Synthesis and characterization of cationic surfactants and their interactions with drug and metal complexes.

Two new cationic surfactants, n-hexadecyl-3-methylpyridinium bromide and n-heptadecyl-3-methylpyridinium bromide have been synthesized and characterized in solid state by FT-IR, and in solution by 1H- and 13C-NMR spectroscopy. The values of critical micelle concentration (CMC) were determined by UV-visible spectroscopy and conductometry. Interaction of synthesized surfactants with two anionic drugs, i.e., diclofenac sodium {[2-(2, 6-Dichloroanilino) phenyl] acetic acid} and ketoprofen [(RS)-2-(3-benzoylphenyl) propionic acid] was studied by UV-visible spectroscopy. Binding constant (K), Gibb's free energy (ΔG) and number of drug molecules (n) per micelle were also calculated. These synthesized surfactants were proved to be efficient in increasing the solubility and bioavailability of drug molecules. In order to check the carrier efficiency of synthesized surfactants against bioactive coordinate, on complexes, interaction of recently reported bioactive zinc complexes was tested with synthesized cationic surfactants by conductometric measurements. Mole fractions (Xcmc) and Gibbs free energy (ΔGcmc) values were also calculated. Both surfactants were further screened for anti-fungal and anti-bacterial activities.

Tuning the band gap of TiO2 by tungsten doping for efficient UV and visible photodegradation of Congo red dye.

Tungsten-doped TiO2 (W@TiO2) nanoparticles, with different percentages of atomic tungsten dopant levels (range of 0 to 6 mol%) have been synthesized by the sol-gel method and characterized by UV-Visible spectroscopy, XRD, SEM, EDX, ICP-OES and XPS analysis. By means of UV-Vis spectroscopy, it has been observed that with 6 mol% tungsten doping the wavelength range of excitation of TiO2 has extended to the visible portion of spectrum. Therefore, we evaluated the photocatalytic activity of W@TiO2 catalysts for the degradation of Congo red dye under varying experimental parameters such as dopant concentration, catalyst dosage, dye concentrations and pH. Moreover, 6 mol% W@TiO2 catalyst was deposited on a glass substrate to form thin film using spin coating technique in order to make the photocatalyst effortlessly reusable with approximately same efficiency. The results compared with standard titania, Degussa P25 both in UV- and visible light, suggest that 6 mol% W@TiO2 can be a cost-effective choice for visible light induced photocatalytic degradation of Congo red dye.

Pharmacological investigations and Petra/Osiris/Molinspiration (POM) analyses of newly synthesized potentially bioactive organotin(IV) carboxylates.

A series of organotin(IV) carboxylate complexes: [Me2SnL2] (1), [n-Bu2SnL2] (2), [n-Oct2SnL2] (3), [Me3SnL] (4), [n-Bu3SnL] (5) and [Ph3SnL] (6), where L=3-(4-fluorophenyl)acrylic acid, have been successfully synthesized and characterized by FT-IR, NMR ((1)H, (13)C) and single crystal analysis. The ligand coordinates to tin atom via carboxylate group. Compound 4 was also analyzed by single crystal XRD analysis. Crystallographic data for trimethyltin(IV) complex showed that the tin has approximate trigonal bipyramidal geometry with the CH3 groups in the trigonal plane. The carboxylate groups bridge the adjacent tin atoms, resulting in polymeric chains. FT-IR and NMR data also support the 5-coordination geometry for the triorganotin(IV) derivatives. In the case of the diorganotin(IV) derivatives a six-coordinate geometry at the tin atom is proposed from spectroscopic data. The Me-Sn-Me bond angle in complexes 1 and 4 was determined from the (2)J[(119)Sn-(1)H] value as 138.4° and 111° that falls in the range of 5-coordinated trigonal bipyramidal and 6-coordinated octahedral geometries, respectively. The synthesized compounds were screened for their biological activities including antibacterial, antifungal and cytotoxicity. The compounds 4-6 exhibit excellent antibacterial, antifungal and cytotoxic activities. The cytotoxicity data reveals that the HL and 1-3 are almost non-toxic and exhibited LD50 values in the range 73.45-675.1µg/mL while 4-6 are found to be cytotoxic to mildly cytotoxic with LD50 values in the range 6.43-13.49µg/mL. The compound interacts with DNA via intercalation of aromatic ring into the base pairs of DNA resulting in hypochromism and minor red shift.

Synthesis, spectroscopic, X-ray crystal structure, biological and DNA interaction studies of organotin(IV) complexes of 2-(4-ethoxybenzylidene) butanoic acid.

Six organotin(IV) carboxylates of the type R2SnL2 [R=CH3 (1), n-C4H9 (2), n-C8H17 (3)] and R3SnL [R=CH3 (4), n-C4H9 (5), C6H5 (6), where L=2-(4-ethoxybenzylidene) butanoic acid, have been synthesized and characterized by elemental analysis, FT-IR and NMR ((1)H, (13)C). The complex (1) was also analyzed by single crystal X-ray analysis. The complexes were screened for antimicrobial, cytotoxic and anti-tumor activities. The results showed significant activity in each area of the activity with few exceptions. DNA interactions studies of ligand HL and representative complex 2 were investigated by UV-Visible absorption spectroscopy and viscosity measurements. The results showed that both ligand HL and complex 2 interact with SS-DNA via intercalation as well as minor groove binding.

Calcium supplements: an additional source of lead contamination.

The risk posed by the quantity of heavy metal lead present in Ca supplements is of grave concern. Some lead levels have been measured up to the extent of regulatory limit set by the United States. Calcium supplements inevitably get contaminated with lead as both are naturally occurring elements having the same charge density. Therefore, it is imperative to indicate the level of this toxic metal in these supplements in order to create awareness among consumers. The calcium in the supplements is derived from natural as well as synthetic/refined sources (chelated or non-chelated). In this study, a sophisticated analytical technique, atomic absorption spectrometer (both with FAAS and GFAAS modes of atomization), was used for the purpose of analyzing Pb contents in 27 commonly used Ca supplements manufactured by different national and multinational companies. The daily intake of lead through these supplements was calculated. Only 10% of the calcium supplements analyzed met the criteria of acceptable Pb levels (1.5 µg/daily dose) in supplements/consumer products set by the United States. It was also found that Pb intake was highest in chelated calcium supplements whereas lowest through calcium supplements with vitamin D formulation. The Pb concentration in calcium supplements was significantly increased (p < 0.001) according to their composition. In order to validate our results from the study conducted, IAEA-certified reference material (animal bone, H-5) was analyzed for Pb levels. The limit of detection of the method used was 0.05 µg/g and a 95% lead recovery of IAEA-certified reference material (animal bone, H-5).

Substituted benzenediol Schiff bases as promising new anti-glycation agents.

A feature of diabetes is that the rate of protein glycation and the formation of advanced glycation endproducts (AGEs) increases spontaneously due to the abnormally elevated levels of sugar in the blood. The glycation of proteins is associated with a large number of late diabetic complications (retinopathy, neuropathy, atherosclerosis, end stage renal diseases, rheumatoid arthritis and neurodegenerative diseases). The increase in diabetic complications is a major cause of morbidity and mortality, which has increased significantly in the last two decades. Therefore, there is a considerable recent interest in the identification of lead molecules, which can inhibit the glycation process or slow it down considerably. A new class of anti-glycation agents has been identified, based on the spectrofluorimetric analysis of fluorescent advanced glycation endproducts (AGEs), benzenediol Schiff bases, and their structure-activity relationships have been studied. Some of these compounds have shown a promising anti-glycation potential in vitro.

Diorganotin(IV) derivatives of ONO tridentate Schiff base: synthesis, crystal structure, in vitro antimicrobial, anti-leishmanial and DNA binding studies.

Six new diorganotin(IV) derivatives of N'-(2-hydroxybenzylidene)formohydrazide (H(2)L) with general formula R(2)SnL, where R = Ph (1), Me (2), Bu (3), Oct (4), t-Bu (5), Et (6), and L = [OC(6)H(4)CHNNCHO] have been synthesized and characterized by different analytical techniques. Crystal structure of Me(2)SnL (2) authenticated distorted square-pyramidal geometry around the Sn atom. The CV and UV-Vis spectroscopic data indicated intercalation of complexes into DNA with binding affinity varying in the sequence: 3 (1.69 x 10(4) M(-1)) > 1 (1.10 x 10(4) M(-1)) > 2 (9.61 x 10(3) M(-1)). Some of these compounds were found to be good antibacterial, antifungal and leishmanicidal agents.

(2,2'-Bipyridine-κN,N'){[(3-meth-oxy-2-oxidobenzyl-idene-κO)hydrazono]methano-lato-κN,O}dimethyl-tin(IV).

In the crystal structure of the title compound, [Sn(CH(3))(2)(C(9)H(8)N(2)O(3))(C(10)H(8)N(2))], the Sn atom exhibits a penta-gonal bipyramidal coordination geometry defined by two C, three N and two O atoms. The bond distances for Sn-C, Sn-N and Sn-O are in the ranges 2.097 (3)-2.098 (3), 2.298 (2)-2.623 (2) and 2.157 (2)-2.266 (2) Å, respectively. The mol-ecular structure of the monomeric compound is stabilized by three intra-molecular C-H⋯O hydrogen bonds, all involving bipyridine C-H groups.

Dieth-yl[N-(3-meth-oxy-2-oxidobenzyl-idene)-N'-(oxidomethyl-ene)hydrazine-κO,N,O']tin(IV).

In the mol-ecule of the title compound, [Sn(C(2)H(5))(2)(C(9)H(8)N(2)O(3))], the Sn atom is five-coordinated in a distorted trigonal-bipyramidal configuration by two O and one N atoms of the tridentate Schiff base ligand in the equatorial plane, and by two C atoms of ethyl groups in the axial positions. In the crystal structure, inter-molecular C-H⋯O hydrogen bonds link the mol-ecules into centrosymmetric dimers.

Non-occupational lead exposure and hypertension in Pakistani adults.

Hypertension is one of the most prevalent diseases in the developed and developing countries. Based on the long historical association and the provocative findings of blood pressure effects at low level of lead exposure a study was carried out to determine if an association existed between low blood lead concentration and hypertension. In this study the effects of low-level exposure to lead on blood pressure were examined among 244 adults using atomic absorption spectrometer. For quality assurance purpose certified reference materials i.e., Animal blood A-13, Bovine liver 1577 and cotton cellulose V-9 from IAEA (International Atomic Energy Agency) and NIST (National Institute of Standard Technology) were analyzed under identical experimental conditions. The mean age of hypertensive adults was 52 years (range 43 - 66). The mean values of systolic and diastolic blood pressure were (209+/-11.7) (range 170 - 250) and (117+/-3.9) (range 105 - 140) mmHg respectively. Blood lead concentration ranged from 78 - 201 microg/L with a mean of 139 microg/L and 165 - 497 microg/L with a mean of 255 microg/L in normal and hypertensive adults respectively. Increase in systolic blood pressure was significantly predictive with increase in blood lead levels. Body mass index (BMI) and lipid profile including total cholesterol, low density lipoprotein cholesterol, high density lipoprotein cholesterol and triglyceride correlated with blood pressure.