Reactive supercritical fluid extrusion for development of moisture resistant starch‐based foams

The main objective of this work was to reduce barriers that prevent the usage of starch‐based foams by understanding the effect and the sequence of dual‐modification of crosslinked (XL) and acetylated (Ac) starch in one continuous supercritical fluid reactive extrusion (SCFX) process on wetting properties, physicochemical properties, and cellular structure of solid foam. The starch was reacted with epichlorohydrin (EPI) and acetic anhydride (Ac) under alkaline conditions in a twin‐screw extruder in the presence of supercritical carbon dioxide (SC‐CO₂). An increase in EPI concentration from 0.00 to 3.00% increased the degree of crosslinking as measured by DSC and confirmed by the quantification of the glucose units in the solution after acid hydrolysis. We observed a reduction of the glucose units from 93.07% for 0.00% EPI to 6.73% when 3.00% EPI was added. With crosslinking/acetylation processing, contact angle was higher for modified starches, indicating that chemical treatments induced dramatic changes in their surface polarity. Compared with native, the contact angle for dual modified starch increased from 43.1° to 91.7° which indicated their lower wettability. The addition of SC‐CO₂, EPI, and Ac to the formulation reduced the density of the extrudates and increased the expansion ratio. The average cell size in the extrudate determined by scanning electron microscopy was also found to decrease from 150 to 34 μm by the addition of the two reagents. Moreover, the dual‐modification of starches provided more hardness and adhesiveness to the extrudates than was observed for the unmodified starches. © 2010 Wiley Periodicals, Inc. J Appl Polym Sci, 2011     

Identification and Optimization of 4‐Anilinoquinolines as Inhibitors of Cyclin G Associated Kinase

4‐Anilinoquinolines were identified as potent and narrow‐spectrum inhibitors of the cyclin G associated kinase (GAK), an important regulator of viral and bacterial entry into host cells. Optimization of the 4‐anilino group and the 6,7‐quinoline substituents produced GAK inhibitors with nanomolar activity, over 50 000‐fold selectivity relative to other members of the numb‐associated kinase (NAK) subfamily, and a compound (6,7‐dimethoxy‐N‐(3,4,5‐trimethoxyphenyl)quinolin‐4‐amine; 49 ) with a narrow‐spectrum kinome profile. These compounds may be useful tools to explore the therapeutic potential of GAK in prevention of a broad range of infectious and systemic diseases.     

Synthesis and Evaluation of the Anticancer and Trypanocidal Activities of Boronic Tyrphostins

Molecules containing an (cyanovinyl)arene moiety are known as tyrphostins because of their ability to inhibit proteins from the tyrosine kinase family, an interesting target for the development of anticancer and trypanocidal drugs. In the present work, (E)‐(cyanovinyl)benzeneboronic acids were synthesized by Knoevenagel condensations without the use of any catalysts in water through a simple protocol that completely avoided the use of organic solvents in the synthesis and workup process. The in vitro anticancer and trypanocidal activities of the synthesized boronic acids were also evaluated, and it was discovered that the introduction of the boronic acid functionality improved the activity of the boronic tyrphostins. In silico target fishing with the use of a chemogenomic approach suggested that tyrosine‐phosphorylation‐regulated kinase 1a (DYRK1A) was a potential target for some of the designed compounds.     

Synthesis and Evaluation of a Series of Bis(pentylpyridinium) Compounds as Antifungal Agents

A series of bis(4‐pentylpyridinium) compounds with a variety of spacers between the pyridinium headgroups was synthesised, and the antifungal activity of these compounds was investigated. Lengthening the alkyl spacer between the pentylpyridinium headgroups from 12 to 16 methylene units resulted in increased antifungal activity against C. neoformans and C. albicans, but also resulted in increased hemolytic activity and cytotoxicity against mammalian cells. However, inclusion of an ortho‐substituted benzene ring in the centre of the alkyl spacer resulted in decreased cytotoxicity and hemolytic activity, while maintaining antifungal potency. Replacement of the alkyl and aromatic‐containing spacers by more hydrophilic ethylene glycol groups resulted in a loss of antifungal activity. Some of the compounds inhibited fungal PLB1 activity, but the low correlation of this inhibition with antifungal potency indicates PLB1 inhibition is unlikely to be the predominant mode of antifungal action of this class of compounds, with preliminary studies suggesting they may act via disruption of fungal mitochondrial function.     

The influence of delayed light curing on the degree of conversion and polymerization contraction stress in dual-cured resin luting agents

The aim of the study was to assess the effect of delayed photo-initiation on the polymerization contraction stress (PCS) and degree of conversion (DC) of a dual-cure resin-luting agent. Thirty-five disk (6 mm × 1 mm) samples (n = 10 each group) of dual cure resin luting agent for PCS assessment were fabricated and polymerized using two illuminated quartz rods. Based on the delay in photo-initiation, 30 disks were divided among six groups [group A-0 min (min) delay, group B-2 min, group C-4 min, group D-6 min, group E-8 min and group F-10 min]. A non-photoinitiated group (group G – chemical cure – n = 5) was included as control. The PCS for all specimens was assessed using a Tensometer. For DC evaluation thirty-five specimens were divided into seven groups with delays in photo-initiation (group H-0 min, group I-2 min, group J-4 min, group K-6 min, group L-8 min and group M-10 min, group N-chemical cure). DC was assessed using attenuated total reflectance spectroscopic technique. Statistical comparison among groups was performed using analysis of variance (α = 0.05). The maximum and minimum PCS and DC values with delayed photo-initiation was observed in group-C (3.34 MPa) & group-F (2.44 MPa); and group-M (0.78 MPa) and group-H (0.55 MPa) respectively. Chemically cured samples showed the least PCS (group-G, 1.94) and DC (group-N, 0.53) values in their respective categories. PCS significantly decreased with delayed photo-initiation. A significant increase in DC was noticed when photo-initiation was delayed in the dual cure resin luting agent.