M.I. Tariq

N-(X-chlorophenyl)-4-hydroxy-2-methyl-2H-1,2-benzothiazine-3-carboxamide 1,1-dioxide (with X = 2 and 4).

The structures of N-(2-chlorophenyl)-4-hydroxy-2-methyl-2H-1,2-benzothiazine-3-carboxamide 1,1-dioxide and N-(4-chlorophenyl)-4-hydroxy-2-methyl-2H-1,2-benzothiazine-3-carboxamide 1,1-dioxide, both C16H13ClN2O4S, are stabilized by extensive intramolecular hydrogen bonds. The 4-chloro derivative forms dimeric pairs of molecules lying about inversion centres as a result of intermolecular N-H...O hydrogen bonds, forming 14-membered rings representing an R2(2)(14) motif; the 2-chloro derivative is devoid of any such intermolecular hydrogen bonds. The heterocyclic thiazine rings in both structures adopt half-chair conformations.

2,3-Dimethyl-N-[(E)-4-nitro-benzyl-idene]aniline.

In the title compound, C15H14N2O2, the aromatic rings are oriented at a dihedral angle of 24.52 (5)°. The dihedral angle between the nitro group and its parent benzene ring is 9.22 (16)°. In the crystal, molecules interact through aromatic π—π stacking interactions [centroid–centroid separations = 3.8158 (14) and 3.9139 (14) Å].

(E)-2,3-Dimethyl-N-(2-nitro­benzyl­idene)aniline

In the title compound, C15H14N2O2, the 2,3-dimethylanilinic and benzaldehyde groups are planar, with r.m.s. deviations of 0.0101 and 0.0241 Å, respectively, and are oriented at a dihedral angle of 11.69 (3)°. The nitro group is inclined to the benzaldehyde group by 34.02 (9)°. The molecule adopts an E configuration about the C=N bond. In the crystal, molecules are linked via C—H⋯O interactions, giving rise to the formation of zigzag polymeric chains extending along [010]. They are also linked by C—H⋯π, and π–π interactions [centroid–centroid distance of 3.7185 (11) Å] involving symmetry-related aniline and benzene rings. The H atoms of the ortho-methyl group are disordered over two sites with a refined occupancy ratio of 0.69 (2):0.31 (2).

N-[(E)-4-Chloro­benzyl­idene]-2,3-dimethyl­aniline

In the title compound, C15H14ClN, the conformation about the C=N bond is trans and the dihedral angle between the aromatic rings is 51.48 (4)°. In the crystal, some very weak C—H⋯π interactions may help to establish the packing.

Adsorption of pesticides by salorthids and camborthids of Punjab, Pakistan

This study was conducted to examine adsorption of pesticides bifenthrin, carbosulfan, λ-cyhalothrin, cypermethrin, endosulfan, parathion methyl, monocrotophos and 4-nitrophenol by sandy clay loam (S.C.L) and sandy loam (S.L) soils (with varying organic content). There was no significant difference between the observed soil water partitioning coefficient values (K d) derived from linear and nonlinear Freundlich isotherms. Adsorption of pesticides on S.C.L soils was higher than those on S.L soils. K d values showed significant correlations (r 2 = 0.8 − 0.99 and 0.65 − 0.97) with soil organic carbon content (OC) and weak correlations (r 2 = 0.2 − 0.29 and 0.1 − 0.18) with clay contents of S.C.L and S.L soil at p ≤ 0.05, respectively for all pesticides (except monocrotophos). Observed K oc values (soil-water partitioning constants based on the organic C fraction of the soil) were in accordance with the literature values of Wauchope and Tomlin with a maximum deviation of less than 0.5 log units. Ten Quantitative Property-Property Relationships (QPPR) among water solubility, n-octanol water coefficient (K ow) and K oc were proposed for studied pesticides except monocrotophos. The models were considered acceptable when predicted-observed difference for log K ow and log K oc were ≤ 0.3 and ≤ 0.5 log units, respectively, during the validation procedure. This work indicates that the log K oc derived from the log Kow, from some of existing relationships, may be a fair predictor where observed values (i.e., K d and K oc) are not available. Furthermore, predicted leaching potential by groundwater ubiquity scores (GUS) equation was solved by using observed K oc values and literature reported half lives of pesticides. GUS ranked the mobility of nonvolatile compounds i.e., bifenthrin, λ-cyhalothrin, cypermethrin and endosulfan extremely low; methyl parathion very low; 4-nitrophenol low; carbofuran and monocrotophos very high in S.C.L and S.L soils, respectively. Results discussed in this paper provide background to prioritize pesticides or chemical groups that should be evaluated under field conditions with regard to their leaching potential to groundwater in arid climates.

Synthesis, biological evaluation and docking studies of 2,3-dihydroquinazolin-4(1H)-one derivatives as inhibitors of cholinesterases

In search of potent inhibitors of cholinesterases, we have synthesized and evaluate a number of 2,3-dihydroquinazolin-4(1H)-one derivatives. The synthetic approach provided an efficient synthesis of the target molecules with excellent yield. All the tested compounds showed activity against both the enzymes in micromolar range. In many case, the inhibition of both enzymes are higher than or comparable to the standard drug galatamine. With the selectivity index of 2.3 for AChE, compound 5f can be considered as a potential lead compound with a feature of dual AChE/BChE inhibition with IC50=1.6±0.10μM (AChE) and 3.7±0.18μM (BChE). Binding modes of the synthesized compounds were explored by using GOLD (Genetic Optimization for Ligand Docking) suit v5.4.1. The computed binding modes of these compounds in the active site of AChE and BChE provide an insight into the mechanism of inhibition of these two enzyme.

Concentrations of Heavy Metals in Hair and Nails of Young Pakistanis: Correlation with Dietary Elements

Hair and nail samples from young Pakistani adults were separately analyzed for quantification of Cd, Cr, Cu, Ni, Pb, and Zn concentrations. The concentrations of these metals were also analyzed in commonly consumed local foods to evaluate potential correlation of hair and nail concentrations with diet. Pearson correlation coefficients ranged from 0.349 to 0.999, demonstrating diet to be a significant contributor for accumulation of heavy metals in humans.

(E)-1-(4-Meth-oxy-benzyl-idene)-2-phenyl-hydrazine.

In the title compound, C14H14N2O, the dihedral angle between the aromatic rings is 9.30 (6)°. In the crystal, molecules are linked by C—H⋯π and N—H⋯π interactions.

Synthesis, crystal structure determination, biological screening and docking studies of N 1 -substituted derivatives of 2,3-dihydroquinazolin-4(1 H )-one as inhibitors of cholinesterases

Pursuing the strategy of developing potent AChE inhibitors, we attempted to carry out the N1-substitution of 2,3-dihydroquinazolin-4(1H)-one core. A set of 32 N-alkylated/benzylated quinazoline derivatives were synthesized, characterized and evaluated for their inhibition against cholinesterases. N-alkylation of the series of the compounds reported previously (N-unsubstituted) resulted in improved activity. All the compounds showed inhibition of both enzymes in the micromolar to submicromolar range. Structure activity relationship (SAR) of the 32 derivatives showed that N-benzylated compounds possess good activity than N-alkylated compounds. N-benzylated compounds 2ad and 2af were found very active with their IC50 values toward AChE in submicromolar range (0.8µM and 0.6µM respectively). Binding modes of the synthesized compounds were explored by using GOLD (Genetic Optimization for Ligand Docking) suit v5.4.1. Computational predictions of ADMET studies reveal that all the compounds have good pharmacokinetic properties with no AMES toxicity and carcinogenicity. Moreover, all the compounds are predicted to be absorbed in human intestine and also have the ability to cross blood brain barrier. Overall, the synthesized compounds have established a structural foundation for the design of new inhibitors of cholinesterase.

N-{(E)-[4-(Dimethyl­amino)­phen­yl]methyl­idene}-2,3-dimethyl­aniline

There are two independent molecules in the asymmetric unit of the title compound, C17H20N2, in which the dihedral angles between the aromatic rings are 30.34 (11) and 41.44 (8)°. In the crystal, weak C—H⋯π interactions may help to establish the packing.