Mohammad S. Iqbal

Transition Metal Acetylsalicylates and Their Anti-inflammatory Activity

Mononuclear and binuclear transition metal [Co(II), Cu(II), Ni(II) and Zn(II)] acetylsalicylates of the type [M(L) 2], [M(L) 2 Cl 2] and [(M) 2 (L) 4] have been prepared and characterized on the basis of their physical, spectral and analytical data. The complexes have been investigated in an in vivo animal model for anti-inflammatory activity and show a better effect and a more potent action than acetylsalicylic acid.

Glucoxylan-mediated green synthesis of gold and silver nanoparticles and their phyto-toxicity study

A green synthesis of gold and silver nanoparticles having exceptional high stability is reported. The synthesis involves the use of glucoxylans isolated from seeds of Mimosa pudica and excludes the use of conventional reducing and capping agents. The average particle sizes were 40 and 6 nm for gold and silver, respectively. The size of gold particles obtained in this work is suitable for drug delivery as they are non-cytotoxic. In phyto-toxicity tests the gold and silver nanoparticles did not show any significant effect on germination of radish seeds, whereas in radish seedling root growth assay the two particles behaved differently. The silver nanoparticles exhibited a concentration-dependent stimulatory effect on root length, whereas the gold nanoparticles had no significant effect in this test. The likely mechanism of these effects is discussed.

Kinetics and mechanism of thermal degradation of pentose- and hexose-based carbohydrate polymers.

This work aims at study of thermal degradation kinetics and mechanism of pentose- and hexose-based carbohydrate polymers isolated from Plantago ovata (PO), Salvia aegyptiaca (SA) and Ocimum basilicum (OB). The analysis was performed by isoconversional method. The materials exhibited mainly two-stage degradation. The weight loss at ambient-115°C characterized by low activation energy corresponds to loss of moisture. The kinetic triplets consisting of E, A and g(α) model of the materials were determined. The major degradation stage represents a loss of high boiling volatile components. This stage is exothermic in nature. Above 340°C complete degradation takes place leaving a residue of 10-15%. The master plots of g(α) function clearly differentiated the degradation mechanism of hexose-based OB and SA polymers and pentose-based PO polymer. The pentose-based carbohydrate polymer showed D(4) type and the hexose-based polymers showed A(4) type degradation mechanism.

Thermal analysis of some natural polysaccharide materials by isoconversional method

Isoconversional thermal analysis of some important polysaccharides from functional foods is reported. Various thermal parameters including apparent activation energy (Ea), pre-exponential factor (A) were worked out, and the fitness of data to different models describing the degradation kinetics of polysaccharides was studied. The polysaccharides from Mimosa pudica (MP), Plantago ovata (PO), Argyreia speciosa (AS), Acacia nilotica (AN), P. ovata husk (HK) and Acacia modesta (AM) exhibited multistep degradation while those from Astragalus gummifer (AG), Salvia aegyptiaca (SA) and Ocimum basicilicum (OB) degraded mainly in single step. Generally, the degradation was exothermal. The average Ea values as determined by Flynn-Wall-Ozawa method were found to be in the range 132-187 kJ mol(-1). The mean comprehensive index of thermal stability (ITS) fell in the range 0.33-0.43. All the materials under investigation except those from SA and AS appear to be as stable as some of the important commercial materials used as pharmaceutical ingredients. Model-fitting analysis revealed that the major degradation step follows first-order kinetics.

Development and validation of a high performance liquid chromatographic method for the simultaneous determination of potassium clavulanate and cefadroxil in synthetically prepared tablets

A simple, sensitive and rapid high performance liquid chromatographic method was developed and validated for the simultaneous determination of potassium clavulanate and cefadroxil in synthetically prepared tablets. Chromatographic separation and detection was carried out on a C-18 column using 0.05 M potassium dihydrogen phosphate buffer (pH 5.0) and acetonitrile in the ratio of 94: 06 (v/v) as mobile phase at wavelength of 225 nm. The method was linear in the concentration range of 3.75–22.5 μg/mL for potassium clavulanate and 15–90 μg/mL for cefadroxil. The flow rate was 1.0 mL/min and the total analysis time was less than 10 min. The mean recoveries was found to be greater than 99% with RSD less than 1.0%. The proposed method was validated by performing linearity, recovery, specificity, robustness, LOD/LOQ and within-day and between-day precision. The chromatographic results obtained from the synthetically prepared tablets show that the method is highly precise and accurate for the simultaneous quantitation of clavulanate potassium and cefadroxil.

Mechanochemical synthesis and in vitro anti-Helicobacter pylori and uresase inhibitory activities of novel zinc(II)-famotidine complex.

The mechanochemical synthesis and characterization of a zinc complex with famotidine is described. The complex was characterized by microanalysis and a number of spectroscopic techniques. The complex was of M:L dihydrate type. Derivatization of famotidine with zinc appears to enhance the activity of the drug by inhibiting the growth of Helicobacter pylori (two reference and 34 clinical isolates). The complex inhibited the growth of H. pylori in an MIC range of 1–8 μg mL−1. The anti-H. pylori activity of the zinc–famotidine complex against antibiotic-resistant strains was nearly comparable to that of antibiotic-susceptible strains. The complex was found to be far less toxic than the parent drug, as demonstrated by its higher LD50 value. In the human urease enzyme inhibition assay the complex exhibited significant inhibition. The new complex appears to be more useful in eradicating both the antibiotic-susceptible and antibiotic-resistant strains of H. pylori.

Synthesis, Characterization and Biological Properties of Anions of Bivalent Transition Metal [Co(II) and Ni(II)] Complexes With Acylhydrazine Derived ONO Donor Schiff Bases

Some acylhydrazine derived ONO donor Schiff bases and their Co(II) and Ni(II) complexes have been prepared having the same metal ion (cation) but different anions. These synthesized metal(II) complexes have been characterized on the basis of their elemental analyses, magnetic moment, molar conductance, and IR and electronic spectral data. All of the Schiff base ligands function as tridentates and the deprotonated enolic form is preferred for coordination. In order to evaluate the effect of anions on the bactericidal activity, these synthesized complexes, in comparison to the uncomplexed Schiff bases have been screened against bacterial species., Escherichia coli, Staphylococcus aureus and Pseudomonas aeruginosa and the results are reported.

Arabinoxylan-mediated synthesis of gold and silver nanoparticles having exceptional high stability

A green synthesis of highly stable gold and silver nanoparticles (NPs) using arabinoxylan (AX) from ispaghula (Plantago ovata) seed husk is being reported. The NPs were synthesized by stirring a mixture of AX and HAuCl(4)·H(2)O or AgNO(3), separately, below 100 °C for less than an hour, where AX worked as the reducing and the stabilizing agent. The synthesized NPs were characterized by surface plasmon resonance (SPR) spectroscopy, transmission electron microscopy (TEM), atomic force microscopy (AFM), and X-ray diffraction (XRD). The particle size was (silver: 5-20 nm and gold: 8-30 nm) found to be dependent on pH, temperature, reaction time and concentrations of AX and the metal salts used. The NPs were poly-dispersed with a narrow range. They were stable for more than two years time.

Antibacterial dimeric copper(II) complexes with chromone-derived compounds

A new series of six chromone-derived compounds and their Cu(II) complexes have been synthesized and characterized by their physical, spectral and analytical data. The ligands and their Cu(II) complexes were screened for their in vitro antibacterial activity against four Gram-negative (Escherichia coli, Pseudomonas aeruginosa, Salmonella typhi, Shigella flexneri) and two Gram-positive (Bacillus subtilis, Staphylococcus aureus) bacterial strains by agar-well diffusion method. The ligands were found to exhibit either no or low-to-moderate activities against one or more bacterial species whereas, the Cu(II) complexes exhibited moderate-to-high activity. The ligands which were inactive before complexation became active upon complexation with the Cu(II) metal ion and less active became more active.

Synthesis and Toxicity Evaluation of Some N4-Aryl Substituted 5-Trifluoromethoxyisatin-3-thiosemicarbazones.

A series of twenty one N4-aryl substituted 5-trifluoromethoxyisatin-3-thiosemicarbazones 3a-3u was synthesized by the reaction of trifluoromethoxyisatin 1 with different arylthiosemicarbazides 2 in aqueous ethanol (50%), containing a few drops of acetic acid. Their structures were established on the basis of analytical (CHN) and spectral (IR, 1H-NMR, EIMS) data. All the synthesized compounds were evaluated for their toxicity potential by a brine shrimp lethality bioassay. Ten compounds i.e., 3a, 3e, 3i-3l and 3n-3q proved to be active in this assay, displaying promising toxicity (LD50 = 1.11 × 10−5 M − 1.80 × 10−4 M). Amongst these, 3k, 3n and 3o were found to be the most active ones (LD50 = 1.11 × 10−5 M − 1.43 × 10−5 M). Compound 3k showed the highest activity with a LD50 value of 1.11 × 10−5 M and can, therefore, be used as a lead for further studies. Structure-activity relationship (SAR) studies revealed that the presence of strong inductively electron-attracting trifluoromethoxy substituent at position-5 of the isatin moiety played an important role in inducing or enhancing toxic potentiality of some of the synthesized compounds.