Muhammad Tahir Hussain

Synthesis, antioxidant activities and urease inhibition of some new 1,2,4-triazole and 1,3,4-thiadiazole derivatives

New series of 4,5-disubstituted-2,4-dihydro-3H-1,2,4-triazole-3-thiones (8a-j) and 2,5-disubstituted-1,3,4-thiadiazoles (9a-h) were synthesized by dehydrative cyclization of hydrazinecarbothioamide derivatives (7a-k) by refluxing in 4N aqueous sodium hydroxide and by overnight stirring with polyphosphoric acid, respectively. The structures of the newly synthesized compounds were characterized by IR, (1)H NMR, (13)C NMR, elemental analysis and mass spectroscopic studies and the synthesized compounds were screened for their antioxidant and urease inhibition activities. N-(2,4-Dimethylphenyl)-5-(4-nitrophenyl)-1,3,4-thiadiazol-2-amine (9h) showed excellent antioxidant activity more than the standard drug whereas 4-(2,4-dimethylphenyl)-5-(3-nitrophenyl)-2,4-dihydro-3H-1,2,4-triazole-3-thione (8d) and 4-(2,3-dimethylphenyl)-5-phenyl-2,4-dihydro-3H-1,2,4-triazole-3-thione (8e) exhibited potent urease inhibitory activities.

Synthesis and Antimicrobial Activities of Some Isocoumarin and Dihydroisocoumarin Derivatives

A new series of the isocoumarin derivatives of ibuprofen, fluribiprofen, naproxen, valproic acid and 1-naphthoic acid have been synthesized via condensation of homophthalic acid with their respective acid chlorides. The conversion of the latter two isocoumarins into ( dl )-3,4-dihydroisocoumarins has also been achieved. Most of the synthesized compounds showed antifungal and antibacterial activities.

ADSORPTION STUDIES OF MERCURY ON ZIRCONIUM OXIDE FROM AQUEOUS SOLUTION

The adsorption of mercury on zirconium oxide from aqueous solution has been studied in relation to concentration of adsorbent and adsorbate. The influence of contact time, buffer composition, pH, and foreign ions was also investigated. Thiosulfate, iodide, thiocyanate, EDTA, cyanide and Li(I) drastically reduced adsorption. Adsorption of other metal ions under the same conditions was also investigated. Based on these data, separation of mercury from antimony and neodymium can be achieved.

Production of rhamnolipid surfactant and its application in bioscouring of cotton fabric

In the present study, a biosurfactant was synthesized by using a bacterial strain of Pseudomonas aeruginosa in minimal media provided with n-heptadecane as sole carbon source under shake-flask conditions. The biosurfactant was isolated (by acid precipitation, solvent extraction, and rotary evaporation), purified (by column chromatography and TLC), identified (by FAB-MS, FTIR, and 1D-(1)H NMR), and chemo-physical characterized (by tensiometry). Two principal rhamnolipid congeners were identified as dirhamnolipid RRC10C10 and monorhamnolipid RC10C10 with a CMC of 50mg/L. The biosurfactant, hence produced, was applied in sole and in combination with pectinase in scouring of cotton fabric in contrast to conventional scouring agents of NaOH and anionic surfactant SDS. The scoured cotton fabric was investigated for its weight loss, residual oil and grease, wettability, whiteness, and tensile strength. The results were compared both for conventional and biological approaches. The scouring with biosurfactant plus pectinase was equivalent to or better in efficiency than conventional alkaline scouring. The former process is additionally environmentally friendly and bio-compatible. Scanning electron microscopy of cotton fabric showed that the alkaline scouring deteriorates the fabric texture whereas bioscouring with biosurfactant plus pectinase gently removes hydrophobic impurities from the cotton fabric.

Synthesis, urease inhibition, antioxidant and antibacterial studies of some 4-amino-5-aryl-3H-1,2,4-triazole-3-thiones and their 3,6-disubstituted 1,2,4-triazolo[3,4-b]1,3,4-thiadiazole derivatives

A new series of 4-amino-5-aryl-3H-1,2,4-triazole-3-thiones, bearing various methoxybenzyl- and methoxyphenethyl groups, was synthesized by refluxing potassium hydrazinecarbodithioate salts in dilute aqueous solution of hydrazine hydrate. These salts were formed by the reaction of acid hydrazides and carbon disulfide in methanolic potassium hydroxide solution at 0-5 °C. 4-Amino-5-aryl-3H-1,2,4-triazole-3-thiones were condensed with different substituted aromatic acids to yield 3,6-disubstituted-1,2,4-triazolo[3,4-b]1,3,4-thiadiazoles. The structures of the synthesized compounds were characterized by infrared (IR), 1H and 13C nuclear magnetic resonance (NMR), elemental analysis and mass spectrometric (MS) studies. All the synthesized compounds were screened for their urease inhibition, antioxidant and antibacterial activities. Some compounds showed excellent urease inhibition activity, more than the standard drug. Others exhibited potent antioxidant activity. All the compounds showed significant antibacterial activities as compared to the standard drug.

Synthesis, Acetylcholinesterase and Alkaline Phosphatase Inhibition of Some New 1,2,4-Triazole and 1,3,4-Thiadiazole Derivatives

A new series of 4,5-disubstituted-2,4-dihydro-3H-1,2,4-triazole-3-thiones (6a–s) and 2,5-disubstituted-1,3,4-thiadiazoles (7a–h) was synthesized by intramolecular dehydrocyclization of various 1,4-disubstituted thiosemicarbazide derivatives (5a–s) by refluxing in 4 N aqueous sodium hydroxide and by overnight stirring with polyphosphoric acid, respectively. The structures of these compounds were characterized by IR, 1H and 13C NMR, elemental analysis and mass spectroscopic studies. All the synthesized compounds were screened for their acetylcholinesterase and alkaline phosphatase inhibition studies. Most of the tested compounds showed promising activities, amongst them (6k) and (6q) showed excellent acetylcholinesterase inhibitory activity with IC50 0.241 ± 0.012 and 0.260 ± 0.013 µM, respectively, as compared with those of standard drug whereas the compound (6p), with IC50 0.044 ± 0.001 µM, was found to be the most potent inhibitor of alkaline phosphatase.

ADSORPTION OF EUROPIUM ON MANGANESE DIOXIDE FROM BINARY MIXTURES OF AQUEOUS SULFURIC ACID AND METHANOL

Abstract The adsorption of europium on manganese dioxide from a binary mixture of aqueous sulfuric acid and methanol has been studied in relation to the concentration of adsorbate. The influence of contact time, composition of binary mixture, and foreign ions was also investigated. Citrate, chromate, molybdate, EDTA, Cr(III), Fe(III), and Al(III) drastically reduce adsorption. Adsorption of other metal ions under the same conditions was also investigated. Based on the observed data, separation of europium from mercury can be achieved.

Chemistry of isocoumarins: synthesis and biological screenings of Homalicine and dihydrohomalicine

Total synthesis and selected biological activities of naturally occurring homalicine and (dl)-dihydrohmalicine are described.

2-[(2-Meth-oxy-benzyl-idene)amino]-phenol.

In the title compound, C14H13NO2, the azomethine double bond adopts an E conformation and the benzene rings form a dihedral angle of 77.70 (7)°. In the crystal, molecules are linked by O—H⋯N and C—H⋯O hydrogen bonds and arranged in a zigzag fashion, forming infinite chains parallel to the c axis, resulting in a graph-set R 2 2(9) motif.

Computing the Metric Dimension of Gear Graphs

Let G = (V, E) be a connected graph and d(u, v) denote the distance between the vertices u and v in G. A set of vertices W resolves a graph G if every vertex is uniquely determined by its vector of distances to the vertices in W. A metric dimension of G is the minimum cardinality of a resolving set of G and is denoted by dim(G). Let J2n,m be a m-level gear graph obtained by m-level wheel graph W2n,m ≅ mC2n + k1 by alternatively deleting n spokes of each copy of C2n and J3n be a generalized gear graph obtained by alternately deleting 2n spokes of the wheel graph W3n. In this paper, the metric dimension of certain gear graphs J2n,m and J3n generated by wheel has been computed. Also this study extends the previous result given by Tomescu et al. in 2007.