A very large diversity space of synthetically accessible compounds for use with drug design programs

We have constructed a very large virtual diversity space containing more than 10¹³ chemical compounds. The diversity space is built from about 400 combinatorial libraries, which have been expanded by choosing sizeable collections of suitable R-groups that can be attached to each link point of their scaffolds. These R-group collections have been created by selecting reagents that have drug-like properties from catalogs of available chemicals. As members of known combinatorial libraries, the compounds in the diversity space are in general synthetically accessible and useful as potential drug leads. Hence, the diversity space can be used as a vast source of compounds by a de novo drug design program. For example, we have used such a program to generate inhibitors of HIV integrase enzyme that exhibited activity in the micromolar range.     

Ganglioside analysis by thin-layer chromatography matrix-assisted laser desorption/ionization orthogonal time-of-flight mass spectrometry

Metastable decomposition of ions generated in matrix-assisted laser desorption/ionization (MALDI) mass spectrometers complicates analysis of biological samples that have labile bonds. Recently, several academic laboratories and manufacturers of commercial instruments have designed instruments that introduce a cooling gas into the ion source during the MALDI event and have shown that the resulting vibrational cooling stabilizes these labile bonds. In this study, we compared stabilization and detection of desorbed gangliosides on a commercial orthogonal time-of-flight (oTOF) instrument with results we reported previously that had been obtained on a home-built Fourier transform mass spectrometer. Decoupling of the desorption/ionization from the detection steps resulted in an opportunity for desorbing thin-layer chromatography (TLC)-separated gangliosides directly from a TLC plate without compromising mass spectral accuracy and resolution of the ganglioside analysis, thus coupling TLC and oTOF mass spectrometry. The application of a declustering potential allowed control of the matrix cluster and matrix adduct formation, and, thus, enhanced the detection of the gangliosides.     

(Z)-3-p-tolylsulfinylacrylonitrile as a chiral dienophile: diels-alder reactions with furan and acyclic dienes

The behavior of (Z)-3-p-tolylsulfinylacrylonitrile (1) as a chiral dienophile has been evaluated from its reactions with furan and acyclic dienes. Electrostatic interactions of the cyano group with the sulfinyl one restrict the conformational mobility around the C-S bond, thus controlling the pi-facial selectivity, which is almost complete in all cases, the approach of the diene from the less-hindered face of the dienophile (that bearing the lone electron pair) in the predominant rotamer being the favored one. The regioselectivity is also completely controlled by the cyano group. Additionally, the reactivity of compound 1 as well as its endo-selectivity are both higher than those observed for the corresponding (Z)-3-sulfinylacrylates, thus proving the potential of sulfinylnitriles as chiral dienophiles.     

Activities of Individual Ions From Infinite Dilution to Saturated Solutions

A new procedure, which provides a closer approximation for the junction potentials than the Henderson equation, is tested to reduce new emf data for the chloride ion in CsCl solutions and previously measured data for individual ions in aqueous solutions of KCl, NaCl, and NaBr. The liquid junction potential is calculated from numerical integration of its basic equation without assuming constant mobility or using concentrations instead of activities. The mean ionic activity coefficients of the salts, obtained from the activity coefficients of the individual ions, show good agreement with values reported in the literature. The activity coefficients of the individual chloride ion at 25°C in aqueous solutions of CsCl up to 3 molal and in KCl solutions were measured using a chloride ion-selective electrode. It has been confirmed that the activity of the chloride ion is equal to the activity of the cation in CsCl solutions and, contrary to the prediction of hydration theory, it is higher than the activity of the cation in aqueous KCl solutions. The New Hydration Theory has been developed to overcome the shortcomings of the older hydration theory and has been used to smooth the experimental activity coefficients of the individual ions in aqueous solutions and to extrapolate them up to the saturated solution.     

Novel (E)- and (Z)-3(5)-(2-hydroxyphenyl)-4-styrylpyrazoles from (E)- and (Z)-3-styrylchromones: the unexpected case of (E)-3(5)-(2-hydroxyphenyl)-4-(4-nitrostyryl)pyrazoles

An efficient synthetic method for the preparation of (E)- and (Z)-3(5)-(2-hydroxyphenyl)-4-styrylpyrazoles has been developed. The reaction of (E)- and (Z)-3-styrylchromones with hydrazine hydrate afforded the corresponding (E)- and (Z)-4-styrylpyrazoles, respectively, saved 4′-nitro-derivatives where both (E)- and (Z)-4′-nitro-3-styrylchromones afforded (E)-3(5)-(2-hydroxyphenyl)-4-(4-nitrostyryl)pyrazoles. The reaction mechanism for these transformations was discussed and the stereochemistry of all products was assigned by NMR experiments.     

Improving the rate of convergence of interior point methods for linear programming

This paper proposes a procedure for improving the rate of convergence of interior point methods for linear programming. If (x ^k ) is the sequence generated by an interior point method, the procedure derives an auxiliary sequence ( ). Under the suitable assumptions it is shown that the sequence ( ) converges superlinearly faster to the solution than (x ^k ). Application of the procedure to the projective and afflne scaling algorithms is discussed and some computational illustration is provided.     

Synthesis and antimalarial effects of 2-(3,4-dichloroanilino)-7-[[[(dialkylamino)alkyl]amino]]-5-methyl-s-triazolo[1,5-a]pyrimidines

3,4-Dichlorophenylisothioeyanate ( 10 ) was allowed to react with 2-methy1-2-thiopseudourea to give methyl 4-(3,4-dichlorophenyl)(dithioaltophanimidate ( 11 ) (41%), which upon treatment with hydrazine afforded 3-amino-5-(3,4-dichloroanilino)-s-triazole ( 12 ) (54-91%). Ring-closure with ethyl acetoacetale in acetic acid afforded 2-(3,4-dichloroanilino)-5-methyl-s-triazolo[ 1,5-α ]-pyrimidin-7-ol ( 13 ) (81%). Chlorination with phosphorus oxychloride gave 7-chloro-2-(3,4-dichloroanilino)-5-methyl-s-triazolo[1,5-α ]pyrimidine ( 14 ) (98%), which was condensed with various amines to yield the desired 2-(3,4-diehloroanilino)-7-¶[(dialkylamino)alkyl]arnino¶-5-methyl-s-triazolo[ 1,5-α]pyrimidines ( 6 a-d). The structures of the s-triazolo[ 1,5-α ]pyrimidines were based on nmr spectroscopy and ring stability considerations. Several of the amino-s-triazolo[ 1,5-α ]pyrimidines possessed antimalarial activity against P. berghei in mice.     

Calorimetric study of room temperature adsorption of N2O and CO on Cu(II)-exchanged ZSM5 zeolites

Copper ion-exchanged ZSM5 zeolites have been prepared with different cooper loadings from under- to over-exchanged levels. The adsorptions of N₂O and CO at 303 K have been studied using calorimetric method and infrared spectroscopy. The samples were additionally characterised by ammonia adsorption at 423 K. The active sites for both N₂O and CO are Cu(I) ions, which were formed as a result of pre-treatment in vacuum at 673 K.

Room temperature adsorption of nitrous oxide at low equilibrium pressures (up to 66.7 Pa) resulted in small amounts of chemisorbed N₂O (<0.2 molecule per one Cu ion). Differential heats of N₂O adsorption between 80 and 30 kJ/mol were obtained. Differential heats of CO adsorption between 140 and 40 kJ/mol were obtained. The obtained amounts of chemisorbed species in the investigated systems and the values of differential heats of both nitrous oxide and carbon monoxide demonstrate the dependence on the copper content.     

New Bio-Based Furanic Materials Effectively Absorb Metals from Water and Exert Antimicrobial Activity

Development of sustainable bio-based materials for removal of toxic contaminants from water is a high priority goal. Novel bio-based binary and ternary copolymers with enhanced ion-exchange, adsorption and antibacterial properties were obtained by using plant biomass-derived diallyl esters of furandicarboxylic acid (FDCA) as crosslinking agents and easily available vinyl monomers. The synthesized copolymer materials showed higher sorption capacities for Ni^II, Co^II and Cu^II compared to the commercial ion-exchange resins, and they maintained their high metal adsorption capacities for over 10 cycles of regeneration. The synthesized copolymer gels containing 1–5 wt % of the crosslinker showed excellent water absorption capacities. The synthesized copolymers with 1 % crosslinker content showed swelling ratios high enough to also act as moisture absorbents. Synthesized copolymers with crosslinker content of 10 wt % performed as contact-active antibacterials by inhibiting the growth of Gram-positive (S. aureus) and Gram-negative bacteria (E. coli, K. pneumonia) in suspension tests.