A novel cadmium(II) complex of bipyridine derivative: synthesis,X-ray crystal structure,DNA-binding and antibacterial activities

Abstract

A mononuclear cadmium(II) complex of formula [Cd(5,5′-dmbipy)₂(OAc)₂]·2H₂O (5,5′-dmbipy = 5,5′-dimethyl-2,2′-bipyridine and OAc?=?acetato ligand) has been synthesized and characterized by FT-IR, UV–Vis, ¹H-NMR, elemental analysis and single-crystal X-ray structure analysis. The molecular structure of the complex shows a distorted tetragonal antiprism CdN₄O₄ coordination geometry around the cadmium atom, resulting in coordination by four nitrogen atoms from two 5,5′-dmbipy ligands and four oxygen atoms from two acetate anions. The interaction of this complex to FS-DNA (fish sperm DNA) has also been studied by electronic absorption, fluorescence and gel electrophoresis techniques. Binding constant (K_b), Stern–Volmer constant (K_sv), number of binding sites (n) and bimolecular quenching rate constant (k_q) have been calculated from these spectroscopic data. These results have revealed that the metal complex can bind effectively to FS-DNA via groove binding. The calculated thermodynamic parameters (ΔH°, ΔS° and ΔG°) show that hydrogen bonding and van der Waals forces have an important function in the Cd(II) complex–DNA interaction. The antibacterial effects of the synthesized cadmium complex have also been examined in vitro against standard bacterial strains: one Gram-positive (Staphylococcus aureus, ATCC 25923) and one Gram-negative (Escherichia coli, ATCC 25922) bacteria, using disk diffusion and macro-dilution broth methods. The obtained results show that the Cd(II) complex exhibits a marked antibacterial activity which is significantly better than those observed for its free ligand and metal salt for both Gram-positive and Gram-negative bacteria. However, this metal complex is a more potent antibacterial agent against the Gram-positive than that of the Gram-negative bacteria.

Communicated by Ramaswamy H. Sarma     

Functional response of different stages of Hippodamia variegata (Col.: Coccinellidae) to Diuraphis noxia (Hemiptera: Aphididae) on two wheat cultivars

As one of the most important natural enemies of aphids, lady beetles have been widely used for the control of pest aphids. Important to the efficiency of natural enemies is their functional response to varying prey densities. In this study, the functional response of Hippodamia variegata Goeze (Col.: Coccienllidae) to different densities of Diuraphis noxia Mordvilko was examined on two wheat cultivars with different resistance levels under laboratory conditions (25 ± 1°C, 65 ± 5% RH and 16:8 L:D photoperiod). Our results revealed that all stages of H. variegata exhibited a type II functional response, in that predation decreased with increasing prey density. Searching efficiency (a) and handling time (T_h) of third instar larvae on the Sardari cultivar were 0.0285/h and 0.0079 h, while for fourth instar larvae these values were 0.0561/h and 1 × 10^?8 h, for males these values were 0.0412/h and 0.0173 h and for females were 0.059/h and 0.0168 h. The corresponding values for the back cross cultivar for third instar larvae were 0.0475/h and 0.0782 h, for fourth instar larvae were 0.0753/h and 0.0529 h, for males were 0.045/h and 0.0060 h and for females were 0.0516/h and 0.0077 h. This study demonstrated that these wheat cultivars do not have a significant effect on the functional response parameters of H. variegata life stages, except for the searching efficiency of third instar larvae and the handling time of male adults. The possible application of this species against Russian wheat aphids in an integrated pest management programme is also discussed.     

The fauna and distribution of house dust mites in residential homes of Bandar Abbas District,Southern Iran

This study was designed to determine the occurrence, distribution and abundance of house dust mites (HDM) in residential homes in Bandar Abbas (Hormozgan Province), because of numerous complaints of allergies in this oriental city. The study area was divided in five sampling zones based on population density and geographical distribution. In each sampling zone 10 houses were randomly selected. A total of 50 home dust samples were collected using a portable vacuum cleaner for 2 min from 1 m² of the surface of mattresses, carpets, sofas and furniture in residential houses. After collection, samples were immediately frozen. Mite species were identified and counted using standard methods and keys. Of the sampled houses 88% (44 houses) were contaminated with at least one HDM species. Three species were identified: Dermatophagoides pteronyssinus (63.1%), D. farinae (32.8%) and D. evansi (4.1%) (Pyroglyphidae). Our findings indicate a relationship between HDM density and moisture and temperature of residential places. The high contamination rate of residential houses (88%) and the favourable environmental conditions for these arthropods stress that they should be considered as important allergic causing agents.     

Middle Permian calcareous algae and microproblematica (Dalan Formation, Dena Mountain, High Zagros, SW Iran)

Calcareous algae and microproblematica have been studied in the Middle Permian part of the Dalan Formation in Dena Mountain, Zagros, southwest Iran. Murgabian (=Wordian) microfossils are the most diversified. The assemblages encompass, among the dasycladales, Anthracoporella spectabilis, Epimastopora piae, Epimastoporella japonica, E. likana, Paraepimastopora? cf. densipora n. comb., Gyroporella cf. nipponica, G.? aff. fluegeli n. comb., G.? aff. symmetrica, G.? aff. digitula n. comb., Mizzia yabei; among the gymnocodiaceans, Gymnocodium bellerophontis, G. nodosum, Permocalculus cf. digitatus, P. forcepinus, P. cf. fragilis, P. plumosus, P. cf. solidus, Tauridium? sp.; among the “phylloid algae” Eugonophyllum? sp.; among the other incertae sedis algae Stacheoides sp., Ungdarella uralica, Fourstonella (Efluegelia) johnsoni, and among some microproblematica alternatively assigned to foraminifers or algae Aeolisaccus dunningtoni, Tubiphytes obscurus, Pseudovermiporella nipponica, P. sodalica, and P. longipora. Each taxon is briefly characterized, whereas a more detailed analysis of the epimastoporacean algae is given. Among them, the genera Epimastopora and Epimastoporella are emended. All the described microfossils have a relatively broad stratigraphic distribution in the Permian period but they are paleoecologically important. They are indeed confident micropaleontological Middle Permian proxies, particularly for shallow-marine, warm, well-oxygenated and relatively high-energy environments. They were affected by the end-Guadalupian crisis because they strongly decrease in the upper carbonate unit of the Dalan Formation and are not found in the Triassic sediments of the area.     

Expression of cysteine proteinase type I and II of Leishmania infantum and their recognition by sera during canine and human visceral leishmaniasis

In this study, the mature domains of type I (CPB) and type II (CPA) cysteine proteinases (CPs) of Leishmania infantum were expressed and their immunogenic properties defined using sera from active and recovered cases of human visceral leishmaniasis and sera from infected dogs. Immunoblotting and ELISA analysis indicated that a freeze/thaw extract of parasite antigens showed similar and intensive recognition in both active cases of human and dog sera but lower recognition in recovered human individuals. The total IgG of actively infected human sera was higher than in recovered cases when rCPs were used as antigen. In contrast to dog sera, both active and recovered human cases have higher recognition toward rCPB than rCPA. Furthermore, the asymptomatic dogs in contrast to the symptomatic cases exhibited specific lymphocyte proliferation to both crude antigens and rCPs.     

Comparison of old and new wheat cultivars in Iran by measuring germination related traits,osmotic tolerance and ISSR diversity

A primary concern of modern plant breeding is that genetic diversity has decreased during the past century. This study set out to explore changes in genetic variation during 84 years of breeding by investigating the germination-related traits, inter-simple sequence repeat (ISSR) fingerprinting and osmotic stress tolerance of 30 Iranian wheat (Triticum aestivum L.) cultivars. Seeds were planted under control and osmotic stress (?2, ?4 and ?6 bar) in three replications. The ISSR experiment was carried out using 32 different primers. Genotypes were divided into two groups (old and new) each containing 15 members. The results of ANOVA showed that highly significant differences existed among genotypes and among growth conditions. The results showed that during breeding in some traits such as coleoptile length and seedling vigor index, a significant decrease has been occurred. New cultivars had a mean coleoptile length of 33 mm, shorter than that of old cultivars (42 mm) under osmotic stress of ?6 bar. Genetic variance of root length, shoot length and seedling vigor index for old cultivars were 1.59, 1.93 and 45,763, respectively, significantly higher than those for new cultivars (0.55, 1.08 and 27,996, respectively). This difference was also verified by ISSR results as the polymorphism information content was 0.28 in old cultivars, higher than that of new cultivars (0.26). These results prove this claim that during breeding, genetic diversity has decreased for many germination-related traits and breeders are better to pay more attention to genetic diversity.     

Inhaled Lead Exposure Affects Tracheal Responsiveness and Lung Inflammation in Guinea Pigs During Sensitization

Total and differential white blood cells (WBC), and cytokines, levels in serum were examined in guinea pigs exposed to inhaled lead acetate. Different groups of guinea pigs including: control (group C), sensitized group (group S), and exposed animals to aerosol of three lead concentrations during sensitization (n?=?6 for each group) were studied. Total and differential WBC counts of lung lavage, serum cytokine (IFNγ and IL-4), levels and tracheal responsiveness to methacholine and ovalbumin were measured. All measured values were significantly increased except for IFNγ/IL-4 ratio which was significantly decreased in nonexposed sensitized and those exposed to all lead concentrations compared to control group (p?<?0.05 to p?<?0.001). Most measured values in animals exposed to higher lead concentration were also significantly higher than group S except for tracheal responsiveness to methacholine and lymphocyte count. Lead concentration significantly increased in lung tissues of animals exposed to all three lead concentrations (p?<?0.001 for all cases). These results showed that lead exposure during sensitization can induce greater increase in tracheal responsiveness, total WBC, eosinophil, neutrophil, and basophil counts as well as serum level of IL-4. It can also cause a decrease in lymphocyte count, IFNγ level, and IFNγ/IL-4 ratio especially in its high concentration. Therefore inhaled lead exposure may cause increased severity of asthma during development of the disease.