Intralaboratory validation of cell-free translation assay for detecting ricin toxin biological activity

A cell-free translation (CFT) assay for determining ricin biological activity was validated. The statistical data from the validation study showed a high level of precision within and between runs of the assay. The assay was specific for determining ricin biological activity in food-based matrixes and discriminated ricin from other ribosome-inactivating proteins. The mean bias (relative error) between measured ricin concentrations of 3 validation samples and their nominal concentrations was 1.1, 6.6, and 20.3%, while the coefficient of variation (CV) was 14.1, 7.7, and 13.5%, respectively, demonstrating good precision, accuracy, and linearity. The CVs of ricin concentrations in 2 ricin-containing samples calculated from a dilution series were <5 and <12%, respectively, demonstrating very good parallelism. The analyte stability of ricin-containing samples stored for 1 month either at 4 or -20 degrees C, the stability of ricin stock solutions, and the results of assays executed by different analysts and using different luminometers were evaluated. The statistical validation data confirmed that the 4-parameter logistic equation, y = (a - d)/[1 + (x/c)b] + d, provided an accurate representation of a sigmoidal relationship between the measured response and the observed ricin concentration for the CFT assay.     

Molybdenum: biological activity and metabolism

Molybdenum and tungsten are available to all organisms, with molybdenum having the far greater abundance and availability. Molybdenum occurs in a wide range of metalloenzymes in bacteria, fungi, algae, plants and animals, while tungsten was found to be essential only for a limited range of bacteria. In order to gain biological activity, molybdenum has to be complexed by a pterin compound, thus forming a molybdenum cofactor. In this article I will review the way that molybdenum takes from uptake into the cell, via formation of the molybdenum cofactor and its storage, to the final modification of molybdenum cofactor and its insertion into apo-metalloenzymes.     

Molecular dynamics simulations using the drude polarizable force field on GPUs with OpenMM: Implementation,validation, and benchmarks

Presented is the implementation of the Drude force field in the open‐source OpenMM simulation package allowing for access to graphical processing unit (GPU) hardware. In the Drude model, electronic degrees of freedom are represented by negatively charged particles attached to their parent atoms via harmonic springs, such that extra computational overhead comes from these additional particles and virtual sites representing lone pairs on electronegative atoms, as well as the associated thermostat and integration algorithms. This leads to an approximately fourfold increase in computational demand over additive force fields. However, by making the Drude model accessible to consumer‐grade desktop GPU hardware it will be possible to perform simulations of one microsecond or more in less than a month, indicating that the barrier to employ polarizable models has largely been removed such that polarizable simulations with the classical Drude model are readily accessible and practical.     

The COMPASS force field: parameterization and validation for phosphazenes

A new, condensed-phase optimised ab-initio force field, COMPASS, has been developed recently. In this paper, the validation of COMPASS for phosphazenes is presented. The functional forms of this force field are of the consistent force field (CFF) type. Charges and bonded terms were derived from HF/6–31G1 calculations, while the nonbonded parameters (L-J 9-6 vdW potential) were initially transferred from the polymer consistent force field, pcff, and optimised using MD simulations of condensed-phase properties. As a validation of COMPASS, molecular mechanics calculations and molecular dynamics simulations have been made on a number of isolated molecules, liquids, and crystals. The calculated molecular structure, vibration frequencies, conformational properties for isolated molecules, crystal cell parameters and density, liquid density, and heat of evaporation agreed favourably with most experimental data. The special conformational properties of the tetracyclophosphazenes, (NPCI₂)₄ and (NPF₂)₄, in the solid state are discussed based on molecular mechanics and CASTEP ab-initio calculations. The effect of nonbonded cutoff distance and different algorithms for pressure control in NPT simulation was also investigated. Finally, molecular dynamics using the COMPASS force field was used to predict properties of three isomers of high-molecular-weight amorphous poly(dibutoxyphosphazenes). In this case, excellent agreement was achieved between densities and glass transition temperatures obtained from dynamics and experimental data.     

Synthesis and biological activity of trans-tiliroside derivatives as potent anti-diabetic agents

A set of novel trans-tiliroside derivatives were synthesized. The structures of the derivatives were identified by their IR, 1H-NMR, and MS spectra analysis. Their anti-diabetic activities were evaluated on the insulin resistant (IR) HepG2 cell model. As a result, compounds 7a, 7c, 7h, and trans-tiliroside exhibited significant glucose consumption-enhancing effects in IR-HepG2 cells compared with the positive control (metformin). This research provides useful clues for further design and discovery of anti-diabetic agents.     

Synthesis and biological activities of nitro-hydroxy-phenylquinolines; validation of antibiotics effect over DNA gyrase inhibition and antimicrobial activity

A family of 11 nitrophenol 2-nitro-5-(4-substituted phenylquinolin-2-yl)phenol derivatives (4, 4a-j) was effectively synthesized as antimicrobial medications. A mixture of the substituted 3-hydroxy-4-nitrobenzaldehyde substituted aromatic amine and substituted phenylacetylenes were used to synthesis the title compounds 4, 4a-j. Antimicrobialactivity potential of 4, 4a-j was evaluated against Streptococcus pyogenes (MTCC 442), Staphylococcus aureus (MTCC 96), Pseudomonas aeruginosa (MTCC 424), and Escherichia coli (MTCC 443). DNA gyrase inhibition studies carried out to understand the mechanism ofaction of the antimicrobial effect of target compounds. HRBC membrane stabilization (in vitro) property was also assessed as a representative human cellular cytotoxic effect of 4, 4a-j since HRBC alike lysosomal cells and the lysozyme activity leads to inflammation and its adverse effects in cellular systems. Results reveal that compounds 4c and 4h have remarkable antibacterial activity and screened for further preclinical studies.     

Celastraceae sesquiterpenoids: biological activity and synthesis

Plant extracts of the Celastraceae have been used for centuries throughout South America and China as insect repellents and insecticides in traditional agriculture, and also for the treatment of a plethora of medical ailments from stomach complaints and fever to rheumatoid arthritis and cancer. Many of the medicinally interesting properties associated with these crude preparations have now been attributed to a large family of highly oxygenated sesquiterpenoids based on a tricyclic dihydroagarofuran skeleton. In this article, the structural diversity and range of biological activities associated with this intriguing class of natural products are examined with a view to stimulating interest in their total synthesis. Existing synthetic endeavours towards their synthesis are also evaluated.     

Diarylthiopyrimidines and pyridines: Synthesis and biological activity

Prior work with diarylethers of pyrimidine, pyridine, and benzene showed encouraging antitumor results. As an extension of that work the synthesis of diarylthio derivatives of pyrimidine and pyridine has been accomplished. The synthetic scheme employed the nucleophilic displacement of chlorines from trichloropyrimidine, 1 , dichloropyrimidines 4 and 6 , and 2,6‐dichloropyridine 8 using the anion of thiophe‐nols 2 . Antitumor evaluation by the National Cancer Institute showed no useful activity.