronedarone, and their major metabolites, N-desethylamiodarone (NDEA) and N-desbutyldronedarone (NDBD), demonstrate inhibitory effects on CYP3A4 and CYP2J2 with U.S. Food and Drug Administration–recommended probe substrates. In addition, both amiodarone and dronedarone are known P-gp inhibitors. Hence, the concomitant administration of these antiarrhythmic agents has the potential to augment the systemic exposure of rivaroxaban through simultaneous impairment of its clearance pathways. Currently, however, clinical data on the extent of these postulated drug–drug interactions are lacking. In this study, in vitro inhibition assays using rivaroxaban as the probe substrate demonstrated that both dronedarone and NDBD produced reversible inhibition as well as irreversible mechanism-based inactivation of CYP3A4- and CYP2J2-mediated metabolism of rivaroxaban. However, amiodarone and NDEA were observed to cause reversible inhibition as well as mechanism-based inactivation of CYP3A4 but not CYP2J2. In addition, amiodarone, NDEA, and dronedarone, but not NDBD, were determined to inhibit P-gp–mediated rivaroxaban transport. The in vitro inhibition parameters were fitted into a mechanistic static model, which predicted a 37% and 31% increase in rivaroxaban exposure due to the inhibition of hepatic and gut metabolism by amiodarone and dronedarone, respectively. A separate model quantifying the inhibition of P-gp–mediated efflux by amiodarone or dronedarone projected a 9% increase in rivaroxaban exposure.

Mitochondrial superoxide reduction and cytokine secretion skewing by carbon nanotube scaffolds enhance ex vivo expansion of human cord blood hematopoietic progenitors.

UNLABELLEDnIn this study, we report that surface functional groups of single walled carbon nanotubes (f-SWCNT) are critical for mediating survival and ex vivo expansion of hematopoietic stem and progenitor cells (HSPC) in human umbilical cord blood (UCB). In comparison to amide (-O-NH2) and polyethylene-glycol (-PEG) functionalized SWCNT, carboxylic acid (-COOH) variants gave optimal viability support which correlated with maximal reduction of lethal mitochondrial superoxides in HSPC. Cytokine array illustrated that f-SWCNT-COOH maintained higher proportion of HSPC associated cytokines and minimal level of differentiation promoting factors. Transplantation of f-SWCNT-COOH expanded grafts in sub-lethally irradiated immunodeficient mice resulted in higher engraftment of HSPC in bone marrow compared to control when they were co-transplanted with non-expanded cells from the same UCB. Expanded grafts mediated higher survival rate of mice compared to non-expanded grafts due to lower graft-versus-host-disease which is likely a consequence of proportion of immune cells in the grafts.nnnFROM THE CLINICAL EDITORnUmbilical cord blood (UCB) is a potential source of hematopoietic stem and progenitor (HSPC) cells. One major hurdle for its clinical use is the insufficient yield of cell number. The authors in this study elegantly demonstrated the importance of various functional groups on single-walled carbon nanotubes (f-SWCNT) in enhancing ex vivo expansion of HSPC in UCB. The findings may pave a way for having UCB as a source for HSPC for clinical use in the future.

Ex Vivo Expansion of CD34+CD90+CD49f+ Hematopoietic Stem and Progenitor Cells from Non‐Enriched Umbilical Cord Blood with Azole Compounds

Umbilical cord blood (UCB) transplants in adults have slower hematopoietic recovery compared to bone marrow (BM) or peripheral blood (PB) stem cells mainly due to low number of total nucleated cells and hematopoietic stem and progenitor cells (HSPC). As such in this study, we aimed to perform ex vivo expansion of UCB HSPC from non‐enriched mononucleated cells (MNC) using novel azole‐based small molecules. Freshly‐thawed UCB–MNC were cultured in expansion medium supplemented with small molecules and basal cytokine cocktail. The effects of the expansion protocol were measured based on in vitro and in vivo assays. The proprietary library of >50 small molecules were developed using structure‐activity‐relationship studies of SB203580, a known p38‐MAPK inhibitor. A particular analog, C7, resulted in 1,554.1u2009±u200927.8‐fold increase of absolute viable CD45+CD34+CD38–CD45RA– progenitors which was at least 3.7‐fold higher than control cultures (pu2009<u2009.001). In depth phenotypic analysis revealed >600‐fold expansion of CD34+/CD90+/CD49f+ rare HSPCs coupled with significant (pu2009<u2009.01) increase of functional colonies from C7 treated cells. Transplantation of C7 expanded UCB grafts to immunodeficient mice resulted in significantly (pu2009<u2009.001) higher engraftment of human CD45+ and CD45+CD34+ cells in the PB and BM by day 21 compared to non‐expanded and cytokine expanded grafts. The C7 expanded grafts maintained long‐term human multilineage chimerism in the BM of primary recipients with sustained human CD45 cell engraftment in secondary recipients. In conclusion, a small molecule, C7, could allow for clinical development of expanded UCB grafts without pre‐culture stem cell enrichment that maintains in vitro and in vivo functionality. Stem Cells Translational Medicine 2018;7:376–393

Clinical Applications of Carbon Nanomaterials in Diagnostics and Therapy

Nanomaterials have the potential to improve how patients are clinically treated and diagnosed. While there are a number of nanomaterials that can be used toward improved drug delivery and imaging, how these nanomaterials confer an advantage over other nanomaterials, as well as current clinical approaches is often application or disease specific. How the unique properties of carbon nanomaterials, such as nanodiamonds, carbon nanotubes, carbon nanofibers, graphene, and graphene oxides, make them promising nanomaterials for a wide range of clinical applications are discussed herein, including treating chemoresistant cancer, enhancing magnetic resonance imaging, and improving tissue regeneration and stem cell banking, among others. Additionally, the strategies for further improving drug delivery and imaging by carbon nanomaterials are reviewed, such as inducing endothelial leakiness as well as applying artificial intelligence toward designing optimal nanoparticle-based drug combination delivery. While the clinical application of carbon nanomaterials is still an emerging field of research, there is substantial preclinical evidence of the translational potential of carbon nanomaterials. Early clinically trial studies are highlighted, further supporting the use of carbon nanomaterials in clinical applications for both drug delivery and imaging.