Chung-Hin Chui

Antitumor activity of diethynylfluorene derivatives of gold(I)

A list of diethynylfluorenes and their gold(I) derivatives have been studied for their antitumor activity as a function of their structure-activity relationships. End-capping the fluoren-9-one unit with gold(I) moieties could significantly strengthen the cytotoxic activity in vitro on three human cancer cell lines with induction of reactive oxygen species generation on Hep3B hepatocellular carcinoma cells and exhibit attractive antitumor activity from in vivo nude mice Hep3B xenograft model with limited adverse effects on vital organs including liver and kidney.

In vivo anti-tumour activity of corilagin on Hep3B hepatocellular carcinoma

We have investigated the potential in vivo anti-tumour activity of corilagin using the Hep3B hepatocellular carcinoma cell line and an athymic nude mice xenograft model. The purity of corilagin was confirmed by high performance liquid chromatographic analysis. Corilagin was administrated intraperitoneally for a continuous period of 7 days at a concentration of 15 mg/kg of body weight per day. A significant inhibition of tumour growth was observed when treated mice are compared with control groups. Furthermore, analysis of enzymes markers of liver function, including alanine aminotransferase and asparate aminotransferase, suggested that current therapeutic dosage of corilagin did not exert adverse effect on liver. Our observations support the view that corilagin is considerably effective to retard the in vivo growth of xenografted Hep3B hepatocellular carcinoma.

Corilagin is a potent inhibitor of NF-kappaB activity and downregulates TNF-alpha induced expression of IL-8 gene in cystic fibrosis IB3-1 cells

Corilagin (beta-1-O-galloyl-3,6-(R)-hexahydroxydiphenoyl-d-glucose), a gallotannin identified in several plants, including Phyllanthus urinaria, has been shown to exhibit versatile medicinal activities. As far as possible anti-inflammatory effects of corilagin, only few reports are available, and the potential use of corilagin as possible therapeutic molecule for cystic fibrosis has not been evaluated. In the present paper we report experiments aimed at determining the activity of corilagin on nuclear factor kappaB (NF-kappaB) binding to DNA target and on the expression of the major pro-inflammatory gene involved in cystic fibrosis, interleukin-8 (IL-8). Both IL-8 mRNA content and IL-8 protein secretion were analyzed in cystic fibrosis bronchial IB3-1 cells stimulated by tumor necrosis factor-alpha (TNF-alpha), one of the most potent pro-inflammatory agents. The data obtained demonstrate that corilagin binds to NF-kappaB, inhibits NF-kappaB/DNA interactions and affects IL-8 gene expression in TNF-alpha treated IB3-1 cells. In addition, corilagin inhibits TNF-alpha induced secretion of MCP-1 and RANTES, exhibiting low or no effect on the release of G-CSF, IL-6 and VEGF. Therefore, corilagin might be of interest for experimental anti-inflammatory therapy of cystic fibrosis.

Platinum–Acetylide Polymers with Higher Dimensionality for Organic Solar Cells

A new series of platinum(II)-acetylide polymers P1-P3 containing thiophene-triarylamine chromophores of different dimensions were synthesized and their electronic band structures, field-effect charge transport, and application in bulk heterojunction solar cells were evaluated. These materials are soluble in polar organic solvents and show strong absorptions in the solar spectra (with the highest absorption coefficient of 1.59×10(5)  cm(-1) from thin films), thus rendering them excellent candidates for bulk heterojunction polymer solar cells. The spin-coated polymer thin films showed p-channel field-effect charge transport with hole mobilities of 1.90×10(-5) to 7.86×10(-5)  cm(2)  V(-1)  s(-1) for P1-P3 and an improved charge carrier transport was found for P2 with higher molecular dimensionality than P1. The dependence of their photovoltaic properties and dimensionality was also investigated. Even if the polymers possess relatively high bandgaps and narrow absorption bandwidths, the highest power conversion efficiency of 2.24 % can be obtained based on blends of P3 with [6,6]phenyl-C(61)-butyric acid methyl ester (PCBM) (1:5, w/w) under AM1.5 simulated solar illumination. The present work indicates that multidimensional polymers exhibit a better photovoltaic performance over the linear polymers under the same measurement conditions and can provide an attractive approach to developing highly efficient conjugated metallopolymers for efficient power generation.

Recent advances in research of natural and synthetic bioactive quinolines

Many natural products that consist of quinoline core are found to be bioactive and the versatility of quinoline and its derivatives have attracted great attention in the field of drug development. As a result, in recent years, many green and sustainable synthetic approaches for the synthesis of structurally diverse quinolines have been developed. This review covers four main aspects, namely bioactive quinoline alkaloids, the biological activity and mechanism of action of quinoline-based compounds as well as various quinoline syntheses.

Dynamic dual stage phosphorescence chromatic change in a diborylated iridium phosphor for fluoride ion sensing with concentration discriminating capability

By adding a strongly electron-accepting B(Mes)2 group to the ppy-type ligand of phosphorescent iridium(III) cyclometalated complexes, more stabilized metal-to-ligand charge-transfer (MLCT) states can be obtained by transferring electron density from the pyridyl moiety to the boron atom of the B(Mes)2 group in the metallophosphors to give red phosphorescence. Taking advantage of the binding effect between boron atom and F− ion, the phosphorescent emission color of the iridium(III) cyclometalated complex can be dynamically changed by the external F− ions sequentially from red to yellow and to green through modulation of the charge-transfer emitting states, representing very unique F− ion sensing behavior. In the first step, destabilization of the MLCT states is caused by the weak binding between boron and F− ion, which is then accompanied by switching of the MLCT process to form high-energy MLCT states as induced by the strong binding between boron and F− ion in the second step. Not only does the dynamic phosphorescence chromatic variation depend significantly on the substitution mode of the B(Mes)2 moiety on the ppy ligands, but the dynamic emission response also would pave the way to the development of a novel F− ion sensor showing a unique concentration discrimination feature in aqueous solution with good color reversibility and optical response to the naked eye, high selectivity and sensitivity. All of these data provide valuable insight into the molecular design of a new generation of F− ion sensors featuring both concentration discriminating capability and good potential for practical applications.

Development of formaldehyde-free agar/gelatin microcapsules containing berberine HCl and gallic acid and their topical and oral applications

The safety issues of biomedical applications have been a major concern in recent years. Drug delivery associated with microencapsulation technology has been focused on as microencapsulated drugs are believed to promote comparative therapeutic efficiency on human absorption and prolong the life cycle of drugs. The most commonly applied crosslinker is formaldehyde in a gelatin microencapsulation system, which is considerably toxic to the human body. To reduce the risks involved when using formaldehyde, agar was associated with gelatin as the wall matrix materials of microcapsules as it could crosslink with gelatin to give a gel network in the microcapsules formation. Here we report the development, characterization and safe use of agar–gelatin microcapsules. We further demonstrate that both oral and topical applications are possible using the berberine HCl and gallic acid loaded microcapsules respectively. Microcapsules containing both drugs were prepared combining the optimal parameters identified. The mean drug loading efficiency and the mean particle sizes of the berberine HCl loaded microcapsules were 78.16% and 16.75 μm respectively, while those of gallic acid loaded microcapsules were 70.28% and 21.98 μm respectively. The compositions and surface morphology of berberine HCl and gallic acid containing microcapsules were examined using Fourier transform infrared (FTIR) spectroscopy and scanning electron microscopy (SEM). The in vitro controlled release models demonstrated that the drugs could be gradually released from the microcapsules. The minimum inhibitory concentrations (MICs) and anti-Staphylococcus aureus activity also proved that the berberine HCl loaded microcapsules exhibited better antibacterial activity towards Staphylococcus aureus when compared with those of the original drugs. The in vitro drug delivery model also demonstrated the delivery of berberine HCl from microcapsule treated textiles into nude mice skin. The in vivo mice disease model also showed that gallic acid loaded microcapsules were helpful in the treatment of acute liver and kidney toxicity after an overdose administration of acetaminophen. The development of agar–gelatin microcapsules was demonstrated to be an efficient, deliverable tool for both oral and topical applications.

A charged iridophosphor for time-resolved luminescent CO2 gas identification

A phosphorescent CO2 gas probe based on an iridium(III) complex with 2-phenylimidazo-[4,5-f][1,10]phenanthroline ligand has been developed. Its phosphorescence is quenched by the addition of CH3COO−. The quenched phosphorescence can be recovered by bubbling CO2 into the detecting solution. This phosphorescent CO2 probe exhibits higher photostability and reduced photobleaching than some of the reported organic fluorescent probes. A time-resolved photoluminescence experiment was performed for CO2 gas detection, which could effectively remove the background fluorescence and improve the sensitivity and signal-to-noise ratio of the sensor in complicated media.

Antiproliferative Activity of the Extract of Gleditsia sinensis Fruit on Human Solid Tumour Cell Lines

Background: The fruit extract of Gleditsia sinensis Lam. (GSE) is a traditional herbal medicine that is saponin-rich. However, its activity on solid tumour cell lines has never been demonstrated. Methods: The activity of GSE was demonstrated in four cancer cell lines (breast cancer MCF-7, MDA-MB231, hepatoblastoma HepG2 and oesophageal squamous carcinoma cell line SLMT-1) using MTT assay, anchorage-independent clonogenicity assay, DNA laddering and in situ cell death detection. Results: The mean MTT50 (the mean concentration of GSE to reduce MTT activity by 50%) ranged from 16 to 20 µg/ml of GSE. An anchorage-independent clonogenicity assay showed that all of the four solid tumour cell lines gradually lost their regeneration potential after treatment with GSE, DNA fragmentation and TUNEL analysis demonstrated that the action of GSE is both dose- and time course-dependent. Conclusions: Our results suggest that GSE has a cytotoxic activity and can induce apoptosis in human solid tumour cell lines.

Preparation of 8-hydroxyquinoline derivatives as potential antibiotics against Staphylococcus aureus.

This work describes the preparation of quinoline compounds as possible anti-bacterial agents. The synthesized quinoline derivatives show anti-bacterial activity towards Staphylococcus aureus. It is interesting to observe that the synthetic 5,7-dibromo-2-methylquinolin-8-ol (4) shows a similar minimum inhibitory concentration of 6.25μg/mL as compared to that of methicillin (3.125μg/mL) against Staphylococcus aureus.