Chemistry

Optimisation of the Microplate Resazurin Assay for Screening and Bioassay-guided Fractionation of Phytochemical Extracts against Mycobacterium tuberculosis
Because of increased resistance to current drugs, there is an urgent need to discover new anti-mycobacterial compounds for the development of novel anti-tuberculosis drugs. The microplate resazurin assay (MRA) is commonly used to evaluate natural products and synthetic compounds for anti-mycobacterial activity. However, the assay can be problematic and unreliable when screening methanolic phyto...


Piper betle Leaves: Profiling Phenolic Compounds by HPLC/DAD–ESI/MSn and Anti-cholinesterase Activity
Piper betle L. is a widely distributed plant in the tropical and subtropical regions, its leaves being largely consumed as a masticator and mouth freshener. The purposes of this work were to characterise the phenolic profile of this species and to improve knowledge of its anti-cholinesterase properties. The phenolic composition of P. betle leaf aqueous and ethanol extracts was characterised by ...
Evaluation of Anti-oxidant and Acetylcholinesterase Activity and Identification of Polyphenolics of the Invasive Weed Dittrichia viscosa
The bioactive metabolites derived from weeds have attracted the interest of the food and pharmaceutical industries due to their health benefits. To evaluate the anti-oxidant and acetylcholinesterase activity of Dittrichia viscosa extracts and characterise the polyphenolic metabolites using the LC coupled with diode-array detection (DAD) and positive mode electrospray ionisation (ESI) MS method ...


Ultra-performance LC Separation and Quadrupole Time-of-flight MS Identification of Major Alkaloids in Plumula Nelumbinis
As an essential medicine and tea source in many countries, Plumula Nelumbinis potentially exerts its major biological activities through its alkaloids. However, the activities of Plumula Nelumbinis are not fully understood due to the lack of studies on its chemical components. To establish an ultra-performance liquid chromatography combined with diode-array detector (UPLC/DAD) method, coupled t...
Identification and Quantitation of Phenolic Compounds from the Seed and Pomace of Perilla frutescens Using HPLC/PDA and HPLC–ESI/QTOF/MS/MS
Perilla frutescens (L.) Britt., an essential traditional Asian crop and Chinese medicine, potentially exerts anti-oxidation effects through its phenolic compounds. These compounds have already been reported in perilla seed, however, little is reported in Perilla pomace, the primary waste during oil production of Perilla seed. To investigate major phenolic compounds in perilla seeds and pomaces ...


Liquid Chromatography–Mass Spectrometry and Chemometric Analysis of Ricinus communis Extracts for Cultivar Identification
Seeds of Ricinus communis contain the toxic protein ricin, a 64 kD heterodimeric type II ribosome-inactivating protein that has been used in several high-profile poisoning incidents. The ability to determine which cultivar the toxin was isolated from via an LC–MS method would be of significant use to law enforcement and forensic agencies. To analyse via LC–MS and chemometrics (principal com...
Effect of shear condition on the thermal stabilization of ethylene-propylene-carbon monoxide terpolymer
The thermal decomposition behavior of the terpolymer of ethylene, propylene, and carbon monoxide (EPCO), stabilized by calcium hydroxyapatite (CHA) as an acid scavenger and 2,2’-oxamidobis-[ethyl-3-(3,5-di-t-butyl-4-hydroxyphenyl)propionate] (OHP) as a radical scavenger, was investigated in terms of shear, temperature and stabilizer composition. The optimum composition of two stabilizers was ...

Reagent vibrational, rotational and isotopic effects on stereodynamics of the H + OCl → OH + Cl reaction
The quasi-classical trajectory method has been employed to investigate the initial vibrational and rotational effects of the title reaction on an improved ab initio potential energy surface for the 11A′ state. Meanwhile, isotopic effect has also been studied at collision energy of 19 kcal/mol. The product rotational alignment factor 〈P2(j′ k)〉, angular distributions of P(ϕr), P(θr) an...
Topologically identical, but geometrically isomeric layers in hydrous α-, β-R
The hydrothermal reaction of uranyl nitrate with rubidium nitrate and arsenic (III) oxide results in the formation of polymorphic α- and β-Rb[UO2(AsO3OH)(AsO2(OH)2)]·H2O (α-, β-RbUAs) and the anhydrous phase Rb[UO2(AsO3OH)(AsO2(OH)2)] (RbUAs). These phases were structurally, chemically and spectroscopically characterized. The structures of all three compounds are based upon topologically i...

Novel ethylenediamine-gallium phosphate containing 6-fold coordinated gallium atoms with unusual four equatorial Ga–N bonds
A novel ethylenediamine-gallium phosphate, formulated as Ga(H2NCH2CH2NH2)2PO4·2H2O, was synthesized under hydrothermal conditions. The crystal structure, including hydrogen positions, was determined using single-crystal X-ray diffraction data (monoclinic, a=9.4886Å, b=6.0374Å, c=10.2874Å, and β=104.226°, space group Pc) and the bulk was characterized by chemical (Ga–P–C–H–N) and t...
Self-assembled ultra small ZnO nanocrystals for dye-sensitized solar cell application
We demonstrate a facile chemical approach to produce self-assembled ultra-small mesoporous zinc oxide nanocrystals using sodium salicylate (SS) as a template under hydrothermal conditions. These ZnO nanomaterials have been successfully fabricated as a photoanode for the dye-sensitized solar cell (DSSC) in the presence of N719 dye and iodine–triiodide electrolyte. The structural features, crys...

Two novel norlignans from Gymnotheca chinensis
Two novel norlignans, gymnothedelignans A and B were isolated from the whole plants of Gymnotheca chinensis. These norlignans possess a rare 2/5 epoxy benzocycloheptanone skeleton. Their structures were established on the basis of 1D and 2D NMR spectral data analysis, and the absolute stereochemistry of gymnothedelignans A and B was further confirmed by single crystal X-ray diffraction analysis...
Recent progress in the chemistry and chemical biology of microbial signaling molecules: quorum-sensing pheromones and microbial hormones
Communication among microorganisms is mediated by secretion and detection of microbial signaling molecules such as quorum-sensing pheromones and microbial hormones. The molecules elicit the regulation of important genes necessary for microbial survival and often play important roles in interspecies or even inter-kingdom communication. Recent progress in the study of the signaling molecules has ...
Chemoselective reductions and iodinations using titanium tetraiodide
Titanium(IV) halides are extensively used in carboncarbon bond forming reactions as a Lewis acid and low valent titanium halides promote reductive coupling reactions of carbonyl compounds. In most of these reactions, ligands of titanium halides are chloride or bromide. On the other hand, titanium(IV) tetraiodide had been rarely used in organic synthesis until the late 1990s. Since 2000 several ...
Real-time measurements of nitrosamines in air
The ion-molecule chemistry of the three common reagent ions used in selected ion flow tube mass spectrometry (SIFT-MS), H3O+, NO+ and O2 +, has been extended to include reactions with seven nitrosamines. Theoretical calculations enabled the dipole moments and polarizabilities of the nitrosamines studied to be found and from these, the proton transfer rate coefficients have been calculated. In a...